Patent ID: 7165014

Claim:
A partial discharge monitoring apparatus for a rotating electric machine, said partial discharge monitoring apparatus comprising: a partial discharge detecting circuit including first and second frequency band detecting circuits which include first and second attenuators, first and second bandpass filters, and first and second peak hold circuits, respectively; and a controller CPU, wherein the first and second frequency band detecting circuits simultaneously measure each signal output from a partial discharge sensor located in the rotating electric machine, the controller CPU controls measurement ranges of the first and second frequency band detecting circuits by controlling the first and second attenuators, the first and second bandpass filters allow signals which have passed through the first and second attenuators to pass if the signals fall within first and second frequency bands, respectively, the second frequency band of the second bandpass filter being higher than the first frequency band of the first bandpass filter, the first and second peak hold circuits detect a peak value of an input signal when the input signal, among the signals which have passed through the first and second bandpass filters, exceeds a signal detection level, the second peak hold circuit operating only when the first peak hold circuit has operated, detection time for detecting the signal input into each of the first and second peak hold circuits includes a peak hold time, a reset time, and a dead time, wherein the peak hold time is within a range of 1 μs to 2 μs, the dead time is within a range of 6 μs to 100 μs, and the peak hold time is variable, and a next-occurring signal is detected after the dead time has elapsed.