Transient recovery voltages and circuit-breaker performance

EXPERIENCE with power circuit breakers has frequently shown that two breakers of identical design may give radically different performances, even though the operating voltages and short-circuit currents to which they are subjected are the same. Studies of the conditions surrounding these circuit breakers have traced the cause to the differences in the manner in which the recovery voltage has appeared across the contacts of the circuit breakers subsequent to the final interruption. This voltage which occurs between the final arc voltage and the 60-cycle recovery voltage is an equalizing phenomenon defined as the transient recovery voltage. To take it into account in breaker applications, studies have been made of the transient voltages which can occur on systems, and other studies have been made of the response of the circuit breakers to transient recovery voltages.