Effects Of Temperature On Time-Domain Dielectric Diagnostics Of Transformers

Time-domain dielectric testing techniques, namely the Return Voltage Measurement (RVM) and Polarisation and Depolarisation Current (PDC) measurement are being used by the power utilities for assessment of the condition of transformers oil-paper insulation. However, it has been found that the results of these tests are highly influenced by operating temperature. It requires adequate experience and extreme care to interpret the RVM and PDC results in the presence of temperature variations and thermal instability. This paper reports a detailed study on the effects of temperature on RVM and PDC measurements on a transformer under controlled laboratory conditions