Description

Surge Circuit Breaker

The SCB1-3-25 is a purpose designed SPD disconnector. It may be used to provide over current protection for any shunt connected SPD with an Imax rating up to 200kA or an Iimp rating to 25kA. The SCB1-3-25 is generally used at main switchboards. It effectively coordinates with any upstream supply circuit breaker or fuse.

Operation. All power line SPDs must be protected by an over current protective device (OCPD). Traditionally these have been fuses or circuit breakers but neither are really suitable to effectively protect the SPD in the event of its failure or in the event of a prolonged system overvoltage. Under normal operating conditions an SPD draws no more than a few milliamps of AC current from the supply but in the event of a transient disturbance it must instantly pass many thousands of amps. Fuses or circuit breakers chosen to pass this impulse current will not protect the SPD against an AC overvoltage nor necessarily prevent its failure to a short circuit before the fuse or circuit breaker trips. The fuses or circuit breaker ratings required to pass these impulse currents present coordination challenges with upstream OCPDs. The SCB1-3-25 is designed to trip at AC currents more than 3 amps but will pass impulse currents up to 25kA 10/350us. Tests have proven that the SCB will trip during a phase to phase voltage fault across a phase to neutral SPD with no damage to the SPD. The SCB may simply be reset. With a trip current of only 3A the SCB easily coordinates with upstream OCPDs. Novaris SPDs uniquely utilize electronic alarms and can detect the loss of supply due to tripping of the SCB.

Compatibility. The SCB1-3-25 can be used with all Novaris SD, SDN and SDEV products designed for LV distribution up to 200kA 8/20us rating and for SG products up to 25kA 10/350us.