The detection and measurement by the wide-band apparent charge method of partial discharges occurring in liquid-filled power transformers and shunt reactors during dielectric tests are covered. This standard covers the measuring instrument, calibrator characteristics, test circuits, calibration procedure, and partial discharge measurement during induced-voltage tests.

This test procedure applies to the detection and measurement by the wide-band apparent charge method of partial discharges occurring in liquid-filled power transformers and shunt reactors during dielectric tests, where applicable.

Partial discharge measurements in transformers and shunt reactors may preferably be made on the basis of measurement of the apparent charge. Relevant measuring systems are classified as narrow-band or wide-band systems. Both systems are recognized and widely used. Without giving preference to one or the other, it is the object of this document to describe the wide-band method. General principles of partial discharge measurements, including the narrow-band method, are covered in IEEE Std 454-1973 [7]1, IEC 270 (1981) [2], and IEC 76-3 (1980) [1].