Validation of a Pole-Mounted Distribution Transformer Model for Electromagnetic Transient Studies by Field Tests Using an Actual-Scale Distribution Line

The authors have previously proposed a transient simulation model of pole-mounted distribution transformers and its improved model that takes the skin effect of the secondary winding into account. However, the model has been validated only by laboratory tests with a low-voltage pulse generator. To show the accuracy of the model when used in a realistic situation, in this paper, field-test results using an actual-scale distribution line are presented. The following four cases are considered in the validation. Case1 (direct lightning hit is assumed): impulse current is injected into one phase of the high-voltage wires. Case2 (induced lightning is assumed): impulse current is injected into the bonded three phases of the high-voltage wires. Case3 (backflow lightning is assumed): impulse current is injected into the low-voltage neutral wire. Case4: the same conditions as Case1 except that surge-arrestors are installed for the transformer. All results obtained from the field test are compared with corresponding simulation results by considering the transient behavior of the grounding system. It is confirmed that the transformer model gives accurate results in the realistic situations.