Patent ID: 9110105
Filing Date: 2015-08-18
Classification: G01R

Abstract:
1. A PD sensor for a PD signal-analyzing system having a known coupling, said sensor comprising: a capacitor component having a predetermined capacitance for capacitive coupling to an electrical power apparatus in which a PD is suspected at a location distant from the sensor; and an impedance transformance device including a buffer amplifier having an input side connected directly to the capacitor component and an output side configured for connection to a PD signal-analyzing system having a known coupling impedance, the impedance transformance device being constructed and arranged to convey a PD signal from the input side to the output side, the impedance transformance device having a first effective impedance at the input side and a second effective impedance at the output side, the first effective impedance being much larger than the second effective impedance; whereby the capacitance of the capacitor component in combination with the first effective impedance inherently effects a low frequency filter cutoff much lower than the low frequency cutoff that would be caused by the capacitance of the capacitor component in combination with the known coupling impedance, and said low frequency cutoff includes a bandwidth of low frequencies for indicating the occurrence of a PD at a distance from the sensor.