INSTRUMENT TRANSFORMER AND FERRORESONANCE SUPPRESSION CIRCUIT

摘要

PURPOSE: An instrument transformer and a ferroresonance suppression circuit having a ferroresonance suppression function are provided to perform altogether ferroresonance suppression by a resonance suppression device and the damage suppression of the resonance suppression device itself. CONSTITUTION: An instrument transformer(11) is installed on a main electric line(10) of an electric power system and is used to indirectly perform the voltage detection of the main electric line. The instrument transformer includes a ferroresonance suppression circuit(21). The ferroresonance suppression circuit includes a resonance detection circuit(22), a control circuit(23), a switch(24) and a resonance suppression device(25). The resonance detection circuit includes an LPF(Low Pass Filter)(26), a rectifier circuit(27) and a determination circuit(28). The control circuit controls the switch based on whether ferroresonance occurs or not and based on the logic of a determination signal from the determination circuit. The resonance suppression device suppresses the excessive temperature rise of the resonance suppression device itself while suppressing the ferroresonance. [Reference numerals] (23) Control circuit; (29) Timer