Reproducibility of Partial Discharge Measurements on Surface Discharges according to IEC 60270 at DC and AC Voltage

Partial discharge measurement at AC voltage is one of the most important diagnostic tools for testing and evaluating the condition of high-voltage equipment. The requirements for the measuring system, the test setup and the test procedure as well as the evaluation methods are defined in IEC 60270. Acceptance criteria and measurement procedures are defined in the corresponding standards of the different equipment. For partial discharge measurements at DC voltage stress, the requirements have to be questioned, due to the different partial discharge behaviour of some defects and the lack of experience at DC voltage. Due to the increasing use of HVDC transmission systems in the future transmission grid, partial discharge measurement at DC voltage is becoming more and more important. For this reason, the applicability of IEC 60270 for partial discharge measurements at DC voltage was examined in different round robin tests. After the already published measurement results on epoxy insulators and measurements on a needle-plate arrangement, this paper presents investigations on surface discharge arrangements and analyses, compares and discusses the results of the different laboratories.