scope:

This guide describes the test procedure for electrical measurement of partial discharge (PD) in bushings and instrument transformers using wide-band measuring instruments for the evaluation of the apparent charge level of PD occurring under AC and DC test voltages.

Purpose

For the detection of PD events in bushings and instrument transformers when subjected to high voltage tests, it is common practice to measure the apparent charge of the current pulses originating in insulation defects. Depending on the bandwidth used for electrical PD signal processing, this process is characterized as either narrow-band or wide-band signal processing. Without preference for either method, this document focuses on the wide-band PD signal processing described in IEC 60270.

The general diction of this guide, when referring to PD measurement systems, reflects the common use of it within AC systems. PD measurement is also mandatory during testing of DC system components under DC high voltage and is, therefore, also considered in this guide. Since synchronization between partial discharge and voltage waveform is not possible in this case, there is no time based pattern for the measured partial discharge.