GB605886A - Apparatus for the selective switching-off of sections of line of an electric distribution network - Google Patents

Abstract

605,886. Protective cut-out systems; electrically-released switches; retarding action of switches. LANDIS & GYR SOC. ANON. Sept. 25, 1945, No. 24834. Convention date, Sept. 26, 1944. [Class 38 (v)] In apparatus for the selective switching-off of sections of a distribution network, for example on the failure of a quick-acting distant cut-out, each main switch 1 has a time-relay 7 dependent on voltage only and connected to the mains in such a manner that, apart from the switches beyond the short-circuit point, only the switch next before that point is opened, whilst the others remain closed due to the higher potential and longer switching time of their relays. Upon a short-circuit at 44, the contacts 5, 6 of the undervoltage relay 4 close and coils 8a, 9a and 31 are energized. The latter rotates a pin 19 on a spring-urged armature 32 clear of a contact-carrying arm 15 on a spindle 13 which is then rotated by a spring 17 to close contacts 14, 18. This closing movement is braked by coils 8a, 9a which act on an S- shaped armature 10 on the spindle 13, so that the time required for closing is dependent upon the voltage in the mains adjacent the switch 1 and increases for switches away from the shortcircuit point. Closure of contacts 14, 18 energizes a relay 30 which closes holding contacts 23, 26 and contacts 37, 38 in the trip-circuit of switch 1. When the latter opens, all the relays 7 are restored to their normal positions. The time of closing of contacts 14, 18 for a given voltage may be adjusted by a lever 39, 41 acting on the armature 10, or by adjustment of the fixed contact 18. The under-voltage relay 4 may be replaced by an over-current relay or by a combination of the two kinds of relay. The armature 10 is so shaped that the first half of its movement is braked, but the remainder is not, so that the contact pressure is thereby increased. The cores of the electromagnetic brake may contain insets of high initial permeability metal, such as " Mumetal" (Registered Trade Mark), arranged on the outer sides of the cores in order to increase the braking effect.