Question

Two 3-phase transformers are proposed to be connected in parallel to serve a large load. Transformer 1 is wye-delta, and Transformer 2 is wye-wye. Which of the following statements is most correct?
(A) The transformers should not be paralleled.
(B) The transformers may be. paralleled if the neutral of Transformer 2 secondary is
unconnected and the turns ratio of Transformer 2 is 1.732 times the turns ratio of
Transformer 1.
(C) The transformers may be paralleled if the neutral of Transformer 2 secondary is
unconnected and the turns ratio of Transformer 1 is 1.732 times the turns ratio of
Transformer 2.
(D) The secondary neutrals of Transformer 1 and 2 mayor may not be connected, but the
transformer turns ratios, impedances, and kVA ratings must be matched to achieve
maximum output.

Answer 1

Answer :- * There are some conditions to be satisfied by the transformer, which they are going to work for parallel operation. The conditions are: 0 11 The voltage ratings of the two transformers should same The polarity of the transformers should be same The phase sequence of the transformers must be same The transformers connected in paralled should be same phasor group. the above three conditions can be easily available but the 4th condition is not satisfied by the given two transformers. same - Transformer 1 whe- delta belongs to +30 connection or 180+ 3 6 connection as it is one type of phasor group Transformer 2: wye - wye belongs to d-conne- etcon cor) 180 connection , it belongs to other type of phasor group tion (A): The transformers should not be paralled. correct state ment.