US1871300A - Telephone system - Google Patents

Description

Aug; 9, 1932.

J. A. BUR'GENER TELEPHONE SYSTEM Filed May 26. 1930 Patented Aug. 9, 1932 UNITED STATES PATENT oFFca lJOHN A. BURGENER, OF HINSDALE, ILLINOIS, ASSIGNOR, BY HESNE ASSIGNMENTS, TO ASSOCIATED ELECTRIC LABORATORIES, INC., F CHICAGOr ILLINOIS, A CORPORATION OF DELAWARE TELEPHONE vsnnsrnm In automatic and semi-automatic systems this apparatus comprises directively operable switches and in manual systems, particularly -those arranged for automatic traffic distribution, the apparatus will include various answering and completing circuits. The common apparatus is ordinarily made accessible to the subscribers lines and trunk lines by means of non-numerical switching devices which serve to automatically connect a calling line with an available unit of the apparatus. Switching devices of two generaltypes are in common use for this purpose; namely, lineswitches which are associated individually with lines and connect with idle switching apparatus, and finder switches which are associated with switching units and connect with calling lines.

Telephone lines such as those above-referred to are subject to certain unstandard conditions which effect the exchange switching apparatus. These conditions may result from faults occurring on the lines themselves or from the accidental removal of a substation receiver from the switchhook. When such a condition exists on a line, the associated non-numerical switch will operate to connect the line with a common apparatus unit. The particular apparatus unit involved will, of course, lie-withheld from regular use until the defective line is disconnected therefrom. Holding the apparatus in this manner decreases the efficiency .of the exchange and, unless corrected promptly, may seriously interfere with the exchange service.

The common method of dealing with this condition is to provide alarm signals for the various apparatus units subject to being held out of service by defective lines. The signals enable the exchange attendant toV readily locate apparatus being held in this manner so that steps can be taken to disconnect the defective lines. In order that this procedure may be effective it is necessary that the attendant inspect the signals frequently which is usually -impractical for economic reasons. Furthermore, lines that have been disconnected will remain out of service, even though the defective condition is removed, until such time as the attendant can make the necessary tests and reconnect the line. This method is even more unsatisfactory in unattended exchanges for obvious reasons and since such exchanges are usually relatively small, the possibility of service interference from defective line is disproportionally large.

The present invention is designed to deal with the above discussed conditions in a 'reliable and eliicient manner. One of the fea- "tures of the invention is the arrangement whereby defective lines are automatically disconnected from the exchange apparatus after a predetermined time. Another feature is the arrangement for maintaining such lines disconnected until the defective condition is removed whereupon the cleared lines are immediately restored to service. Both of these functions are performed quickly and surely without the intervention of an attendant. A further feature is the provision of a simple and relatively inexpensive common timing device for controlling the disconnecting apparatus. 'An incidental feature is the arrangement whereby the line relay of a well known type of lineswitch is adapted to perform additional duties.

The foregoing paragraphs indicate the scope of the invention which is disclosed in one of its narrower phases in the accompanying drawing. This drawing comprises Figs. 1 and 2, shows by means of the usual conventional circuit diagrams the manner of employing the invention in connection with subscribers lines in an automatic telephone system equipped with non-numerical switches of the lineswitch type. The application of the invention to other types of telephone systems and in connection with trunk lines will be readily apparent.

Referring now to Fig. 1, T represents an ordinary automatic substation associated with a subscribers line terminating in linement and automatlc rotary movement. Comated under control of a timin mon su ervisory relay uipment SR is associate with a group of rst selectors. This relay equipment comprises the low-resistance supervisory relay 51 through which battery is fed to the release relays of the various selectors, and a slow relay for operating the alarm circuit. The slow relay shown is of the so-called dash-pot t pe, which is characterized by extremely s ow operation and quick release. Timing switch TS consists of an ordinary rotary switch of any convenient size having movement only in a forward direction, and a group of counting relays operinterrupter TI. A set of contacts inthe ba of the timin switch TS is allotted to each of the first se ectors of a group. The timing interrupter shown is of the cam type although any source of timed interruptions will be satisfactory. The impulsing rate may be adjusted to any desirable figure, for example at half-minute intervals, which in the instant case will allow a period of three minutes before a connection is released.

Referring now to Fig. 2 there is shown a rotary lineswitch adapted to operate with the first selector and timing switch shown in Fig.

1. This switch is of the usual non-homing type and is provided with a two-step line relay which functions under certain conditions as a disconnecting relay, as will be explained in later paragraphs. l

A better understanding of the featuresof the invention will be had from a detailed description of the various operations involved in establishing a connection and in disconnecting a faulty line. Assumin first that the subscriber at substation T initiates a call, Irelay 12 of the lineswitch will operate over a circuit including contacts 15 and 16, the outer armatures of relay 11, the two line conductors 1 and 2, and the subscribers loop. Relay 12 on operating closes a circuit from supervisory ground, through the upper winding of pull-down magnet 13, to main battery at the master switch. The magnet operates and pushes the plun er into the bank, thereby closing contacts 1 20 which extends the calling line over theJ trunk comprising conductors 34-37 to selector S. Contacts 15 and 16 open when magnet 13 operates and relayv 5 due to its slow release characteristic and main-l tain-magnet 13 o rated until a ground is returned.v by the selctor. Immediately after the call is extended to the selector, relay 21 operatesiover the callin loop and completes a circuit for relay 22 which also operates. Relay 22 prepares the impulsing circuit and opens the clrcuit of the release magnet at its lower armature, marks the selector in the banks of the timing switch at its upper armature, and at armature 26 connects a holding ground to release trunk conductor 36 to energize the lower winding of. magnet 13 and maintain the lineswitch in operated position. Supervisory relay 51 operates in series with relay 22 and closes a circuit for the dash-pot relay 52 which will start its operation. The calling subscriber will then dial the Iirst digit of a telephone number and relay 21 will respond and transmit a corresponding series of impulses to relay 23 and vertical magnet 33 in series. The magnetoperates in the usual way to step the wipers to the called level. Relay 23 operates in response to the first impulse of the series and, being slow-to-release, maintains its armatures actuated during the series of impulses. Oifnormal springs 30 and 31 close upon the first vertical step of the wipers and a circuit is completed for relay 24 including the interrupter contacts of rotary magnet 32, oE-ormal contacts 31, and the upper armature of relay 23, to ground at armature 26. Relay 24, operates, completes a locking circuit for itself independent of relay 23 at armature 27, and at its upper armature prepares a circuit for the rotary magnet. Shortly after the last impulse of the series relay 23 restores and completes a circuit for the rotary magnet which operates and steps the wipers in on the first set of bank contacts of the called level. The opening of the interrupter contacts allows relay 24 to release, which in turn opens the circuit of the rotary magnet. The interrupter contacts re-establish the circuit for relay 24, this time in series with relay 25. In case the trunk now engaged by the wipers is busy, the ,test wiper will encounter ground on the test contact which shunts relay 25 and permits relay 24 to operate. The stepping circuit is again completed and the wipers are advanced to the next set of contacts as hefore. This cycleof operation is repeated until the test wiper encounters an ungrounded contact marking an idle trunk, at which time switching relay 25 operates in series with vrelay 24. Relay 24, however, does not operate dueto the high resistance of relay 25. Relay 25 disconnects the incoming talking conductors from line relay 2l and extends them by wayof its outer armatures to the talking Wipers which are engaging the contacts associated with the talking conductors of the idle trunk. It may be assumed, for example, that the trunk selected is the one comprising conductors 43--45 terminating insecond selector S1. Relay also disconnects the test wiper from its lower terminal and instead connects it to itsupper terminal to prepare a holding circuit for itself, and at armature 29 disconnects ground from the lower armature of relay 21 to prevent the release of the switch The 4,dash-pot relay is adjusted to operate very slowly, for example, requiring twelve seconds .to close its contacts after its circuit is completed. In case the subscriber dials within a reasonable time after seizing the selector, the supervisory relay will thus be released before the dash-pot relay completes its operation and the timing switch will not be actuated. The subscriber continues to. dial and complete the .connection in the' usual way which is of no particular interest as far asthe invention is concerned.

The foregoing paragraphs describe the 0perations in the case of a normal call. Assume now that the subscriber at substation T accidently knocks thereceiver from the switchhook or removes it to make a call and then the previous case as will supervisory relay 51.

lin case the subscriber does not operate the calling device the switch will remain in normal position and consequently the relays will remain operated. After a predetermined time dash-pot relay 52 will close its contacts.7

-thereby completing a circuit for stepping magnet 65 of timing switch TS. This magnet operates and interrupts its own circuit advancing wipers 66 and 67 one step at a time. The wipers will be stepped ahead until wiper 67 encounters. the contact associated with' Iselector S to which ground is connected by way of the upper armature of relay 22. This ground will cause the operation of relay 64 which opens the circ-uit of the stepping magnet at its upper armature, prepares a holding crcuit for thecounting rela\ys 61-63 at its lower armature, and connects up interruptor contacts 74 at armature`73. It isi assumed for convenience that the timing interrupter TI is arranged to operate in a complete cycle every half-minute. and consequently contacts 74 close at half minute intervals. When these contacts are closed for the first time following the operation of relay 64 a circuit is closed for the upper winding of relay 61 including the upper armatures of relays 61, 62, and 63 and armature 7 3 of relay 64. ,Relays 61--63 are two-step relays and operate only their contacts designated by the Roman numeral T when energized over the upper winding. Relay 61 on operating, as just described, prepares a circuit for its two windings in series by operating armature 68. As the interrupter continues to operate contacts 7 4 will be opened, thereby removing the shunt ronithe lower winding of relay 61 which will now operate fully and actuate the remainder of its armatures. This relay on o eratin in its Second step switches its init-ia Aoperating circuit over to relay 62 at its upper armature,

and at its lower armature, prepares a holding circuit for relay 62. The next closure of the impulsing contacts will operate relay 62 in its first step and on the opening of the interrupter contacts relay 62 will operate fully and transfer the operating circuit to relay 63. Relay 62 at its lower armature opens the holding circuit or relay 61 which now restores. The third closure of the interruptor contacts will operate relay 63 in its first step and, when the interrupter contacts open, this relay will operate fully and lock to ground at the lower armature of relay 64, prepare a new `operating circuit for relay 61 and open the holding circuit of relay 62. -On the forth closure of the interrupter contacts, relay 61 will operate as before and complete a locking circuit, this time through the lower armature of relay 63. The fth closure of the interrupter contacts will operate relay 62 which locks through armature 72 and the lower armature of relay 61 and connects wiper 66 to the impulse contacts by way of the upper armature of relay 63 and armature 73. It will thus be seen that five impulses are required to operate the three counting relays to their present positions, and I assuming that these' impulses are at one-half minute intervals, a period of two and onehalf minutes has elapsed since the timing switch was associated with the selector. Aft-l er the lapse of another half minute, interrupter contacts 74 will again close and ground will be extended by way of these contacts,

armature 73, upper arma-ture o relay 63 and armature 6 9, wiper 66. and conductor 35 to relay 11 of the lineswitch LS. Relay 11, operates, disconnects the talking conductors of the line from the trunk leading to the selector and bridges itself across these conductors and closes a circuit for operating a line identifyingsignal. Relay 11 also connects ground potential to the test conductor by operating Varmature 14, thereby marking the line busy .in the banksof the connectors. Relay 21 of the selector will restore immediately upon the opening of the loop and relay 22 will restore line disconnected from the .lineswitch substation will be opened in the usual way ing of relay 12 acall a loop circuit 4is closed over conductors the Roman numeral I when its lower winding 1s energized 1n serles with. resistance 14;.

until such .with the upper winding of relay 12 and mag- 5 l thereafter. The removal of ing loop'will thus beextended to the first se. Xiidhnhdrg release trunk conductor 36 will lector in the usual way whlch 'wllllreturn ielease pull-down magnet 13 ofthe lineswltch a ground on release trunk conductor 36 to and thus free the trunk for use by other lines. Referring back to the lineswitch, relay 11 w111 remain locked up overfthe loop of the sub. scribers line and, of course, will maintain the This ground returned `from the selector will 12 over which the relay was being held operated, and will permit the relay to restore. Assume 'now'that the'subscriber at substa-A In case the subscriber ailsto dial Wlthln tion T notices the yreceiver off the hook and a reasonable period, the timing swltch aslrestores it thereby removing the-unstandard Soclated wlth the selector will operate as has condition from the une. The loop at the been prevwusly descrlbed and, at t1on of the predetermined time, w1ll connect ground to conductor 35 which by way of wiper 18 and armature 15 will operate re lay 12, It will be noted that resistance I4 is not in the circuit at this time and relay 12 will operate fully, The operation of armature 22 will open the -circuit of relay 11 which will restore and relay 12 will bridge itself across the line. Relay 12 will thus remain locked up over and relay 1 1 will restore and reconnect the line to the lineswitch so that an originating call will now operate the switch exactly as in the previously described connection.

While the foregoing description deals w1th cconditions arising from a receiver left ol the switchhook, the'operation will be substantially the same for faults occurringon the lines, such as conductors l and 2 becoming -crossed or conductor 2 becoming grounded. In any event the line will be disconnected from the exchange switching apparatus and will beclocked in this condition until such time as the lin-standard condition is removed or disappears. I

Lineswitch LS1 of Fig. 2 is arranged to operate in'connection with the selector and timing switch shown in Fig. 1. The operatioon the initiation of a call is as follows: Wlicn the subscriber at substation T1 initiates to the ground 1 and 2, from ground at the lower armature 4of relayJ 11', and through the upper armatures of relays l2 and 11', lower windin series with resistance 14', to battery.. Relay 12 is a two-step relay and operates only its armatures. designated by ductors of the line from said apparatus when and for re-connecting said talking conductors to said apparatus when the unstandard condition is removed from the line.

A 2. In a telephone system, a plurality of lines, a trunk each line and normally connected thereto, means-individual to each line for disconnectl ing the line from the associated switch when an unstandard condition exists on the line and for reconnecting 'the line to the switch when the unstandard condition is removed, and means common to'all of said lines for controlling the initial operation of said first means.

3. In a telephone system, a line, a trunk selecting switch individual to said line and normally connected thereto, a relay for disconnecting the line from said switch, a control device for operating saidrelay responsive to an unstandard condition on the line.l

The operation of armature 21 circuit for the upper winding of relay 12, relay 11', and magnet 13 in series. The actuation ofthe lower armature of relay 12 connects test wiper 19 to the junction of relay l1 and magnet 13. If the trunk on which th wipers are standing is busy, wiper 19 will encounter a ground and this ground will shunt relay 11 and cause magnet 13 to advance the wipers one step to the next set of contacts. This operation will be repeated time as lan idle trunk is encountered. Relay 11 willthen energize in seriescompletes a net 13. The magnet, however, will not operate due to the relatively high resistance of relay 11. Relay. 1l will switch the test wiper over from its previous connection to upper terminal of the rela)7 thus preparing a holding circuit for itself, and will connect the talking conductors through to the wipers at its upper and lower armatures. The callated independent of said device as long as the unstandard condition exists on the line.

4. In a telephone system, a line terminating in an individual trunk selecting switch, a branch of said line accessible to other that is inits second step.

relay 12 will` automatically disconnecting the talking conand means for maintaining said relay oper-` `maintain relay 11 in operated condition.

also shunt the upper winding yof the relay the expirathe line loop to ground at the lower armaan unstandard condition exists onthel line selecting switch individual to i yio switches, a relay for disconnectin the line from said switch and for marking t e branch busy to said other switches, a control device for operating said relay responslve to an unstandard condition on the line, and means for maintaining said relay operated independent of said device as long as the unstandard condition exists on the line.

5. In a telephone system, a line, switching apparatus, a relay, meansfor connecting the line to said apparatus responslve to an unstandard condition on the line, means for operating said relay, and contacts on said relay for disconnecting the line from said apparatus and for bridging itself across the conductors of the line.

6. In a telephone system, a plurality of lines, switching apparatus adapted to be seized by any line on which a call is initiated or on which an unsta-ndard condition exists, a relay' associatedl with each line, contacts on said relays for disconnecting the associated line from the seized apparatus and or bridging the relay across the line, and a common timing device for operating the relay associated with the particularline on which an unstandard condition exists.

7 In a telephone system, a switching device equipped with wipers, a line comprising two conductors normally connected to said wipers, a relay, and contacts operated by said relay to disconnect said conductors from said wipers and to bridge the relay across said conductors. l

8. In a telephone system, afline, a nonnumerical trunk selecting switch individual to said line, a numerical switch accessible to said first switch, means for operating said first switch to seize said second switch responsive to an unstandard condition on the line, means for freeing both of said switches while the unstandard condition remains on the line, andmeans controlled by said second switch for operating said last means.

9. In a telephone system, a line terminating in an individual lineswitch, other switches accessible to said lineswitch, means for operating said lineswitch to seize one of said other switches responsive t0 an unstandard condition on the line, means for freeing both of said switches, and a timing device controlled by said one switch for rendering said last means e'ective a predetermined time after the seizure of said one switch.

10. In a telephone system, lines terminating in individual non-numerical switches, numerical switches accessible to said nonnumerical switch-es, a timing device common to said numerical switches, means for operating a non-numerical switch to seizean idle one of said numerical switches responsive to an unstandard condition on the associated line, and means controlled by said device for freeing both of said switches after a predetermined time. l

i 11. a telephone stem, a subscribers line e uipped with a -ca ling device, a switch callingy device, means for operating said first l switch toe connect with an idle one of said second switchesresponsive to the initiation of a call on said line, and means for disconnecting said line from 4said first switch in case the callingsubscriber fails to operate-the callin device withinna predetermined time after mitiating the call.

12. In a telephone system, a line terminatingin a trunk selecting switch, a two-step line relay for the switch, meansfor operating said relay in its first step responsive to the initiation of a call or tocan unstandard condition on the line whereby said switch is caused to hunt for and connect with andmeans for operatingsaid relay in its second step to free said trunk when an unstandard condition exists on the line.

13. In a telephone system, a non-numerical switch terminating a line, a. two-step line relay for the switch adapted eration of the switch when pperated in its first step and to disable the switch whemoperated i'n its second step, means for operating the relay in its first step responsive to the initation 'of a call on the line, and means for operating the relay in its second step 'responsive to an unstandard condition on' the line.

14. In a telephone system, a line, a nonnumerical switch terminating said line, trunks accessible to said switch, Land a combination line and disconnect relay in said switch for initiating the switch to extend a calling line to an idle one of said trunks and for disconnecting the line an idle trunk,Y

to initiate the op-v operation of said from said one trunk in` case an unstandard condition exists on the line.

15. In a rotary lineswitch, a line relay for' initiating the operation of the switch, a switching relay for extending the ltalking conductors of the switch through t'ofthe wipers, a resist-ance', an operating circuit for the line relay including normally closed'contacts of the switching relay and saidresistance,

disable the switch when operated in its sec-` ond step, a switching relay for extending the talking conductors of the switch through to the wipers, a circuit for operating the line relay in its iirst step including normally closed contacts of the switching relay, and a circuit for operating the line relay in its second step including normally open contacts of the switching relay.`

17. In a telephone system, a plurality of automatic switches, means-for extending connections to said switches, a delay device commo'n to said switches, a timing switch, a hunting .switch associated with said timin switch, means responsive to the extension o a connection t one of said automatic switches for operating said delay device, means controlled by said device for operating said hunting switch to connect with said one automatic switch, and means responsive to said hunting switch effecting said connection for initiating the operation of said timingswitch.

18,. In a telephone system, a plurality of automatic switches, means for extending connections to said switches, a delay device common to said switches, a timing switch comprising a group ofcounting relays common to said switches, means responsive to the extension of a connection to one of said automatic switches for operating said delay device, means controlled by sald device for associating `said timing switchlwith said one switch individually, and means for initiating-the operation of said timing switch responsive to its association with the automatic switch.

19. In a telephone system, a plurality of `automatic switches, means for extending connections to said switches and for directively operating the same to further extend the connections, a timing device, means for connecting said device with a switch to which a connection has been extended in case the directive operation of the switch is delayed for a predetermined interval, and means for disconnecting said device from the switch in case the switch is directively operated within a predetermined interval after said device is connected thereto.

20. In a telephone system, a pluralityof automatic switches', means for extending a connection to one of said switches, means controlled over the connection for operating the switch to further extend the connection, a timing device common to said switches, means effective in case the operation of the switch is delayedI for a pre-determined interval after the connection has been extended thereto for associating the timing device with the switch individually, and means controlled by the timing device for releasing the switch vfrom the connection in case' the operation thereof is delayed for a predetermined interval after theass'ociation of the timing device therewith.

21. The combination with a line comprisingtwo conductors, of a switching device connected to said line, a timing device associated with said switching device, a second by said second timing device for disconnecting said line from the swithing device.

22. The combination with a line comprising two normally unconnected conductors, of a switching device terminating said line, and means responsive to the short circuiting of said conductors for disconnecting the line from said switching device and for maintaining the line disconnected only so long as said conductors are short circuited.

23. The combination with a line comprising two normally unconnected conductorsLof a switching device terminating said line, a

relay, means responsive to the short circuit` ing ofsaid conductors for completing an operating circuit for said relay, and means controlled by said relay for disconnecting .the

. line from said switching device and for completing a holding circuit for itself over the short-circuited conductors.

24. In a telephone system, lines terminating in trunk selecting'switches, a plurality of trunk lines accessible to said switches, a timing device common to said .trunk lines for releasing the trunklines after a predetermined interval/ and means'for rendering said device individual to a trunk line while said predetermined interval is being measured.

In witness whereof, I hereunto subscribe my name this 23d day of May, A. D. 1930.

n JOHN A. BURGENER.

timing device, means in the switching del vice for operating` said first timing device,

means controlled by said first timing device for connecting said second timing device to said switching device, and means controlled

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