How is the open circuit test of a transformer performed?

The open circuit test of a transformer is performed by applying voltage to one of the windings while the other winding is left disconnected or open. The voltage is typically applied at the rated voltage level. During this test, measurements are taken for the input voltage, current, and power. The power is measured to determine the no-load losses of the transformer, primarily the core losses, which include hysteresis and eddy current losses. This test is crucial for understanding the performance characteristics of transformers and ensuring efficient operations. While this procedure is essential for transformers, similar principles can be applied in oil testing transformers, highlighting the importance of maintaining high-quality insulating oils for the longevity and reliability of transformer operations.