What is a Full Capacity Tap?

Frequently Asked Questions Connections Definition 

A full capacity tap is one through which the transformer can deliver its rated kVA output without exceeding the specified temperature rise.

Transformers may be designed with full capacity taps ABOVE or BELOW nominal (FCAN and FCBN, respectively). Full capacity taps allow for the input primary voltage to be increased or decreased from its nominal voltage while retaining its ability to deliver its rated kVA output without exceeding it’s specified temperature rise.