Assessment of the allowable short-term overloads in power transformers including condition management

The decision about the nominal power of each substation transformer is made based on the peak load value and in the contingency criteria during emergency situations. As emergency criteria, some facilities in Brazil consider that when one transformer is disconnected, the other ones in the same substation need to supply the total load. Others facilities consider that a substation can assume an amount of extra load, up to 30% of its total load from other substations. In both cases, the overload on each transformer must not exceed 20%.