GB732354A - Relay chain circuits - Google Patents

Abstract

732,354. Automatic exchange systems. LICENTIA PATENT-VERWALTUNGS GES. Jan. 22, 1952 [Jan. 22, 1951], No. 1812/52. Class 40 (4). Impulses are reverted from a position P to a main position Q by a relay selector, the relays of which are arranged in a chain. The chain relays step automatically when continuous battery is applied to a control line La by a switch Sch at the main position. The impulses operate the driving magnet DM of a step-bystep switch M until test relay C disconnects battery or until La is grounded by a marking contact T4 at P.. The chain relays are selfholding relays which remain operated by residual magnetism when the excitation is removed. Chain relay contacts in the circuits controlled by the selector are not shown. Relays A, B (only contacts are shown) are operated when the selector is in use. When the switch Sch is closed, relays S1, J, I, O are energized in series but only S1 operates at first and short-circuits its high resistance winding. Relays I and J then operate and O follows after a short delay to interrupt the circuit and thereby to restore both S1 and J. Relays S2, J, II are energized in series with the release winding I(R) of relay I, and S2 operates. Relays II and J operate and the circuit is interrupted as relay I falls back. The relays I, II, III, &c. are operated and released in succession until battery is cut off either by test relay C or key T4, the latter being operative as shown, when relay IV operates. The chain is stepped to normal automatically when battery is connected again to the chain either :by opening T4 or by restoring C, the last relay X being released when winding X(R) energizes in series with resistance W. The chain may alternatively be returned to normal by a release relay Ab which energizes the release winding of the last operated chain relay.