Patent ID: 7498818
Filing Date: 2009-03-03
Classification: G01R

Abstract:
1. For use with an electrical generator having a rotor with an electrically conductive rotor body, an insulated field winding wrapped around the rotor body, the field winding being connected to receive an exciter voltage at first and second exciter nodes, and a rotor grounding brush providing a grounding path between the rotor body and electrical ground, a system for detecting an open condition of the grounding path, the system comprising: first and second buffer resistors coupled at a common node on one side of the first and second resistors, the opposite sides of the first and second resistors being coupled to respective one of the first and second exciter nodes; a signal generator coupled to apply a periodic oscillating voltage signal to the common node; a sense resistor coupling the signal generator to electrical ground; a low-pass filter having an input coupled to receive a positive and a negative sense resistor voltage representative of a positive and negative voltage across the sense resistor, and having an output coupled to deliver a filtered positive sense resistor voltage signal and a filtered negative sense resistor voltage signal; and a microcontroller coupled to the low pass filter and programmed to calculate a total capacitance between the insulated field winding and electrical ground to detect the open condition of the grounding path.