Modeling, Analysis, and Detection of Internal Winding Faults in Power Transformers

The winding interturn fault is critical in power transformers since its effect is not easily comprehensible at lower magnitude in the signatures of terminal voltages and currents. This paper presents a new and efficient approach for diagnosing the occurrence of incipient turn-to-turn short circuits in the windings of power transformers. The transformer is modeled in steady state and no-load operation. The analysis shows that the phase difference between the input voltage and input current in the faulty primary winding is changed in a manner that makes it a good measure to find the fault. A set of laboratory experiments on a custom-built transformer under various levels of faults confirms our theoretical analysis and results.