Research on a Permanent Magnet Trip Device for DC Miniature Circuit Breakers

The article investigates the structure of a permanent magnet tripping device used in non-polarized DC miniature circuit breakers, proposing a permanent magnet arrangement relative to the moving iron core as an alternative to the traditional built-in spring design. Dynamic and static characteristics of this permanent magnet tripping device were calculated using simulation software and compared with those of a traditional tripping device. The results indicate that when a short-circuit current occurs, the permanent magnet tripping device can execute tripping actions more accurately and rapidly compared to the traditional design, ensuring efficient and stable operation of the miniature circuit breaker. Subsequent transient tripping experiments conducted on circuit breakers equipped with both types of tripping devices validated the accuracy of these findings.