GB434118A - Method of connections which effects a delayed release of station protective switches when a non-permissable voltage arises between neutral and earth - Google Patents

Abstract

434,118. Protective cut-out systems. SCHIELE & BRUCHSALER-INDUSTRIEWERKE AKT.-GES., Baden-Baden, Germany, and CRABTREE & CO., Ltd., J. A., Lincoln Works, Walsall. Jan. 29, 1934, No. 2922. Convention date, Jan. 27, 1933. [Class 38 (v)] Automatic circuitbreakers; electromagnetic switches.-An arrangement for releasing a station protection switch automatically on the occurrence of an excess p.d. between earth 2 and the neutral O of a polyphase system R, S, T, O, as for example when it is crossed by an h.t. line, comprises a spiral spring 3 connected to O and arranged to act on an oscillatory body 4 having a contactcarrying arm 5. The time-relay 1 is normally connected between O, 2 by means of closed contacts on its armature and the arm 5. When excess p.d. occurs, the coil 1 attracts its armature and imparts an impulse to 3, 4, at the same time breaking its own energizing circuit. When, at the end of its backward swing, 5 re-energizes the coil 1, it receives another impulse, and this process is repeated until contact 5A on arm 5 engages the adjustable contact 5B and energizes the trip coil 12a. Other forms include a known type of timerelay which breaks its own energizing circuit and makes that of the trip coil, and a bimetal strip similarly functioning. In Fig. 1 (not shown), the time-relay operates without breaking its own energizing circuit. The timerelays are stated to be located outside the box containing the protection switch.