how to test a current transformer polarity?

To test a current transformer (CT) polarity, first, ensure the CT is de-energized for safety. Use a multimeter set to measure AC voltage. Connect the primary side of the CT to a known current source, then measure the voltage across the secondary terminals. The polarity is correct if the voltage readings are in phase (i.e., the same direction) with the primary current. If the readings are out of phase, the CT is incorrectly connected, indicating reversed polarity.