Transformer capacity calculation method:

Firstly, the rated voltage of the transformer is selected. The voltage on the high voltage side is equal to the voltage on the grid. The voltage on the low voltage side is 10% or 5% higher than that on the low voltage side, which depends on the transformer grade and the impedance voltage.

The second is the selection of rated capacity. In calculating the transformer load, the maximum comprehensive load should be counted first, and the kW value of the active load should be converted to the apparent power kVA. If two transformers are used, then the capacity of each transformer can be selected according to 70% of the maximum comprehensive load, and one transformer should be considered according to the total load, with appropriate reserve. Margin. Other brand parameters can be considered properly in combination with transformer products.

Let me give you an example to show you how to calculate. Select 35/10kV transformer, assume the maximum load is 3500kw, power factor is 0.8, two transformers, capacity S = 0.7 *3500/0.8 = 3062kVA, choose 3150kVA transformer, voltage ratio is 35kV/10.5kV. The load is active power kW, and it will become apparent power kVA, divided by 0.8 is roughly the load power factor.