GB1172345A - Surge Arrester - Google Patents

Abstract

1,172,345. Surge diverters. SIEMENS A.G. 16 May, 1968 [22 Sept., 1967], No. 23449/68. Heading H2H. A surge diverter includes a current-sensitive element which breaks the circuit through the diverter when the current is excessive. In the embodiment shown, a surge in a conductor connected to terminal 3 of the diverter can escape to earth through terminal 28 by breaking down a spark gap 14 between two copper discs 6, 8. The current flows by way of a voltagedependent resistance diso 10 and a disconnecting device 21 which includes a soldered joint 20 and a fusible wire 23. The wire may be in the form of a strip. When the surge has been dissipated, the spark gap 14 should be automatically restored, but if this does not occur, the small current still flowing heats the disc 10 and softens the joint 20 so that a spring 27 pulls a pin 18 from the joint and breaks the circuit. Too large a surge current may destroy the disc 10, and in this case the wire 23 fuses rapidly to break the circuit more quickly than could the soldered joint 20. In order that a small current should cause disconnection at the joint 20 rather than at the wire 23, the minimum response current of the wire must be higher than that of the joint.