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1. (WO2014192217) LEAKAGE CURRENT CALCULATION DEVICE AND METHOD FOR CALCULATING LEAKAGE CURRENT 


IPC:  G01R 31/02 

Applicants:  TANASHIN DENKI CO., LTD. タナシン電機株式会社 

Inventors:  MATSUSHITA, Kenya 松下 賢也 SAWADA, Masakatsu 澤田 真克 
Title:  LEAKAGE CURRENT CALCULATION DEVICE AND METHOD FOR CALCULATING LEAKAGE CURRENT 
Abstract: 
Provided is a leakage current calculation device capable of calculating an accurate leakage current value in which the effect of noise has been suppressed. The configuration comprises: a toground voltage measurement means for measuring, over a predetermined interval, toground voltages inputted in each phase of a threephase motor; a zerophase current measurement means for measuring, over a predetermined interval, a zerophase current, which is the toground leakage current that flows through the threephase motor; a basic AC voltage waveform extraction means for extracting, from the toground voltage, a basic AC voltage waveform having a frequency in the same phase as the toground voltage of each phase; a frequency component extraction means for extracting, in the frequency band containing the frequency of the basic AC voltage waveform, a zerophase current component of said frequency band; and a leakage current value calculation means for calculating the leakage current value IOcos θ flowing through the toground resistance component, excluding the toground capacitance component of the threephase motor, among the toground leakage currents by integrating the zerophase current components of the frequency band in an interval corresponding to gap between zerocrossings of the basic AC voltage waveform.
