Patent GB-661884-A (GB)
Title: Switching system for establishing a number of connections by means of one or more multiple switches, for example, for use in an automatic telephone exchange or the like
IPC: H01H67/06
Filed: 1948-09-10
Abstract: 661,884. Automatic exchange systems. STANDARD TELEPHONES & CABLES, Ltd. Sept. 10, 1948 [Sept. 13, 1947], No. 23840/48. [Class 40 (iv)] A multi-switch described in Specification 658,295, the general construction of which is shown in Fig. 1, is employed as a group selector controlled by a register controller, outlets being selected by comparing potentials. Comparison of potentials. Registration of a digit in the register-controller connects the member RF to one of ten reference alternating current potentials in known manner and closes start selection contacts ss to operate relay Hpr, which energizes relay Ar, Fig. 7, over conductor a1 and the multi-switch comprising the preceding selector. Relay Ar operates the power magnet P1, corresponding to magnet 39 in Fig. 1, to rotate the carriage 25 so that contact members I, II move over contacts E, D. Characteristic potentials are connected to wires e1n of the free outlets of the individual selectors in the succeeding switching stage, in the same manner as shown connected to wire e1. These characteristic potentials are thus connected in turn to the primary of transformer TR1 of the comparator, Fig. 6, and when a characteristic potential corresponds in voltage and phase with the reference potential applied by RF to transformer TR2, a rectifier tube SV1 becomes inert to cause discharge tube SV2 to ionize and operate Wpr and test relay Tr, Fig. 7, which releases magnet P1 to halt the carriage. Direct current potentials may be used for comparison instead of alternating current, as described in Specification 577,088. Direct current test. Operation of relay Wpr connects relays Dtr, Dpr via the preceding selector, wire c1 and contact member II to the inlet wire d1n of the subsequent selector, so that if battery is present, in the manner, of contact A4, Fig. 7, both test relays operate, provided that not more than one register is trying to seize the outlet concerned, in which case a double-test takes place in known manner. Through connection. If the direct current test is successful, operation of Dpr releases Hpr and removes the operating ground of relay Ar, whereupon magnet H and relay Ar operate in series to a ground on wire e of the preceding selector. Operation of magnet H, corresponding to magnet 96 of Fig. 1, is individual to a horizontal level of the multi-switch and moves a slidable ring-shaped member 92 into first operative position to complete selection of the individual switch. Magnet H also operates power magnet P2 which causes cams 64, 65, Fig. 3, to make one revolution to advance the feelers 68, 69, the feelers in the selected level pushing the corresponding contact-finger 3 to close the selected contacts, the member 90 pushing the ring 92 to lock all contact-fingers in that level in their advanced or retracted positions. Wires a1-d1 are thus brought into contact with wires a2-d2 and ground is connected to wire e2 of the selected outlet. Movement of the ring into locking position opens contacts. RII-RI3 to release magnet P2 and relays Tr, Wpr, the last restoring the doubletest relays Dtr, Dpr in the register controller, which resumes initial condition. The common mechanism is now free to make another connection. Non-successful direct-current test. If the D.C. test is unsuccessful, for instance due to the simultaneous seizure of the selected outlet by another selector, test relays Dpr, Dtr will not operate and relay Dmr pulls up slowly to release Hpr so that Wpr and Tr restore, after which Dmr releases to restore the register-controller to initial condition so that a further attempt is made to obtain the desired connection. Release of connection. Release of ground from wire e1 of the preceding selector restores relay Ar and magnet H, whereupon the switch releases. Specifications 565,785 and 632,220 also are referred to.