Apparatus and method for detecting partial discharge at turn-to-turn insulation in motor

摘要

Apparatus and method for partial discharge detection of turn-to-turn insulation in motor has a surge generator for generating a surge voltage to the windings of the motor by applying a pulse voltage, and a partial discharge current detector for detecting partial discharge currents between the winding turns of the motor. The surge generator generates in and between the windings of the motor the surge voltage that has the rise time and fall time corresponding to the rise time of the surge voltage observed at the motor terminal when the motor is driven by an inverter, and that is repeated at a frequency of 50 Hz to 20 kHz.

主权项

1. An apparatus for detecting partial discharge at a turn-to-turn insulation in a motor, comprising:
a surge generator including a capacitor configured to charge a DC current, a first switch, and a second switch, wherein the first and second switches are configured to be operated together as a push-pull circuit; and a partial discharge current detector configured to detect partial discharge currents between turns of the windings of said motor; wherein the surge generator is configured to generate and apply, to windings of said motor, a repeating surge voltage pulse with: a regular period, a substantially constant voltage level, and positive-negative symmetry with respect to a zero voltage level; wherein the surge generator is configured to apply the repeating surge voltage pulse to the windings of the motor such that: the first switch switches the output of the capacitor to thereby control the rising of the repeating surge voltage pulse, and the second switch switches the output of the capacitor to thereby control the falling of the repeating surge voltage pulse; wherein in order that said surge generator effects a higher voltage between turns of the windings than a voltage between the windings and a core of said motor, said surge generator generates said repeating surge voltage pulse in and between said windings of said motor, at a repetition frequency selected within a range of 50 Hz to 20 kHz; and wherein in order that said partial discharge current detector detects partial discharge currents occurring only between turns of the windings of said motor, then at a time of applying said repeating surge voltage pulse to the windings:
a core of the motor is coupled to ground or a lower voltage side of the surge generator; and,a non-tested phase of the winding is coupled to the lower voltage side of the surge generator, coupled to ground via an end resistor, or experiences a floated voltage.