Abstract
This paper investigates partial discharge (PD) characteristics that lead to the erosion of silicone rubber (SR) polymer under AC stress and DC stress of both polarities. The experiments are performed on high temperature vulcanized (HTV) SR material samples. The inclined plane test apparatus, constructed in accordance with IEC 60587 requirements, is employed to produce the surface partial discharges and the resulting accelerated aging of the specimens. Two commercial instruments are used to obtain the PD data. A concurrent analysis of visual observations of discharge and PD data is performed to classify discharges based on the severity of material degradation that each type causes. Three types of PD are identified and characterized using diagrams of charge magnitude versus time and a signal processing technique called time-frequency mapping. Individual pulse waveshapes of each type of discharge are also analyzed. PD pulse waveforms are analyzed according to their amplitude, energy, pulse width, and frequency spectrum. These pulse waveform parameters are evaluated and compared for the eroding discharge pulses under AC and DC voltage stresses. It is found that the stages of material degradation during IPT are related to the variations in discharge magnitude and the location of pulse clusters on the time-frequency maps.
Highlights
IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
A review of publications pertaining to partial discharge (PD) measurement on polymer insulators showed that the research has mainly focused on the detection of surface pollution severity and dry band arcing under the AC stress [22,23,24,25]
Based on the depth of sample erosion and relatively shorter times to failure, it is concluded that the DC test at 2.7 kV is more severe than AC test at 4.0 kVrms
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Since the late 1960s, polymer transmission class insulators have been replacing ceramic and glass insulators on HVAC lines in coastal and industrial pollution areas [1]. 1970s, following an increase of in-service HVDC transmission lines, polymer insulators were adopted for some DC lines [1]. DC insulators attract more airborne pollution due to electrostatic attraction. Leakage current (LC) and dry band arcing (DBA) activity may develop on contaminated surfaces of polymer insulators
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