What is the efficiency of an open transformer bank using two 50 kVA pots?

To determine the efficiency of an open transformer bank using two 50 kVA transformers, it is essential to understand how the transformers work together in this configuration. When transformers are connected in parallel, their power ratings can be combined to yield an overall efficiency that is greater than the individual ratings, depending on the load conditions.

In this scenario, the two transformers each have a rating of 50 kVA. When they are combined, they can handle a total capacity of 100 kVA. However, the "efficiency" mentioned in the context of transformer banks doesn't refer to the total kVA rating but rather the actual output versus losses in the system. Normal efficiency for transformer operation typically ranges between 85% to 95%.

The answer of 86.6 kVA likely represents a realistic estimate of the effective output of the transformer bank, taking into account inevitable losses due to heat, core losses, and copper losses inherent in transformer operation. This figure indicates a balance between the total capacity of the transformers and their operational efficiency under realistic conditions.

If the question had options well above the nominal capacity of 100 kVA, those wouldn't be feasible numbers for an open transformer bank using two 50 kVA units, as the configuration simply wouldn't support that level