US2444078A - Trouble alarm system - Google Patents

Trouble alarm system Download PDF

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US2444078A
US2444078A US446521A US44652142A US2444078A US 2444078 A US2444078 A US 2444078A US 446521 A US446521 A US 446521A US 44652142 A US44652142 A US 44652142A US 2444078 A US2444078 A US 2444078A
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relay
contact
armature
conductor
circuit
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US446521A
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Weaver Allan
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AT&T Corp
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Bell Telephone Laboratories Inc
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04MTELEPHONIC COMMUNICATION
    • H04M3/00Automatic or semi-automatic exchanges
    • H04M3/08Indicating faults in circuits or apparatus

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  • This invention relates to communication syscentral station upon receiving an indication off-H the existence of a trouble condition at an outlying station to perform a roll call of all of the outlying stations in the course of which each outlying station is afforded opportunity to identify any trouble conditions that may exist tliereat.
  • Another object of the invention is to cause the roll call operation to be performed automatically upon the occurrence of a trouble condition at any of the outlying stations.
  • a further object of the invention is to provide for the transmission from the central cnice of signals for selectively calling a particular one of the outlying stations which has identified a trouble condition.
  • a further object of the invention is to provide at the outlying stations means responsive to signals for remedying an existing trouble condition.
  • the invention features a vibrating relay system for generating the signals for calling the outlying stations.
  • the invention also features a sequence switch mechanism for controlling the vibratory relay signal generating mechanism to eiect the transmission of station calling signals in roll call manner.
  • two communication paths extend between the central or principal station, which may be an attended station, and the outlying or subordinate stations which may be unattended stations.
  • One of these paths is a transmission path from the standpoint of the central station and at the central station the signal transmitting mechanism is associated with this path Whereas at the outlying stations the signal receiving mechanisms are associated with this path.
  • the other communication path is a receiving path from the standpoint of the central station and the signal receiving mechanism of the central station is associated with it, whereas the signal transmitting mechanisms of the outlying stations are associ-ated with this path.
  • Both of the transmission paths are normally in marking condition and when a trouble condition occurs at any one of the outlying stations a relay 12 Claims. (Cl. 177--353) assigned to the detection of that particular trouble condition will be operated and will cause the central oice receiving communication path to go to spacing condition, which is interpreted by the central oice as an indication that a trouble condition has occurred at one of the outlying stations.
  • the central station In response to the spacing condition imposed by one of the outlying stations the central station transmits over the other path a signal which is received by all of the outlying stations to condition them to respond to their respective call signals for reporting whether or not 'a trouble condition exists at each station as called and the identity of an existing trouble condition.
  • the central station automatically transmits in succession the call signal of each of the outlying stations.
  • each of the outlying stations transmits a signal consisting of a single impulse in the event that there is no trouble condition thereat, Whereas if there is a trouble condition the station transmits a signal consisting of ⁇ a plurality of impulses, the number of impulses being determined by the identity of the trouble condition.
  • the central station there are a plurality of banks of indicators, one bank corresponding to each of the outlying stations and each bank containing at least as many indicators as there are trouble condition detectors at the outlying station plus an indicator for indicating a troublefree condition of a station.
  • each bank of indicators becomes associated with a sequence device which is responsive to the signaling impulses transmitted by the outlying stations.
  • the sequence device advances from normal position one step for each impulse received from an outlying station and at the end of the single impulse or train of impulses comprising the signal from an outlying station the trouble condition indicator selected by the sequence device is operated and remains operated.
  • the sequence device returns automatically to normal condition in preparation for reception of the next outlying station signal.
  • signal responsive selector mechanisms at the outlying stations may control devices for remedying trouble conditions such as the substitution by switching operations of spare circuits 'for circuits reported to be defective. It is also 'Within the contemplation of the invention to con- ⁇ trol by means of the selector mechanism at the station.
  • Fig. 2 is a diagrammaticicircuit View showing signal transmitting mechanism Aat'the fcentral' 01?-- -ce and also showing circuits for timing the automatic operation of that oflice;
  • Fig. 3 is a diagrammatic'circuit view showing signal generating relay systems at theicentralfofflee and also showingsequence devices for con- -1 trolling the sequence of operations thereat;
  • FIG. 4 is a diagrammatic'circuitview showing signal receiving and transmitting mechanism at i Vanvoutlying station
  • Fig. 6 is adiagrammatic view indicating another voutlying station
  • Fig. 7 is'a diagrammatic View showing how Figs.
  • the outer upper fronti contact ofthe transmitting rel-ay such as ...the relay TI in Fig. 4, is connected to ground and the inner upper. front contactl is connected .to
  • each of thel outlying stations has a break key, designated 40
  • the reference numeral I2 designates ⁇ the communication loop upon which signals are transmitted from the central oice station to the outlying stations.
  • One conductor of the communication loop I2 is connected to the'outer back and inner front contacts of a pulse transmittingrelay 2P which is normally deenergized and is controlled by pulsing dial 28I Aand other elements, and the other conductor of the loop I2 vis connected to the outer front and inner back contacts of the relay 2P.
  • the two armaturesof relay 2P are connected to the two left-hand armatures of a sending relay 2S.
  • the outer left-hand back con- ⁇ tact and inner left-hand front contact of relay 2S are connected to grounded battery and the ou-ter left-hand front contact and inner left-hand back contact are connected to ground.
  • a polarized receiving relay such as-the relay 402 in Fig. 4 and 46Min Fig. 6 has its upper winding'connected in theupper conductor of loop I2 and its lower winding connected in the lower conductor of the loop.
  • the loop is completed by connecting the upper winding -of relay 662 to the lower winding.
  • the right-hand or marking contact of each of the receiving relays such as H32 and 53%2, which is the contact engaged by the armature when the line is in the idle (marking) condition, is connected to grounded battery'and the left-hand or spacing contact of each of the receiving relays is connected to ground.
  • an open door alarm relay 5D is controlled by a switch 502 which is open when the door with which it is associated is closed and which closes when the door is opened, and the switch thereupon remains closed.
  • a plurality of switches 502 associated with diierent doors may be connected in parallel for controlling the single open door alarm relay 5D so that the relay Will become energized when any one of the doors is opened.
  • Fig. 5 also shows a re detector device which consists of a normally energized relay 5F, the energizing circuit of which includes the fusible conductive link 508. Upon the occurrence of a fire at the outlying station fusible link 508 will be melted, thus interrupting the circuit of relay 5F.
  • the grounded armature of relay 5F is engageable with a back contactl from which a conductive path extends through local alarm lamp 509, conductor 5I I, back contact and lower armature of relay 5B
  • the relay 5AIO prepares an energizing circuit for the relay 5B
  • the stepping switch 4SS is in the normal or idle condition with its contact brushes in the zero position so that the energizing circuit for relay 5B
  • relay 5AIO completes an energizing circuit for the transmitting relay 4TI from the grounded front contact and armature of rel-ay '5AIO over conductor 524, conductor 424, inner right-hand armature and back contact of a Hold relay 4H, conductors 406 and 407, middle left-hand 'armature and back contact of relay 4C, conductor 408, inner armature and back contact of relay 4A, conductor 409, winding of transmitting relay 4TI, conductor 4I I, back contact and armature of relay 4T2 to grounded battery.
  • Relay 4TI thus becomes energized to place that portion of the communication loop II whi-chextends toward the central oflice station in spacing condition.
  • the relay 5H in addition to interrupting the original energizing circuit for the relay 5AIO, also interrupts the conductive paths to all of the other relays in the series 5A, and at its outermost lower armature and front contact operates relay 551 which prepares a holding circuit from ground on its armature through the front contact and conductors 5513 and ⁇ 458 for a Starttrelay 4ST. No further operation occurs at the outlying station shown in Figs. 4 and 5 as an immediate and direct result of the release of the relay 5F,
  • relay 5D Had the troublecondition at the outlying station been that of an open door instead of a fire the relay 5D would have become operated and would have completed an energizing circuit previously described for the relay 5A5. This relay would have become energized and would have caused the energization of relay 5H fro-m the outermost upper grounded armature of relay 5A5, would have completed its own holding circuit to the conductor 506 at its innermost upper armature, would have prepared an energizing circuit for its 4associated relay 5B5 at its lower armature and front contact to the No.
  • a circuit is yalso completed -rom conductor
  • rIlhe armature and'back contact of relay-l 21' arein the venergizing circuit lof re- 'lay IIQ, but as this relay had'not ⁇ yet been ener- .gized-,fthe' operation of relay I'I has no immediate reflect.
  • Relay 7IIIVI serves to time the operation of relay-IQ,r as will be described later.
  • the ⁇ armaturefof "relay 2R is connected to groundedbattery anduponengaging -its front contact completesacircuit for the flowof current through. resistorf2-03.
  • the battery connection tothe armature of relay 2R is positive and Ac ondensers 236 and 2631 connected in series across resistor 2il3become charged to
  • the plate circuit rof tube 2B includes the relay 2U'-which is :energized'during the interval that tube 2B: is' conductive.
  • energizing circuit extends from the grounded Airont contact of relay 2U through the'anrnature
  • Step switch 3C is preferably of the type iinwhich the contact brushes are ⁇ advanced upon :the back stroke of the stepping magnet and accordingly the contact arms are stepped to .the No. ⁇ 1 contact of each bank when the tube 2B is cut off.
  • Ground is connected over the brush andNo. 1 contact ⁇ of bank 363 and over conductor rSQI to the contact No. 12 of contact bank l3BE lisoil-ncrmal L a v'ground connection ris.
  • the grounded front con- Atact completes an energizing circuit forfthe step- Vping'rnagnet 3C of a stepping switch which will lbe referred to generally by the reference number *3C and which' has six c'ontactbrushes and banks Jof contacts identified 3CI to BCS, inclusive.
  • the 8 over conductor 3 I 9, conductor 24 I Sly-and conductor H9 to the left-hand yfront contact of relay IQ, the cooperating armature of kwhich is connected toone.
  • the No. 1 contact ci the bank 366 is connected by conductor 32
  • v to contacts Nos. 15 and 16 of contact bank 3B5 of the sequence switch 3B which has notyet advanced from its ⁇ normal position so that no electrical circuit is established.
  • Stepping switch 3C in the rst step while stepping switch 3B remains unoperated is the energization of re- ,lay 2W.
  • the relay 2W At its right-hand armature and front contact the relay 2W connects grounded battery ⁇ over conductor 222, outer right-hand armature and back contact of a relay 2X, which at this time is deenergized, and Iconductor 223 to the arma- Iture of a relay ZY which at this time is deenergized and as the relayfZY has no back contact connection, no electrical circuit is completed.
  • relay 2W completes acircui-t from the grounded outer left-hand armature and back contact of relay 2X, conduc- Central ofce sends preliminary signal
  • the relay 2S reverses the battery and ground connections to transmitting loop I2, thus impressing a spacing condition on the'loop I2. ⁇
  • the inner right-'hand armature of relay 2S is operable between back and front contacts,'both Vof which are connected to ground.
  • the armature is connected to the grid side of the input circuit of an electron discharge tube 2C and the input circuit includes a resistor and battery in series between the gridy and cathode, with the battery poled positively toward the grid', a condenser between vthe grid and cathode, a second resistor and battery' in series between the grid and cathode, withthe battery poled negatively toward the grid for biasing the discharge tube to cut-off, and a varistor between the iirstmentioned resistor and the grid side of the condenser.
  • the plate circuit of the discharge tube 2C includes the relay ZY so that that relay is energized during the interval that the tube remains conductive.
  • a battery connection from the right-hand armature of the relay 2W to the armature of the relay ZY has previously been traced. With the relay ZY now energized this battery connection is extended over conductor 236, right-hand armature and back contact of relay 2V, conductors 231 and 331, and winding of stepping magnet 3B of the Stepp-ing switch, hereinbefore also referred to as 3B, to ground.
  • the relay '2Y is released and the stepping magnet 3B advances its associated brushes to their rst position on its back stroke.
  • relay 2S The outer right-hand front contact of relay 2S is connected to battery and its armature is connected by conductor 238 to one terminal oi the winding of relay 2Z the other terminal of ⁇ which is connected by conductors 239 and 339 to the outermost left-hand back contact of relay 3AA, the ⁇ armature of which is grounded.
  • the energizing circuit of relay 2Z is completed and that relay operates to interrupt the energizing circuit for relay 2S.
  • the relay 2S releases slowly and (l) restores the loop I2 to marking condition; (2) momentarily removes ground from the grid side of the input circuit to discharge tube 2C to activate the tube and thus ⁇ effect the advancement of stepping switch 3B another step; and ⁇ (3) interrupts the energizing circuit forthe relay 2Z.
  • relay 'Ihe relay 'ZZ has a ⁇ slow-to-release characteristic, and upon its release it again completes the energizing circuit for the relay 2S, again sending the loop I2 to spacing, advancing the brushes of stepping switch 3B another step and interrupting its own energizing circuit. From this it will be apparent that the relays 2S and 2Z form a vibratory system for sending out upon the communication loop I2 alternate marking and spacing impulses and for advancing the brushes of stepping switch 3B one step for each transition of the line condition from marking to spacing or spacing to marking. l
  • the odd-numbered contacts of bank 3B2 down to and including contact No. 9 are connected to even-numbered ones of the contacts of bank 3CI and since the brush associated with bank 3CI is now in engagement with the contact No. 1 no conductive path is completed to the ground on that brush as the brush of contact bank 3B2 is advanced step by step.
  • the brush associated with contact bank 3B2 is connected by conductor 333 to the right-hand armature and left-hand front contact oi relay 3AB.
  • the right-hand back contact of relay 3AB is connected through the winding of relay 3AA to grounded battery, so that the relay 3AA will become energized when the brush of bank 3B2 picks up a ground connection.
  • the odd-numbered ones of the contacts of bank 3B2 are also connected by a group of conductors through the windings of odd-numbered ones of the relays represented by IDI and IDIIJ but as those relays have grounded battery connection of the same polarity as that connected to the relay 3AA neither the relay 3AA nor any one of the 10 4relays IDI to IDIU will be energized as the brush associated with contact bank 3B2 advances over the odd-numbered contacts down to and including the No. 9 contact.
  • the even-numbered contacts of bank 3B4 are connected to odd-numbered contacts of the bank BCI, excluding contact No. 1 of bank 3CI, and to even-numbered ones of the series of relays IDI to IDI.
  • the brush associated with contact bank 3B4 is connected by conductor 334 to the right-hand front contact and left-hand back contact of relay 3AD and the left-hand armature of relay 3AD is connected through the winding of relay SAC to grounded battery which is of the same polarity as the batteries connected to the windings of the relays IDI to IDID, so that the relay 3AC cannot become energized during the advancement of stepping switch 3B while the brush associated with bank 3CI engages its No. 1 contact.
  • relay 2S which represents the signal that is being transmitted by relay 2S
  • the energization of relay 2S puts the loop I2 in spacing condition and causes the oddnumbered steps of stepping switch 3B and that the energization of the relay 22 causes the loop to return to marking condition and effects the even-numbered steps of switch 3B, this being accomplished by cutting off relay 2S.
  • incident to the eleventh step of the sequence switch relay 2S is energized and seeks to energize relay 2Z.
  • relay 3AA prevents the energization of relay 2Z and therefore the energizing circuit of relay 2S is not interrupted and the loop I2 remains in spacing condition for a longer interval than the previous spacing intervals, under the control of other factors which Will now be described.
  • the middle armature of relay 3AA cooperates with a front contact that is connected to grounded battery and the armature is connected by conductors 34
  • the innermost armature and front contact of relay 3AA completes the energizing circuit for relay 3AB which operates. At its left-hand armature and front conartefacts:
  • 11 tact relay' can ⁇ vestablishes its @Warhol-ding. circuit; from groundson contactNoirJ-ll officontactibank 3132 ⁇ ⁇ through vconductor 13362::- At its fright-.handr armature and back contact thecrelay .SAB inter: ruptsy the energizingcircuit for the .relay SAA which releases. .Relay 'SAAhas a slow-release characteristic'andupon; releasingv it removes .the holding battery connectionior the relay 2S and completes the energizingcircuit for the relay 2Z which becomes-energized to release the relay 2S.
  • The-spacing lconfdtio'nxon'loop I2 endures until relay 2S has :releasedat which time .the loopagaingoes to marking condition and discharge tube 2C is-operated'to advance stepping switch 3Bfto its twelfth position.
  • bankeSBf where afconductor extends from contact No. 12 to contact No. 1 of bank SC3..
  • Atlits ⁇ inner left-hand armature vand frontcontact therelay 2X ' provides a holding circuit' from conductor 2H, Which is-receiving ground from contact-ibankiltfat. everystep of'vthe stepping switch and is holding relay 2W.; At its outer lefthand"'arniature fandY-back contact ⁇ the ⁇ relay 2X interrupts-I the previously straced energizing circuitl forfthe relay 2S,1so'.as .to terminate the vi.- bratory operati'on'frof: relays 2Sv and 2Z, with relay 2S-remaining ⁇ .in released condition, in WhichAtl was ,placed by. ⁇ the operationof relay .2Z.
  • the relay 2X completes theenergizing cir* cuit-forLv the relayx.2V from ground .through thearmature andrrcantS contact; conductorfzd yfand, Windingfof ⁇ relay 2V iso-grounded battery.
  • the re*- lay ziffurther;V interrupts at its rightshandarrna-v ture and backfcontact the direct venergizing-1cir"- cuit-forL the ⁇ I stepping lmagnet 3B ,for Which the buzzer-energizing circuit has already been rsubsti-l tute'd".
  • relay 402 ' is connected;byjcorrductorAI6 to one; terminal ofV a'condenser i 1 ",f;tl;le .other terminal of which is connecter'tojone terminal of a polar magnet 41 Bi'the otheriterm'inal of which is con-.
  • the disclsure'ofthe" patent isgin'corporated-herein'byireference asfpartofthe present T' pulses of'cur-rent
  • the armature is provided withj Y from ytheneutra/1f' position@ to fone side'gqtiieii to:
  • Step-by-step selectors of the type disclosed in the patent to Field are provided with' contacts which are engaged by a contact arm carried by the step-by-step wheel or disc for the completion of electrical circuits. completed ⁇ through the check pawl as a circuit element, so that as th'e Contact arm comes into engagement With a contact, as it is being advanced step by step, an electrical circuit is not completed if the advance continues but only if there is a pause in the signal train which permits the check pawl to engage a stop pin and hold the disc or wheel in the position to which ithas been advanced.
  • selectors of this type When selectors of this type are employed in a system, all may have their electrical contacts in the same relative positions, such as in the eleventh, thirteenth, fifteenth and seventeenth steps as shown in Fig, 4. Taking the thirteenth step as an example,.it is not necessary to send thirteen impulses in regular succession in order to cause the Selector to reach that position.
  • the selector may be provided with one or two stop pins intermediate the rest position and the thirteenth step, whereby the thirteenth step may be reached by the transmission of sets of impulses which total thirteen, with a pause between each two sets of impulses.
  • the disc of one selector closes an electrical circuit if the system operates on a two-digit call and all of the remaining discs return to their normal positions, with the exception that the second set of impulses may correspond to the rst digit for some other selector in the system and the disc of that selector may be held in its iirst digit position, although it will close no electrical circuit in this position.
  • the transmission of a single impulse will restore all of the selectors to normal.
  • a plurality ci discs will be held at the end of the second set of impulses, the number being smaller than the numberfwhich The electrical circuits are 14 were held at the end of the 'rst set of implses. At the end of the third set of impulses only one of the discs will have been advanced to a position to close an electrical circuit.
  • the contact discs of all of the selectors in the system will be advanced to the eleventh step.
  • a similar electrical circuit will be completed which, in the case of the station shown in Figs. 4 and 5, extends from grounded battery through the selector disc and contact arm, the eleventh step contact, conductor 4 I 9, and winding of relay 4SI to ground.
  • the relay 4SI prepares a holding circuit for the relays 4S2, 4S3 and 4S4, none of which is at this time energized.
  • relay 4SI removes ground connection from a relay 4B, Which has no eiect because the relay 4B is not at this time energized.
  • relay 4SI completes the ⁇ energizing circuit for the hold relay 4H through conductor 426, conductor 42'I and the right-hand Winding of relay 4H to grounded battery.
  • the relay 4Sl also completes the energizing circuit for relay 4E over conductors 426 and 428 and winding of relay 4E to grounded battery.
  • the relay 4E establishes a holding circuit for relay 4H over conductor 429, inner left-hand armature and front contact and left-hand winding of relay 4H to grounded battery.
  • the relay 4E prepares its own holding circuit from ground through its right-hand winding, conductor 432 and conductor 4I6 to the armature of line relay 402.
  • an-d front contact relay 4E prepares a holding circuit for the relay SBI, which will be traced later, Relay 402 returns to marking following the long spacing pause after the eleventh step and completes the holding circuit for relay 4E.
  • the relay 402 also steps the discs of all of th'e selectors to the twelfth step, where none of the selectors has a holding pin and accordingly all are returned to the normal position, thus releasing the relay 4SI vand corresponding relays at all of the outlying stations and leaving the relays 4E and 4H energized and held fat all outlying stations.
  • lef'erence is ⁇ made tolj the ⁇ factl that, the ⁇ relay f AI101fhas been ,assumed tobe' energizeddu-e.-to?v theoperation of. the fire detection apparatus at the station shown in Figs. .4 fandff andlthat this.
  • conductor l 4 armature .fand back contact l of.A relay vllGr, ⁇ conductorsrllt ⁇ Iand 534, back contact ,and
  • relay AI y would inqturnenergze .relay 5l-Iso ⁇ that after relay 4H hasbeen operated, relay BIrlwillloel in the operatedcondition. Since it hasbeen assumed that relay 5H. Waspreviously energized ithe: relay 5AI Y does not-become energized.
  • Relay IDI thus becomes energized and attracts itsarrnatures, of Which there .are as many asthere may Y beg-troublel conditions at outlying stations to bev registered;y
  • the ⁇ front contactslof-the relay IDI areindiyidually connected to the Wind? ingsnofzrelays, such as relays IEI, IEIfand'IEZll', which control 'individual alarm A'lamps IB I; IB I i and IBZEiJ' -Additional"conductors v35 IB to 35v-IJ are connected 'to contacts No.
  • Th'usthe front# contacts oftherela'y IDM are connectedtoflampf controlling relays,l of ⁇ which y the relays IFIQv IFI II an'dlFZ' areshoWn. It'v Will: be understoodthat there will be as many ofthe IDseries-r'elays'asil therev are Aoutlying stations in the'system and thatrtherefwillifbef,as many relays in eachfof the series: represented by -'the I E''relays" and fthe.. IF relays in lFig. l 'as 'there are i trouble .conditions to.;be. registered...
  • relay .Itl' has released, to ⁇ grounded;battery-.fv At.- itsLlef-t-hand armature and frontficontact the re'.u layd Q. completes a holding .circuit vfrom i ground-y edlbattery through-:the: lefteliandwinding of the relaygconductors -I I9, ⁇ 2I.9;'and.3I'9--,th1'ough thev interconnected conta-.cts of ycontact .banks- 3GB, all oflwhich :are connected.y together except; the Zero Contact;Y to the; grounded brush Mthroug-h i contactH No.; 2 io.- that: bank which the brush.l at: this time:- engagesr It 1 will 'beapparent that; relay; IQ rwlllij be:;held-energized until therl brushes offstepping switch 302 have completed a.-cyclefandfh-ayebeen
  • relay IQ can become energized only when relay ILis in marking condition with its armature engaging the dead left-hand or marking contact.
  • the energizing circuit for the relay IQ is controlled not only by the arrival of the brushes of stepping switch 30 at their No.2 contacts, but also by the relay
  • the release of the relay 2Vat the end of the rst cycle of stepping switch 3B results in the completion of a circuit from grounded battery on the brush associated with the stepping switch bank 302 through the No. '2 contact of that bank, conductor 356, conductor 256, outer back contact and outer left-hand armature of relay 2V, conductor 251, left-hand armature and back contact of a relay 255, conductor 266 and primary Winding 258 of a transformer to ground.
  • a circuit is also completed in parallel with Ithe primary 258 of the transformer from conductor 251 through conductor 254, left-hand winding of relay 255 to ground.
  • Relay 255 h-as a slow-to-operate characteristic and a-ccordingly its operation is delayed.
  • the rise in flow of current through transformer primary 258 will produce an impulse in the secondary 259 of the transformer which is connected acros-s the input circuit of an electron discharge tube 2A between the grid and cathode of that tube.
  • the polarity of the impulse will be such as to charge condenser 26I positively on the grid side of the input circuit, thereby overcoming the effect of the negative biasing battery which is in series with the high value grid leak resistor connected between the grid and cathode.
  • Tube 2A will be rendered conductive and will continue to conduct until the charge on condenser 26
  • relay 255 establishes a holding circuit for itself from grounded batly through .the right-hand winding of the relay, front contact and inner right-hand armature, conductors 265, '365 and 314 to the No. 2 contact of contact bank 306 which at this time is engaged by its grounded armature. Since all of the contacts of bank 306 except the zeroand No.
  • relay 2 6 has a slightly retarded operating characteristic which will not prevent it from operating during the time that the discharge tube 2A is conductive but which will permit relay 264 to operate before the relay 2 8 operates, the stepping of sequence switch 3C will be prevented. ⁇ Since the energizing circuit of relay 264 includes the outer righthand armature and b ack contact of relay 255, that circuit will be interrupted when relay 255 becomes operated and held. Relay 264 preferably has a slow-to-release characteristic such that it does not release until relay 2 6 has released. Thus the relay 264 prevents the energization of stepping magnet 30 in response to the first operation of relay 2 6, but Will not prevent such energization in response to subsequent operations of relay 2 6 while relay 255 remains operated and held. l
  • the armature of relay 2BD is connected to positive battery and the back contact with which the armature cooperates is connected to the grid side of the input circuit of a discharge tube 2D.
  • the input 'circuit of the tube 2D is similar to that of tube 2B, the diiference being that the second condenser in the circuitis in shuntl with the leakage resistor only instead of being in shunt 4with the leakage resistance and the biasing battery. Under the normalcondition thetube 2D is biased negatively to cut-olf by. its biasing battery, although current is flowing through resistor 261 and condenser 268 is'charged.
  • Central oice sends first selective-signal of rollA f call pleted by the relay ZY as discharge tubeZC re.
  • control of relay 2S isrestored to relay 2Z and these relays operate in vibratorymanner to transmit marking and spacingimpulses of uniform duration and to ad- ⁇ Vance the brushes.
  • stepping switch 3B step by step until the brush Yassociated with bank 3132 reaches the No. l1 contact which is connected to ground.
  • relay ZBD renders tube 2D conductive through relay 2BC and the latter relay operatesr'elay 2W to start sequence switch 3B 'through' another'cycle;v another station calling signal would be transmitted onloop l2 withing of stepping switch 3B under the control of relay 2V.
  • the signal comprising the succession of impulses shown in Fig. 9 which has been transmitted during the second cycle of the stepping switch 3B is receivedv at all of the outlying stations associated with loop l2 and operates the receiving line relays, such as the relay 402, in accordance therewith.
  • the receiving line relays operate the magnets, such as M8, of the step-bystep selector, and since along pause of spacing nature follows the first impulse the contact disc of that one of the selectors which has a stop pin in the first step position will be held at the rst step during the long spacing interval and all of the others will be restored to normal position. It will be assumed for the purposes of this description that the selector in the outlying station shown in Figs.
  • a circuit is completed from grounded battery, contact disc and arm and thirteenth contact of the step-bystep selector, conductor 45
  • the relay 4S2 completes a holding circuit through conductor 452 and the lefthand front contact and armature of relay 45
  • the energizing circuit for the relay llSi was interrupted when the contact disc of the selector stepped from the eleventh to the thirteenth position but since the relay 4S! is slow to release, the holding circuit for relay 452 is in fact completed.
  • the relay 455il also completes a circuit from ground through the back contact and inner right-hand armature of relay 4S! when that relay has released, winding of relay 4B, movable front and stationary back contact of relay 4B operable in make-before-bre-ak manner, innermost right-hand armature and front contact of relay 4S2 which is very slow to release and therefore holds even after relay 4S
  • Relays 4B and 4D both become energized but as the relay 4B has a slow-to-operate characteristic relay ⁇ 4D becomes operated first.
  • the relay 4D seeks to interrupt the holding circuit for any relay in the series 5B, the circuit eX- tending from ground, right-hand armature and back contact of relay 4D, conductor 454, winding of relay 4G, conductors 456 and 556 to the upper armatures of all of the relays in the series 5B. It has previously been assumed that the energizing circuit for the relay 5B!!! had been prepared but not completed. Accordingly, there had been no circuit completed through the upper armaturesV of any of the 5B series relays and the operation of the right-hand armature of relay 4D has no effect, eitheron the relay EBI or on the relay 4G.
  • the left-hand armature of relay 4D cornpletes the energizing circuit for the Start relay 4ST which has a slow-to-operate characteristic.
  • the relay 4B attracts its armature after the relay 4D has operated, establishes a holding circuit for itself from the ground at the back contact and inner armature of relay 4st, winding of relay 4B, front contact and armature of relay 4B, conductor 451 and outermost armature and iront contact of relay 4S2 to grounded battery, and interrupts the energizing circuit for the relay 4D through the chain of armatures and contacts of relays 4S2, 433 and 4S4. Ground is thus removed from the armatures at the head of all of the chain circuits controlled by the relays 4S2, 4S3 and 4S4 so that no other chain circuit path can be inadvertently completed.
  • First outlying station transmits trouble identifying signal
  • the relay 4ST upon being energized completes its own holding circuit at its innermost iront Contact and armature through conductors 458 and 553, front contact and armature of relay 557 to ground.
  • relay 4T impresses a spacing impulse on the loop l i extending to the central oice station by means of its two upper armatures.
  • All of the contacts in the bank SSI are connected to ground with the exception of the zero contact and this is true of the bank -4SS3.
  • the numbered contacts of the bank i552 are connected to the energizing windings of the corresponding ones of the series of relays- 5B.
  • the No. contact of bank 4SS2 is connected by conductors 623 and 523 to relay EBID as previously described.
  • the No. 5 contact is connected-by conductorsliil and 555' to relay ⁇ 5B5 ⁇ and the No. 1 contact is connected by conductors itz and ⁇ 562 to relay EBI. Following the stepping of brushes -of steppingswitch SS to the No.
  • each of the relays flTI andjllTZ interrupts the energizing circuit of the other these relays form a vibratory system which causes alternate marking and spacing impulses to be impressed upon loop II.
  • Relay AI releases relay v5H and removes the ground connection for the en- 'ergizing circuit of transmitting relay @TI so that that relay cannot be reenergized and the loop II extending to the central oice station will remain .in marking condition. Although relay 5F ⁇ may remain released to connect ground through lamp li to marking condition.
  • relay .4TIinter-' ⁇ 15 509 seek-ing to reenergize relay 5Al, this relay cannot be reenergizecl as long as the relay AEBN! remains held, which is until relay 4D becomes again energized.
  • Relay 5G operates to interrupt the conductive path from ground on the outer right-hand front Contact of relay fil-I to the armature neXt to the outermost of the lower armatures of relay 5H, so that with relay 5H released; the energizing circuit for relay 5AI will not be completed.
  • the reason for preventing the energization of relay 5M at this time will be set at its inner armature and back contact introduces another interruption in the energizing cir- ⁇ cuit for the relay GTI and at its outer armature and back contact interrupts the direct energizing circuit for steppingmagnet liSS, which is also additionally interrupted at the outer lower armature and front contact of relay GTI.
  • relay 4C At the inner left-hand armature ⁇ -and front contact the relay 4C also completes the energizing circuitof 'relay 466 inparallelwith relay 4A, and the relay 466 interrupts the circuit through the operating winding of relay 13C; so that the circuit cannot be completedagain until relay 4C, which is now held through lits right-hand winding, is released.
  • the purposes of relay @Sii is to provide for the transmission of signals to identify two or more trouble conditions when they eXist at one outlying station, as will be described later.
  • the relay 4C At its outer'left-hand'armature the relay 4C transfers the battery connection supplied over the middle armature of relay 4ST tothe stepping magnet llSS'through its interrupter contacts. The magnet 4SS thereafter operates in .buzzer manner to advance ⁇ its brushes to the zero contacts, where advancement is interrupted due to movement of the brush SSI out of Vengagement with a 'grounded contact.
  • relay 5H became released and the effect of its release is to close the prepared energizing circuit for the relay 5A5, which reenergizes the relay 5H and prepares an energizing circuit for the relay EBS;
  • the relay 5A5 also applies ground through conductors 524, 324, inner right-hand armature and iront contact of relay 4H and conductor 442 to the zero contact of bank SSI in preparation for reenergization of stepping magnet GSS and in parallel to conductor 459, outer right-hand amature and front contact of relay 4ST tothe middle left- ⁇ hand armature of relay 4C in preparation for the reenergization of relay 4TI, which at this time is prevented due to the fact that the relay 4C is energized.
  • the brush associated with bank yGSSI extends the ground connection from relay 5A5 through the stepping magnet dSS and the relays 4A and 4C, upon releasing, complete the energizing circuit for the stepping magnet'and for the transmitting relay liTI.
  • the relay 466 also releases and again completes a vconductive path between the brush associated with bank 4SS2 and the operatingwindingof relay 4C;
  • the relays ATI and ATZ again operate in vibratory manner to transmit alternate spacing and marking impulses to loop I I andthe brushes of stepping switch IISS advance until the brush associated with contact bank 4SS2 reaches its No.
  • relay 5 contact and completes the energizing' circuitfor relay 5B5 through relay 4C.
  • Five spacing impulses with intervening marking impulses have beentransmitted and loop I I isthere- 26 upon restored to marking condition, relay 5B5 is' locked through its upper winding to relay 4D and the energizingcircuit of stepping magnet ASS is transferred to its interrupter contacts whereby the ,brushes are advanced in buzzer manner to their zero positions where they come to rest and release relays 4A, 4C and 466.
  • relays 5B5, 4C, 4A and 466 will be energized, relay 5B5 being held to the back Contact and right-hand 3U armature of relay 4D, and relay 4C being held to the ground on Contact bank 4SS3 and in turn holding the relays 4A and 466.
  • Stepping magnet SS isPart operation in buzzer manner to advance the brushes rapidly and relay 5A5 is released by the relay 5B5, thus completing the conductive path through its lower armature and back contact to the lower armature of relay 5AI ⁇ Il. If relay 5AIO had become energized simultaneously with the relay EAS the release of relay 5A5 results directly in preparation of the energizing circuit for relay 5BIll. If the relay 5A!
  • relay BAI would become energized and immediately reenergize relay 5H and would prepare the energizing circuit for relay EBIIl.
  • the brushes of stepping magnet @SS in advancing rapidly encounter the No. 10 contacts the energizing circuit of relay EBIU is not completed because the energizing circuit of relays 5B I l] and relay 4C is interrupted at the back contact and armature of relay 466.
  • the brushes of sequence switch ISS continue to advance in buzzer manner to their zero positions whereupon another cycle is initiated due to the fact that relay 5A!
  • relay 5B1 is i released I in order togpl'ace the-fs'tation.
  • s hdwnfin Figs; 4 and 5 in such condition:thatfgfitis ⁇ capable of responding to -thenext roll fcallyand indicating that it istrouble-'free-if that-conditionfstill exists:
  • relay- ⁇ 5A ⁇ Following" the transmission of'a trouble signal Woull'il, ⁇ upon'the return otthestepping switchfbrushes to normal, restart relaysATl fand 4T2 and" the advancement of the ⁇ - 'stepping Asvviteh brushes to'effect the transmission .ofy one spacing impulse, and the energizationand locking of the relayV 5B1, whereby a'fal'se indication. of absenceV of a trouble condition would. be tran s ⁇ mitted.

Description

June 29, 1948. A. WEAVER TROUBLE ALARM SYSTEM 6 Sheets-Sheet 1 Filed June 10. 1942 SNQBV Il IN I( 4 .gotta om .3mm Q o. .5 a7 n M! w b3 r L I L H j D M d h .n E NQ H H E BNS o9# @WS f f Re b V 1g d me@ H [WEBS K Si e@ was d f f/. 4 El u" n IP l- T wzwwvmwlo V l nl -4 .51 E WH b Uhu wl. (3 H H Em LS HW. HW 5P RQ E Il NH Env SEM, :n .UW .D- V NE Tuvo j r 4 MU mi @nf /Nl/EN TOR A WEA VER A Tom/Ev `June 29, 1948. A. WEAVER v TROUBLE ALARM SYSTEM 6 sheetssheet 2 Filed June 10, 1942 //ENTOR WEA VER A r roRA/E v www Jane 29, '1948.
Filed June 10. 1942 A. WEAVER TROUBLE ALARM SYSTEM 6 Sheets-Sheet 3 IIIIHI- l /NVENTOR A. WEA VER `lune 29, 1948. A. WEAVER 2,444,078
TROUBLE ALARM SYSTEM I Filed June 1o, `1942 v e sheets-sheet 4 POL AR/ZED A r rom/Ey l June 2 9, 1948. A. WEAVER 2,444,078-
u TROUBLE ALARM SYSTEM Filed June 1o, 1942 e sheets-sheet 5 ATTORNEY 'June 29, 1948. A. WEAVER` 2,444,078
TROUBLE 'ALARM SYSTEM Filed June 10, 1942 6 Sheets-Sheet 6 A r rom/AE v Patented June 29, 1948 'mounts ALARM srs'rEM Allan Weaver, Port Washington, NQY., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application .inne 10, 1942, Serial No. 446,521
This invention relates to communication syscentral station upon receiving an indication off-H the existence of a trouble condition at an outlying station to perform a roll call of all of the outlying stations in the course of which each outlying station is afforded opportunity to identify any trouble conditions that may exist tliereat.`
Another object of the invention is to cause the roll call operation to be performed automatically upon the occurrence of a trouble condition at any of the outlying stations.
A further object of the invention is to provide for the transmission from the central cnice of signals for selectively calling a particular one of the outlying stations which has identified a trouble condition.
A further object of the invention is to provide at the outlying stations means responsive to signals for remedying an existing trouble condition.
The invention features a vibrating relay system for generating the signals for calling the outlying stations.
The invention also features a sequence switch mechanism for controlling the vibratory relay signal generating mechanism to eiect the transmission of station calling signals in roll call manner. i
In accordance with the preferred embodiment of the invention two communication paths extend between the central or principal station, which may be an attended station, and the outlying or subordinate stations which may be unattended stations. One of these paths is a transmission path from the standpoint of the central station and at the central station the signal transmitting mechanism is associated with this path Whereas at the outlying stations the signal receiving mechanisms are associated with this path. The other communication path is a receiving path from the standpoint of the central station and the signal receiving mechanism of the central station is associated with it, whereas the signal transmitting mechanisms of the outlying stations are associ-ated with this path.
Both of the transmission paths are normally in marking condition and when a trouble condition occurs at any one of the outlying stations a relay 12 Claims. (Cl. 177--353) assigned to the detection of that particular trouble condition will be operated and will cause the central oice receiving communication path to go to spacing condition, which is interpreted by the central oice as an indication that a trouble condition has occurred at one of the outlying stations.
In response to the spacing condition imposed by one of the outlying stations the central station transmits over the other path a signal which is received by all of the outlying stations to condition them to respond to their respective call signals for reporting whether or not 'a trouble condition exists at each station as called and the identity of an existing trouble condition.
Following the conditioning of the outlying stations the central station automatically transmits in succession the call signal of each of the outlying stations. As each of the outlying stations is called it transmits a signal consisting of a single impulse in the event that there is no trouble condition thereat, Whereas if there is a trouble condition the station transmits a signal consisting of `a plurality of impulses, the number of impulses being determined by the identity of the trouble condition.
At the central station there are a plurality of banks of indicators, one bank corresponding to each of the outlying stations and each bank containing at least as many indicators as there are trouble condition detectors at the outlying station plus an indicator for indicating a troublefree condition of a station. As ea-ch of the outlying stations is called by the central station, its bank of indicators becomes associated with a sequence device which is responsive to the signaling impulses transmitted by the outlying stations. The sequence device advances from normal position one step for each impulse received from an outlying station and at the end of the single impulse or train of impulses comprising the signal from an outlying station the trouble condition indicator selected by the sequence device is operated and remains operated. The sequence device returns automatically to normal condition in preparation for reception of the next outlying station signal.
It is Within the contemplation of the invention that signal responsive selector mechanisms at the outlying stations may control devices for remedying trouble conditions such as the substitution by switching operations of spare circuits 'for circuits reported to be defective. It is also 'Within the contemplation of the invention to con- `trol by means of the selector mechanism at the station.
contact. neotions 01k battery Yand ground to the communiciated selector at the central oice station and also showing the receiving relays andassociated apparatus thereat;
Fig. 2 is a diagrammaticicircuit View showing signal transmitting mechanism Aat'the fcentral' 01?-- -ce and also showing circuits for timing the automatic operation of that oflice;
Fig. 3 is a diagrammatic'circuit view showing signal generating relay systems at theicentralfofflee and also showingsequence devices for con- -1 trolling the sequence of operations thereat;
4 is a diagrammatic'circuitview showing signal receiving and transmitting mechanism at i Vanvoutlying station;
iFig. 5 is a diagrammatic .circuit view showing trouble condition detecting apparatus at the outlying station;
' Fig. 6 is adiagrammatic view indicating another voutlying station;
Fig. 7 is'a diagrammatic View showing how Figs.
1 yto 6,`in|clusive,'may be arranged tos-how a complete system, Figs. 1, 2 and 3-showing the central -oflice'station and Figs.l 4,*5 and- 6 showing the outlying stations; land Figs. 8 .to 14, inclusive; are'diagrammatic rep-l resentations vof various station calling signals.
General description kof system Referringvnowfto they drawings thereference numeralA Il designatesafnormally Vclosed communioation loop which includes at the central offlee station the polar linerelay IL andthe alternating current Arelay i IK. The communication loop 'I I extends through the upper armatures vand -backcontacts of a--transnu'ttng relay 'll 'at a first outlying station shown in Figs; 4 and 5 then in `serial manner through two armatures-and back conltacts of transmitting-relays of 'other outlying stations and terminates at theupper armatures of the transmitting relay BTI of` a l'lnal outlying At the final outlying-station positive battery is connected to the outer upper back contact and to the inner upper front contact of re- -lay;6TI. and ground is connected totheouter upper front contact and t-o the innerl upper'back .contact of .the relay so that when the-relay is deenergized, which is'the normalcondition, positive battery isV connec-tedto the upper conductor of thecommunication loop II and ground is connectedto the lower conductor of thatv loop so.
.that current will flow. over 4the loop in a given zdirection and -this direction of flow of current is @such as to maintain the armature of receiving line relay IL -(Fig. 1) on its left-hand or marking When relayY BTI is: energized the concation loop II are reversed and the armature of line relay `IL-will-he shifted to its right-hand or spacing contact-which is connected t-o grounded battery.
At leach of the intermediate outlying stations on the communication loop II the outer upper fronti contact ofthe transmitting rel-ay. such as ...the relay TI in Fig. 4, is connected to ground and the inner upper. front contactl is connected .to
positive battery, so that when relay 4TI becomes y versed,` thus causing the relay IL-to goto its spacing condi-tion. Each of thel outlying stations has a break key, designated 40| and BBI in Figs. 4 and -6, respectively, in one side of the loop I I and when one ofthebreak keys is operated current to the central ofce station will be cut 01T. Since the relay IK at the central -oice station is an alternating current relay it remains energized as long as current' is ilowing in either direction in the communication loop and, accordingly, does not release its grounded armature in response to op- :eration of the transmitting relays at any of the outlying stations. However, when current is cut ol in the loop II due to the operation of one of the break keys the relay IK becomes deenergized and releases its armature. The function of relay IK will lce described later.
The reference numeral I2 designates `the communication loop upon which signals are transmitted from the central oice station to the outlying stations. One conductor of the communication loop I2 is connected to the'outer back and inner front contacts of a pulse transmittingrelay 2P which is normally deenergized and is controlled by pulsing dial 28I Aand other elements, and the other conductor of the loop I2 vis connected to the outer front and inner back contacts of the relay 2P. The two armaturesof relay 2P are connected to the two left-hand armatures of a sending relay 2S. The outer left-hand back con-` tact and inner left-hand front contact of relay 2S are connected to grounded battery and the ou-ter left-hand front contact and inner left-hand back contact are connected to ground. be apparent from this that the upper conductor of the kcommunication loop l2 is normally connected to positive battery through the outer armatures oi relays 2S and 2P and the lower conductor of the loop is normally connected to ground through the inner armatures of the relays. When either 'of the relays 2S and 2P is energized these connections are reversed, ground becoming connected to the upper conductor of the loop I2 and positive battery becoming connected to the lower conductorof'the loop. 'I'here is no circumstan-ce under which the relays 2P and 2S should be operated simultaneously as thiswould establish the same marking condition in the loop that exists'when neither of those relays is energized.
At' each ofthe outlying stations a polarized receiving relay, such as-the relay 402 in Fig. 4 and 46Min Fig. 6 has its upper winding'connected in theupper conductor of loop I2 and its lower winding connected in the lower conductor of the loop. At the nnal outlying station the loop is completed by connecting the upper winding -of relay 662 to the lower winding. The right-hand or marking contact of each of the receiving relays, such as H32 and 53%2, which is the contact engaged by the armature when the line is in the idle (marking) condition, is connected to grounded battery'and the left-hand or spacing contact of each of the receiving relays is connected to ground. Upon the 4operation of either of the relays 2P or 2S the ilow of current through the loop I2 will he reversed and the armatures of all of the receiving relays will go to their left-hand or spacing contacts.
It will i Since the automatic operation of the system results from the occurrence of a trouble condition at one of the outlying stations, the initiation f an alarm will rst be considered. Reierring to Fig. the outlying station is provided with a plurality of different types of trouble condition detectors. For example, an open door alarm relay 5D is controlled by a switch 502 which is open when the door with which it is associated is closed and which closes when the door is opened, and the switch thereupon remains closed. If desired, a plurality of switches 502 associated with diierent doors may be connected in parallel for controlling the single open door alarm relay 5D so that the relay Will become energized when any one of the doors is opened. The armature of relay 5D is connected to ground and the front contact is connected through local alarm lamp 503, conductor 504, back contact and lower armature of relay `5B5, conductor 506, innermost lower armature and back contact of relay 5H, conductor 501 and winding of relay 5A5 to grounded battery. Fig. 5 also shows a re detector device which consists of a normally energized relay 5F, the energizing circuit of which includes the fusible conductive link 508. Upon the occurrence of a lire at the outlying station fusible link 508 will be melted, thus interrupting the circuit of relay 5F. The grounded armature of relay 5F is engageable with a back contactl from which a conductive path extends through local alarm lamp 509, conductor 5I I, back contact and lower armature of relay 5B|0, conductor SI2, one of the armatures and back contacts of relay 5H, in the showing of Fig. 5 the outermost upper armature and back contact, although it might be any other armature and back contact of that relay, conductor 5I3, and winding of relay 5AI 0 to grounded battery.
Trouble 'occurs at outlying station Assuming for the purpose of illustrating the operation Iof the system that the conductive path just describe-d has been completed by the release of the armature of relay 5F due to the occurrence of a re, the relay 5AIO will be energized.` At its outermost' upper armature the relay 5AIO completes an energizing cir-cuit from ground through conductors 5I4, EIS and 5H, winding of relay 5H to grounded battery whereby the relay 5H will be energized. At the innermost upper armature and front contact of relay EAI!) a holding circuit therefor will be completed to conductor 5I2 and back through the original energizing circuit, including the lower armature and back contact of relay 5B|0, to the ground at the armature of relay 5F, so that the relay 5AIO will remain energized after the connection of conductor 5I3 t0 conductor 5I2 has been broken at the outermost upper armature and back contact of relay 5H upon the energization of that relay. At its lower armature the relay 5AIO prepares an energizing circuit for the relay 5B|0 from ground through the front contact and lowerrnost armature of relay 5H, conductor 5I8, back contact and lower armature of relay 5AI, `conductor 5I0, lower armature and back contact of relay 5A5, conductor 52I, lower armature and front contact of relay SAID, conductor 522, lower winding of relay 5B|0, conductor 523, conductor 423 -of Fig. 4 to the No. l0 Contact of contact bank 4552 of stepping switch 4SS. At this time the stepping switch 4SS is in the normal or idle condition with its contact brushes in the zero position so that the energizing circuit for relay 5B|0 is merely prepared but is not completed. At its middle upper front contact and armature relay 5AIO completes an energizing circuit for the transmitting relay 4TI from the grounded front contact and armature of rel-ay '5AIO over conductor 524, conductor 424, inner right-hand armature and back contact of a Hold relay 4H, conductors 406 and 407, middle left-hand 'armature and back contact of relay 4C, conductor 408, inner armature and back contact of relay 4A, conductor 409, winding of transmitting relay 4TI, conductor 4I I, back contact and armature of relay 4T2 to grounded battery. Relay 4TI thus becomes energized to place that portion of the communication loop II whi-chextends toward the central oflice station in spacing condition. The relay 5H, in addition to interrupting the original energizing circuit for the relay 5AIO, also interrupts the conductive paths to all of the other relays in the series 5A, and at its outermost lower armature and front contact operates relay 551 which prepares a holding circuit from ground on its armature through the front contact and conductors 5513 and`458 for a Starttrelay 4ST. No further operation occurs at the outlying station shown in Figs. 4 and 5 as an immediate and direct result of the release of the relay 5F,
Had the troublecondition at the outlying station been that of an open door instead of a fire the relay 5D would have become operated and would have completed an energizing circuit previously described for the relay 5A5. This relay would have become energized and would have caused the energization of relay 5H fro-m the outermost upper grounded armature of relay 5A5, would have completed its own holding circuit to the conductor 506 at its innermost upper armature, would have prepared an energizing circuit for its 4associated relay 5B5 at its lower armature and front contact to the No. 5 contact of stepping switch bank 4SS2, thus cutting off at its lower back contact the possibility of preparing an energizing circuit for the relay EBI@ or to any other relay in the 5B series numbered above 5B5, in view of the isolation of conductor 57N from the ground provided at the lower armature and front contact of relay 5H. It is to be understood that the dotted lines in the conductor EIS and in the conductor 52| indicate that lower armatures and back contacts of other relays in the 5A series are included in the conductive path extending to .the lower armature of relay 5AIO. It will also be understood that there may be more than vten relays in the 5A and 5B series for responding to the detection of additional trouble conditions and in the event that additional 5A and 5B relays are required, the lower back contact of the relay 5AI 0 would have a connection to the lower armature of the next relay in the 5A series. All of the relays in the 5A series have their middle upper armatures connect-ed to the conductor 524 so that upon the operation of any of those relays the energizing :circuit for the relay 4TI is completed.
Central office responds to trouble occurrence The imposition of a spacing condition on communication loo-p II by the relay 4T! causes the line relay IL at the central loflice station to go to its right-hand or spacing contact, the relay IK remaining energized by the reversed current in the loop II. The armature of line relay IL completes an energizing circuit for slow-operating relay 2R from. grounded battery at the spacing contact of relay IL through the armature, conductor I0 I, right-hand armature and back contact of relay IQ; conductor |02; Aconductor 202,-, and -winding .of `relay`2R, to ground. A circuit is yalso completed -rom conductor |02 through conductor -IIlG and winding of relay I iJI to ground, so that'relay' I 01 becomes energized. rIlhe armature and'back contact of relay-l 21' arein the venergizing circuit lof re- 'lay IIQ, but as this relay had'not` yet been ener- .gized-,fthe' operation of relay I'I has no immediate reflect. Relay 7IIIVI serves to time the operation of relay-IQ,r as will be described later.
' The `armaturefof "relay 2R is connected to groundedbattery anduponengaging -its front contact completesacircuit for the flowof current through. resistorf2-03. The battery connection tothe armature of relay 2R is positive and Ac ondensers 236 and 2631 connected in series across resistor 2il3become charged to |change the potential on the gridfof'y an electron discharge tube 2B from negative with respect to the cathode, as normally provided by the negative terminal of a biasing battery 2938, to'apositive potentialwith -jrespect' to the cathode,whereby the tube 2B is rendered conductive. rThe delay aiorded by the slow-operating characteristic of relay 2R provides lfor operation of tube 2l?,l only in response to along .spacing-'condition' of loop I I-so .that the` tube 2B shall notibe :operated'in response to hits on the tential on Vthe grid of tube 2B to a negative value relativeto the cathode. Thus the `combination of lresistors rand condense-rs first operate and then afterl an interval cut ofi the tube 2B and the inl'terval during which the tube isl operated is independent of relay 2R, which remainsoperated.
The plate circuit rof tube 2B includes the relay 2U'-which is :energized'during the interval that tube 2B: is' conductive.
energizing circuit extends from the grounded Airont contact of relay 2U through the'anrnature,
'conductor 2l I, conductor 2I2, conductor SI2 and winding of steppingy magnet -3C to grounded 'battery. "Stepping switch 3C is preferably of the type iinwhich the contact brushes are `advanced upon :the back stroke of the stepping magnet and accordingly the contact arms are stepped to .the No.` 1 contact of each bank when the tube 2B is cut off.
With the brushes of stepping switch' 3C advanced to the first position, no circuits are established through contact banks 3CI and SC2 because their No. 1 contacts have no connection.
Ground is connected over the brush andNo. 1 contact `of bank 363 and over conductor rSQI to the contact No. 12 of contact bank l3BE lisoil-ncrmal L a v'ground connection ris. extended The grounded front con- Atact completes an energizing circuit forfthe step- Vping'rnagnet 3C of a stepping switch which will lbe referred to generally by the reference number *3C and which' has six c'ontactbrushes and banks Jof contacts identified 3CI to BCS, inclusive.- The 8 over conductor 3 I 9, conductor 24 I Sly-and conductor H9 to the left-hand yfront contact of relay IQ, the cooperating armature of kwhich is connected toone. terminal cf'the'left-hand winding of the relay, the other terminal being connected to grounded battery. yThe left-hand winding of the relay vIQ is a holding winding but since, as pre- 'viously stated, the relay IQ is notyetY energized, a
holding circuit for that relay is merely prepared at this time by the ycontact bank -3C`5. The No. 1 contact ci the bank 366 is connected by conductor 32|v to contacts Nos. 15 and 16 of contact bank =3B5 of the sequence switch 3B which has notyet advanced from its `normal position so that no electrical circuit is established.
From the foregoing it will be apparent that the only operation performed by the Stepping switch 3C in the rst step while stepping switch 3B remains unoperated is the energization of re- ,lay 2W. At its right-hand armature and front contact the relay 2W connects grounded battery `over conductor 222, outer right-hand armature and back contact of a relay 2X, which at this time is deenergized, and Iconductor 223 to the arma- Iture of a relay ZY which at this time is deenergized and as the relayfZY has no back contact connection, no electrical circuit is completed. At its left-hand armature the relay 2W completes acircui-t from the grounded outer left-hand armature and back contact of relay 2X, conduc- Central ofce sends preliminary signal At its left-hand armatures the relay 2S reverses the battery and ground connections to transmitting loop I2, thus impressing a spacing condition on the'loop I2.` The inner right-'hand armature of relay 2S is operable between back and front contacts,'both Vof which are connected to ground. The armature is connected to the grid side of the input circuit of an electron discharge tube 2C and the input circuit includes a resistor and battery in series between the gridy and cathode, with the battery poled positively toward the grid', a condenser between vthe grid and cathode, a second resistor and battery' in series between the grid and cathode, withthe battery poled negatively toward the grid for biasing the discharge tube to cut-off, and a varistor between the iirstmentioned resistor and the grid side of the condenser. When the right-hand inner armature of relay2S is in engagement with either of its contacts the condenser is charged to negative on the gridside by the negative biasing battery and the tube -is biased to cut-off. During the interval in which the inner right-hand armature of relay ,ZS is in transit from one contact to the other ground is removed from the gri-d side of the'input'circuit and the battery which is poled positivetube 2C continuesto be conductive is prolonged due to the fact that the varistor prevents the condenser from discharging directly back to ground when the armature of relay 2S completes its transit and the return of the grid to -its original condition of negative charge on the grid side is delayed by the grid leak resistance of high value. The plate circuit of the discharge tube 2C includes the relay ZY so that that relay is energized during the interval that the tube remains conductive. i i
A battery connection from the right-hand armature of the relay 2W to the armature of the relay ZY has previously been traced. With the relay ZY now energized this battery connection is extended over conductor 236, right-hand armature and back contact of relay 2V, conductors 231 and 331, and winding of stepping magnet 3B of the Stepp-ing switch, hereinbefore also referred to as 3B, to ground. Upon the cutting off of plate current in the discharge tube 2C the relay '2Y is released and the stepping magnet 3B advances its associated brushes to their rst position on its back stroke.
The outer right-hand front contact of relay 2S is connected to battery and its armature is connected by conductor 238 to one terminal oi the winding of relay 2Z the other terminal of` which is connected by conductors 239 and 339 to the outermost left-hand back contact of relay 3AA, the` armature of which is grounded. Thus the energizing circuit of relay 2Z is completed and that relay operates to interrupt the energizing circuit for relay 2S. The relay 2S releases slowly and (l) restores the loop I2 to marking condition; (2) momentarily removes ground from the grid side of the input circuit to discharge tube 2C to activate the tube and thus` effect the advancement of stepping switch 3B another step; and `(3) interrupts the energizing circuit forthe relay 2Z. 'Ihe relay 'ZZ has a` slow-to-release characteristic, and upon its release it again completes the energizing circuit for the relay 2S, again sending the loop I2 to spacing, advancing the brushes of stepping switch 3B another step and interrupting its own energizing circuit. From this it will be apparent that the relays 2S and 2Z form a vibratory system for sending out upon the communication loop I2 alternate marking and spacing impulses and for advancing the brushes of stepping switch 3B one step for each transition of the line condition from marking to spacing or spacing to marking. l
The odd-numbered contacts of bank 3B2 down to and including contact No. 9 are connected to even-numbered ones of the contacts of bank 3CI and since the brush associated with bank 3CI is now in engagement with the contact No. 1 no conductive path is completed to the ground on that brush as the brush of contact bank 3B2 is advanced step by step. The brush associated with contact bank 3B2 is connected by conductor 333 to the right-hand armature and left-hand front contact oi relay 3AB. The right-hand back contact of relay 3AB is connected through the winding of relay 3AA to grounded battery, so that the relay 3AA will become energized when the brush of bank 3B2 picks up a ground connection. The odd-numbered ones of the contacts of bank 3B2 are also connected by a group of conductors through the windings of odd-numbered ones of the relays represented by IDI and IDIIJ but as those relays have grounded battery connection of the same polarity as that connected to the relay 3AA neither the relay 3AA nor any one of the 10 4relays IDI to IDIU will be energized as the brush associated with contact bank 3B2 advances over the odd-numbered contacts down to and including the No. 9 contact.
The even-numbered contacts of bank 3B4 are connected to odd-numbered contacts of the bank BCI, excluding contact No. 1 of bank 3CI, and to even-numbered ones of the series of relays IDI to IDI. The brush associated with contact bank 3B4 is connected by conductor 334 to the right-hand front contact and left-hand back contact of relay 3AD and the left-hand armature of relay 3AD is connected through the winding of relay SAC to grounded battery which is of the same polarity as the batteries connected to the windings of the relays IDI to IDID, so that the relay 3AC cannot become energized during the advancement of stepping switch 3B while the brush associated with bank 3CI engages its No. 1 contact.
All of the contacts of bank 3B3 except the zero contact are connected together and to ground and the brush associated with the bank 3B3 is connected to conductor 3I'I to provide a substitute ground for the energizing circuit of relay 2W which ground is not independently elective at this time since the brush associated with contact bank 3C4 has maintained relay 2W energized through the No. 1 contact of that bank as stepping switch 3B advances.
The earliest connection in the bank 3B5 is at contact No. 15 and in the bank 3BG is at contact No. 12 but when the several brushes of stepping switch 3B reach their contact No. 11 the brush associated with bank 3B2 finds ground on its contact No. 11 and completes the energizing circuit for the relay 3AA. VThe relay becomes operated and at its outermost armature it interrupts the energizing circuit for the relay 2Z. By reference to Fig. 8, which represents the signal that is being transmitted by relay 2S, it may be seen that the energization of relay 2S puts the loop I2 in spacing condition and causes the oddnumbered steps of stepping switch 3B and that the energization of the relay 22 causes the loop to return to marking condition and effects the even-numbered steps of switch 3B, this being accomplished by cutting off relay 2S. It will also be seen that incident to the eleventh step of the sequence switch relay 2S is energized and seeks to energize relay 2Z. However, relay 3AA prevents the energization of relay 2Z and therefore the energizing circuit of relay 2S is not interrupted and the loop I2 remains in spacing condition for a longer interval than the previous spacing intervals, under the control of other factors which Will now be described.
The middle armature of relay 3AA cooperates with a front contact that is connected to grounded battery and the armature is connected by conductors 34|, 342 and 242 to conductor 23| extending to the Winding of relay 2S so that relay 2S will be held energized should the relative timing of operation of relays 2S, 2Z, 3AA and stepping magnet 3B be such that relay 2Z operates and interrupts the energizing circuit for relay 2S before the energizing circuit of relay 2Z is interrupted at the left-hand armature and back contact of relay 3AA. This is desirable since the slow-release characteristics of relay 2Z might permit relay 2S to release and return the loop I2 to marking condition. The innermost armature and front contact of relay 3AA completes the energizing circuit for relay 3AB which operates. At its left-hand armature and front conartefacts:
11 tact relay' can `vestablishes its @Warhol-ding. circuit; from groundson contactNoirJ-ll officontactibank 3132` `through vconductor 13362::- At its fright-.handr armature and back contact thecrelay .SAB inter: ruptsy the energizingcircuit for the .relay SAA which releases. .Relay 'SAAhas a slow-release characteristic'andupon; releasingv it removes .the holding battery connectionior the relay 2S and completes the energizingcircuit for the relay 2Z which becomes-energized to release the relay 2S. The-spacing lconfdtio'nxon'loop I2 endures until relay 2S has :releasedat which time .the loopagaingoes to marking condition and discharge tube 2C is-operated'to advance stepping switch 3Bfto its twelfth position.
Thereis no `connection tocontact No. 12 of bank SBZ andino' change ofcondition is encoun. teredby anyfoflthe'other. brushes ofzswitch 3B'.
except'in bankeSBfwhere afconductor extends from contact No. 12 to contact No. 1 of bank SC3.. HereY groundiis applied from the -brushassociated with 'bank 3C3.over conductor Bill;v contactNo. 12 and brush of ibank Bgconductors. int-Band` E43-and the wind-ingrof relay 2X toxgrounded bat.- tery,and'relay=.f2X ispoperated.
Atlits` inner left-hand armature vand frontcontact therelay 2X 'provides a holding circuit' from conductor 2H, Which is-receiving ground from contact-ibankiltfat. everystep of'vthe stepping switch and is holding relay 2W.; At its outer lefthand"'arniature fandY-back contact `the `relay 2X interrupts-I the previously straced energizing circuitl forfthe relay 2S,1so'.as .to terminate the vi.- bratory operati'on'frof: relays 2Sv and 2Z, with relay 2S-remaining`.in released condition, in WhichAtl was ,placed by.` the operationof relay .2Z. following thefreleaseof relay SAA', andzthusfmaintaining steady marking condition of communication loopA 12.?, At its buter lrightehand. armature `the relay transfers; thefenergizing.` circuit for stepping'` magnet 3B fromY al direct"connection4 through the conductor'f33i! .tow'an indirect connection `through the -interrupterncontacts of stepping#magnet 3B,y thev circuit being: traced from batteryfthrough the right-hand'frontfcontact and .armature of Vrelay 2W; conductor. 2225.outerright-hand.v armature, andfront'contactfofarelay 2X,V conductors 244 and SMLfinfterrupter :contacts -of-stepping.- magnet 3B through"thefzwin'dingof the magnet to. ground. l The fstepping;magnet 3B thus operates in buzzermanner;` an'derapidlyf and automatically Iadvances its' brushes aroundatotithe zero yor rest position.rv Until' :ani fadditionalcontrol effected by'fthe. .relay4 2X`-is ydescribed.ritt-willi. be. assumed merely that l thefstepiline.k YSwitch `3Bfjstarts tooperate in buzzer man-ner and `thefbrnshes.lea'vecontacts No. ,12. 1
At its inner right-hand armature andy front' contact the relay 2X completes theenergizing cir* cuit-forLv the relayx.2V from ground .through thearmature andrrcantS contact; conductorfzd yfand, Windingfof `relay 2V iso-grounded battery. The re*- lay ziffurther;V interrupts at its rightshandarrna-v ture and backfcontact the direct venergizing-1cir"- cuit-forL the`I stepping lmagnet 3B ,for Which the buzzer-energizing circuit has already been rsubsti-l tute'd". At its innerleft-hand armature and backf contact the relayfZV) furtherl interrupts the energizing circuit, forthe relay 2S which .has-already' been interruptedzby .the relay 2Xv Theoperation.- offrelay 2V causes its outerleft-hand armature to belvdisengaged :from a back contact from whicha conductivepathgnot yet identied extends-to the No. -2 -contact.= of the stepping, switch .bank113C2..r. Since the-brushes ofy the stepping.: switch 3C are 1 not-yet 1- in engagement' with their: No 2 contacts;
theilrelay 2Vtdoesanot'tinterruptanelectrical cir-a cuit and romj thi'szitlwill be apparentthatthe ope; eration `of relayl 2V atx-this time. performs'nodirect operation; i.. i i
l When' the fbrush associated with'y .thezzcontactf bank .3BE v'encountersfthe contact:No.oltotzthati; bank a; .circuit is completed;throughlthel contacts. Nos; 15V i and :5.16, i which are iconnectedatogether;T fromrgroundlon l. the'` brushfiassociatedI .with bankvl wf 306 through thezNo't-il.. contactmf `thatzbank, con-.x
w Asupreviously set forth the'A outer .armature `.ofi relay 2U connects .ground ,to .theaconductive 'path'L consisting of yconductors 2 k2. and@ l 2rextendingftof stepping `magnet 362s@ thatfthe magnet lisienerfI gized preparatoryA toistepping the: brushes to the.;- No. 2. contacts;- Asthefbrushes oistepping` switch; 3B'=passfr'o1n:contact'No 16 .to contact .Nor 1'7,"v relay I2U Yis vreleasedvand.then-brushesofvstepping` switch .C'arie steppedto the Neo2-contacts. lThef brushes of the stepping switchz3Bi'in-the mean'- J time;continue'stoy be advanced .to-their zero positions'.` andino .circuitichanges I are: eiectedasn the= brushes complete ztheirrfcycle and'move intornor-Y mal or zeropositionexcept Vthat asthe :brush associated with contact ybank:3B3.g moves out offen gagementwith thellast ofxthe interconnected/icona..-
' tacts andinto'thefzerofposition,grourrdon the in'-Y terconnected contacts is removed fromconductors 3H andi I' in .thefholding irouitsfor therelays. 2W :and 2X so. that. those relays. are released .andrv 5.. the-xfrelayi2vfiwhich Was held.. energized .-'by the relayZX'is also released. Y l
. Befrev describinguthe-isequenceoffl operations whichf. occurs .f as :.aaresult of Vthe-stepping Lof the: brushes 'of stepping.- switch' Y3C to theflNo; 2J con# m tactaftne* eiect produced :at .ther-outlying; stations. by f the,` transmission ofy thefalternate :marking and r. spacingI signals, inl: accordance withithefpatternl shown vin Figu due torth'e vibratory operationfof. the lrelays: ZSEandJZZias influenced followingi the 4K5l eleventh-5transitionbyfthe relays SAA# and 53AB'- Wilt be described. l Olfiz'tlvying stations respond-l. to preliminary l signal in AFigi 4,' the' 'armature' o iijl thexpolarreceiving.
relay 402 'is connected;byjcorrductorAI6 to one; terminal ofV a'condenser i 1 ",f;tl;le .other terminal of which is connecter'tojone terminal of a polar magnet 41 Bi'the otheriterm'inal of which is con-.
nectedftofground. The pola'rIrriagnet418I is thei operating instrumentality l ofiL af stepJby-step selector fmechanism`A -suclrf -asjv .that l disclosed yin Patent; 1,`34=-325 6,L gran-ted*Nine-15311920;L to AJ, C.
Field;` The disclsure'ofthe" patent isgin'corporated-herein'byireference asfpartofthe present T' pulses of'cur-rent The armature is provided withj Y from ytheneutra/1f' position@ to fone side'gqtiieii to:
the vop'p'osite-`-side-and-Jbackft the neutral fposition; 4The contact Wheel. ora di-'scis provided witl'rselectivelyY locatdipinsawhich:willfbe engaged by a cheek pawlV` sooiatediwitli thearmature' lei/erf,
when@thaanatcrealever is` momentari'ly-l per;`
" 13 mittd to be at rest in the neutra'l position after having been operated through `a plurality of cycles or half cycles and such pawl prevents the contact ldisc or Wheel from returning to normal position under the iniiuence of its restoring spring. When a plurality oi such selectors with differently located stop pins respond to signals consisting of current reversals, a, pause in the transmission of'signals will cause those Which have stop pins, presented to their check pawls to be held in the positions to which they have been advanced, Whereas all selectors which have no stop pins in those positions Will return to normal position under the influence of the disc restoring springs. When transmission of current reversals is resumed, those discs Which were held in advanced positions are further advanced from those positions Whereas in all oi the selectors the discs of which were restored to normal, those discs are again advanced from the normal position.
Step-by-step selectors of the type disclosed in the patent to Field are provided with' contacts which are engaged by a contact arm carried by the step-by-step wheel or disc for the completion of electrical circuits. completed `through the check pawl as a circuit element, so that as th'e Contact arm comes into engagement With a contact, as it is being advanced step by step, an electrical circuit is not completed if the advance continues but only if there is a pause in the signal train which permits the check pawl to engage a stop pin and hold the disc or wheel in the position to which ithas been advanced. When selectors of this type are employed in a system, all may have their electrical contacts in the same relative positions, such as in the eleventh, thirteenth, fifteenth and seventeenth steps as shown in Fig, 4. Taking the thirteenth step as an example,.it is not necessary to send thirteen impulses in regular succession in order to cause the Selector to reach that position. The selector may be provided with one or two stop pins intermediate the rest position and the thirteenth step, whereby the thirteenth step may be reached by the transmission of sets of impulses which total thirteen, with a pause between each two sets of impulses. During the pause at the end of the iirst set of impulses those selectors which have stop pins in the positions to which' the discs of all of the selectors have been advanced, will be held and the discs of the remaining selectors will be restored to normal, In a two-digit system only one disc would be so held and all of the others would be returned. In a three-digit system a plurality of discs would be held and the remainder would be restored to normal. Upon the resumption of transmission of impulses, all of th'e selector discs would again be advanced, some from their initial positions and one or more from its advanced position. At the end of the second group of impulses the disc of one selector closes an electrical circuit if the system operates on a two-digit call and all of the remaining discs return to their normal positions, with the exception that the second set of impulses may correspond to the rst digit for some other selector in the system and the disc of that selector may be held in its iirst digit position, although it will close no electrical circuit in this position. Following the closure of the electrical circuit the transmission of a single impulse will restore all of the selectors to normal. If the system is operable upon a three-digit call a plurality ci discs will be held at the end of the second set of impulses, the number being smaller than the numberfwhich The electrical circuits are 14 were held at the end of the 'rst set of implses. At the end of the third set of impulses only one of the discs will have been advanced to a position to close an electrical circuit.
In the arrangement shown in Fig. 4 only a single battery on the marking contact of line relay 402 is employed for energizing selector magnet 4I8 but the condenser 4II serves to give a polar effect to impulses. In the idle condition th'e condenser is charged positively on the side toward the battery and negatively on the side toward the magnet 4I8, and no current is flowing through the magnet. When the relay 402 goes to spacing the condenser discharges through the magnet 4 I 8 and rocks the armature to one side of the magnet. If the relay 402 returns to marking before the discharging current has died out condenser 4II will be recharged and the charging current will rock the armature to the other side of magnet 4I8 without any pause of the armature in the neutral position. A pause in the signaling train of either marking or spacing nature will permit the armature of magnet 4I8 to go to its neutral position because the charging or Idischarging current for condenser 4I'I dies out before the end of the pause. l
Since as shown in Fig. 8 the signal transmitted by the relays 2S and 2Z consists of eleven transitions followed by a `pause of spacing nature, the contact discs of all of the selectors in the system will be advanced to the eleventh step. At each of the outlying stations a similar electrical circuit will be completed which, in the case of the station shown in Figs. 4 and 5, extends from grounded battery through the selector disc and contact arm, the eleventh step contact, conductor 4 I 9, and winding of relay 4SI to ground. At its left-hand armature and front contact the relay 4SI prepares a holding circuit for the relays 4S2, 4S3 and 4S4, none of which is at this time energized. At its inner right-hand armature and grounded back contact the relay 4SI removes ground connection from a relay 4B, Which has no eiect because the relay 4B is not at this time energized. At its outer right-h'and armature and grounded front contact relay 4SI completes the `energizing circuit for the hold relay 4H through conductor 426, conductor 42'I and the right-hand Winding of relay 4H to grounded battery. The relay 4Sl also completes the energizing circuit for relay 4E over conductors 426 and 428 and winding of relay 4E to grounded battery.
At its left-hand armature and front lcontact the relay 4E establishes a holding circuit for relay 4H over conductor 429, inner left-hand armature and front contact and left-hand winding of relay 4H to grounded battery. At its inner right-hand armature and front contact the relay 4E prepares its own holding circuit from ground through its right-hand winding, conductor 432 and conductor 4I6 to the armature of line relay 402. At its outer right-hand armature an-d front contact relay 4E prepares a holding circuit for the relay SBI, which will be traced later, Relay 402 returns to marking following the long spacing pause after the eleventh step and completes the holding circuit for relay 4E. The relay 402 also steps the discs of all of th'e selectors to the twelfth step, where none of the selectors has a holding pin and accordingly all are returned to the normal position, thus releasing the relay 4SI vand corresponding relays at all of the outlying stations and leaving the relays 4E and 4H energized and held fat all outlying stations.
lef'erence; is `made tolj the {factl that, the `relay f AI101fhas been ,assumed tobe' energizeddu-e.-to?v theoperation of. the fire detection apparatus at the station shown in Figs. .4 fandff andlthat this.
hastcausedltherelay `llTI to bei operated to..-plac'e ther communicationloop'l I .leading to vthe cenA trai 4oice station in spacing, condition.. Thevfol,n lowing sequence of yoperations is. 4predicatedfupon this;l assumption `but the operational: differences whichrwould result froma trouble-free condition.
of, the station shown -in Figs. 4 and 5 Willalso be mentioned;
.At its outer ighthand. 'armature ,and ffront, contactpthe relay` 4H. connectsground through f,
conductor l 4:armature .fand back contact l of.A relay vllGr,` conductorsrllt` Iand 534, back contact ,and
lower armature of relayBI ,tothe second lowest arrnaturevof,` relay1 Ill-L. ,From thefback,contact withwhich thisarmature ofurelay "5H'cooperates, conductor .531 extends tdoneterminalfof thel relay; 5AI vvthe other; terminal @of vwhich is -connested-to.groundedgbattery. Thus-ii relay 5H were not-energized,l the relayf5AI would become energizedrto indicatethat no trouble condition existed atthe station and-,the relay 5AI Wouldbe front Contact to conductor 53E vand .to the outer rightehandarmatule yand ifront contactfof rel-ay.
4H1 .through conductor 538.'- The relay AI ywould inqturnenergze .relay 5l-Iso` that after relay 4H hasbeen operated, relay BIrlwillloel in the operatedcondition. Since it hasbeen assumed that relay 5H. Waspreviously energized ithe: relay 5AI Y does not-become energized.
At its outer left-handarmature and frontcon-k tact the relay lllllconnectsground over conductorl 44 It Winding .oigrelay lIT2, .onductor'tllzg inner?- most lowerarmaturegand frontco-ntact `of relayl IITI to grounded battery.- Thesingle*armatureof the relayl-llzremoves battery from the cony ductorAII .in the energizingQrcuitforthe relay TI fsothatthat relay is deenergized. The relay KITE.: is. sloWTto-release andy -accor(.lingly an. interval elapsesfrbeforegit releases to restore the ComunicationA loop II toward 'thefcentral. olce station to marking condition. Atits inner-,righthand armaturetherelay IH transferstheA ground connection suppliedover conductoiui beginning i atltlre upper middle` armature and Afront contact` tact =andouter armature of `relay IIA; conductor` llbacl; contact anniI outer lethandarmature of relay IIC and conductor Illltogthe middle armaturefof start` relay AST. y The back )contact- With Whichthe armature of relaySI'` cof operates is connectedto groundedbattery but as the relayis not energizedat this'timeandrrelaym ATI is. in process-z of being. .released an, electrical'. circuity :through the stepping `magnet #ISS is. not:
yet completed.'
Whenl relayA STI releases;fitnopensgthe;enerf gizingcircuit forrelay III'Z which isjalso aslowrelease relayy and which upon release-restores the. battery connection to conductor llgtamextendingf to Athe winding `offrelay IITI.; However,v theflatter relay WiIln'Otat this time be re.energizedbecause` ground connectionf. has,` Irwell:-y 1'em0ved;;tthe inner right-hand armaturebfzrelay AH:
325 held from its innermost upper armai'rureandy 161" prepares to :conducir: roll-f f'ctlfr of."
outlying stations.:
The operations ywhich take place' at the outfA lying stations/in response to reception Yofthejsig-'j nalY represented'in Fig. 8 occurduringljthe'- long spacing interval following the eleventh'transition; Following `this there is a steady marking interval"v on loop I2the duration of Which isjdetermned, by the time involved in the restoration of 'stepg ping switch 3B to normal and by thereleasetime of lthe relay L2V Whichyi's slowjto release, The restoration 'of the marking condition on .the com;` munication loopII due tothe 'release' of'relayj IITI causes the relay ILto be driven to themark# ing condition whereby .the'relay 2Rfisv released. Thisdoes not cause tube 2B toj operate;since` positive battery' .is disconnected* from'. condenser 206." The relay IL also releaseth'e relayA |01', lthe' purpose of which Willbe described later. r
`With y.the brushes vof stepping svvitch'3C"adA vanced to the No. 2'contacts as previously :lescribed, a circuit is completed from ground on" the brush vassciatetiv with `bank aol through the, No.2 Contact of the bank, conductor 35I'A,"con ductor 352A, conductorlIBZA in Fig.1andWind-" ing of relay IDIfto grounded battery. Relay IDI" thus becomes energized and attracts itsarrnatures, of Which there .are as many asthere may Y beg-troublel conditions at outlying stations to bev registered;y The armatures oflth'e relay'IDIare connected to individual contacts of lbank IAI of avstepping 'switch IAL The `front contactslof-the relay IDI areindiyidually connected to the Wind? ingsnofzrelays, such as relays IEI, IEIfand'IEZll', which control 'individual alarm A'lamps IB I; IB I i and IBZEiJ' -Additional"conductors v35 IB to 35v-IJ are connected 'to contacts No. 3 to Noi 11,'"inclusive, ofbank-@CI and extend through coz'iductors"352BI to 3525' andv conductors I 52B to |525 to additionallrelays ofthe ID series, of which only thefrelaLy-f I Dl'fis shown. lAll of the ID relays have'ftl'i'eir"v` armaturesv connected to" theconductorsextending to the contacts oisteppin'g switch-l bank; IAI and their front v,contacts connected to individual re# lays-fior controlling 'alarm' lamps. Th'usthe front# contacts oftherela'y IDM) are connectedtoflampf controlling relays,l of `which y the relays IFIQv IFI II an'dlFZ' areshoWn. It'v Will: be understoodthat there will be as many ofthe IDseries-r'elays'asil therev are Aoutlying stations in the'system and thatrtherefwillifbef,as many relays in eachfof the series: represented by -'the I E''relays" and fthe.. IF relays in lFig. l 'as 'there are i trouble .conditions to.;be. registered...
:'Uponzthearelease'of 'relay I'I "a ciro'uitisv com-.1f pleted .from the.. grounded-.brush associated with': Contact .bank 364 through the No.;..2 "'c'ontaot of? that bank, `conductors. 3If4,12!4 :and IIA`4,right.-f hand :Winding oi. relay` IQ, Yconductorel I:3`,:;armaf ture and baci; Contact .of relay. |01; assumingthat';
relay .Itl' has released, to` grounded;battery-.fv At.- itsLlef-t-hand armature and frontficontact the re'.u layd Q. completes a holding .circuit vfrom i ground-y edlbattery through-:the: lefteliandwinding of the relaygconductors -I I9,` 2I.9;'and.3I'9--,th1'ough thev interconnected conta-.cts of ycontact .banks- 3GB, all oflwhich :are connected.y together except; the Zero Contact;Y to the; grounded brush Mthroug-h i contactH No.; 2 io.- that: bank which the brush.l at: this time:- engagesr It 1 will 'beapparent that; relay; IQ rwlllij be:;held-energized until therl brushes offstepping switch 302 have completed a.-cyclefandfh-ayebeen' restored fto their zero positions: At :its rightfhanda armaturetheV relayY lQrtransfers- -ther;-conneotionr ofrxthearmature 4ofi: reoeivinggline rela-WI Lffrom the energizing circuit of the relays |61 and 2R to the stepping magnet of stepping switch IA through the right-hand front contact of relay IQ, lconductor II6 and conductor II1, `winding of stepping magnet IA to ground. A conductive path extends in parallel with the one just `described, from conductor II6, throughv conductor II-8 and winding of slow-release relay IM to ground.
Neither .the stepping magnet IA nor the relay IM will become energized at the instant that relay IQ is operated, because relay IQ can become energized only when relay ILis in marking condition with its armature engaging the dead left-hand or marking contact. The reason for this is that the energizing circuit for the relay IQ is controlled not only by the arrival of the brushes of stepping switch 30 at their No.2 contacts, but also by the relay |01, and the relay I61 is controlled by the relay IL prior to the energization of relay IQ so that the relay I 01 cannot prepare nor complete .the energizing circuit for the relay IQ until the relay IL has been restored to marking condition. The purpose of this timing control of the energization of relay IQ by the receiving relay IL is to prevent the energization of relay IQ before the loop II has been restored to marking condition due to release of the relay 4TI at the outlying station wherea trouble condition exists, under the control .of the Hold relay 4H at that station. If this timing control were not provided and the stepping switch should be stepped to the No. 2 contacts before the relay IL had gone to marking condition an energizing circuit for =the stepping magnet IA and the relay IM would be compieted by the relay IQ and the energization of these instrumentalities is not desired at this time. Since the right-hand armature of relay IQ effects a transfer of the connection from the armature of relay IL, the energizing circuit for the relays |61 and 2R are opened at that point so that those relays will not respond to nor follow any signals thereafter received from outlying stations during the time that relay IQ is held energized from contact bank 305. v
The release of the relay 2Vat the end of the rst cycle of stepping switch 3B results in the completion of a circuit from grounded battery on the brush associated with the stepping switch bank 302 through the No. '2 contact of that bank, conductor 356, conductor 256, outer back contact and outer left-hand armature of relay 2V, conductor 251, left-hand armature and back contact of a relay 255, conductor 266 and primary Winding 258 of a transformer to ground. A circuit is also completed in parallel with Ithe primary 258 of the transformer from conductor 251 through conductor 254, left-hand winding of relay 255 to ground. Relay 255 h-as a slow-to-operate characteristic and a-ccordingly its operation is delayed. The rise in flow of current through transformer primary 258 will produce an impulse in the secondary 259 of the transformer which is connected acros-s the input circuit of an electron discharge tube 2A between the grid and cathode of that tube. The polarity of the impulse will be such as to charge condenser 26I positively on the grid side of the input circuit, thereby overcoming the effect of the negative biasing battery which is in series with the high value grid leak resistor connected between the grid and cathode. Tube 2A will be rendered conductive and will continue to conduct until the charge on condenser 26| which was produced by the impulse in the transformer leaks off through the grid leak resistor and nega- 259 a pulse in the opposite direction which charges condenser 26| in the reverse direction. Thus the tube 2A is cutoff if current had not already ceased to flow inits plate circuit.` It will be apparent from this that relay 255should be sufficiently slow to operate, Ithat it will not open the circuit of transformer primary 258 until tube 2A has operated relay 2 6 `.which in turn has operated relay ZBD. The relay 255 establishes a holding circuit for itself from grounded batly through .the right-hand winding of the relay, front contact and inner right-hand armature, conductors 265, '365 and 314 to the No. 2 contact of contact bank 306 which at this time is engaged by its grounded armature. Since all of the contacts of bank 306 except the zeroand No. l contacts are connected together, the relay 255 will remain energized until the stepping switch 30 has completed its cycle and its brushes have returned to their zero positions. The reason for interrupting the circuit of transformer primary 258 following the activation of tube 2A will be set forth hereinafter. y
At the same time that the pulse is generated in secondary 259 of the transformer for activating discharge tube 2A a circuit is completed from conductor 251 through conductor 263, winding of relay 264, conductor 21,0, outer right-hand armature and back contact of relay 255 to ground. At its armature and back contact the relay 264 prevents the completion of a circuit which the relay 2 8 seeks to complete from ground through its outer front contact and armature, armature and back contact of relay 264, conductors 266, 2 I 2 and 3 I 2 and winding of stepping magnet 30 to grounded battery. Were it not for the provision of the relay 264 the brushes of sequence switch `30 would be stepped to their third contact at this time, which is not desired. If the relay 2 6 has a slightly retarded operating characteristic which will not prevent it from operating during the time that the discharge tube 2A is conductive but which will permit relay 264 to operate before the relay 2 8 operates, the stepping of sequence switch 3C will be prevented.` Since the energizing circuit of relay 264 includes the outer righthand armature and b ack contact of relay 255, that circuit will be interrupted when relay 255 becomes operated and held. Relay 264 preferably has a slow-to-release characteristic such that it does not release until relay 2 6 has released. Thus the relay 264 prevents the energization of stepping magnet 30 in response to the first operation of relay 2 6, but Will not prevent such energization in response to subsequent operations of relay 2 6 while relay 255 remains operated and held. l
The armature of relay 2BD is connected to positive battery and the back contact with which the armature cooperates is connected to the grid side of the input circuit of a discharge tube 2D. The input 'circuit of the tube 2D is similar to that of tube 2B, the diiference being that the second condenser in the circuitis in shuntl with the leakage resistor only instead of being in shunt 4with the leakage resistance and the biasing battery. Under the normalcondition thetube 2D is biased negatively to cut-olf by. its biasing battery, although current is flowing through resistor 261 and condenser 268 is'charged. Upon the energizationof relay ZBD .the positive battery is disconnected from the grid circuit and condenser 258 discharges but tube 2Dv is not rendered con.- ductive. Upon the release of relay 2 9 the energizing circuit of relay 2BD is interrupted and after an interval the relayv 2BD releases. Condenser 268 becomes recharged. and raises the potential of the grid of tube 2D so that the tube is rendered conductive. The interval during which tube 2D is conductive is.y controlled by leakage resistor269 and the second condenser 21|.
Central oice sends first selective-signal of rollA f call pleted by the relay ZY as discharge tubeZC re.
sponds to the operationl of relay 2S- As in the rst cycle of operation` of stepping switch y3B- ground is applied from-contact bank 3B3 when the brushes step to the No. lcontact to hold relay 2W. operated and this groundremains connected throughout the Acycle of switch 3B. At the bank 3B2 ground is applied from the brush associated with bankiG'l through theNo. 2 contact of that bank, No. 1 Contact and brush of bank SBZ, con-- ductor 333, right-hand armature and back. contact of relay. 3AB and winding of relay BAA to groundedbattery.. As in the` case of the long. spacing interval after the eleventh transition as shown in Fig. 8 the relays BAA and "BAB control therelays 2S and 2Z to prolong the spacing interval following the rst transition,as shown in Fig..9. Following the operation ofy relay SAB and thefrelease of relay AAthe control of relay 2S isrestored to relay 2Z and these relays operate in vibratorymanner to transmit marking and spacingimpulses of uniform duration and to ad-` Vance the brushes. of stepping switch 3B step by step until the brush Yassociated with bank 3132 reaches the No. l1 contact which is connected to ground. This causes another cycle of the relays SAA and y3AB to control the relays 21S and ZZ to introduce a long spacing interval following the eleventh transition,y as in the first cycle of stepping switch 3B, and this long interval is shown in Fig. 9. y
Upon the release of relay SAA rby the relay BABy relay. ZZ releases relay 2S to `produce a 'twelfth' transition to marking and the brushes of stepping switch 3B'are stepped to the twelfth position. The marking interval thus produced isv only of normal length because the relay 2S interrupts the circuit ofrelay 2Z which releases to complete the circuit for 2Swhich again becomes' energized to drive theploop vI2 to spacing condition and to step the brushes.V of stepping switch 3B to the No. 13 contact. In the twelfth position of the brushes of steppingI switch 3B' the brush associatedivith bank- SBS did not receive Vground connection from the brush and bank'3'C3; as it did in 'the' precedingcycle because'the brushes of switchjCfare now on the No.` 2 contacts and the contacts Nos'. 2`to'l1, inclusive, are connected to conta-ct l\T'o.' A 14 of bank Bby' conductor 316:
' In the thirteenth positionthe brush associated with contact bank SB again receives ground connection thistirne fromthebrush and No. 2'fcontact of stepping switch bankSC" and conductor 31.4 so that; another cycle off the relays 3AA and `SAB- is iintroducedyto control the relays 2S and Zwiththe resultthat a long spacinginterval is introduced after the'thirteenth transitionl After the, relays BAA Vand SAB 'have' operated relay 2S is released to restorethe loop |2"to marking condition andthe brushescf sequence switch 3B are steppedto the No; ll'contacts.
'At 'contact No; llfln the bank SBS ground is applied'vfrom-"bank 3C3^over conductors 316; 343 and-Mato energize relay ZXwhich in turn energizesrelay 2V. These relays perform the same functions as previously described, namely; interruptionfoftheenergizing circuit for the relay 2Sjand transfer of the energizing circuit for the stepping magnet 3B tof includethe interrupter contacts. As thel brushassociated with'stepping switchbank 3BE traverses contacts Nos. 15 and lgthe energizingcircuit for the relay 2U is not completedgas it wasY in the previously described cycle because groundgconnectionis no longer applied lto rconductor 32! onthe cont-act No. 1v of bankA BGE. Thus the brushes of stepping switch Cyremainbn-their No.2 contacts while the brushes of stepping switch 3B are rapidlyadvancedto' their zero'position.' When-the brushes reach the'zero positionytherbrush associated with bank it` t removes the holding' ground connection from'relays, ZW and 2X which release, the latterin turn releasing the relay 2V. Upon'the releaseof relay '2V the samecircuit changes occur whichtookplaceupon its release at the end :of
. the preceding cyzcle ofst'epping switch'SB, namely;.preparation"of an energizing circuit for the relay-2S,`at" the inner' left-handA armature and back contact 'of relay' 2V, which circuit however is now openatthe-left-hand armature and front contact =of-relay 2W, and" preparation of an energizing circuit for the stepping magnet 3B at the right-hand,l armature and back contact of relay'EV, which circuit isopen at the armature andfront-'contactbf relay ZY and at the righthandrarmiature andv front contact lof relay 2W.
Atpits outer-left-hand armature and back contact `the relay 2V 'reconnects grounded battery, still'suppliedat thebrush and No; 2 contact of ycontactbanksI SC2*7 to'conductor 251. Since relay 25FahasV previously disconnected the primary 258 of the transformerfrom conductor2 5'1 the transformer'does not'become energized; Were it not for the provision of relay 255to interrupt the pathto transformer primary 258, the transformergupon thel'release of relay 2V, would befreoperated to render tube'ZA-conductive which in turn would 'operate relay Z- which-in turn would operate relay EBD. Since relay ZBD renders tube 2D conductive through relay 2BC and the latter relay operatesr'elay 2W to start sequence switch 3B 'through' another'cycle;v another station calling signal would be transmitted onloop l2 withing of stepping switch 3B under the control of relay 2V.
All outlying stations react to first signal of roll call The signal comprising the succession of impulses shown in Fig. 9 which has been transmitted during the second cycle of the stepping switch 3B is receivedv at all of the outlying stations associated with loop l2 and operates the receiving line relays, such as the relay 402, in accordance therewith. The receiving line relays operate the magnets, such as M8, of the step-bystep selector, and since along pause of spacing nature follows the first impulse the contact disc of that one of the selectors which has a stop pin in the first step position will be held at the rst step during the long spacing interval and all of the others will be restored to normal position. It will be assumed for the purposes of this description that the selector in the outlying station shown in Figs. 4 and 5 is the one which holds on the rst step and all others are restored to normal. Following the long spacing interval the transitions numbered 2 to Il, inclusive, are received and step the selectors ten steps, the selectors at the station shown in Figs. 4 and 5 reaching the eleventh position and the selectors at all other stations reaching the tenth position. The contact discs at all of the stations except the one shown in Figs. 4 and 5 and except the one at the station which has a pin on the tenth step will be restored to normal in the interval following the eleventh transition. The station with the pin in the tenth position will be restored to normal following the thirteenth transition. Since, as previously stated, all of the selectors have a stop pin in the eleventh position the selector shown in Fig. 4 will be held -at the eleventh position and the relay 4S! will be operated. All of the con trols which relay 45| is capable of effecting were effected when the relay 4SI was operated in response to the signal shown in Fig, 8 and, accordingly, no further operations are performed except the preparation of a holding circuit for relays 4S2, 453 and 4S4, Following the long interval the twelfth and thirteenth pulses are received followed by another pause of spacing nature. The selector shown in Fig. 4 is advanced to the thirteenth position and is held by a stop pin.
First outlying station is selected At the station shown in Figs. 4 and 5 a circuit is completed from grounded battery, contact disc and arm and thirteenth contact of the step-bystep selector, conductor 45|, and winding of relay 4S2 to ground. At its left-hand armature and front contact the relay 4S2 completes a holding circuit through conductor 452 and the lefthand front contact and armature of relay 45| to grounded battery. The energizing circuit for the relay llSi was interrupted when the contact disc of the selector stepped from the eleventh to the thirteenth position but since the relay 4S! is slow to release, the holding circuit for relay 452 is in fact completed. The relay 455il also completes a circuit from ground through the back contact and inner right-hand armature of relay 4S! when that relay has released, winding of relay 4B, movable front and stationary back contact of relay 4B operable in make-before-bre-ak manner, innermost right-hand armature and front contact of relay 4S2 which is very slow to release and therefore holds even after relay 4S| has released, inner right-hand armatures and back contacts of relays 4S3 and 4S4, conductor 453 and winding of relay 4D to grounded battery. Relays 4B and 4D both become energized but as the relay 4B has a slow-to-operate characteristic relay `4D becomes operated first.
At its right-hand armature and back contact the relay 4D seeks to interrupt the holding circuit for any relay in the series 5B, the circuit eX- tending from ground, right-hand armature and back contact of relay 4D, conductor 454, winding of relay 4G, conductors 456 and 556 to the upper armatures of all of the relays in the series 5B. It has previously been assumed that the energizing circuit for the relay 5B!!! had been prepared but not completed. Accordingly, there had been no circuit completed through the upper armaturesV of any of the 5B series relays and the operation of the right-hand armature of relay 4D has no effect, eitheron the relay EBI or on the relay 4G. The left-hand armature of relay 4D cornpletes the energizing circuit for the Start relay 4ST which has a slow-to-operate characteristic. The relay 4B attracts its armature after the relay 4D has operated, establishes a holding circuit for itself from the ground at the back contact and inner armature of relay 4st, winding of relay 4B, front contact and armature of relay 4B, conductor 451 and outermost armature and iront contact of relay 4S2 to grounded battery, and interrupts the energizing circuit for the relay 4D through the chain of armatures and contacts of relays 4S2, 433 and 4S4. Ground is thus removed from the armatures at the head of all of the chain circuits controlled by the relays 4S2, 4S3 and 4S4 so that no other chain circuit path can be inadvertently completed.
First outlying station transmits trouble identifying signal The relay 4ST upon being energized completes its own holding circuit at its innermost iront Contact and armature through conductors 458 and 553, front contact and armature of relay 557 to ground. At the outer right-handv armature and front contact ci relay 4ST an energizing eircuit for the transmitting relay 4T! is completed from ground at the middle upper front Contact armature of energized relay SAIE), over conductors 524, 424, 459, outer right-hand front contact andarmature of relay 4ST, conductor 401, middle left-hand armature and back contact of relay 4C, conductor 408, inner armature and back contact of relay 4A, conductor 499, winding of relay 4TH, conductor 4H and back contact and armature or relay 4T2 to grounded battery. The relay 4T! impresses a spacing impulse on the loop l i extending to the central oice station by means of its two upper armatures.
At the middle armature and front contact oi relay 4ST a circuit is completed from grounded battery through conductor 448, outer left-hand armature and back contact of relay 4C, conductor 441, outer armature and back contact oi relay l41A, :conductor :446, outerlower front contactof relay lll-TI -and armature by which-it is engaged i upon the 'energizationot thev relay, conductorv M4,
winding of' stepping magnet lconductor M3,
brush and zero contactiofbank ASSI; conductorl M2, front contact :and inner right-hand= armature of relay All-I to conductor 424 which is receiving ground 'connection from the upper middle armature of relay SAID. Thus the stepping mag'- net ESS is energized preparatory to stepping its.A
rupts the energizing circuit for the relay T2 and the energizing circuitfor stepping magnet SS at its lower armatures and front contacts so that the brushes of the sequence switch @15S are stepped to their No. l contact.
All of the contacts in the bank SSI are connected to ground with the exception of the zero contact and this is true of the bank -4SS3. The numbered contacts of the bank i552 are connected to the energizing windings of the corresponding ones of the series of relays- 5B. Thus the No. contact of bank 4SS2 is connected by conductors 623 and 523 to relay EBID as previously described. Similarly, the No. 5 contact is connected-by conductorsliil and 555' to relay` 5B5` and the No. 1 contact is connected by conductors itz and` 562 to relay EBI. Following the stepping of brushes -of steppingswitch SS to the No. 1 contacts, direct ground isapplied at the bank /iSSi to the steppingmagnet ASS thus providing such ground connection independently of ythe inner right-hand armature of relay'llH and the middle upper armature of relay EAIU. Since the lrelay iiBl is the only relay of the 5B series, the
energizing circuit for which has beenassumed to be prepared by its associated '5A series relay, namely, EAIU, no electrical circuit is 'completed by the brush associated with bank BSSZ over conductor 463, back contact and armature of Va relay 466, conductor iii? and energizing winding of relay 4C to grounded battery, so that the relay @C is not at this time energized. The brush associated with contact bank @SSS prepares, in all positions except the zero position,=a holding circuit for the relay llC from-ground over conductor 454 to the front contact associated with the right-hand armature of relay'llC.
Since each of the relays flTI andjllTZ interrupts the energizing circuit of the other these relays form a vibratory system which causes alternate marking and spacing impulses to be impressed upon loop II. Each time that relay TI is energized it completes the energizing circuit for stepping magnet BSS and each time it is released. it restores the loop I I to marking condition and interrupts the circuit of magnet GSS so thatthe brushes of .stepping switch' ISS are advanced one step immediately following each spacing impulse. Thistransmission of alternate impulses and advancement of the brushes continues until the brush associated with the bank fiSSZ reaches contact No. 10 at which time the energizing circuit of relay 5BIO is completed over the previously described circuit which includes the operating winding of relay 4C. vAt its upper armature and front contact the relay BI completes its holdingcircuitthroughrelay` 4G to the ground on the right-hand armatureof relay-llD and at its lower armatureand-back contact it interrupts theh'olding'circuit -for the relay SAID which releases. Relay AI releases relay v5H and removes the ground connection for the en- 'ergizing circuit of transmitting relay @TI so that that relay cannot be reenergized and the loop II extending to the central oice station will remain .in marking condition. Although relay 5F `may remain released to connect ground through lamp li to marking condition. The relay .4TIinter-'` 15 509, seek-ing to reenergize relay 5Al, this relay cannot be reenergizecl as long as the relay AEBN! remains held, which is until relay 4D becomes again energized. Relay 5G operates to interrupt the conductive path from ground on the outer right-hand front Contact of relay fil-I to the armature neXt to the outermost of the lower armatures of relay 5H, so that with relay 5H released; the energizing circuit for relay 5AI will not be completed. The reason for preventing the energization of relay 5M at this time will be set at its inner armature and back contact introduces another interruption in the energizing cir- `cuit for the relay GTI and at its outer armature and back contact interrupts the direct energizing circuit for steppingmagnet liSS, which is also additionally interrupted at the outer lower armature and front contact of relay GTI. At the inner left-hand armature `-and front contact the relay 4C also completes the energizing circuitof 'relay 466 inparallelwith relay 4A, and the relay 466 interrupts the circuit through the operating winding of relay 13C; so that the circuit cannot be completedagain until relay 4C, which is now held through lits right-hand winding, is released. The purposes of relay @Sii is to provide for the transmission of signals to identify two or more trouble conditions when they eXist at one outlying station, as will be described later. At its outer'left-hand'armature the relay 4C transfers the battery connection supplied over the middle armature of relay 4ST tothe stepping magnet llSS'through its interrupter contacts. The magnet 4SS thereafter operates in .buzzer manner to advance `its brushes to the zero contacts, where advancement is interrupted due to movement of the brush SSI out of Vengagement with a 'grounded contact.
When the brush associated with bank GSSB reachesitszero Vposition it releases the relay 4C which in turn releases the relay 4A, the relay 466. The relays 3A and 4C again prepare the energizing circuit for relay [STI and the direct energizing circuit for stepping magnet SS but these circuits are not completed because relay remains released under the control of relay BIiL From this it will be seen that ten spacing impulses separated by marking impulses have beentransmitted to the central office station to Outlying station operation when two o1"- mor l trouble conditions exist for operating the stepping magnet might be dis-` connected by relay 4ST before the advancement of the brushes had been completed.
Before describing the operation of the central omce station in response to the signal transmitted to identify the trouble condition represented by the relay SAI il the operation of the station shown in Figs. 4 and 5 when two trouble conditions have occurred will be described. It will be assumed for this purpose that following the energization and locking of relay 5AIII under the control of relay Fbut before the completion of transmission of the signal controlled by the relay SAID and the relay 5BIIl, the relay 5D operated and attempted to complete the energizing circuit for the relay SAS. That circuit could not be completed while the relay EAI remained energized because the` circuit was interrupted at the innermost lower` armature and front contact of relay 5H, which was held energized by the relay 5AIO. Consequently, no energizing circuit for the relay SBS was prepared at the lower armature of relay SAE, so that the brush associated with contact bank SSZ could not complete an energizing circuit for relay 5135 as it encountered the No. 5 contact of that bank. Upon the release of relay BAIIJ as the relay 5B!!! became energized through the contact bank IISSI and relay 4C, relay 5H became released and the effect of its release is to close the prepared energizing circuit for the relay 5A5, which reenergizes the relay 5H and prepares an energizing circuit for the relay EBS; The relay 5A5 also applies ground through conductors 524, 324, inner right-hand armature and iront contact of relay 4H and conductor 442 to the zero contact of bank SSI in preparation for reenergization of stepping magnet GSS and in parallel to conductor 459, outer right-hand amature and front contact of relay 4ST tothe middle left-` hand armature of relay 4C in preparation for the reenergization of relay 4TI, which at this time is prevented due to the fact that the relay 4C is energized.
Upon the arrival of the brushes of sequence switch HSS in their zero positions, the brush associated with bank yGSSI extends the ground connection from relay 5A5 through the stepping magnet dSS and the relays 4A and 4C, upon releasing, complete the energizing circuit for the stepping magnet'and for the transmitting relay liTI. The relay 466 also releases and again completes a vconductive path between the brush associated with bank 4SS2 and the operatingwindingof relay 4C; The relays ATI and ATZ again operate in vibratory manner to transmit alternate spacing and marking impulses to loop I I andthe brushes of stepping switch IISS advance until the brush associated with contact bank 4SS2 reaches its No. 5 contact and completes the energizing' circuitfor relay 5B5 through relay 4C. Five spacing impulses with intervening marking impulses have beentransmitted and loop I I isthere- 26 upon restored to marking condition, relay 5B5 is' locked through its upper winding to relay 4D and the energizingcircuit of stepping magnet ASS is transferred to its interrupter contacts whereby the ,brushes are advanced in buzzer manner to their zero positions where they come to rest and release relays 4A, 4C and 466.
It will now be assumed that the trouble conditions to which the relays 5D and 5F are respon- 1 sive occur in the reverse order, namely, with the and will energize the relay 5H. If they occur simultaneously, both the relays 5A5 and EAII) will be energized and locked but only the energizing circuit for the relay 5B5 will be prepared slncethe relay 5A5 interrupts at its lower armature and back contact the conductive path to the lower armature of relay 5AIO through which the energizing circuit for the relay 5B| will be prepared subsequently. Relays 4TI and 4T2 are set in operation to transmit alternate marking and spacing impulses to loop II and the brushes of stepping switch IISS are advancedstep by step until the No. 5 contacts are reached when relays 5B5, 4C, 4A and 466 will be energized, relay 5B5 being held to the back Contact and right-hand 3U armature of relay 4D, and relay 4C being held to the ground on Contact bank 4SS3 and in turn holding the relays 4A and 466. Stepping magnet SS is putin operation in buzzer manner to advance the brushes rapidly and relay 5A5 is released by the relay 5B5, thus completing the conductive path through its lower armature and back contact to the lower armature of relay 5AI`Il. If relay 5AIO had become energized simultaneously with the relay EAS the release of relay 5A5 results directly in preparation of the energizing circuit for relay 5BIll. If the relay 5A! 0 had not become energized simultaneously with the relay 5A5but was waiting to be energized relay 5H would be released by relay 5A5, relay BAI would become energized and immediately reenergize relay 5H and would prepare the energizing circuit for relay EBIIl. As the brushes of stepping magnet @SS in advancing rapidly encounter the No. 10 contacts, the energizing circuit of relay EBIU is not completed because the energizing circuit of relays 5B I l] and relay 4C is interrupted at the back contact and armature of relay 466. Thus the brushes of sequence switch ISS continue to advance in buzzer manner to their zero positions whereupon another cycle is initiated due to the fact that relay 5A! 0 has remained energized and relay Bl has not become energized and a second signal consisting of ten spacing impulses with intervening marking impulses will be transmitted while the brushes are reaching the No. 10 contact whereupon relay 5B I 0 will be operated and locked to the relay 4D, relay EAIIJ will be released `and the brushes of sequence switch ASS will advance to their zero positions and come to rest. It will be apparent from the foregoing that the stepping switch ASS will undergo one cycle of operation for each trouble condition that has occurred prior to the calling of the outlying station shown in Figs. 4 and 5 or that comes in during the transmission of trouble alarm signals from that station and that a separate set of alternate spacing and marking impulses representing a trouble condition will be transmitted during each cycle of the sequence switch IISS. It will also be apparent that the signal to identify any trouble condition will not be transmitted v.more.thanionce Withoutl specific call `1 or* .such .retransmission '-by'f the 'cen tral'- o'lce;
become locked .-totheD' relay-Which is operable 5B Il, conductor= 536;- armature f .and back` contactl 1 next to the :outermost lower: armature' of. relay.A 5H, which will be deenergizedif there-Aisne.trouA ble condition, conductoril andv/inding ofrelay' 5A| to grounded battery.- Thesrelay 5A! becomes.
operated `and held ina'mannersimilarto the relays5A5 andjEAlaoperatesthe relay 5H,V and prepares an energizing circuitforv the relay-"SBR Upon the 'operation of.- the Vrelay y 4ST. in Aresponse' to the-roll call signal 'fori the station shown in Figs. land 5 the systemoff'relays'dTl'.and/GT2 is started and the brushesbf stepping: sWtchSS are stepped to'the No. -`l'rcontact followingqthey rst spacing impulseztransmitte'd to loop 'l I. the No. 1 contact-ofbankf4SS2ftheenergizing circuitA for relay,` Elll. is completed! throughA the relay @C whereby; the 'transmission' of further spacing impulses: isestopped': andl` the stepping'v magnet ISS lis put intobuzvzer operationlt'o'lm-Vv store `the brushes ytothe-zerospositiorr lThe relay 5B! locks, not to then-,relay` 413i ats-inthe caseofi' the relays 5B5andf l'ebutfinstead to the -outer right-hand armaturela'nd 'front-:contact v.or relay 4E.. The reason for,.this,-;is qthat ,When 'the relay 5E is released under thecontrol of ajrelease. signal as will be presently: describedgthe; relay 5B1 is i released I in order togpl'ace the-fs'tation. s hdwnfin Figs; 4 and 5 in such condition:thatfgfitis` capable of responding to -thenext roll fcallyand indicating that it istrouble-'free-if that-conditionfstill exists:
It is not desirableifto yrelease;fthefother'relays AinI the 5B. series, such as relaysY 5B15and15BI0xWhen the station release signalisfreceived' asithis would permit the ycontinuiI-igtroublesconditions:toireL assert themselves as they did-*ein ,ther beginning.
Accordingly, the other 'relaysfinl the, 5B series; are locked to the relayyliDwsofthat;they IWillnotV be" released until after #the troublefcondition's :have
been cleared and the station-has again-been" called7 Whether -in roll ical] of all'vstaftions orby` specic individual call to test-the -stationi It should be noted thatWhen-anyonegfofrthe -relay series 5B, suchasthe lrelay SBBior 5BIO', becomes energized its :locking circuit;is completed through the Winding of l relay lGfWhiclithereupon :becomes operated andhe1d',` thus interrupting the potentialenergizing circuitfcr .thefrelay' 5A l. .The purposein thusinterruptingr3thatcirr` l cuit is to'preventthetransmission/ofithe'signal indicating a trouble-free condition-3followingthe transmission of a signal indicating avtrouble condition. When .the .holdf-relay becon-iesgenergized it completes theV energizing circuit for the relay 5A! if there is no trouble.conditionatthe station, otherwise` it `does-not; complete tl{1e cir;-
condition lresult sin theene'rgization-of relay A5H which prevents 'the energi'zation 'of 'relay EAI. Hovveverhfollowing the tr-ansmissionzof the signal wheh identifies @trouble@editionthefrelyjt is released and would thereupon complete the energizing circuit for the relayA 5A l were itr not for `the". provision of the relay'fAG. to 'interrupt suchenergizinglcircuit. Operation of relay-{5A} following" the transmission of'a trouble signal Woull'il,` upon'the return otthestepping switchfbrushes to normal, restart relaysATl fand 4T2 and" the advancement of the`- 'stepping Asvviteh brushes to'effect the transmission .ofy one spacing impulse, and the energizationand locking of the relayV 5B1, whereby a'fal'se indication. of absenceV of a trouble condition would. be tran s`mitted.
There is the'possibility that' a troublefondition may occur after relay ril-I has becomeenergized,
andib'efqefh'e .stepping swiehibrusnsee .returned to .their zero positions incidentv to ,transl missen jof me ile-acume signal." Undef these circumstances the v"stepping will 'Y restart immediately for ythe transmission ofthe trouble signal, 'thus f producing contradictory reports at the` central oicefstationl The k'lfact thatutheuf trouble'condition is of 'recent occurrenceniay be deduced'from such contradictory reports, or the outlying station maybe recheclied, in vWhich case the transmission or [the "n-trouble. signal will,
be estopped and @my the trqupiesignaiwi1ibe *transmitted Outlying station rez'uquistes Zine i Reference. has` previeuslrbeen made to the. fact. .thatwhen relay. 5H; becomesenersiaedit c0111.-
pletes .atil lowermost arm'atureand .front congized i through yits innermost front y c-orilzazlt and Wimirs' O'f" th, relai t0 erguadaibatterrwhen theirelay'dsr 1sfoperated by the remy 4D. The @purpsecf the'reiayi 551l is to enablethe station show nl'in Figs. 4 and'to deteririiriel when.` the transmission of all trouble sigifi alsh'as'beenfcomv pletedfsgo as` to prel'zl'udeA fthe" station from transmittiig" signals to'identiflr troubleconditionsv Which-` niay subsequently 'occur during Vthe roll callV ff'stations. "'.Relay4 '5l-I isenergized las long as any relay inthe series `5A is energized and when anyrelay in thejAV seriesjis Waiting` to be energizedfsuch Waitingbeing due to thelfact that Ianother ofthe relays in the series is already (ilfffl gized, the relay 5H will be released on1y`long` enough for the Waiting relay to be energiaed and will be imnediatelyf'reenergized. However,
when signalsl representing all of the" trouble conditions" have been transmitted andthe relays in thev series 5A have been released, the relay 5H willbe releasedlandwillnot be -reenergiz'ed The re1ayf`55'l Will"thereupon 'be released andafter a delay intervaliwill interrupt 'the holding circuit vfor theY relay.4ST which Will release.' This Will prevent. the relay. 4T| frombeing operated under the control rof a subsequently oc-curringtrouble condition Y.sov that the `station has noW been deprived of vth'ejability .to transmit. troublelidentid ication signals. -Were itfnot forthe'provision of .the release of' relayAST, following the transmission; of vsignals .appropriate to thel then` existing ,condition ofthejstat-on, the? station could at.
anyA time during z h'e roll call seize -control of .the
cuit Qf relay femmine fleafforl 12h-Bft@ liloble 755. vloon ptt-extending towardfthe `cent1-a1 cnice i. and
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Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2505728A (en) * 1945-06-14 1950-04-25 Teletype Corp Selective signaling system and apparatus
US2557392A (en) * 1947-03-17 1951-06-19 Teletype Corp Combined telephone and telegraph system
US2574774A (en) * 1949-04-30 1951-11-13 Westinghouse Air Brake Co Remote-control system
US2583088A (en) * 1950-09-13 1952-01-22 Bell Telephone Labor Inc Alarm signaling system
US2607843A (en) * 1948-11-12 1952-08-19 Bell Telephone Labor Inc Remote control and supervisory system
US2629088A (en) * 1950-09-30 1953-02-17 Gen Railway Signal Co Centralized traffic controlling system for railroads
US2667533A (en) * 1950-05-10 1954-01-26 Teletype Corp Automatic message switching system
US2871286A (en) * 1953-11-18 1959-01-27 Bell Telephone Labor Inc Message transmission system
US2901728A (en) * 1951-04-10 1959-08-25 North Electric Co Supervisory control system
US3046525A (en) * 1958-09-16 1962-07-24 Bell Telephone Labor Inc Supervisory control system
US3223977A (en) * 1961-10-23 1965-12-14 Stromberg Carlson Corp Roll call generator
US3244805A (en) * 1961-06-29 1966-04-05 Ibm Counter controlled remote station transmission to central data collecting station

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US1024444A (en) * 1908-10-17 1912-04-23 Howard E Merrell Automatic signal-operator.
US1877635A (en) * 1927-03-25 1932-09-13 Gen Electric Remote control system
US2082550A (en) * 1933-07-29 1937-06-01 Gen Railway Signal Co Centralized traffic controlling system for railroads
US2082465A (en) * 1929-05-07 1937-06-01 Gen Railway Signal Co Train dispatching system for railroads
US2098910A (en) * 1933-07-26 1937-11-09 Elsie A Blake Remote control system
US2111352A (en) * 1931-08-27 1938-03-15 Elsie A Blake Train dispatching system
US2122112A (en) * 1934-05-23 1938-06-28 Gen Railway Signal Co Centralized traffic controlling system for railroads
US2168786A (en) * 1934-01-19 1939-08-08 Union Switch & Signal Co Remote control system
US2269692A (en) * 1937-08-31 1942-01-13 Bell Telephone Labor Inc Alarm signaling system
US2273231A (en) * 1938-08-03 1942-02-17 Union Switch & Signal Co Remote control system
US2355352A (en) * 1942-04-30 1944-08-08 Automatic Elect Lab Indicating system

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1024444A (en) * 1908-10-17 1912-04-23 Howard E Merrell Automatic signal-operator.
US1877635A (en) * 1927-03-25 1932-09-13 Gen Electric Remote control system
US2082465A (en) * 1929-05-07 1937-06-01 Gen Railway Signal Co Train dispatching system for railroads
US2111352A (en) * 1931-08-27 1938-03-15 Elsie A Blake Train dispatching system
US2098910A (en) * 1933-07-26 1937-11-09 Elsie A Blake Remote control system
US2082550A (en) * 1933-07-29 1937-06-01 Gen Railway Signal Co Centralized traffic controlling system for railroads
US2168786A (en) * 1934-01-19 1939-08-08 Union Switch & Signal Co Remote control system
US2122112A (en) * 1934-05-23 1938-06-28 Gen Railway Signal Co Centralized traffic controlling system for railroads
US2269692A (en) * 1937-08-31 1942-01-13 Bell Telephone Labor Inc Alarm signaling system
US2273231A (en) * 1938-08-03 1942-02-17 Union Switch & Signal Co Remote control system
US2355352A (en) * 1942-04-30 1944-08-08 Automatic Elect Lab Indicating system

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2505728A (en) * 1945-06-14 1950-04-25 Teletype Corp Selective signaling system and apparatus
US2557392A (en) * 1947-03-17 1951-06-19 Teletype Corp Combined telephone and telegraph system
US2607843A (en) * 1948-11-12 1952-08-19 Bell Telephone Labor Inc Remote control and supervisory system
US2574774A (en) * 1949-04-30 1951-11-13 Westinghouse Air Brake Co Remote-control system
US2667533A (en) * 1950-05-10 1954-01-26 Teletype Corp Automatic message switching system
US2583088A (en) * 1950-09-13 1952-01-22 Bell Telephone Labor Inc Alarm signaling system
US2629088A (en) * 1950-09-30 1953-02-17 Gen Railway Signal Co Centralized traffic controlling system for railroads
US2901728A (en) * 1951-04-10 1959-08-25 North Electric Co Supervisory control system
US2871286A (en) * 1953-11-18 1959-01-27 Bell Telephone Labor Inc Message transmission system
US3046525A (en) * 1958-09-16 1962-07-24 Bell Telephone Labor Inc Supervisory control system
US3244805A (en) * 1961-06-29 1966-04-05 Ibm Counter controlled remote station transmission to central data collecting station
US3223977A (en) * 1961-10-23 1965-12-14 Stromberg Carlson Corp Roll call generator

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