Patent GB-460584-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/00
Filed: 1935-07-29
Abstract: 460,584. Automatic exchange systems. AUTOMATIC ELECTRIC CO. July 29, 1935, No. 21528. Convention date, Sept. 6, 1934. [Class 40 (iv)] In a register-controller system, the selectors and register-controller mutually control each other over one of the line wires, initiation of hunting at group selectors and preparation for line selection at connectors being effected by a signal from the register-controller over the other line wire. The control exercised by the selectors, which are of the single motion type, consists in reduction of the resistance of the circuit by short-circuiting a high resistance winding of the line relay, to operate a marginal relay at the register-controller. The marginal relay effects the release and re-operation of the line relay which respectively cause the selector to be kicked off a group contact and to be stepped automatically to the next group contact. Line selection within the selected group at the connector is controlled in a similar manner. The system also comprises primary and secondary line finders, primary and secondary trunks being selected by finder switches associated with the register-controller. A group of register-controllers is provided for a group of 500 subscribers' lines, each 100 of which is accessible to a group of 10 primary finders, the five groups of which are accessible to secondary line finders. After the registercontroller has found an idle secondary trunk, and an idle primary trunk in the group in which the call appeared, the primary finder searches for the calling line and the secondary finder then searches for the primary trunk under control of an A.C. test circuit passing over the wipers of the primary and secondary trunk finders of the register-controller. The finders and selectors are single motion switches having two sets of banks and two sets of wipers at 180 multipled together. The only equipment individual to the finders is an operating magnet, the remaining equipment including spark quenchers for the magnets, being provided in common in the register-controller. The light contacts of two-step relays are marked I. Seizure of register-controller ; non-numerical switching. Line relay 10 marks the line contacts in the primary finders, group contacts in the primary trunk finders 611 ... 617 associated with register-controllers, and operates relay 740 in the register-controller preselected by allotter 33, 34. Relay 750 pulls up and makes driving and test circuits for finder 271 ... 277 which connects the register-controller to an idle secondary trunk. When an idle trunk is reached, test relay 770 operates in series with idle battery over relays 320, 330 in the group selector, locks up, and shortcircuits its upper winding to energize two-step relay 320 which operates contacts I, marginal relay 330 remaining inert. Slow-operating relay 720 pulls up over wiper 913 of control switch S, and makes driving and test circuits for the primary trunk finder, Fig. 6. Circuits for the upper windings of 700, 710 are completed without effect. The calling sub -group is marked by battery on the bank of wiper 611 which is connected to test relay 710, but this relay is shunted over wiper 614 by ground at busy primary trunks. When 710 operates, it kicks the allotter off and makes driving and test circuits for the primary line finder PF, test relay 700 operating when the line is found, this relay being shunted by ground on busy lines. Cut-off relay 20 operates, line relay 10 falls back, test relays 700, 710'hold over their upper marginal windings, and impulse relay 730 in the register-controller pulls up over the calling loop. Slow releasing relay 760 connects dial tone (from Fig. 9) to the calling party, operates magnet 920 of distributer SS which takes a - step to connect up the thousands register, and energizes 870 which connects an A.C. source to the primary of a transformer T. The secondary circuit of T includes A.C. test relay 790 of the selected secondary line finder SF, the circuit passing over wipers of the primary and secondary trunk finders. The driving circuit of the secondary line finder was made by test relay 700 of the primary line finder, and when the A.C. relay 790 operates it removes a shunt from 780 which holds in series with secondary line finder magnet 161 and releases 790. The secondary trunk is not switched through. Operation of register-controller. Relay 730 repeats the digits over slow relay 900 and distributer SS to the registers RA ... RD, relay 900 opening the circuit of distributer magnet 920 at the commencement and closing it at the end of each digit to connect up the registers in turn. As each register RB ... RD goes off normal it prepares for transmission of the previous digit. When RB goes off normal, relay 820 pulls up, operates slow relay 850 over wiper 886 (normal) of the counting switch CS, makes a circuit for the back stroke magnet 885 of CS, and connects battery over marginal relay 830 and the negative conductor to both windings in series of line relay 310 of the first group selector, relay 830 remaining inert. Relay 850 makes a circuit for back stroke magnet 910 of the control switch S. The group selector in its normal position and subsequently in positions immediately preceding. the commencement of groups sends back a signal comprising a reduction of resistance in the circuit of marginal relay- 830 to operate this relay. Relay 830 operates 840 and 820 falls back to shunt down 840, open the circuit of magnet 885 so that CS takes a step, and open the circuit between 830 and the line relay of the group selector. When 840 has released, 820 pulls up again and re-connects 830 to the line relay. The release and re-operation of the line relay causes the group selector to step over a group as will be seen later. This cycle of operations is repeated until CS reaches the terminal grounded over RA and S, whereupon 860 pulls up, locks, causes CS to restore, and operates 810. Relay 850 falls back. Owing to the operation of 810, the next operation of 820 connects the marginal relay 830 to the positive conductor to bring about hunting at the group selector. The relapse of 850 releases 860 and opens the circuit of magnet 910 so that control switch S connects up the hundreds register. The group selector will have found an idle outlet, switched through, and released 830 by the time 860 has relapsed, so that 810 falls back and opens the locking circuit of 820, but this relay is maintained over the off-normal springs of register RC. Relay 850 pulls up again and the register-controller is ready for controlling the 2nd group selector in a similar manner to the 1st. The control of the connector for selection of the tens group is also similar except that the stopping positions of the connector are two contacts before the commencement of the groups. On the last cycle controlling the tens selection, when 820 falls back to step CS to the marked contact, 860, 810 pull up and CS goes home, 830 falls back so that the connector takes one step to the contact preceding the wanted tens group, 820 pulls up again, holds to 810 and connects 830 to 430 in the connector which at this time has both high and low resistance windings in circuit so that 830 remains inert. Relays 850, 860 have by this time relapsed owing to the homing of CS, and 810 therefore falls back to release 430 at the connector. The operation and release of 430 prepares the connector for step-by-step control as will be seen later. The relapse of 810 also connects 830 to the line relay 410 at the connector, the magnet of which pulls up to shortcircuit the high resistance of the line relay to operate 830 which is followed by the operation of 840 and the release in turn of 820, 830, 840, CS and the connector being stepped on the relapse of 820 which operates again on the relapse of 840. These cycles continue until the relapse of 820 steps CS on to the marked contact whereupon 860, 810 pull up, CS goes home and 820 on re-operation is held by 810 which connects 830 to 430 at the connector. Relay 430 has its high resistance winding shorted at this time so that 830, 840 pull up again. At the connector, a successful test disconnects the line relay so that 830 relapses while 850, 860, 810 have been released by the restoration of CS. The relapse of 850 steps the control switch S from the fourth to the fifth positions in which magnet 910 of S is again operated over its interrupter springs and wiper 914 of S which therefore steps to the sixth position in which the holding ground over wiper 913 for relay 720 is removed to release the register-controller. The ground on wiper 913, however, operates 210 in the secondary trunk to prepare for the completion of the speaking connection. Release of register-controller after completed call. Relay 720 operating as described in the preceding paragraph, releases 700, 710 and 770 and magnet 290 of the secondary trunk finder steps until its circuit is opened by the relapse of 750. Relays 780, 730 and 760 fall back in turn and the circuit of 740 is now opened so that when its weighted armature comes to rest 750 falls back. The relapse of 760 releases 870 which makes homing circuits over relay 880 for all the register and control switches, 880 maintaining the register-controller busy to the allotter until this has been done. 1st and 2nd Group selectors, Fig. 4. It will be recalled that, on seizure of the 1st group selector, two step relay 320 operates its contacts I and that when the register-controller is ready to send, line relay 310 operates over both windings in series. The back' stroke magnet 338 is energized over the first contact of bank 345 and short-circuits the high resistance winding of 310 in response to which the marginal relay in the register-controller causes the counting switch to take a step and relay 310 to be released and re-operated by the registercontroller. On the relapse of 310, the magnet is released to kick the selector off the grounded