Field testing of transformers using induced voltage with partial discharge measurement
In late September 2022, a field IVPD (Induced Voltage Withstand Test with Partial Discharge Measurement) test was conducted on a 60 MVA, Um=145 kV power transformer for a Norwegian end customer. The transformer, manufactured by KONČAR – Distribution and Special Transformers, was successfully tested at an induced voltage of 150% of the rated voltage while simultaneously measuring partial discharges.
IVPD testing is part of the routine final testing for power transformers in manufacturing plants. It serves as a dielectric verification of the finished product and is highly sensitive to various types of faults and defects, detectable through partial discharges measurable by electrical, acoustic, and UHF (Ultra High Frequency) methods. This sensitivity, combined with the fact that it is mostly a non-destructive test, makes field IVPD testing a valuable diagnostic tool for in-service transformers suspected of faults or as a final quality check before commissioning new units. However, the need for an independent power source and increased frequency for the higher-than-nominal voltage complicates the test's execution, which is why this method has not yet reached its full potential for field applications.
Given the importance of power transformers and the time and financial costs of returning them to the factory for repairs, field IVPD testing is likely to become an essential tool for assessing transformer condition. By successfully completing this test, the Institute has joined a select group of teams in Europe capable of performing it. Additionally, at the heart of the mobile testing station, developed and operational in a short period, is another product developed by the Institute – the high-power converter KonLab 120. Plans are underway to expand the testing capabilities of the mobile station, enabling field IVPD testing on transformers up to 420 kV voltage class and several hundred MVA rated power.