US1888307A - Telephone system - Google Patents

Description

Nov. 22, 1932.

A. E. CASWELL.

TELEPHONE SYSTE! Filed May 4. 1951 5 Sheets-Sheet l IFITLEFTEFM Hfihur Edward Easuzall Nov. 22, 1932. A. E. CASWELL 1,888,307

TELEPHONE SYSTEM Filed May 4, 1931 '3 Sheets-Sheet 2 lbl l 8 Zbl jrtl YEZ

8 I Irma??? FlFThur Edward 125.511.1511

Nov. 22, 1932. A. E. CASWELL TELEPHONE SYSTEM Filed May 4, 1951 3 Sheets-Sheet 3 rm H'Fl'hur Edward Casmell Patented Nov. 22, 1932 UNITED STATES PATENT OFFICE.

ARTHUR EDWARD CASW EIQL, OLEv LIVERPOOL, ENGLAND, ASSIGNOR T0 ASSOCIATED TELEPHONE & TELEGRAPH COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF DELAWARE TELEPI'IONE SYSTEM Application .filedMay 4, 1931, Serial No. 534,829, and in Great Britain June 18, 1930.

The present invention relates to telephone systems and is more particularly concerned with arrangements for applying routine tests to various pieces'of apparatus, in accordance with what is now usual practice, with the objectof discovering any faults which may occur and allowing them to be attended to before they result in annoyance to subscribers. The chief object ofthe invention is to provide an improved arrangement permitting the satisfactory routining of the apparatus located at the incoming end of a two-wire junction to be effected without causing any appreciable interference to ordinary service.

It may/be stated generallythat, as regards the testing of apparatus having associated with it a special test conductor, it is possible to give'the routiner direct access to this conductor and thus ensure that the routiner only seizes the apparatus in question when it is not already in use and that it is then busied against seizure from its normal means of access during the time the test is being carried out thereon. In the case of apparatus at the incoming end of two-wire junction lines, however, this procedure cannot be followed and there is thus a danger that while routining is taking place a subscriber will seize the junction since it is unguarded at the outgoing end. It has been suggested to open the speaking conductors and apply a warning tone, for instance busy tone, to the junction during the test, but this is not entirely satisfactory in any event and moreover'if the junction or circuit were faulty the routiner might be associated with it for an appreciable time during the whole of which period'the junction would be unguarded at the outgoing end. Hence, if the junction were an early choice in the bank of the hunt ing switch seized by the subscriber, he might be unable to complete his connection as each time he called he would be connected to the same faulty junction or circuit.

According to one feature of the invention, arrangements are made for giving access from the routiner to the outgoing end of the junction and definitely busying it there while the'test is proceeding so that there is no danger of a subscriber being unable to get past the junction under test if it should be found fault-y.

According to another feature of the invention, the control of the apparatus at'the outgoing end of the group of junctions is effected over one of the junctions ofthe group, this junction being only busied to normal service while routine tests are actually taking place.

The arrangement according to the invention, moreover, tests also for the continuity of the junction itself which is naturally not attempted in the arrangement. where the leads are opened during the test. a

The invention will be better understoo from the following description ofone method of carrying it into effect which should be taken in conjunction with the accompanying drawings comprising Figs. 1 to 3 which are intended to fit together with Fig. 2 on the right of Fig. 1 and Fig. 3 below Fig. 2.

Fig. 1 illustrates the apparatus located at the exchange from which the group of junctions concerned are outgoing,

Fig. 2 shows the incoming ends of the junctions and Fig. 3 shows the auxiliary equipment associated with the routiner.

Itshould be mentioned that certain of the relay contacts shown in Fig. 3 are assumed to be carried by relays associated with a routiner of known type which are not shown and while this will be specially referred to as the de scription'proceeds, the contacts have been dis.- tinguished by enclosing them in a small rectangle.

It is assumed that the two junctions shown are accessible at the outgoing end from a hunting switch JF which may be of either numerical or non-numerical type, that is to say, it may perform only a hunting operation or it may first be set by impulses. It is also assumed that at the incoming end of each junction a line relay such as relay 1A is connected across the two speaking conductors l0 and 11 either permanently or temporarily, and the operation of this relay energizes a slow relay 113, not shown, which then at armature Zb-l applies potential to a guardor release trunk conductor 12 which is extended forward to succeeding switches and also to the test bank of the access switches, such as AS, Fig. 3, associated with the routiner.

As regards the junction to be used for control purposes, which in the arrangement shown is the first choice of the hunting switch JF, but which in some circumstances might more satisfactorily be the last choice, the two conductors 13 and 1 1 of this junction are arranged to pass through contacts 121 and p2 respectively of a relay 1? in the auxiliary equipment associated with the control junction, this relay energizing and switching through the said conductors when the junction is seized for normal purposes. The conductors 15 and 16 of the same junction also pass through contacts M1 and N2 of relay RT,

ig. 2, at the incoming end to enable the proper controls to be exercised. As regards the remaining junctions in the group however, the control equipment is merely tapped oil at the two ends and thus wiring is simplified and apparatus saved.

When a test is to be made it is first necessary to take into use the control junction and it is clearly impossible in this case to obtain access to the distant end without unjustifiably complicating the apparatus so that for this junction alone it has to be assumed that if it is not marked busy at the incoming end it is free at the outgoing end also. In case, however, the junction or outgoing circuit should be in some respect faulty and a subscriber should be connected thereto, the seizing of the junction for routining purposes will connect up number unobtainable or busy tone to the junction conductor 16, and subsequently the junction will be busied so that the subscriber on replacing his receiver when he hears the tone will be enabled to take into use another junction when he makes a further attempt to set up a call.

The routiner itself may be arranged to perform any desired functions depending upon the precise nature of the apparatus connected to the junction at the incoming end.

When the routining operation is to be initiated, the usual start key will be operated and when the access switch AS, Fig. 3, connects with the first junction of the group extending from the particular distant exchange under consideration, that is, in the arrangement shown, the control junction, relay SL, which is individual to that group of junctions, will be energized by earth transmitted over conductor 17. If this junction is already in use, the line relay 2A will be operated, resulting in the operation of the release relay 2B, not shown, in the well-known manner. At armature 2b1 earth will be connected to the release trunk conductor 18 for this circuit and therefore, to the appropriate contact on the routiner access switch private bank with which wiper 3c of the access switch AS will be in engagement.

The routiner will therefore wait until the junction becomes tree and when this occurs relay PE, not shown, in the routiner will operate its armature p01 and this will energize relay RT which is also individual to the particular group of junctions under consideration. Relay RT thereupon at armature rt?) completes a lockin g circuit for itself, at armature r254 applies busy tone by way of the busy tone transformer BT T interrupter I and con- P denser QA to conductor 16 and at armatures M1 and M2 disconnect-s the junction from its normal circuit and connects earth to the conductor 15 over conductor 22, in order to energize relay LA, Fig. 1, at the distant exchange over armature p1. Relay LA in operating, at armature lal energizes relay B which at armature bl prepares a step-on circuit for the distributor switch SD, at armature b2 applies earth over conductor 21 to the bank of the hunting switch J F in order to busy the junction, at armature b3 prepares a test circuit for the junctions to be routined later, at armature b4 applies number unobtainable or busy tone over condenser QB to conductor 13, and at armature lights the supervisory lamp corresponding to the junction over wiper 1b and corresponding bank contact of the distributor switch SD.

The routine test now takes place on the apparatus associated with the control junction and when it is completed certain circuit operations take place in the routiner which result in the energization of relay TF. This relay thereupon at armature tfl opens the circuit of relay LA, Fig. 1, for a sutlicient period to allow the distributor switch SD to step its wipers to the next junction due to the circuit completed from earth, armatures 1(11 and b1, winding of the driving magnet SDDM of the distributor switch to battery, if desired through the winding of a low-resistance supervisory relay in known manner.

Relay H, Fig. 1, is of sufiiciently low resistance to constitute a busy marking and if the next junction is already busy, relay H will be short-circuited and thus be unable to operate. When, however, the junction becomes free, relay H operates from earth,

armature b3, winding of relay H, resistance YA to battery, and at armature 71.1 completes the following circuit for relays LB, Fig. 1, and L, Fig. 3: earth, right-hand winding of relay L, left-hand winding of relay L, armatures tal, all, and 5Z2, conductor 23, armature r62, conductor 16, armatures 712 and 72,1, winding of relay LB to battery. Relay L only is operated in this circuit and it thereupon short-circuits its high resistance left-hand winding over operated armatures Z1 and 7362 which latter armature will be operated at this time if the test is proceeding satisfactorily. The consequent reduction of resistance in the circuit permits relay LB to opcrate, and at armature Zbl it completes a circuit from battery, winding of relay LG, armature Z61, wiper 2b and bank contact of the distributor switch SD, junction conductor 11, bank contact and wiper 2c of the access switch AS, Fig. 3, armature Z3, winding of relay TB to earth. The current in this circuit will be sufficientto operate relay LC but not relay TB and the former thereupon completes a circuit from earth, armature Z01, wiper lb and bank contact of switch SD, junction conductor 10, bank and wiper Z0 of switch AS, armature Z2, right-hand winding of relay TA to battery. Relay TA thereupon at armature m3 locks up to the routiner test earth over conductor 26, at armature m1 brings down relay L and at armature m2 releases relay PF which by connecting earth to lead 24 permits the test to proceed.

It will be noticed that the connections just described constitute a test for synchronism between the distributor switch SD at the distant exchange and the access switch AS associated with the routiner at the incoming exchange since, if the latter switch should be associated with junction other than that with which the wipers of the distributor switch SD are connected, both relays TA and TB will be operated if the junction conductors are looped and neither if the junction is not in use. In'these circumstances, the alarm relay AL connected to conductor 25 will be operated from routiner test earth over conductor 27, armatures 5Z4, m2 and 661 and the consequent lockin up of relay PF over either armature we or armature tb2 will prevent the test being continued by removing earth from the conductor 24 at armature pfl. It should be pointed out that the earth supplied over armature $7 1 is also disconnected from conductor 24 at this time since relay SR, not shown, is operated at the conclusion of the test on the control junction and remains operated until all junctions extending from the exchange under consideration have been routined.

At the conclusion of each test, relay TF associated with the routiner will operate its armature tfl momentarily thus allowing relay LA at the distant exchange to release for a period sufiicient to advance the wipers of the distributor switch SD one step. The access switch AS at the main exchange is also advanced one step and the test on the junction connected with then proceeds as soon as relay TA associated with the routiner has de-energized on the return of the routiner to normal and relay H in the distant exchange has operated in response to the idle condition of the junction.

It will be appreciated therefore that a very simple arrangement has been devised whereby the routine testing of apparatus associated with junction lines at the incoming end may be placed on a satisfactory basis with the use of only a small amount of additional equipment and moreover without resulting in any appreciable increase of the testing time.

What I claim as new and desire to secure by Letters Patent is: s

1. In a testing system, a first station, a second station, a plurality of junctions originating in the first station and terminating in the second station in automatic switches, all of said junctions being accessible at the first station for regular service to the second station, routine testing equipment at the second station for routine testing saidautomatic switches and having means for successively associating it with said switches, and. means at the first station controlled by said equipment over a certain one of said junctions for marking each junction busy to its normal means of access at the first station while said equipment is testing the switch in which that junction terminates.

.2. In a testing system, a first station, a second station, a plurality of groups of junctions originating in the first station and terminating in the second station, all of said junctions being accessible at the first station for regular traffic to the second station, testing equipment at the second station for testing a junction and having means for associating it with each group of junctions separately and connecting it successively to the terminating ends of the junctions of each group, and means at the first station individual to each group of junctions for cooperating with said testing equipment to perform the tests on each junction, each individual means controlled over a certain junction of the associated group by said equipment.

3. In a telephone system, a branch exchange, a main exchange, a plurality of twowire junctions originating in the branch exchange and terminating in the main exchange, all of said junctions being accessible at the branch exchange for regular trafiic to the main exchange, testing equipment at the main exchange for testing the continuity of both wires of each junction, a distributor switch controlled by the testing equipment for successively connecting the equipment to the terminating ends of said junctions, and a switch at the branch exchange controlled over a certain one of said two-wire junctions by the testing equipment at the main exchange to connect potential to the originating end of each junction while the testing equipment is connected to the terminating end in order that said equipment can test the continuity of each junction, said switch at the branch exchange marking each junction busy to its normal means of access while it is being tested.

4. In a telephone system, a. branch exchange, a main exchange, a group of junctions originating in the branch exchange and terminating in the main exchange in automatic switches, all of said junctions being accessible at said branch exchange for regular traflic to said main exchange, testing equipment at said main exchange for testing the functions of said automatic switches, a distributor switch operatedby said equipment for connecting it to said automatic switches successively, means at the main exchange for associating said equipment with one of said junctions, said equipment thereupon functioning to perform its tests on said automatic switches, a junction busying switch at the branch exchange, and means associated with said one junction at the branch exchange and controlled over said one junction by said equipment for operating said busying switch in synchronism with said distributor switch to thereby busy the originating end of each junction to its normal means of access while said equipment is testing the automatic switch at the terminating end of the same junction.

5. In a testing system, a first station, a second station, a plurality of groups of junctions originating in the first station and terminating in the second station, all of said junctions being accessible at the first station for regular traffic to the second station, testing equipment at the second station for test ing a junction and having means for associating it with each group of junctions separately and connecting terminating ends of the junctions of each group, means at the first station individual to each group of junctions for cooperating with said testing equipment to perform the tests on each junction, each individual means controlled over a certain junction of the associated group by said equipment, and means at said branch exchange for visually indicating the connection of said equipment to the automatic switch of each junction.

6. In a telephone system, a branch exchange, a main exchange, a group of junctions extending from said branch exchange to said main exchange, all of said junctions being accessible to said branch exchange for regular trafiic to said main exchange, testing equipment at said main exchange, controlling apparatus for said equipment and associated with one of said junctions at the main exchange, auxiliary controlling apparatus associated with said one junction at said branch exchange, means at said main exchange for connecting the control apparatus thereat to said one junction, said controlling apparatus and said auxiliary controlling apparatus thereupon functioning to connect said testing equipment to each junction of the group to perform a test thereon, and means at said branch exchange operated by said auxiliary controlling apparatus for marking each junction busy to its normal means of access while said testing equipment is connected thereto.

it successively to the tur 7. In a telephone system, a branch exchange, a main exchange, a group of junctions originating in the branch exchange and terminating in the main exchange in automatic switches, all of said trunks being normally accessible at the branch exchange for regular traffic to the main exchange, routine testing equipment at the main exchange for routine testing said automatic switches and having a distributor switch operated thereby for connecting the equipment successively t0 the terminating ends of said junctions to give the equipment access to said automatic switches, means for associating said equipment with a certain one of junctions at the main exchange independently of said distributor switch to cause said equipment to test all of said automatic switches, means at the branch exchange associated with said certain junctions for marking said certain junction busy to its normal means of access while said equipment is associated therewith, and a busy-marking switch at the branch exchange controlled over said certain junction by said equipment and in synchronism with said distributor switch for marking each junction busy to its normal means of access at its originating end while said equipment is connected to its terminating end.

In testimony whereof I aflix my signa- ARTHUR EDVVABD CASWELL.

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