Principle and Influencing Factors of the Transformer Sympathetic Inrush

The phenomenon of sympathetic interaction between transformers is very likely to occur when a transformer is energized onto a system to which other transformers are already connected. Based on the transformer equivalent circuit and the flux variation, the attenuation principle of the single transformer's inrush current is analyzed and the corresponding formula is obtained. Then the principle and characteristics of sympathetic inrush are studied in depth. Finally, the influencing factors are investigated such as system resistance, parallel or series transformers and the load of a connected transformer.