Surge withstand performance of MCB used as backup overcurrent protection of SPD

This paper presented an experimental study on the surge withstand performance of MCBs (Miniature Circuit Breaker) which are tendentiously used as backup overcurrent protection of SPDs. The maximum and 15-shots withstand capability of MCBs for 10/350μs and 8/20μs surges were found through test and compared with those of fuses. Meanwhile the surge withstand capability of the MCBs with various a.c. switching capability and characteristic curves were compared. Then the damaged and triggering mechanism of MCB under surges was investigated. The residual voltage of MCB under 8/20μs surges and the surge withstand capability of MCCB (Moulded Case Circuit Breaker) under 10/350μs surges were discussed finally.