Patent ID: 9465065
Filing Date: 2016-10-11
CPC Classification: G01R

Claim Text:
1. A leakage current calculation device, comprising: ground voltage measurement means for measuring ground voltages respectively inputted to phases of a three-phase motor driven by an inverter device using a specific AC power supply as a power supply in a specific period, zero-phase current measurement means for measuring a zero-phase current which is a ground leakage current flowing through the three-phase motor in a specific period, basic AC waveform extraction means for extracting a basic AC voltage waveform having a frequency having a phase identical with a phase of the ground voltage of each phase from the ground voltage, frequency component extraction means for extracting a zero-phase current component of a frequency band comprising at least the frequency of the basic AC voltage waveform from the frequency band, and leakage current value calculation means for calculating a leakage current value flowing through a ground resistance component of the ground leakage current other than a ground capacitance component of the three-phase motor by integrating the zero-phase current component of the frequency band in a period corresponding between zero crossings of the basic AC voltage waveform, wherein the basic AC waveform extraction means extracts the basic AC voltage waveform by dividing a sum of the ground voltages inputted to the respective phases by 3.