scope:

Foreword

The voltage endurance test for full size stator bars and coils has been used by generator manufacturers and users for almost 40 years. The first version of the recommended practice was issued in 1985. Its use over the years showed that the recommended practice needed to be clarified, and ambiguities needed to be eliminated. The present version has attempted to do this. Compared to the first version, there are no major differences in the testing procedure.

This recommended practice was prepared by the Dielectrics and Electrical Insulation Society (DEIS) Voltage Endurance Technical Committee.

Scope

This recommended practice covers the voltage endurance testing of form-wound bars and coils for use in large rotating machine stator windings. Such testing is defined for machines with a nominal voltage rating up to 30 000 V. These tests are to be applied at 50 Hz or 60 Hz and may be done at either room temperature or elevated temperature. (Testing at 50 Hz or 60 Hz may yield different times to failure for comparable samples.) The specimen to be tested should be representative of the bars or coils used in the machine, and should include the complete insulated bar and external grading construction that the machine winding would have. Special features different than those used in the machine should not be added to the test specimens.