GB163308A - Improved apparatus for protecting electric supply circuits comprising aerial lines - Google Patents

Abstract

163,308. Akt.-Ges. Brown, Boveri, et Cie. May 15, 1920, [Convention date]. Protective arrangements for electric supply circuits. Apparatus is provided for preventing the action of the automatic switching-in device of the maximum current switch of a feed line in the case of a pendulating or intermittent short circuit. A relay in parallel with the maximum current switch controls a time relay permitting the closure of the maximum current switch only after the expiration of a certain period of time following re-establishment of normal circuit conditions. In switching in the feed line a with busbars b alive, a time relay m is energized closing contacts n completing the closing circuit of the maximum current switch c with automatic closing device e. If a short-circuit is present on the line d, the relay g is energized, breaking at contacts f the circuit of the time-relay m, thereby preventing closure of the switch c. On cessation of the short-circuit, the relay m is again energized, and, after a period of time determined by the setting of the time-element mechanism o, the contacts n are bridged and the main switch c is automatically closed. If the short-circuit recurs before this action is completed, the relay g is again energized and the core of the relay m drops to its initial position.