transformer

Transformer manufacturers recommend a maximum overload of 125% at rated temperature.

Heat is the number one enemy of transformers. If the ambient temperature for example is 42 deg Celsius, you can not load your transformer at its rated kVA.

If you can control the temperature buildup inside the transformer, practically, you can load a 100 kVA transformer with 500 kVA or more.

See IEEE standards for loading transformers at different temperatures.

you can take 80% efficiancy of atransformer at safe level

The amount of load depends on overall power factor (p.f) of the load.

The load in KW (or MW) = Transformer KVA (MVA) x overall p.f (cosØ) of the load.

The power factor depends on the type of loads; the p.f for the induction motors is close to 0.8.

Thanks,

- MS