An Insulation Monitoring Method for Transformer Windings Based on Electroluminescence Effect

Abstract

Currently, the insulation monitoring method for transformer windings mainly monitors voltage, current, leakage inductance, leakage magnetic field, temperature, and dissolved gas in oil. However, these methods often have the disadvantages of low sensitivity, inability to locate, and slow response time. This paper presents a novel insulation monitoring method for transformer windings based on electroluminescence. In this method, electroluminescent coatings are sprayed on the sides of the blocks between pancake windings. The electric field intensity between the windings is measured according to the coating’ luminance, then the winding insulation state is monitored, and faults can be located. To verify this method, we make a transformer winding model based on the principle of capacitive voltage division. Interturn and interlayer insulation faults are simulated by changing capacitors. The results show that the method has an error of less than 3% in measuring the electric field between transformer pancake windings and is feasible for transformer winding insulation monitoring. In addition, this method also can be used for the detection of transformer winding deformation.