Research on Two-stage Cascade SPD Coordination under Different Loads

摘要

Lightning overvoltage is one of the most threats to the low-voltage electrical equipment. According to the statistics, the average loss of low-voltage electrical equipment caused by lightning overvoltage accounted for 70% in all loss. Therefore, it is necessary to install Surge Protection Device (SPD) to prevent serious damage of low-voltage electrical equipment caused by lightning overvoltage. The tradition method to install SPD is mainly relying on the IEC 61024.1 which just provides experience guidance without detail simulation. In fact, the load has great influence on coordination of cascade SPD. This paper discussed the influence of different loads on the two-stage cascade SPD coordination by establishing the corresponding model using electromagnetic transient analysis software (ATP-EMTP). It is found that the characteristic of electrical equipment has certain influence on the coordination of two-stage cascade SPD, especially the inductive electrical equipments. In this case, the coordination of two-stage cascade SPD may fail.