A Study on the fuse and its requirements for class II SPD disconnectors

The SPD disconnectors currently in use are those recommended by manufactures of SPDs. In Europe, fuses are commonly used as SPD disconnectors, on the other hand, in Japan, molded-case circuit breakers (MCCBs) are commonly used. However, the condition regarding SPD disconnectors that the manufacturers use for selecting the appropriate SPD disconnector is not clearly laid out , and standardization has not been achieved. Consequently, in various academic-conference papers and technical reports, various issues concerning SPD disconnectors recommended by manufacturers have been raised. This report presents first clearly lays out the requirements concerning to class-II SPD disconnectors and then presents the evaluation results concerning to the characteristics of the fuse produced specifically for SPD disconnector and the MCCB which is often used as a SPD disconnector. These evaluation results confirm that under specific usage conditions, the fuse make the more effective as SPD disconnectors.