New tools for diagnostic measurements on power transformers

With the advancing age of power transformers, a regular check of the operating conditions becomes more and more important. The Dissolved Gas Analysis (DGA) is a proven and meaningful method such that if increased proportions of H2 and hydrocarbon gases are found in the oil, the fault must be located as soon as possible. In order to find out the reason for high gas values, further tests have to be performed for the transformer. Common test methods are: Winding resistance measurement, On-Load Tap Changer (OLTC) test, turns ratio and excitation current measurement, measurement of leakage reactance, Frequency Response of Stray Losses (FRSL), Frequency Response Analysis (FRA), Capacitance and Dissipation factor measurement and Partial Discharge (PD) measurement