What is his calculation? Trouble you prawn.
Transformer economic operating coefficient is 0.75. Transformer output capacity and power factor, the power factor is 1 when the transformer output current is the largest, generally require more than 0.9. When the power factor is 1, the transformer output current I = 250KVA / (1.732 * 0.4KV * 1) = 361A. The observed current is the most intuitive. Three-phase active power P = 1.732 * U * I.
The maximum load KW number is determined by the actual use of the power factor of the device because KVA is apparent power and KW is active power. If there is no reactive power in the load device, such as all incandescent lamps, Of the pure resistance of the device, the transformer can theoretically carry 250KW load, the actual use, because there are power lines on the reactive power exists, so the need for discount.
250KVA transformer, the maximum capacity to load how much KW power? This is a bit of a problem, it is difficult to correct answer. Is it possible to ask how much the maximum load of the 250KVA transformer is KW? Or, how much amperes the maximum output current? If you ask, then answer you, the maximum output current is about 250 × 1.445 ≈ 361A or so
