Patent ID: 6147616
Filing Date: 2000-11-14
Classification: H02H

Abstract:
An automatic power interruption and re-supply relay for an electric power line comprising:an anomalous voltage detector coupled to three phase buses for detecting unbalanced voltage and anomalous voltage of three phases;a phase detector for detecting an open-phase, negative-phase, and interruption of electric power;an overcurrent detector for detecting overcurrent on each electric power line;a zero current detector for detecting zero current on each electric power line;a breakdown detector for detecting an anomalous state of relays installed on the electric power lines and machinery installed in an industrial site; anda central processing unit (CPU) implemented with a microprocessor for comparing and analyzing information from said detectors with preselected reference values and determining and processing the anomalous state;wherein said anomalous voltage detector comprises:a rectifier for rectifying the voltage of the three phases to provide a ripple of 120 Hz;an amplifier for amplifying the ripple; andan analog/digital (A/D) converter for performing A/D conversion with respect to the amplified ripple for two periods of 16.6 ms to provide an output, and said phase detector comprises:a waveform shaping unit for converting common frequency of the three phases into square waves of the same periods; anda phase detection CPU for counting the square waves (converting a phase angle into a time) to detect the open-phase and the negative-phase with respect to each phase.