Patent GB-588063-A (GB)
Title: Improvements relating to testing arrangements in electric selective switching systems
IPC: H04Q3/42
Filed: 1945-01-26
Abstract: 588,063. Auto matic exchange systems. SIEMENS BROS. & CO., Ltd., and CLARK, R. I. H. Jan. 26, 1945, Nos. 2128 and 5918. [Class 40 (iv)] In an arrangement for testing two outlets from a switch simultaneously, two test relays are provided, each having a single changeover contact normally connected in series with the drive or controlling magnet and shunting an auxiliary relay, each contact also individually shunting an appropriate switching relay. The front contacts of the test relays apply busy potential to the outlets in such a manner that operation of the test relay for a preferred outlet prevents the busying of the other outlet and contacts of the auxiliary and test relays are arranged to prevent simultaneous operation of both switching relays. Fig. 1 shows a uniselector having two sets of double-ended wipers cooperating with four sets of banks and giving access to five groups of 40 outlets each. Outlets for digit 1 are on contacts 11-30 of banks 1 and 3 ; for digit 2 on contacts 31-50 of banks 1 and 3 ; for digit 3 contacts 1-20 of banks 2 and 4 ; for digit 4 contacts 21-40 of banks 2 and 4 ; for digit 5 contacts 1-10 of banks 1 and 3 and 41-50 of banks 2 and 4. Test relays TP and TS test outlets from pairs of banks 1, 2 and 3, 4 respectively. On seizure line relay A, release relay B, code relay CA and dialling relay C operate. The incoming impulses are received on a relay chain CA ... CD, CO, the last being a change-over relay, and these relays mark the wanted group in banks M1, M2 and also control wiper switching. For digits 3 and 4 the code relays operate the wiper switching relays WA, WB. For digit 5, the switch hunts over outlets 1-10 of the oddnumbered banks, whereupon WA and WB are operated over bank M3 and the switch then hunts over outlets 41-50 of the even-numbered banks. Release of C completes a circuit for the magnet over banks 1 and 3 or 2 and 4. If a primary outlet (e.g. on bank 1) is found free, test relay TP operates to earth over the M-bank and battery over the P-bank. Relay TP locks and busies the outlet through its lefthand coil, and interrupts the driving magnet circuit. Auxiliary relay G operates, followed by switching relay HA which locks to the incoming P wire and short-circuits TP which then releases. Secondary test relay TS operates in the same manner if the primary outlet is busy. If both outlets are free, both relays operate, but TP disconnects the locking circuit for TS which releases when G operates. If a number greater than 6 is dialled CO and CC mark the normal contact of the switch, a test relay operates immediately and NU tone is sent out. If all outlets are busy, the switch is stopped on the last contact to send out busy tone. In a modification, Fig. 2 (not shown), for giving access to 40 outlets for each of 10 digits, two switches have their wipers connected in parallel, one switch giving access to outlets of groups 1-5, the other to outlets of groups 6-10. A relay chain of six relays, together with a change-over relay, is provided for marking purposes, the change-over relay being arranged to drive one or other selector according to which set of digits the dialled number belongs. The relay register and test circuit are arranged as a circuit common to several selectors with which they may be associated as required. In a further modification, the counting device counts up to ten impulses and marks any one of ten marking wires. The selector may be provided with four marking wipers connected in pairs over contacts of the wiper switching relay, one pair being connected to one test relay and the other pair to the other relay. By this means groups of up to 100 outlets may be had.