GB396481A - Improvements in and relating to leakage indicators and protective cut-out arrangements for alternating current circuits - Google Patents

Abstract

396,481. Indicating faults. BRITISH POWER RAILWAY SIGNAL CO., Ltd., GLENN, S. L., and PIERCE, E. E., Windsor Works, Slough. March 14, 1932, No. 7565. [Class 37.] A leakage indicator for alternating current circuits, which may also control protective cutout arrangements, comprises a defiectional type instrument with a movable element 4, control coils 7, 8, and a graduated scale 6 with centre zero, where the effect of the control coils is to neutralize each other, the coils 7, 8 being energized from the respective line conductors 1, 2, so that leakage on either line produce a deflection of the pointer 5. The movable element 4 may be arranged to actuate contact members 15, 16 in an auxiliary circuit including visible or audible devices 23, 25, 27 for indicating normal conditions or a predetermined degree of leakage in either conductor. The movable element may also co-operate with contacts in a relay circuit for operating isolating switches for the defective conductor. To make the device more sensitive, the movable element may include a winding 10 connected across the line conductors. In a modified arrangement, the coils 7, 8 are connected to the line conductors through transformers. In a further modification the indicating devices are controlled through relays, the windings of which are in shunt with the control coils 7, 8.