Patent GB-305956-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04M3/32
Filed: 1927-10-10
Abstract: 305,956. Automatic Telephone Manufacturing Co., Ltd., and Pearce, O. A. Oct. 10, 1927. Semi-automatic exchange systems.- A routine tester is described for testing the functions of repeaters, as shown in Fig. 11, similar to that described in Specification 268,058, which are used in conjunction with coders for setting up calls from an automatic exchange to call indicators at a manual exchange as in Specification 229,371. Primary and secondary 25-point distributor switches for connecting up the repeaters in turn are similar to those described in Specification 292,691, two primary distributors being shown each having access to 24 secondaries, each of which has access to 20 repeaters. A test control switch CS, Fig. 3, steps between each individual fest and lamps controlled thereby indicate the test applied. If a fault is found alarm apparatus operates, due to CS remaining still, and the lamp indicates the fault, while distributor lamps indicate the particular repeater. The tests and the corresponding contacts of CS are :-(2) repeater busy, (3) non-operate high resistance test of impulse relay, (5) operating impulse relay, (6) battery reversal on impulse relay while finding coder, (7) junction loop, (8) pulsing into coder (9) code sending; (10 - - 13) reception of four digits, (14) private guard, (15, 16) private guard, calling loop opened, (17) switching relay test, (18) battery reversal on outgoing lines, (19, 20) transmission test of each line separately, (21, 22) busy flash, (23 - - 25) test complete. Re-set and stepon arrangements are described for recommencing routining after a fault is found. Provision is also made for alarms when a switch sticks, continuous routining and stepping past dead positions. Keys are a so provided for making more severe tests, and for imitating faults in order to test the routiner. In the Provisional Specification is described a substantially identical routiner in which the tests are applied in a different order. Initiation of testing and inter-test stepping of distributor switches. Start key 10, Fig. 10, is pressed to energize, relays S, Fig. 6, SS, Fig. 4, connecting 40 impulses per minute to relay DR, Fig. 6, from conductor 20. Relay P is also impulsed at 10 per second over conductor 19, Fig. 4, so that two-step relays DA, DB pull up in turn, relay TC operating in parallel with the initial circuit of DB. Relay DB releases DA, TO, P, and is itself dependent on relays TO, KA. The second impulse to P was also repeated to magnet DM1 of secondary distributor SD to step it to its second contacts connected to the first repeater. Group indicating lamp 59 and individual lamp 61 are lighted. When the first repeater has been tested, control switch CS, Fig. 3, is on its contacts 23, and relay TO operates to release DB. Relay P is again impulsed to repeat the above operations, SD is stepped to its third contacts, and the second individual lamp is lighted. When all the repeaters connected to SD are tested, relay TO energizes as before, but also completes a circuit over contact 21 of wiper SD60 for relay TS, Fig. 4, which locks up. Relay DB is released so that DA pulls up, and at the next pulse to relay P, relay DC energizes, and magnet DM4 of primary distributor PD1 is impulsed. The first six wipers of PD1 are stepped on and DM5 is then operated over its interrupter springs and wiper 58 (2) to step the remaining six wipers. The second group indicating lamp is now lighted. SD is homed over its wiper 90 from earth at 88, Fig. 4. Relay DC releases TS so that the next pulse to P operates DB as before and steps the secondary distributor associated with the second contacts of PD1. DA, DC, P are released. Routining proceeds until PD1 reaches its 25th contacts, when the test leads are extended to PD2. Relay DX is energized over wiper 92 (25) and transfers the stepping circuit to magnet DM2 of PD2. When all the repeaters have been tested, relay TU, Fig. 6, operates over wiper 95 (25), lights a lamp and operates an alarm relay AM, which disconnects relay P, DR and connects an audible signal. The attendant restores key 10 and the distributors return to normal over back contacts of relay SS. Seizure of repeater. Operation of relay DB on initiation of testing energizes relay RS, Fig. 9, and earth is extended from 62, Fig. 8, to wiper 68 of CS throughout the test cycle. RS steps switch CS to its second contacts and also operates relay TB. The momentary energization of relay TC in parallel with DB operates relay TA, and if the repeater is busy its guarding earth holds up TA until the repeater becomes idle, when earth is connected over back contacts of TA to busy the repeater and to step switch CS to its third contacts. Earth is connected from contacts 120 of relay S to wiper 118 of CS to light successive indicating lamps during the test. Testing. Relay TH, Fig. 8, operates over wiper 68 of CS and completes a high-resistance loop, including unoperated contacts of relay OT, Fig. 5, operated contacts of TH, right-hand winding of relay TF, and resistances 146, Fig. 5, and 135, Fig. 8, across conductors 122, 145, Fig. 2, to the impulse relay A, Fig. 11, of the repeater. If the said relay is of correct resistance it will not operate, but if it is low in resistance it will operate and current in the loop will then be reversed during hunting of the coder-finder, due to operation of relay DD, Fig. 11; relay TF will then operate to energize relay NOT, Fig. 8, preventing the operation of relay ATH and holding up test. If the said impulse relay does not operate, an impulse over contact 151 of DR, Fig. 6, front contacts 153 of TH, Fig. 8, and back contacts 154 of ATH energizes two-step relay TV. The next pulse operates relay ATH to release TY, and switch CS is stepped to its fourth and fifth con. tacts in turn, relay TH releasing at the first step. Relay ATH completes the repeater loop at 160 cutting out resistance 135, and the impulse relay A operates, followed by TF, as described above. Relay OT, Fig. 5, is now energized to disconnect the loop, and connect an impulse from 151 to operate two-step relay OL, and the next pulse now steps CS to its 6th contacts. Relay OTC now operates over wiper 68 and looks up, releasing OT, OL and shorting resistance 146 in the loop, so that TF again operates until the repeater finds an idle coder, when normal current flow will be restored in the loop. Two-step relay TM is energized by this operation of TF, and OS steps to position seven. Relay TD now energizes over wiper 68, and if the outgoing positive and negative lines from the repeater connected to wipers 202, 192 are earthed and connected to battery respectively, high-resistance relays TE, ATE will pull up in turn over 192, 202 respectively, testing the continuity of the lines, and CS is then stepped to position 8. Relay TN is now operated over wiper 68 and looked up. When TM energized the incoming repeater, leads were looped via conductor 125, Fig. 2, 126 - - 131, conductor 241, Fig. 7, armature 215 of relay SW, 216 - - 218, 138 - - 142. Two-step relay CC, Fig. 9, of the impulsing relays CC, SC, SW, SZ, is now connected in a circuit including interrupter contacts 210, Fig. 9, and operates at the first pulse, energizing in turn relay SW. Contact 215 in the loop is opened, but interrupter contacts 220 out of phase with 210 close the loop. The next pulse at 210 energizes relays SC, SZ; while 220 sends an impulse to the coder. Relay SZ releases CC at 213, so that the impulse relays all release. Three more cycles of operation of the relays sends three further digits 1 to the coder. Each make- and-break of contacts 224 of CC energizes in turn relays E, F, G, H, Fig. 4, after which CS is stepped to its 9th contacts by earth at 226. Relay TN energized relay TJ meanwhile to shortcircuit the repeater switching relay HA so that the call-indicator equipment is not operated. The coder sends one positive pulse for each digit 1 such that polarized relay LP is impulsed, causing switch CS to step to contacts 10, 11, 12, 13 in turn, after which relay TR is operated over wiper 68 to step CS to position 14. Operation of TR also connects a pulse from 151, Fig. 6, to relay TV which energizes, and the next pulse is repeated by relay TW to relay TX which energizes fully at the end of the pulse. If the repeater is properly guarded, earth over wiper 112 of SD is now extended to energize relays TY, ATY, Fig. 7, in parallel, and these relays lock up to wiper 112. When repeater relay A operated, relays B, BS and RG operate, and after the code impulses are sent out, relay CZ is operated from the coder. Normally reply by the operator would release CZ and relay H would switch through. At the next pulse from 151, TW again energizes and this time locks up, opening the calling loop so that the repeater relays A, B release, but B3, CZ remains operated. High-resistance relay RG is now connected to the private lead to release TY, ATY corresponding to the release of preceding switches in a normal connection. Relay RG also releases. The repeater is again fully guarded; relay TZ is operated thereby and steps CS to its 15th contacts. If any part of this test breaks down, relay GR operates from earth over 254 - - 259 to guard the repeater by earth at 116; GR is slow to operate to prevent it operating between the release of ATY and energization of TZ. If the test is successful, CS is stepped to its 17th position over a front contact of TZ. Relay TG operates over wiper 68, locks up and forms an outgoing repeater loop, including relay R, Fig. 9, to operate the repeater switching relay H corresponding to the manual opera tor plugging in, and CZ releasing. Stepping of CS from position 15 disconnected slow-release relay TR, TX, TW, TZ release in turn. Relay A, Fig. 11, energizes again in series with TF, TL, the latter also energizing. Relay B then pulls up. CS now steps to position 18, where earth over wiper 68 energizes rela