Parallel can provide the total capacity is not the sum of the capacity of the two transformers, or how to calculate? What is the principle of allocation of load load, that is, how to allocate two transformer load capacity?
The total capacity of the two transformers in parallel is not a simple addition of the capacity of the two transformers. Even if the rated capacity of the two transformers is exactly the same, the impedance of the two transformers can not be exactly the same due to the existence of design / manufacturing errors. Based on the principle of the parallel circuit, the transformer with a small impedance will share a larger current, A transformer has been overloaded and another transformer is not yet fully loaded. Can be based on the measured value of two transformer impedance (on the nameplate). Calculate the transformer with a small impedance to reach full load, the load of another transformer, the sum of the two is the total capacity of the two transformers in parallel.
In fact, the transformer capacity selection is usually about 25% greater than the actual load, so the reality is usually not a full load, while the other has been a serious overload situation.
After the parallel capacity can be provided is the sum of the capacity of the two transformers ---- If the two transformers capacity is the same, after the parallel capacity can provide the total capacity of the two transformers are the sum of capacity. If a 1000kva transformer and a 800kva transformer in parallel, the parallel can provide the total capacity of 1600kva.
The distribution of load load and what principles, that is, how to allocate two transformer load capacity --- transformer parallel to meet the three conditions: 1, two transformer transformer ratio equal; 2, two impedance voltage equal; 3, two Transformer capacity should be as close as possible, should not exceed 3: 1. To meet these three conditions in parallel, the load is evenly distributed to two transformers.
If the transformer voltage ratio is equal (equivalent to the equivalent of the induced potential), the impedance voltage (equivalent to the transformer internal resistance) are equal, then they output the current is equal, that is, the load is evenly distributed. The total capacity is the sum of their capacity. Otherwise, the impedance of the output voltage of the small current, its load rate is relatively high, when its load current reaches full load, the impedance voltage has not reached a full load, if the load at this time for the total Capacity, then the total capacity is less than the sum of the two capacity. This is a strict argument. In fact, the two transformers of the impedance voltage difference is very small, the load distribution is also very small difference, in addition, the so-called transformer is a little overload, nor is it so strict, so the actual total capacity and the difference between the two capacity Not big.
In order to prevent the load distribution is too uneven, the capacity of these two transformers should be as close as possible, should not exceed 3: 1, because the capacity of the large impedance voltage is small, it has reached full load, and that small capacity is still in the owe Load, its role is not fully play out, it is not the significance of the parallel.
The above is the answer 2009-10-8 02:31.
At the end of the said, "the large capacity of the impedance voltage is small, it has reached full load, and that small capacity is still in the obvious underload, its role is not fully play out", wrong, apologize. Should be large capacity transformer impedance voltage, and small capacity impedance voltage is small, the load rate is high, the output current to reach full load, resulting in a larger capacity of the transformer can not put its big capacity advantage fully play out, this is Very unfavorable.
