Test Analysis of Insulation and Moisture Resistance of Insulation Support Plate of Electrical Penetration in Containment of Nuclear Power Plant

The variation trend with temperature and relative humidity of water absorption, dielectric loss, relative permittivity, insulation resistance, volume resistivity, surface resistivity, and dielectric strength of polysulfone are measured. Polysulfone used as the insulating support plate on the medium voltage electrical penetration is designed and produced by Nuclear Power Institute of China (NPIC). The result shows that the relative humidity of environment has a significant effect on the water absorption of polysulfone. When the ambient temperature is 23℃ and the relative humidity increases from 30% to 98%, the corresponding water absorption increases from 0.012% to 0.106%, with a growth rate of 783.3%. The insulation resistance decreases gradually with the increasing of ambient temperature and relative humidity, with a maximum decreasing of 99.82%. However, the interphase insulation resistance of the insulation support plate of the electrical penetration is always greater than 200 TΩ. At the same time, the insulation resistance is greatly affected by its surface resistivity. The variation trend of insulation resistance and surface resistivity with ambient temperature and relative humidity is very close. The relative permittivity and dielectric strength are little affected by the ambient temperature and humidity. The insulation support plate of the medium voltage electrical penetration designed and produced by NPIC is with excellent moisture resistance and electrical insulation performance, and can work stably and reliably in high voltage, high temperature and high humidity environment.