GB646196A - Improvements in commutators having a marking multiple common to several marking devices - Google Patents

Abstract

646,196. Automatic exchange systems. COMPAGNIE GENERALE D'ELECTRICITE. March 14, 1946, No. 7984. Convention date, Sept. 7, 1943. [Class 40 (iv)] In a marker selection control system in which the markers employ separate current sources and simultaneous testing takes place over a common marking multiple, in the event of a cross-connection occurring, the two test relays involved operate in series with the two current sources in a symmetrical circuit. Operation of each test relay is followed by that of a vibrating relay in the associated marking device and these relays which operate non-synchronously destroy the symmetry of the test circuit and thus bring up a third relay of one of the markers which causes the associated selector to step on, and break down the cross-connection. As shown, when a cross-connection between the two selectors S1 and S2 occurs, the test relays 1 of the markers A and B operate in series with the current sources U in a circuit over the marking switches D and the common marking multiple; but since the circuit is symmetrical no potential difference exists across the relays 3. However, the test relays bring up the associated relays 2 which thereupon vibrate non-synchronously, each alternately removing and reconnecting the short-circuit across the resistor R1 in the corresponding marking device, so that when one resistor is in circuit and the other is short-circuited, the relay 3 of the first marking device operates to the potential difference produced across it and steps its associated selector, whereupon both the test relavs release and the selectors continue their searches. Specification 668,261 is referred to. Reference has been directed by the Comptroller to Specification 651,264.