why open circuit test is performed in transformer?

The open circuit test in a transformer is performed to determine the core losses, which include hysteresis and eddy current losses, as well as to measure the transformer’s no-load current and no-load voltage. During this test, the secondary winding is left open while the primary winding is energized at its rated voltage. This allows engineers to assess the transformer’s efficiency and performance under no-load conditions, providing essential data for design and operational assessments.