Protection of LV networks

Which protection system is preferable, fuse or circuit breaker, has long exercised the minds of engineers. As LV networks become more sophisticated the choice becomes more complex and no longer one of simple overload and short circuit protection. More stringent safety needs, efficient use of energy and automation, and the advances in the two technologies must influence the choice. To select the most appropriate solution for a particular application requires not only a full understanding of the needs of the application, but also a good appreciation of the “state of the art” and the relative merits of the fuse and circuit breaker approaches. For example: fused devices are covered by two British Standards which are not fully integrated. As a result, such devices can unknowingly be de-rated. Moulded case circuit breakers, on the other hand, can interrupt large fault currents and discriminate fully with each other. As application requirements and the performance of devices advance, the emphasis is moving from the use of fuses to circuit breakers