SURGE CIRCUIT BREAKERS (SCB)

BRITEC Surge Circuit Breakers (SCB) are an over current protection device specially designed for the protection of parallel connected single port AC power line surge protectors

Traditionally SPD over current protection was provided by conventional circuit breakers or fuses, but this is not ideal for two reasons;

1. To pass the high frequency surge currents the fuses or circuit breakers need to have a higher AC current rating than consistent with good protection against overheating and fire within the SPD.
2. Surge currents can cause the fuses to blow or a circuit breaker to trip even when the SPD is still healthy, this is called nuisance tripping and it may not be detected, this leaves the facility with no surge protection until the trip is noticed.

SCB’s are designed to discriminate between power frequency (50-60Hz) currents and the high frequency currents produced by lightning and power line switching transients.

This discrimination means that are able to have markedly different tripping currents for the two types of waveform allowing them to provide a high degree of protection to the SPD at power line frequencies whilst allowing very large surge currents to be passed without the risk of nuisance tripping that is characteristic of fuses and conventional circuit breakers when used to protect parallel connected SPD’s.

The SCB eliminates these problems by having an AC power (50-60Hz) tripping current of only 3 Amps whilst also having a very high surge current tripping value of 80,000 Amps at 8/20μs, or 25kA at 10/350 μs depending on the model. It is this ability to discriminate between power and surge frequencies that make the SCB the ideal choice for protection of parallel connected surge diverters.

SCB, with excellent characteristics of high breaking capacity of power frequency short-circuit current, strong withstanding capacity of impulse and 3 A tripping action under power frequency current, meets the SPD matching requirements.