Heat generation and failure in padmount transformers due to zero sequence saturation

After a transformer failed following a double phase fault, there was an interest in understanding how the fault mechanism led to the failure. This paper investigate this fault condition in detail and demonstrate the underlying challenges in correcting the failure. The system electrical and thermal models were developed and simulated to analyze the transformer response under double phase fault conditions. Experimental measurements validated the simulation results on a real three phase distribution transformer. This paper presents the results from simulated and experimental analysis from double phase fault on a Yg-Yg distribution transformer.