A Study on Reliability Based Assessment for High Voltage Induction Stator Windings

Currently high voltage induction motors are widely used and play a significant role in many fields including water power plants. Though reliable, the power equipment has been known to have several maintenance problems. These equipment problems often result in an excessive maintenance cost per fiscal year, which has been derived either from a traditional time-based maintenance schedule or a non-scientific asset management of equipment repair/replacement. In order to reduce the financial burden of equipment replacement, it is imperative to develop a sound evaluation method of the reliability of the power motors either by accurately predicting the rate of fault occurrence or by standardizing the diagnosis of the high voltage induction motors. The purpose of this paper was to develop a standard evaluation algorithm for the condition of the stator windings of high voltage induction motors. Several technical tests were utilized in this study including the measurements of AC current (Delta I), dissipation factor (tan delta), partial discharge (PD) magnitude, and polarization index (P.I.). The AC current test produced additional information on the insulation strength of the stator winding of water supply pump motor in operation. The suggested algorithm based on the Risk-Based Maintenance method could make a significant contribution to the reliability assessment.