IMPROVEMENTS IN OR RELATING TO OVERCURRENT OR OVERLOAD PROTECTIVE ARRANGEMENTS HAVING GRADED OPERATING TIMES

摘要

1,274,117. Protective arrangements. SPRECHER & SCHUH A.G. 20 Nov., 1970 26 Nov., 1969], No. 55298/70. Heading H2K. An overload protective arrangement for a network comprises a plurality of time-delay relays 6a ... 6e having elements to adjust their time delays in steps, circuit breakers 7a ... 7e controlled by the relays and a computer 9 connected to the relays to determine the location of a fault and effective to cause the setting of the adjusting elements of the relays so that the relay or relays 6c, 6d nearest the fault is or are set to operate in the shortest time t 0 and that or those nearer the supply or supplies 1, 10 to the network have progressively increasing operating times t 1 , t 2 . In a network having one supply point, the relays are overcurrent relays, but in a network having two supply points the relays are directional overcurrent relays. It is stated that the computer may be connected to the operating elements, adjusting elements and switching elements of the relays by telephone trunk lines, high-voltage carrier frequency, or microwave lines, or laser channels.