Significance of SFRA in Mechanical Condition Assessment of Transformer

Transformers subjected to system faults, overload conditions and accelerated ageing, might be near end-of-life at an earlier stage. The fault-rate is expected to increase in networks and it will be more than the rated short circuit capacity for the old units. To assess the life of a transformer, knowledge of the mechanical integrity is relevant. Since existing methods for mechanical condition assessment cannot detect all fault-types, there is need for more sophisticated methods of condition assessment in order to keep the fault-rate as low as possible and fast diagnosis of the fault in transformer. Sweep Frequency Response Analysis (SFRA) is such a technique used to diagnose the mechanical condition of the core and windings. The deviations with respect to the reference signature within a defined frequency band indicate a particular fault. Such cases of transformer fault and its proper diagnostics by SFRA is discussed in this paper in detail.