Patent ID: 7034515
Filing Date: 2006-04-25
Classification: G01R

Abstract:
1. An instantaneous voltage dip detection device comprising: phase shifting means for shifting a supply voltage waveform by a predetermined angle and generating a phase shift voltage waveform; phase lock means for detecting the zero voltage phase of the supply voltage waveform; supply voltage waveform threshold generating means for generating a supply voltage waveform threshold acting as a voltage dip determination reference with respect to said supply voltage waveform in synchronization with said phase lock means; phase shift voltage waveform threshold generating means for generating a phase shift voltage waveform threshold acting as a voltage dip determination reference with respect to said phase shift voltage waveform; determination region setting means for setting a part or all of absolute values of said supply voltage waveform threshold and phase shift voltage waveform threshold that are larger than a predetermined value as being a comparative determination effective region; supply voltage waveform comparing means for outputting a voltage dip detection signal based on the comparison between said supply voltage waveform and the supply voltage waveform threshold, in the case where said determination region setting means determines as being a comparative determination effective region of the supply voltage waveform; and phase shift voltage waveform comparing means for outputting a voltage dip detection signal based on the comparison between said phase shift voltage waveform and the phase shift voltage waveform threshold, in the case where said determination region setting means determines as being a comparative determination effective region of the phase shift voltage waveform.