Correct Answer : Option (D) : Open circuit test
Explanation : An open circuit test is also known as a no-load test. It is used to find the iron loss at the rated applied voltage to the primary side. Iron loss of the transformer is not varying with a change in load. The iron loss also helps to determine the voltage regulation and efficiency of the transformer. Open circuit test of a transformer is carried out on the low voltage side by keeping the high voltage side open.
