the standard of Partial Discharge Measurement
Dec 11, 2024
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A partial discharge measurement is some other necessary way to confirm the transformer's insulation system, making sure that no hazardous PD sources exist. The cause of a PD measurement is to notice and localize areas where partial discharges are about to occur, commonly cavities or conducting particles inside of the insulating material. Those areas are uncovered to greater dielectric stresses, which can be very detrimental to transformers insulation (e.g. electric powered breakdown) in the long run. So typically PD measurements are carried out in conjunction with dielectric checks (Induced voltage test).
IEC 60076-3
Annex A "Application guide for partial discharge measurements during AC withstand voltage test on transformers according to 12.2, 12.3 and 12.4
IEC: 60270
"Partial discharge measurements
IEE: C57.12.90
Clause 10.8/10.9: "Induced voltage tests
Because the partial discharge measurement and the induced voltage test are carried out simultaneously, the corresponding measuring circuit of the customized vector group is consolidated in the next section ("Induced voltage test", see 10.5 Appendix: Measure arrangement of customized vector group).
A partial discharge is a partial voltage breakdown within a series of insulating elements between two electrodes (of different potentials). It can be interpreted as an electric charge from one position to another. For very fast changes the individual insulation links between two line terminals can be regarded as a number of series connected capacitors, which is a potential source for discharges. The excessive stress in these "weak" spots can result from design- or insulating material flaws or deviations in the manufacturing process. Damage to the insulation caused by previous tests is also possible.
