Patent GB-670096-A (GB)
Title: Improvements in or relating to automatic switches for use in telephone or like systems
Inventor: HOPLEY HORACE EDWARD
IPC: H04Q1/24
Filed: 1949-02-10
Abstract: 670,096. Automatic exchange systems. AUTOMATIC TELEPHONE & ELECTRIC CO., Ltd. Jan. 31, 1950 [Feb. 10, 1949], No. 3622/49. Class 40 (iv). In order to test selectors set by applying to their outlets markings from a common control circuit having impulse - responding equipment, a routiner connects to the selectors in turn and transmits a test digit to the control circuit to set the selector to an outlet not used for traffic. The routiner performs different tests on a selector by making a number of different connections to the selector which is set to different test outlets by the test digit. Group selector. A 200 - outlet motor-driven uniselector has two sets of 4 pairs of wipers connectable by a wiper-switching relay WS. The wipers of a pair are staggered 180 degrees and each covers a bank of 52 outlets in alternate half revolutions. The outlets 2-51 are traffic outlets, and the first outlet of the odd-numbered wiper banks is the normal position. The common control circuit (shown below the chain-dotted line) tests free by battery connected over resistance YE to the incoming p-wire. When the circuit is taken into use, relays B, JB disconnect the testing - in circuit. The digit is registered on the counting chain CA ... CF, one of the relays CB ... CF remaining operated if the digit is 1 ... 5. On the sixth impulse relay CO pulls up, followed by CP, and these relays together with one of CA ... CE remain operated if the digit is 6-0. The register relays apply a marking over a lead ML to the wanted group and connect up the wiper-switching relay WS over a lead WD if the wanted group is in the hundred outlets - 1, + 1, P1. If the wanted group is in the evennumbered wiper banks, a strapping from one of leads PLA ... PLF to PLL or PLH completes a circuit for a relay PP after the receipt of the appropriate number of impulses, and PP locks up to energize a latch magnet LM and the driving magnet DM rotates the wipers to contact 52 in the odd-numbered banks, whereon a circuit is completed over the upper winding of PP and a resistance YH in parallel to operate a test relay TA and to release PP. This pre - positioning of the switch ensures sufficient time for hunting during the interdigital pause. The release of the dialling relay C is followed by the operation of DG which initiates hunting. When an idle outlet is found relay H switches through and provides a holding circuit for WS if the latter is operated, and the control circuit is released. Should all the outlets be busy, the switch is rotated to position 52 of the even-numbered banks, and a circuit is closed for relays. TA, OM. The latch magnet LM releases, as it is connected in series with the upper winding of sluggish relay TB. TB disconnects OM, thus operating an overflow meter indivudual to the wanted group over one of the leads MO, and also connects up H which switches the talking wires through to the busy tone circuit. In the case of dead numbers the appropriate leads ML, WD are strapped to leads DN, WSO so that when the dialling relay C releases at the end of the digit, relay WS pulls up and the test relay TA is operated over lead DN when the wipers reach position 52 of the odd-numbered banks. Relay H then switches through to the number unobtainable leads NUT, NUTR. Testing. The routiner connects over access equipment to close a line loop to the talking wires and the usual tests are applied to the relays A, B. It connects battery over a high resistance relay to lead RP,T earths lead RHC to prevent the dialling relay C releasing at the end of the test impulse train, and connects lead RWD to lead WSN (the latter being strapped to those leads WD corresponding to digits not necessitating wiper switching). The routiner transmits a test train of 11 impulses thus operating the register relays CF, CD, CP. At the appropriate impulse, relay PP is energized to pre-position the switch to the last contact of the odd-numbered banks, whereon the high resistance relay connected to lead RPT operates to show that the pre-positioning has been effected and to serve as a check on the stepping speed of the selector. The routiner after PP has released connects low resistance battery to lead RPT to operate TA and so to prevent hunting and disconnects lead RHC to release C. DG operates and TB, H follow to switch the talking connection over wipers 53, 57 to leads R -, R+, which are connected to the routiner. After the usual tests have been made, the routiner releases the switch, and then repeats the above procedure making no connection to leads RHC, RPT, but connecting a battery simulating the idle condition to lead RSC. On the release of C at the end of the test digit 11, a circuit is completed over leads RWD, WSN for relay DG, the wipers step to the first contact of the even-numbered banks, and the routiner is switched through over wipers 54, 58 to the test leads R -, R +. This procedure is performed by the routiner for the third time with leads RSD, WSO strapped, so that WS operates and the switch connects over the last contacts of the banks S1, S5 to the number unobtainable tone leads NUT, NUTR. The completion of the connection is tested by a tone detector in the routiner. Finally the routiner earths the lead RE to mask the battery connected over resistance YA and repeats the third test, thus the switch is set in response to the test digit 11 to the last contacts of banks 52, 56 and busy tone is reverted to the routiner from leads BT, BTR.