Partial-discharge measurement of a high-voltage transformer

摘要

For measuring the partial discharge, the low-voltage winding (NW) of a flyback transformer (T) to be tested is excited with flyback pulses for a short time in order to charge the transformer (T) to the specified high voltage. During the charging process, a partial-discharge detector (D) is decoupled from a measuring impedance (Zm) connected in series to the high-voltage winding (HW) of the transformer (T). The partial discharge is measured during the direct-voltage state existing after the charging process, in which state the coupling between measuring impedance (Zm) and partial-discharge detector (D) is restored. To calibrate the partial-discharge measuring device by means of a calibration pulse of known charge quantity, diodes (D1...Dn) connected into the high-voltage winding and moulded together with the transformer are biased in the forward direction. <IMAGE>