Two different impedance of the transformer, parallel load how to allocate?
When the impedance voltage is equal, the transformer runs side by side:
Because the transformer load distribution is proportional to its rated capacity, and inversely proportional to the impedance voltage. In other words, when the transformer is running in parallel, if the impedance voltage is different, the load is not proportional to the rated capacity of the distribution, parallel transformer current and impedance voltage is inversely proportional to the II / III = UZKII / UZKII or UZKIIII = UZKIIIII, Set two transformers running side by side, the capacity of SNI, SNII, impedance voltage UZI, UZII, then the load of each transformer according to the following formula:
SI = [(SNI + SNII) / (SNI / UZKI + SNII / UZKII)] * (SNI / UZKI)
SII = [(SNI + SNII) / (SNI / UZKI + SNII / UZKII)] * (SNII / UZKII)
That is, S △ I / SII = (SNI * UZKII) / (SNII * UZKI)
According to the above analysis we can see: When two transformers with different impedance voltage are running side by side, the distribution load with large impedance voltage is small. When this transformer is full load, another transformer with small impedance voltage will run over load. Transformer long-term overload operation is not allowed, therefore, only the impedance of the transformer voltage overload operation, thus limiting the total output power, energy loss also increased, it can not guarantee the economic operation of the transformer. Therefore, in order to avoid the impedance voltage difference is too large, so that the parallel transformer load current distribution is uneven, affecting the transformer capacity can not be fully played, the specified impedance voltage can not be a difference of 10%.
Two parallel operating impedance must be equal, because the parallel operation of the transformer load is inversely proportional to the impedance voltage distribution, if the impedance voltage difference is too large, will lead to the occurrence of excessive impedance voltage overload phenomenon is recommended to allow the difference is generally not more than 10% ,
The general formula is St1 = S * Zt2 / (Zt1 + Zt2), St2 = S * Zt1 / (Zt1 + Zt2), where Zt is the per unit value, Zt = Uk% * Sd / 100Sn
Transformer (Transformer) is the use of electromagnetic induction principle to change the AC voltage of the device, the main components are primary coil, secondary coil and core (core). The main functions are: voltage conversion, current conversion, impedance conversion, isolation, voltage regulator (magnetic saturation transformer) and so on. According to the purpose can be divided into: power transformers and special transformers (electric furnace change, rectifier, frequency test transformer, voltage regulator, mine transformer, audio transformers, IF transformers, high-frequency transformers, impact transformers, instrument transformers, electronic transformers , Reactors, transformers, etc.). Circuit symbols commonly used as the beginning of the number. Example: T01, T201 and so on.
The impedance voltage is equivalent to the power supply resistance.
Two impedance voltage is not equal to the parallel operation of the transformer, the impedance of the load distribution of small, low impedance voltage transformer load distribution. Basically inversely proportional.
Generally the same type of transformer, the impedance voltage and capacity is basically inversely proportional to the large transformer impedance voltage is smaller than the small transformer impedance voltage. Parallel operation after the load distribution is basically proportional to the capacity of the transformer.
But this ratio is not exactly the same, so even if the same type of transformer, the capacity difference is too large (more than 3 times), it is not allowed to run side by side.
If it is different types of transformers, the impedance voltage and capacity is not completely inversely proportional to the capacity. The load distribution is even worse.
