Effect of Creep on Failure of Distribution Transformers: An Experimental Evaluation

摘要

The cold load pick up current during frequent energization of the distribution transformers produces high stress and hot spot temperature in their windings. This condition is responsible for elongation in the winding conductors due to creep. The winding conductors between spacers become loose due to elongation which in turn causes turn to turn fault in the winding. Thus, creep causes failure of the distribution transformers. The steady state creep rate is an important design parameter which specifies strain rate in the wire during steady state creep stage. This paper reports the steady state creep rate of the aluminum and the copper wires used in the windings of the 25 kVA distribution transformers.