Virtual instrumentation and its application in diagnosis of faults in power transformers

This paper presents a new approach to detect, localize and investigate the feasibility of identifying winding insulation failures. The diagnosis is based on the time-frequency analysis of signals recorded during lightning impulse tests. The virtual instrument is implemented with an acquisition board inserted into a PC and with software developed with lab view tools which sample the voltage and current signal and furnish the extent of insulation failure. The acquired signal is decomposed using multiresolution signal decomposition techniques to detect and localize the time instant of occurrence of fault