Patent GB-373291-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q1/20
Filed: 1931-02-26
Abstract: 373,291. Automatic exchange systems. AUTOMATIC ELECTRIC CO., Ltd., Strowger Works, and CASWELL, A. E., Ingleside, Milton Road, Edge Lane, both in Liverpool. Feb. 26, 1931, No. 6071. [Class 40 (iv).] A routine tester, for first numerical or first code selectors, tests, amongst other facilities, the return of zone or multiple metering pulses. The routiner is adapted to test switches of the type described in Specification 358,983, and in their general nature the tests applied are similar to those described in Specification 283,991, [Class 40 (iv), Telephones &c.]. Specification 357,186 also is referred to. Normal test. Relay P is energized from the access equipment and earth connected to test start conductor 11 energizes TH, TSDM and relay RA in series. TH locks to 11 and P holds up to earth on 12 if the selector seized is busy. If the lamp indicating key LK1 is operated, LR pulls up and at lr4 enables selector busy lamp ILP to light. The threeminute delay.equipment is started at th11 and after three minutes TB pulls up energizing AL, Fig. 6, to operate LR and the alarm AB, Fig. 1. If the first code selector is free or becomes free during the three-minute period, P releases and TJ pulls up. PAE pulls up in series with BM and YB, but BM does not energize. PE operates. Relay TH completed circuits for IP and IQ, Fig. 4, to operate periodically and, as IQ is slugged, a circuit is completed when IP next operates to energize TSDM and RA. When IQ releases this circuit is broken and TSDM steps wipers a on to the Second contacts. AH pulls up over 5a connecting leads 16 and 17, which are connected to the selector under test, to a bridge comprising AN, AP and retard R. If the circuit, including the selector line relay, is balanced, neither AN nor AP will pull up but if faults occur the following conditions will apply: negative conductor 16 disconnected, resistance earth or battery operates AN ; similar fault on positive conductor 17 operates AP ; conductors reversed, AN and AP both pull up. If the conductors are shorted, the selector line relay would have operated and this is tested later. If either or both relays AN, AP pull up, AM is energized in series with one of the lamps 11LP, 12LP, or 13LP. The circuit to TSDM is opened and the delay alarm is connected. If neither AN nor AP operates, the switch is moved to its third contacts next time IQ releases and the relay bridge across 16, 17 is replaced by resistance YG. No test is made in this position and the switch steps to position 4. The selector line relay operates and connects guarding earth to conductor 12, shorting PAE which restores and releases PE. If PE releases satisfactorily, TS moves to position 5 ; otherwise the alarm is connected and 3LP illuminated. If the selector is acting correct] y a register controller will have been seized and relays energized in the selector connect earth to conductor 18, operating DA. If DA does not operate 5LP lights and the alarm is given. No impulses are sent out from the routiner in this position so that after a predetermined time the register controller releases automatically. Earth is removed from 18, DA restores and the test switch moves to position 8. If DA is maintained lamp 5LP is illuminated and an alarm given. The test switch moves to its tenth position due to the interaction of IP and IQ and as bank 2a is disconnected in positions 8 and 9, the first code selector releases. In position 10 resistance YH is connected across the conductors 16, 17 to test the sensitivity of the selector line relay and earth should again be connected to conductor 12 to release PAE, PE. The test switch steps to position 11 and then to 12. If the guarding earth is not reconnected to 12, 3LP is again lit. When a register controller has again been seized, DA re-operates and wipers a move to position 13. SS operates and connects CC to the pulse springs MPS which pulse at the same rate, e.g. 10 p.p.s. but in phase opposition to springs LPS. When MPS open, CC operates connecting MPS to SDM to rotate the sender switch wipers b. If the zone keys ZSK2..6 (keys not shown) are unoperated, ZSDM will have driven wipers c to their sixth position (over 29). Earth on 23 is therefore connected over 4c and cross connecting frame to 3b which is being rotated by SDM. As the sender switch is being pulsed SA. is operated and LPS pulses to the register controller. When 3b reaches the marked contact, SZ pulls up, shorting LPS and allowing CC to release. SDM steps wipers 5 to their thirteenth position in,which position earth on 2b operates TSDM over 26. Wipers a step to their fourteenth position and SH pulls up connecting the marking earth for 3b from 4c to 3c and connecting YF, which represents the minimum leak resistance allowed in practice, across 16, 17. SA releases when 2b reaches contact 13 allowing SZ to fall away and a second digit is then transmitted to the register controller. When this digit has been sent wipers b are rotated to their twentyfifth position and wipers a to position 15. The register controller routes the call and connection should be extended to conductors 34, 35 and 36, Fig. 2. If this line is not connected with, TT will not be operated and 6LP will remain alight. If the test line is, reached however TT will operate in series with a relay I (not shown) in the first selector and this latter relay will remove earth from 18, allowing DA to restore, TT completes a circuit to TSDM to step wipers a to position 16 and BR pulls up over 5a. At br1 battery is connected to 35 to simulate the battery period of the busy flash and operator hold conditions. TT and I (not shown) restore, earth is replaced on 18, and DA reoperates. Wipers a move to position 17. Relay DD operates over 5a to reverse the connections to 34, 35 to prepare the metering circuit. One metering impulse only should be received for the code sent out. Booster battery is received over 12, operating PAE and BM. BM energizes TSDM (over 25) and ZSDM.(over 24) and when the metering pulse terminates BM and PAE fall away, ZSDM releases moving wipers b to position 7 and MT energizes. MT enables TSDM to move wipers a to position 19 whence it is stepped by IP, IQ to position 21. If BM had not operated the switch would have stopped in position 17 and lamp 7LP would have lit. Should further metering occur ZSDM will be re-operated moving wipers c out of position 7. MT would release and wipers a would remain in position 21 lighting lamp 8LP. If MT is still operated wipers a move to position 22 operating RT over 5a. Conductors 16 and 17 are shorted over 2d and RG operates to connect PPS, which pulse at 20 p.p.s., to RTDM. RTDM steps wipers d and, on the first step, the short across 16, 17 is removed and the first code selector commences to release. When release is complete, earth is removed from 12 and PAE and PE operate to stop RTDM. RG releases, and if the release time of the selector is within the allowable limits, TSDM is stepped over 28 to the twenty-third position. If the time of release is too fast or too slow either lamp FRLP or SRLP would have been lit and AM operated. Earth on 5a is connected over 37 to step the access switch to the next selector and earth is removed from the test start conductor 11. The rotary switches home and all operated relays release. Multiple metering tests. The keys ZSK enable multiple metering tests to be made. To test metering on a call to say the third zone, key 3ZSK is operated. At springs 3zsk2 the fourth bank contact of 2c is disconnected and consequently wipers c are stepped to this contact only. The fourth contacts of 4c and 3c are so wired to 3b to enable a junction to a third zone exchange to be selected. At springs 3zsk1 relay ZS is operated to connect a tone to 16, to busy 36 and to connect the test line seized contacts 15 and 16 of 4a to the automatic stepping circuit of TSDM. The routining proceeds as previously described, wipers a pass through positions 15 and 16 without making a test. If the called exchange is automatic the call is routed to special equipment connected to a spare number. If the called exchange is manual, the operator plugs in and hears the special tone, whereupon she plugs the calling plug into a special routiner jack having the tip and ring connections shorted to simulate " called subscriber replies " conditions. In either case BM will operate from the booster metering pulse received, TSDM will move wipers a to position 18 and ZSDM will move wipers c to position 5. Two more metering pulses must now be received to move wipers c to the seventh position where MT operates and moves wipers a to position 19 whence they move to position 21. If excess metering pulses are received wipers c move on before wipers a reach this position and consequently MT will not be up to re-operate TSDM. If however MT is still up, TSDM reoperates and the test is completed as before described. Routining incoming first-code selectors. An incoming selector does not send out metering pulses but battery reversal takes place when the called subscriber replies. When such a selector is connected with, DS is operated, and wipers c move to their sixth position. When the battery connections are reversed, D operates over 16, 17 and wipers c move to their seventh position. MT operates and the test proceeds as described above. Partial test. The register controller forced release test may be omitted by the operation of key RFRK. Earth is connected to contacts 7 .. 12 of 7a so that the switch steps quickly over these contacts after which testing will proceed normally. False metering. Should a metering pulse be received at any time other than when it is expected, FM, Fig. 1, operates and locks, routining is stopped, AL is operated to give an alarm and lamp 14LP lights. False release. Should the guarding earth on 12 be removed other than at the correct time EP, Fig. 1, operates and locks, an alarm is given and 15LP lights. Switch magnet faults. All routi