Current asymmetry in resistance-reactance circuits

THE DUTY on electrical protective devices, among other factors, is determined by the extent of current asymmetry, which is a function of the circuit short-circuit ratio and the instantaneous value of voltage at which switching occurs. Asymmetrical current consists of symmetrical alternating current and unidirectional current. Depending on the current time constant, expressed either by the short-circuit ratio or power factor, the unidirectional current may be nearly damped out during the first half cycle, or persist for several cycles.