The pulsed electroacoustic method (PEA) has been applied to observe space charge formation under ac application (7 kVpk, 50, 0.1 and 0.001 Hz) in water-treed polyethylene samples in order to understand the degradation mechanism of water trees. A system with phase-resolving capability has been developed to measure the space charge distribution at any phase angle of the applied ac voltage. By comparing the observed charge distributions with theoretically predicted ones, it has been shown that the interfacial polarization due to the difference in conductivity between the treed and the regions without trees dominate the space charge behavior. It has become clear that the PEA method can be a powerful nondestructive method for evaluating water tree length.
|IEEE Transactions on Dielectrics and Electrical Insulation
|Published - 1997
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