Abstract: Switching transients occurring in power systems are often due to circuit breaker (CB) switching. CBs are not designed to close or open at the time of minimum stress (zero voltage for closing and zero current for opening). For example, when a circuit breaker switches a capacitor bank, large and damaging voltage and current transients may occur. Depending on the switching instance, the bus voltage may collapse momentarily to zero then oscillate at high frequencies with high magnitudes. When the circuit breaker of a capacitor bank opens, an arc is often produced which causes transients in current and voltage. To avoid these transients, CBs should ideally be closed at zero voltage and opened at zero current. This is achievable by the Adaptive Sequential Controller (ASC) developed in the Energy Laboratory of the University of Washington. The ASC has the following general features:
The ASC can be used with any single pole breaker, or modern multi-phase breakers with independent phase magnetic operating mechanisms (solenoids). For multi-phase, mechanically-ganged breakers, where only one solenoid is employed, the ASC could be used after additional operating mechanisms are retrofitted to the other phases. At this stage of development, the ASC is not designed to operate as described during faults. Fault interruption will be done by the normal fault clearing mechanism of the circuit breaker.
For more information, please contact M. A. El-Sharkawi