Patent ID: 9335380
Filing Date: 2016-05-10
CPC Classification: G01R

Claim Text:
1. A device for detecting insulation degradation in an inverter-driven motor, comprising: command control means for putting rotation of the motor into a rotation standby state in which rotation of a shaft of the motor is prevented even when an external force is applied to the shaft; means for measuring a zero-phase current in power-feed lines extending between an inverter device and the motor; means for measuring a value of the phase current in at least an (N−1) phase in case of the motor being N-phase driven (where N is a natural number); and calculation means for calculating an insulation resistance of each phase; wherein the means for measuring the zero-phase current measures the zero-phase current that is a total of phase currents fed into respective phases during the rotation standby state, and wherein the calculation means calculates the insulation resistance of each phase based on values of the zero-phase current and the phase current of each phase which are each measured in different rotation standby states that the shaft of the motor is set at N or more different fixing positions.