# Three – phase Transformer connections – Exercise – 1

1. For the star-star connection of three phase transformer, the phase angle between the phase voltages and line voltages on both primary and secondary side is :

(a) 0 degree
(b) 30 degree
(c) 60 degree
(d) 120 degree

Answer
Answer : (b)
Explanation
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2. The phase shift in a star-star connected three phase transformer is :

(a) 0 degree
(b) 30 degree
(c) 60 degree
(d) 120 degree

Answer
Answer : (a)
Explanation
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3. For the parallel operation of three phase transformers, which among the following connection is not applicable?

(a)  Δ – Δ to Y – Y
(b) Y – Δ to Δ – Y
(c) Y – Y to Y – Y
(d) None of these

Answer
Answer : (d)
Explanation
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4. For large low voltage transformers, the most commonly connections used are :

(a) Star- star connection
(b) Delta-delta connection
(c) V connection
(d) All of these

Answer
Answer : (b)
Explanation
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5. If K is the transformation ratio, then the secondary phase voltage of delta-delta connected three phase transformer will be :

(a) 1 / K times of the primary phase voltage
(b) Equal to the primary phase voltage
(c) 1 / K ∧ 2 times of the primary phase voltage
(d)  K times the primary phase voltage

Answer
Answer : (d)
Explanation
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