MCQs of Transformers (Electrical Machine - I - 3140913)

Electrical Machine - I (3140913) MCQs

MCQs of Transformers

Showing 101 to 110 out of 155 Questions

101.

What is the ratio of transformation of ∆ − Y connection?

(a)	Phase transformation X:1, line transformation X:1
(b)	Phase transformation X:1, line transformation √3X:1
(c)	Phase transformation X:1, line transformation 3X:1
(d)	Can’t determine with information available

102.

In a three-phase Y − ∆ (11 clock) transformer, what is the angle difference between primary and secondary phase voltages?

(a)	∆ side lags by 30^o
(b)	Y side lags by 30^o
(c)	Y − ∆ side leads by 30^o
(d)	∆ side leads by 30^o

103.

Which of the following connections is best suited for 3-phase, 4-wire service?

(a)	∆ − ∆
(b)	Y − Y
(c)	∆ − Y
(d)	Y − ∆

104.

In a three-phase Y-Y transformer connection, neutral is fundamental to the

(a)	suppression of harmonics
(b)	passage of unbalanced currents due to unbalanced loads
(c)	provision of dual electric service
(d)	balancing of phase voltages with respect to line voltages

105.

Operating transformers in parallel gives the advantage of

(a)	Reliable loading
(b)	Increased capacity of the power system
(c)	Reducing the capacity of the substations
(d)	All of the mentioned

106.

For the satisfactory parallel operation of two transformers, which of the following conditions is most essential?

(a)	Polarities of all transformer operated in parallel must be the same
(b)	PU impedance of all transformers operated in parallel must be the same
(c)	Voltage ratio of all transformer operated in parallel must be the same
(d)	MVA rating of all transformer operated in parallel must be the same

107.

Which one of the following is not a condition of parallel operation of the transformer?

(a)	MVA Rating of transformers must be same
(b)	Voltage ration of transformers must be the same
(c)	Percentage Impedance of transformers should be the same
(d)	Polarity of transformers must be identical

108.

When operating two or more transformers in parallel, the % impedance of these transformers should be

(a)	Proportional to their kVA rating
(b)	Equal
(c)	not be equal
(d)	none of the above

109.

If the impedance triangles of two transformers operating in parallel are not identical in shape and size, the two transformers will

(a)	Share the load unequally
(b)	get heated unequally
(c)	have a circulatory secondary current even when unloaded
(d)	run with different power factors

110.

Two single-phase transformers A and B are operating in parallel with the same pu impedance and different x/r ratios. Then the total kVA output of both the transformer will be

(a)	< (A+B)
(b)	> (A+B)
(c)	= (A+B)
(d)	= (A+B)/2

Showing 101 to 110 out of 155 Questions