This document is applicable to the charge-based measurement of partial discharges which occur in electrical apparatus, components or systems when tested with alternating voltages (AC) up to 500 Hz or with direct voltage (DC).

This document:
– defines the terms used;
– defines the quantities to be measured;
– describes the measurement frequencies as well as the test and measuring circuits which may be used;
– defines analogue and digital measuring methods required for common applications;
– specifies methods for calibration and requirements of instruments used for calibration;
– gives guidance on test procedures;
– gives some assistance concerning the discrimination of partial discharges from external interference.

The provisions of this document are used in the drafting of specifications relating to partial discharge measurements for specific power apparatus. It deals with electrical measurements of impulsive (short duration) partial discharges, but reference is also made to non-electrical methods primarily used for partial discharge location (see Annex F). Diagnosis of the behaviour of specific power apparatus can be aided by digital processing of partial discharge data (see Annex E) and also by non-electrical methods that are primarily used for partial discharge location (see Annex F).

This document is primarily concerned with electrical measurement of partial discharge in terms of apparent charge for specific power apparatus made during tests with alternating voltage, but specific problems which arise when tests are made with direct voltage are considered in Clause 11.

The terminology, definitions, basic test circuits and procedures often also apply to tests at other PD measurement frequencies, but special test procedures and measuring system characteristics which are not considered in this document may be required. For measurements at higher frequency ranges, see IEC TS 62478 [5]1.

Annex A provides normative requirements for performance tests on calibrators.

NOTE This document defines and provides guidance for charge-based direct electrical PD measurements at the terminals of the equipment under test, differentiating from other PD measurement and detection methods, e.g. acoustic PD techniques or electromagnetic methods in elevated frequency ranges, e.g. ultra-high frequency (UHF).