The Impact of Temperature and Timing on Polarization Index Measurements: A Case Study

Insulation Resistance and Polarization Index (PI) testing are crucial methods for evaluating the insulation condition of induction motors to enhance operational reliability. Temperature correction becomes crucial during fluctuations in PI measurements, posing a challenge when the temperature of the winding cannot be directly measured. A case study on induction motors in the pulp and paper industry highlights the risk of insulation failure when PI correction factors are overlooked, even when initial PI values are within the normal range. This research aims to improve understanding, optimize the interpretation of PI results, provide valuable insights, and offer practical recommendations for the appropriate timing of PI testing in the absence of temperature changes during measurement, as well as the conversion from skin temperature measurements to winding temperature. It is expected that this will contribute to increase effective PI measurement for detect contaminated winding insulation and reduce the risk of insulation failure in induction motors.