scope:

This recommended practice provides a procedure to detect external discharges in form-wound bars and coils and complete stator windings of rotating machines operating in air with a rated line-to-line voltage greater than 4200 V at power frequency. The recommended practice is applicable to bars, coils, and complete stator windings. The recommended practice covers two inspection methods: the visual blackout test, and the use of corona imaging instruments.

Purpose

The purpose of this recommended practice is to suggest specimen preparation, test parameters, and procedures for detecting external discharges associated with bars, coils, and complete stator windings using the above mentioned methods. It also recommends acceptance criteria and a procedure for retest in the event of a test failure.