Modelling and simulation studies of inter-winding faults in a three phase distribution transformer using EMTDC/PSCAD

Distribution Transformer is one of the most important equipment in the power system. Among the various faults, internal winding faults comprise about seventy to eighty percent of modern transformer breakdowns and this is likely to increase since loading transformers to their optimum capacity is becoming normal practice. This paper discusses the modelling of turn to ground and turn to turn faults in PSCAD®/EMTDC™. Transformers generally employ differential relays as optimal protection. Internal faults involving a few turns might not suffice for fault detection hence proving the otherwise dependable relay, unreliable. Thus the model developed here will aid in investigating such protection aspects of transformers. Simulation results considering a sample system are presented.