Measurement and analysis of transient overvoltage distribution in transformer windings based on reduced-scale model

Non-uniform voltage distribution under transient voltage is a primary cause of breakdown of the major insulation of power transformers. Actual power transformer winding has no tap, and is unable to directly measure impulse voltage distribution. Research on the measurement of impulse voltage distribution is important and practical in engineering. According to the relationship between physical quantities, the present study established a simplified shrinkage ratio criterion. Then, the researchers designed a similar ratio 1/20, typed 10 kVA 220 V/2400 V, tapped transformer reduced-scale model, and used the finite element simulation software to simulate the reduced-scale and the original model of the electromagnetic field. Finally, a test platform was built to measure nanosecond pulse voltage and lightning impulse voltage distribution in transformer winding. The researchers also studied the nanosecond pulse width and lightning wave tail time affecting the winding voltage distribution.