GB/T 20833.2-2016

This part of GB/T 20833 specifies the online measurement of partial discharge in the stator windings of rotating motors powered by a frequency converter with a rated voltage of 3 kV or higher, including: ● measurement techniques and instruments; ● arrangement of the test circuit; ● standardization and sensitivity evaluation; ● measurement procedures; ● noise reduction; ● preparation of test results documents; and ● evaluation of test results. This part specifies the partial discharge test system and methods for detecting electrical partial discharge. The same test devices and procedures can also be used to detect electrical sparks and arcs. Note: Due to the voltage distribution along the winding and the different thermal and mechanical effects related to operation, the main differences between online and offline measurements are the vibration between the stator copper and the stator iron core, contact arcs, or temperature distribution. Moreover, especially for hydrogen-cooled motors, the gas and gas pressure for offline and online partial discharge are also different.