GB1250347A - - Google Patents

Abstract

1,250,347. Protective systems. ALLMANNA SVENSKA ELEKTRISKA A.B. 23 Dec., 1968 [29 Dec., 1967], No. 60983/68. Heading H2K. An arrangement for protecting a series capacitor 2 comprises two spark gaps 5, 6, each in series with its own or a common switch device and connected in parallel with the capacitor, a control device 4 being responsive to the current through a spark gap to cause operation of a further switching device to short-circuit the capacitor 2 when the voltage across it becomes excessive. In the arrangement shown an overvoltage across the capacitor 2 causes a gap 5 or 6 to ignite and the resulting current through the gap causes a current transformer 9 or 10 to energize the device 4 which closes a shortcircuiting switch 3 and opens a switch 7 or 8 in circuit with the gap 5 or 6 which ignited. When the fault condition ceases, the reduction in the current through a current transformer 11, connected in series with the switch 3, causes the device 4 to open the switch 3 and after a delay to reclose the switch 7 or 8. A single current transformer may be connected in series with the spark gaps, Fig. 2 (not shown) and a changeover switch may be used instead of the switches 7, 8, Fig. 3 (not shown).