Charge injector calibrating partial discharge measurement circuits - has charge storage capacitor supplied by recharge device and short duration switch

摘要

A charge storage capacitor (Cs), supplied by a recharging device (NL) with a h.v. pref. greater than 100 volts, is connected at one end to an output port (K1) via a first high impedance resistor (RL1) and series capacitor (Ca) and at the other end to the other output (K2) either directly or via a further high impedance resistor (RL2). A short duration switch (SK) is connected between the second output and the resistor-capacitor junction. The outputs are connected to the discharge measurement circuit, with test object ports or, at a min. sepn. of 10 cm., to the metal surface of the specimen container or to the specimen potential and pref. to the conducting injector housing (GM) and/or an e.m. antenna radiator (AS). Both outputs can be bridged by a shunt resistor pref. the characteristic impedance of a connected cable. USE/ADVANTAGE - Extremely simple circuit eliminates disadvantages of conventional ones, including high maintenance internal battery supply and limitations of calibration. Charge pulses not only injected into terminals of test piece but also into metallic, usually earthed, housing of h.v. equipment such as large transformers, SF6 switchgear, generators or motors.