Joy Global Underground Mining LLC

Peter M Dalton

Michael C Jordan

A mining machine including a motor, an adjustable speed drive providing a voltage to the motor, the voltage having an excitation component comprising a magnitude and a frequency for operating the motor at a desired speed and including an additional voltage component for use in detecting a ground fault condition, and a ground fault relay for detecting a ground fault current when the ground fault current exceeds a predetermined threshold.

Ground fault detection methods on variable frequency drive systems

Methods and systems of suppressing ground faults. One system includes a power center including a transformer and a ground fault relay. The system also includes a first motor electrically connected to the power center. The system also includes a first variable speed drive connected to the first motor. The first variable speed drive is configured to vary the speed of the first motor. The system also includes a first common mode choke connected in a series-type connection between the power center and the first variable speed drive. The first common mode choke is configured to suppress a ground current induced by the first variable speed drive.

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New South Wales, Australia

Peter M Dalton