The manner in which harmonic currents affect the current-time characteristic of the watt-hour-meter-type induction disc-overcurrent relay is shown. The torque-current model of the relay is derived and then proved qualitatively by a designed harmonic generator. Test results show that when the input current is in pure sinusoidal, high-order harmonic current will decreases the operating time. When the input current contains harmonic components, if the amplitude of high-order harmonic current is not higher than that of the fundamental frequency current, the error of operating time is not obvious.
|Number of pages||4|
|State||Published - 1985|