THE PHASE PREDICTION DEVICE USING VARIATION CONTACT RESISTANCE OF THE CONTACT POINT OF CIRCUIT BRAKER IN LIVE WIRE STATE

摘要

PURPOSE: A phase absent predicting apparatus is provided to prevent the expansion of accidents due to phase absent based on the change of contact resistance in the contact point of a circuit breaker. CONSTITUTION: A circuit breaker switches a current by being in connection with an electric line through a contactor. A test constant voltage generator(200) generates a test constant voltage signal and inputs a test constant voltage signal. A differential amplifier(400) receives the test constant voltage signal before and after the test constant voltage signal passes through a contactor and amplifies the difference of voltages. An A/D converter(600) converts the output signal of the differential amplifier into a digital signal. A microprocessor(700) calculates the current contact resistance value of the contactor.