STUDY OF TREEING PHENOMENA IN THE DEVELOPMENT OF INSULATION FOR 500 KV XLPE CABLES

This review summarizes research on treeing phenomena i.e. the formatio n of electrical trees and water trees, that has been undertaken in Jap an for the development of 500 kV XLPE cable. Section 1 presents the re sults of factors affecting XLPE cable insulation breakdown under comme rcial ac and lightning impulse voltages. Section 2 verifies the phenom ena of electrical tree formation in XLPE cable insulation using block samples and model cables, and gives the results of studies to determin e the level electrical field stress initiation for such trees. Section 3 summarizes the results of studies on long-term aging characteristic s, which is a particular problem under commercial ac voltages, while S ection 4 explains how this research influenced the design of 500 kV XL PE cable insulation. All authors were members of The investigation com mittee of fundamental process of treeinng degradation' under IEEJ.