Single Phase Transformer
i) The frequency of both transformers which are in parallel must be same.
ii) The ratio of voltage of parallel contacts transformer must be equal. Otherwise a circulating current will be flow from higher potential to lower potential. This is only limited by the independence of those transformers if the ratio is larger different value of this current is also larger which may burnt the winding’s of both transformer.
iii) Phase sequence of parallel connected transformer must be same. Otherwise line voltage will appear across the phase winding’s.
iv) The transformer should be of same phasor group.
v) The ratio of per phase reactance Xe and Rc should be same both the transformer otherwise a circulating current will be flow .
1. If two and more transformer are connected in parallel the service continuity ensure and the system become reliable.
2. Any transformer can be switch off or depending on their load demand.
3. If more transformer works in parallel the chance of over loading of a particular transformer reduce.
4. The cost of stand by unit transformer is reduce.
**A. When one or more transformer works on parallel then chance of fault occurrence will increased.**
B. The maintenance cost become more.
C. The space required for installing the transformer is more.
D. The protective device of transformer is more.