Analysis of Distribution Transformers at Various Insulating Conditions by Frequency Method

The study examines the insulation properties of various power transformers using method of frequency dielectric spectroscopy (FDS). It compares different transformers at the same indoor temperature and analyzes how temperature affects insulation properties. Compared to other methods of diagnosing the insulation system of high-voltage equipment, method FDS allows for separate assessment of quality and specific conductivity in oil and moisture content in the transformer solid insulation. Using capacity measurements via method FDS to determine condition of insulation system has the advantage of being less temperature-dependent compared to the dissipation factor method. However, a drawback of the capacity method is that it is influenced by the insulation geometric arrangement, which varies based on the power transformer type and performance. Given this limitation, when comparing frequency-dependent capacities to assess insulation condition, it is advisable to compare machines of the same construction and power rating.