Discussion on Resistivity Testing Method of Semi-conducting screen in Power Cables

Since there is no specific description on the testing process in the Standards of IEC60502 and IEC60840 (Chinese corresponding Standards are GB/T12706-2002 and GB/T 11017-2002), which is on the testing method of semi-conducting screen in power cables, there exist more uncertainties in the resistivity testing result. To reasonably value the resistivity of semi-conducting screen, samples are prepared with domestic or foreign semi-conducting resin. The resistivity measurement is carried out by four-electrode method in the range of 293-393 K. It is shown that each sample made of domestic or foreign semi-conducting resin has a peak in the range of 353-373 K. In addition, the resistivity of samples varying with time is also studied in detail. It is shown that the resistivity decays slowly with time and runs to a quasi-constant value. Finally, the results are discussed and suggestion on test method of semi-conducting screen is proposed in this paper