What does Dry-Type Self-Cooled Force Air-Cooled Transformer Class AA FA mean?

A dry-type transformer that has a self-cooled rating with cooling obtained by the natural circulation of air and a forced-air cooled rating with cooling obtained by the forced circulation of air. This is sometimes referred to as fan-cooled. Fan cooling can increase a transformer’s kVA rating by 25% to 50% depending on the type and size of the transformer.