how to test transformer with megger?

To test a transformer with a megger, first ensure the transformer is de-energized and disconnected from the power supply. Connect the megger leads to the transformer’s windings, typically between the primary and ground, and secondary and ground. Set the megger to an appropriate voltage (usually 500V or 1000V) and take readings. A high resistance value (typically above 1 M?) indicates good insulation, while low resistance suggests insulation failure. Always follow safety protocols during testing.