ABSTRACT
Transformers are susceptible to damage by secondary short-circuit currents having magnitudes that can be many times rated load current. The damage results from the following effects:
• The I 2R losses in the winding conductors are increased by the square of the current. This increases the temperature rise of the windings. Because protective devices limit the duration of short circuits (as opposed to overloads), the temperature rise of the winding can be calculated by dividing the total energy released by the I 2R losses by the thermal capacity of the conductor.
