Switching Capacitive Kilovolt-Amperes with Power Circuit Breakers [includes discussion

Abstract

Although power circuit breakers are designed primarily to interrupt heavy inductive short-circuit currents, system growth in recent years has produced a greatly increased requirement of interrupting relatively lighter currents which are associated with the switching of capacitive kilovolt-amperes. This capacitive kilovolt-ampere requirement has manifested itself in long-distance high-voltage transmission lines, in relatively long high-voltage cables, and in large size shunt capacitor banks which are becoming a common fundamental unit in system design and operation.1-3 There is not necessarily a relationship between the ability of a circuit breaker to interrupt short circuit currents and its ability to switch capacitance currents. It is widely recognized that high-frequency voltage and current oscillations may be produced which, if uncontrolled, may result in damage to apparatus or system outages. In general, the problem is the severity of the system disturbances produced by the switching operation, either opening or closing, rather than the failure of the circuit breaker to interrupt the current or to close the circuit. It is the purpose of this paper to present: 1. Typical circuit breaker performance in switching capacitive kilovolt-amperes. 2. Circuit behavior and circuit breaker performance considerations from test laboratory and transient analyzer studies. 3. Criteria of acceptable circuit breaker performance in capacitive switching.