Analysis of the Mechanical Condition of the Dry Transformer by Contact Frequency Measurement Method

The article describes the contact analysis of 800 kVA dry power transformer using a frequency analyzer with automatic sweeping for low-middle frequency areas. In the case of dry transformers, the most common error in changing the acoustic emission can also be the incorrect connection of the screws on the fixing structure or when connecting the windings. As a complementary method, a set of different contact measurements can be used, thanks to which it is possible to detect a fault more accurately in the insulation or structural system of transformers. The most suitable additional methods include the SFRA (Sweep Frequency Response Analysis) method using the Megger FRAX instrument. The mentioned method measures the frequency dependence of the transformer conductivity from 20 Hz to 2 MHz in no-load and short-circuit conditions. With the help of these measurements, it is possible to detect a fault in the iron core, in individual windings, branches or connections. The problem of insufficient or incorrect clamp-screw connection was identified by the frequency method SFRA.