What are the conditions for parallel operation of transformers

1. The parallel operation of transformers should meet the following conditions:

1) The winding wiring group is the same.

2) The transformer ratio is the same (with an allowable error of ± 0.) 5%).

3) The impedance voltage is the same (with an allowable error of ± 10%).

4) The capacity ratio should generally not exceed 3:1.

2.When the above parallel operation conditions are not met, the following consequences will occur:

1) If the winding wiring group is different, there will be a large potential difference on the secondary side of the transformer in the same phase. Due to the small impedance of the secondary side of the transformer, a large circulating current will be generated and the transformer will be burned out.

2) If the transformer ratio exceeds the specified error, there will inevitably be circulating current between the two transformer windings due to the potential difference. The larger the error in the transformer ratio, the greater the circulation. This not only causes significant power loss, but in severe cases, it can also burn out the transformer.

3) If the impedance voltage (also known as short-circuit voltage percentage) exceeds the specified error value, it will cause unbalanced load distribution, that is, transformers with large capacity will be under loaded while transformers with small capacity will be overloaded.

4) If the capacity ratio exceeds 3:1, the impedance voltage also differs significantly, and condition 3) cannot be met.