Patent ID: 11881708
Assignee: HAMILTON SUNDSTRAND CORPORATION
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H  G | IPC G  H

Claim 11:
12. A method comprising:
detecting a first voltage across a first resistor between a first DC feeder from a rectifier and ground;
detecting a second voltage across a second resistor between a second DC feeder from the rectifier and ground;
using the first and second voltages to calculate a common mode voltage;
determining the common mode voltage;
determining a fault has occurred base on a change in the common mode voltage that exceeds a predetermined threshold;
determining the fault is located in one of the DC feeders if the common mode voltage is constant, and if the fault is located in one of the DC feeders:
isolating the fault to a positive DC feeder if the common mode voltage is negative; and
isolating the fault to a negative DC feeder if the common mode voltage is positive; and

determining the fault is located in one of the AC feeders if the common mode voltage follows an AC waveform, and if the fault is located in one of the AC feeders:
determining which one of the AC feeders has the fault wherein phase angle of the common mode voltage matches phase angle sensed in one of the AC feeder that has the fault.