Per NEC 450.3 the primary and secondary OCPD can be sized higher than the FLA rating of the transformer. For example, for a 2500kVA transformer 12.47kV primary-4.16kV secondary, the primary can be sized up to 600% and the secondary circuit breaker can be sized up to 300%. My question is why does the NEC allow setting up the primary and secondary way higher than the nominal rating of the transformer FLA?