Power And Distribution Transformer Capacity Calculation Formula

1. Calculate the maximum power of each phase of the load

Add the load power of each phase of A-phase, B-phase and C-phase independently. For example, the total power of the A-phase load is 10KW, the total power of the B-phase load is 9KW, and the total power of the C-phase load is 11KW, and the maximum value is 11KW. (Note: The power of each single-phase device is calculated according to the maximum value on the nameplate, and the three-phase device power is divided by 3, which is equal to the power of each phase of this device.)

For example: C-phase load total power = (computer 300WX10 units) + (air conditioner 2KWX4 units) = 11KW

2. Calculate the three-phase total power

11KWX3-phase=33KW (transformer three-phase total power)

The three-phase total power/0.8 is the most important step. Currently, more than 90% of the transformers on the market have a power factor of 0.8, so it needs to be divided by the power factor of 0.8.

33KW/0.8=41.25KW (total transformer power)

The total power of the transformer is /0.85. According to the Power Engineering Design Manual, the transformer capacity should be selected according to the calculated load. For a single transformer that supplies power with a stable load, the load rate is generally about 85%.

41.25KW/0.85=48.529KW (transformer power to be purchased), then you can choose a 50KVA transformer when purchasing.