How do I choose a transformer? The
According to the nature and size of the load to determine the capacity of the transformer.
The ratio is selected according to the supply voltage and the voltage required for the load.
Select the transformer, you can not choose too large, can not choose too small According to the following method to select the transformer capacity.
???There is a very important data is not provided, is the load at the same time coefficient. Transformer with the actual load and equipment rated power ratio is called the transformer load factor. The concept of the load factor for the load is the probability that the load is used at the same time, also called the coefficient or the simultaneous coefficient, which is the probability of simultaneous use of the device. The total load is 300kw, but they are used at the same time there is a probability that the probability is the load factor. It is impossible to always use at the same time. Of course, you can according to the actual situation to calculate their own, power factor selected 0.80.
??With this formula, s = p * kX / cosφ
Transformer capacity s = device rated power p × transformer load rate kx / power factor cosφ = (300 × kX) × 0.80
This is the transformer capacity.
???Do not know what the motor is used under the circumstances, so it can not be calculated, and only calculate the same time after the generation of the formula into the above formula. If the coefficient is 0.9, then the results of about 340 kVA, are used at the same time, that is, 375KVA, consider a certain margin and spare capacity, that can choose 400KVA.
In addition to the above considerations, in particular, consider the motor starting current factor, select the transformer more reliable. As far as possible by the big do not rely on small. And the standard capacity of the transformer level 315,400,500,630KVA, 315KVA a little small, 500KVA big and no need. So choose 400kvA it
