GB/T 20833.1-2021 Rotating electrical machines—The winding insulation—Part 1:Off-line partial discharge measurements

Scope

This part of GB/T 20833 specifies the general basic norms for offline partial discharge measurement of winding insulation in rotating motors:
—— Measurement methods and instruments;
—— Arrangement of test circuits;
—— Standardization of test procedures;
—— Reduction of noise;
—— Preparation of test results documents;
—— Evaluation of test results.
The test methods described in this part are applicable to stator windings of motors with or without anti-corona layers in the grooves, as well as stator windings of motors manufactured with molded windings or loose windings. In special cases, this part is also applicable to the rotor excitation windings of high-voltage motors. The measurement methods are applicable to tests under sinusoidal AC voltages with a frequency of 0.1 Hz to 400 Hz. See Appendix A.
The interpretation guidelines given in this part are only applicable if the following requirements are met:
—— Measurements are carried out at a frequency of 50 Hz/60 Hz or within the range of 45 Hz to 65 Hz of the power supply frequency;
—— Molded windings and winding components, such as busbars and coils;
—— Windings with anti-corona structures in the grooves, usually effective for motors with a rated voltage of 6 kV and above.
For loose winding motors, molded windings without anti-corona layers in the grooves, and tests outside the 50 Hz/60 Hz frequency range, the interpretation guidelines are not applicable. The offline partial discharge measurement procedures in this part can be used to evaluate the consistency of manufacturing quality or the trend of such windings, and the same applies to the windings of frequency-converted motors.
Note: The test requirements for low-voltage motors with Type I insulation structures are specified in IEC 60034-18-41. The qualification test procedures for high-voltage frequency-converted motors with Type II insulation structures are specified in IEC 60034-18-

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