Short-circuit reactances of multi-secondaries concentric windings transformers

Thanks to the 3D finite elements programs, huge improvements have been achieved in the determination of transformer leakage inductances. However, there is still a trend to build easier calculation models in order to save time during the pre-design phase of a transformer. This paper presents an analytical method to determine short-circuit reactances for multi-secondaries transformers. A correction of an existing expression for two windings has been made. A comparison to measurement results on existing units is performed. The precision of the proposed formula is quite high compared to other complicated programs.