Repair of High Partial Discharge Value due to End-Winding Stator Generator Vibration: a case study

EasyChair Preprint 3435

Abstract

Damaging factor which often occurs in stator winding is located in its end winding. Stator end winding is vulnerable toward vibration on double frequency of electromagnetic field grid system. Looseness symptom on end winding generator in unit 2.3 Priok Power Plant is marked by compound greasing finding and bump test result showed that mostly of end winding natural frequency stayed on the range of 95-115 Hz. Its looseness problem can bring serious impact toward winding insulation because it can develop an abrasion.  The result of insulation abrasion was shown by its x-ray diffraction test. The other finding was corona discharge in overhang end winding area. There were efforts to resolve the looseness of end winding and corona discharge to increase generator age, such as repairing existing ties and adding new end winding ties to increase its rigidity. Bump test result after retying showed that natural end winding frequency shifted from its natural frequency. To repair partial discharge in end winding area, repairing anti corona coating in different voltage connection phase was done. Offline partial discharge test result after repair showed that this method was effective to reduce partial discharge magnitude value to safety level. This method was also effective and adding asset owner’s confidence to operate unit 2.3 generator safely. It could give reference to other power plants facing the same problem.

Keyphrases: End-Winding, natural frequency, partial discharge, vibration

@booklet{EasyChair:3435,
  author    = {Edo Radita and Sendy Putra and Sujadi Sujadi and Putu Utama},
  title     = {Repair of High Partial Discharge Value due to End-Winding Stator Generator Vibration: a case study},
  howpublished = {EasyChair Preprint 3435},
  year      = {EasyChair, 2020}}