Bbc Brown, Boveri & Company, Limited

Pierre Braissant

Ivan De Mesmaeker

A process and device useful in the protection of AC current circuits, particularly of parallel lines supplied at both ends, provided with protection relays at both ends of the line against susceptibility to false triggering as a result of transient signal components and signals disturbances, and particularly useful in providing stepped protection upon initial disconnection at one side of a line after occurrence of a short circuit against the change of energy direction with reversal of the fault direction detected in the protection relay of the sound line on crossing the triggering range of the appropriate characteristics curve, which also leads to false triggerings in multi-system protection relays because of transient switching inaccuracies. On the transition of a protection relay from the blocked to the triggering condition, the process and device maintains the blocking condition for a limited time interval of at least a half period for the phase angle measuring systems with coincidence and anticoincidence signals (k and ak respectively) by means of an interlocking circuit connected to an anticoincidence channel of one measuring system and released for triggering after a predetermined time.

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Vevey, Switzerland

Pierre Braissant