GB834789A - An arrangement for selective protection of a substation in power distribution systems - Google Patents

Abstract

834,789. Protective cut-out arrangements. ALLGEMEINE ELEKTRICITATS-G.m.b.H. July 6, 1956 [July 27, 1955], No. 21703/55. Class 38 (5). In a supply system having two incoming high - voltage feeders interconnected by a circuit-breaker and two outgoing low voltage feeders each connected to one of the high voltage feeders through a low-voltage circuit-breaker and a transformer, a relay arrangement has a directional element which selects for tripping one or other of the low voltage circuit-breakers and an impedance or reactance element which effects the tripping of the high voltage circuitbreaker and the selected low voltage circuitbreaker. Fig. 2 indicates the tripping circuit in which the contacts 14 operated by the directional element control a selector relay 13 having changeover contacts 12 to select the appropriate low-voltage circuit-breaker tripping line 6, 6<SP>1</SP>. The closure of the contacts 10 of the impedance or reactance element causes the energising of a trip relay 9 which closes its contacts. to cause the energizing of the high voltage circuit-breaker tripping line 3 and the selected line 6 or 6<SP>1</SP>. A group of transformers with their associated circuit-breakers may be connected to each high-voltage feeder, the directional element selecting the appropriate group of circuit-breakers.