1 - High short circuit current levels. The main reason of these high currents is the low impedance of parallel connection ( impedances in parallel).
2 - In the fault condition, all parallel transformers may be to tripped due to a single fault
2 - The primary and the secondary rated voltages must be the same.
3 - Vector group is the same in all parallel transformers.
4 - Equal impedance voltage (% impedances).
2 - In the fault condition, all parallel transformers may be to tripped due to a single fault
Although there are some advantages of parallel operation of power transformers, in some cases there is a need for this parallel operation. Some conditions must be satisfied for the parallel operation which can be listed as follows:
1 - The same frequency.2 - The primary and the secondary rated voltages must be the same.
3 - Vector group is the same in all parallel transformers.
4 - Equal impedance voltage (% impedances).
Practically, condition 1 must be satisfied but in the case of small difference in one of the conditions 2, 3, or 4 parallel operation may be possible. Parallel operation with these differences will be explained.