Analysis of Thermal and Electrical Properties of ZnO Arrester Block

초록

Voltage-current characteristics of ZnO surge arresters are highly dependent on temperature in the low-conduction region. ZnO surge arresters experience thermal runaway when the temperature exceeds the acceptavle limit. This phenomenon is associated with the increase of resistive leakage current due to degradation. This paper presents the thermal and electrical characteristics of ZnO arrester blocks under the power frequency AC operating voltages. the leakage currents of ZnO arrester blocks were measured as a function of the time. The temperature profiles of ZnO arrester blocks were observed by the infrared camera. The degradation and the thermal runaway of the ZnO arrester blocks are closely related to the temperature limit, which determines the heat generation and dissipation. As the leakage current was 0.5[mA], the amount of heat generation is smaller than that of heat dissipation. So temperature of the ZnO arrester blocks was rarely changed. On the other hand, as the leakage current was 0.7[mA] and 1[mA], the amount of heat generation was grater than that of heat dissipation. The temperature of ZnO arrester blocks gradually increases and the test specimen experiences thermal runaway. At that time the temperature located at the center of ZnO arrester blocks string was higher compared to that of ZnO block at both edges.