An Improved Method for Identification of Mechanical Damage in an Isolated Transformer Winding Using FRA

Abstract

It is known that the frequency response analysis (FRA) method is the most sensitive for identifying any fault or mechanical damage in transformer windings. In FRA technique, a subsequently measured response needs to be compared with a ‘reference measured response’ for detecting any faults. But in practice, sometimes ‘the reference measurement’ may not be available for some reasons; in that case the measured response alone is not sufficient for identifying any damage in the windings. In this way a limitation has been existed for the conventional FRA method. For addressing this limitation, the author’s research group recently published an innovative FRA based method for identifying the damage in single, isolated winding even in the absence of its’ healthy reference response. In this paper a new method is proposed to overcome few limitations or constraints of the earlier method proposed by this research group. The validity of this newly proposed method was verified using both the simulation results of an equivalent ladder-network model and the experimental results on a 33 kV continuous-disk winding. The pertinent results shows that the method is simple and promising for identifying the fault in the winding even in the absence of its’ healthy reference measurement.