SFRA ability in detection of Deformation in Transformers Windings: A field experience of 400kV 167MVA single phase unit [articol]

Abstract

Sweep Frequency Response Analysis has become very popular now – a - days due to its ability to provid e comprehensive information regarding mechanical as well as electrical condition of power transformers. The SFRA is a comparative method and provides better information when evaluation of Transformer condition is done by comparing actual set of SFRA result s with reference results. This field experience consists 400/220/33KV ICT bank, formed with three single phase unit with capacity of 167MVA each. A heavy fault current was fed by ICT due to failure of LA provided on delta winding formed outside. Mechanical defects ostensibly occur due to a short circuit current flowing through power transformer in case of terminal faults i.e. fault near to power transformer. To know the mechanical integrity of power transformer SFRA test is carried out and is supported by o ther tests i.e. DC resistance, Magnetic balance, Winding resistance, capacitance and tan delta etc. The test results reveals that SFRA is capable of providing more information about mechanical deformation about power transformers compared to other tests.