How is a 3-phase transformer Megger test performed?

To perform a 3-phase transformer Megger test, first ensure the transformer is disconnected from the power supply and properly grounded. Select the appropriate Megger tester from Globecore’s range, ensuring it’s suitable for high voltage insulation testing. Connect the Megger leads to the transformer windings: typically one lead to the primary winding and the other to the ground. For each phase of the transformer, apply the Megger test voltage—usually ranging from 500V to 5kV—depending on the insulation class. Record the insulation resistance readings for each phase; these values should ideally be above the manufacturer’s recommended minimums. After testing, discharge the winding capacitance safely. Repeat the test periodically to monitor insulation health over time, ensuring long-term reliability and safety of the transformer. Regular Megger testing on transformers is vital for assessing the insulation condition and preventing failures.