GB828365A - Improvements in and relating to capacitive voltage transformers - Google Patents

Abstract

828,365. Capacitive voltage transformers; protective arrangements. MICAFIL AKTIENGESELLSCHAFT WERKE FUR ELECTROISOLATION & WICKLEREI - EINRICHTUNGEN. April 12, 1957 [April 12, 1956], No. 11999/57. Class 38 (4). In a capacitive voltage transformer of the type whereby capacitors C1, C2 form a potential divider with an electromagnetic transformer T connected across the earthed capacitor C2, a protective device Z2, comprising at least an impedance, is connected across capacitor C2 to damp oscillations lower than the supply frequency. Z2 comprises a parallel L.C. circuit, resonant of the supply frequency, which acts as an inductive load at lower frequencies thus attenuating them. Z2 may be connected across the secondary winding, or the whole or part of the primary winding of transformer T. Oscillations of the supply frequency are quenched by a spark gap F arranged to be self-extinguishing by a series impedance Z1, which may consist of a capacitor, preferably with a series resistor, and preferably associated with a discharge resistor. The spark gap may be connected before, or after, inductor L1, which suppresses oscillations in the transformer primary circuit and compensates for the volt drop of the capacitive divider. Resistors R1, R2 represent the internal resistance of inductor L1 and transformer T.