No abstract

Ahs tractThis paper reports on the results of B basic inquqr for the purpose of developing extrusion-molded joints (EMJ) for use with 500-kV XLPE cable. The Ruthors have made it clear that the itlctors that govern FMJ perfomance, like cable perqormance, are contaminants in the insulation and protruslons in the semiconductor layer. Through modeling experiments we determined the minimum breakdown strength of EMJ and used this to determine desfgn values for 500-kV P I . Fjnally, we carried out breakdown tests on actual equipment, resulting in the prospect of the pctual realizatfon of 500-kV EM.1.

In the field of HV DC cables, oil impregnated paper insulation is widely used. It has generally been found that polymeric type insulation does not provide sufficient reliability for this purpose. This paper relates to the investigation of polymer insulating materials for HV DC cables.From the results of tests to establish dielectric breakdown strength (EB) in various types of polymeric materials (using sheet samples), modified HDPE, which was produced by introducing a small amount of polar group into HDPE, was selected as a promising new material. The outstanding DC breakdown characteristics in modified HDPE were assumed to be attributable to the improvement of the materials intrinsic breakdown strength due to the presence of high crystallinity polyethylene, in addition to the control of space charge due to the polar group.These tests have proved that the excellent Eg of modefied HDPE make it suitable to cable insulation applications, particularly as its DC EB is 1.5-2.0 times as high as that of a conventional XLPE cable.

No abstract