Transformer Efficiency

To compute the efficiency of a transformer, the input power to and the output power from the transformer must be known. The input power is equal to the product of the voltage applied to the primary and the current in the primary. The output power is equal to the product of the voltage across the secondary and the current in the secondary. The difference between the input power and the output power represents a power loss. You can calculate the percentage of efficiency of a transformer by using the standard efficiency formula shown below:

Example: If the input power to a transformer is 650 watts and the output power is 610 watts, what is the efficiency?

Hence, the efficiency is approximately 93.8 percent, with approximately 40 watts being wasted due to heat losses.