MCQs of Transformers (Electrical Machine - I - 3140913)

Electrical Machine - I (3140913) MCQs

MCQs of Transformers

Showing 71 to 80 out of 155 Questions

71.

Which of the following losses in the transformer varies with load?

(a)	Copper loss
(b)	Eddy current loss
(c)	Hysteresis loss
(d)	Stray loss

72.

What kVA rating is required for a transformer that must handle a maximum load current of 8 A with a secondary voltage of 2 kV?

(a)	4 kVA
(b)	0.25 kVA
(c)	16 kVA
(d)	8 kVA

73.

The maximum efficiency of a transformer occurs when

(a)	Iron loss > Copper loss
(b)	Iron loss < Copper loss
(c)	Iron loss = Copper loss
(d)	Iron loss = Zero

74.

Full load copper loss in a transformer is 1600 W. At half load the loss will be

(a)	400 W
(b)	1600 W
(c)	3200 W
(d)	6400 W

75.

The iron loss for a transformer is 400 W. If the transformer is working at its maximum efficiency then the copper loss will be

(a)	400 W
(b)	1600 W
(c)	200 W
(d)	800 W

76.

If iron loss and full load copper loss of any transformer are denoted by Pi and Pc, then the load corresponding to maximum efficiency is given by

(a)	$\sqrt{\frac{P_{i}}{P_{c}}} \times (k V A_{F L})$
(b)	$\frac{P_{i}}{P_{c}} \times (k V A_{F L})$
(c)	${(\frac{P_{i}}{P_{c}})}^{2} \times (k V A_{F L})$
(d)	None of the above

77.

A transformer has full load iron loss of 900 W and copper loss of 1600 W. At what percentage of the load the transformer will have maximum efficiency?

(a)	90 %
(b)	100 %
(c)	75 %
(d)	80 %

78.

A 500 kVA 2 winding transformer has an iron loss of 3 kW and a full load copper loss of 3.5 kW. Calculate the kVA loading for maximum efficiency.

(a)	345.6 kVA
(b)	320.0 kVA
(c)	462.9 kVA
(d)	240.0 kVA

79.

A 100 kVA, 2 winding transformer has an iron loss of 1 kW and a copper loss of 1.5 kW at normal output current. Calculate efficiency at 0.8 lagging power factor.

(a)	96.96
(b)	75.75
(c)	83.83
(d)	93.93

80.

If Cu loss of a transformer at 7/8th full load is 4900 W, then its full-load Cu loss would be .......watt.

(a)	5600
(b)	6400
(c)	375
(d)	429

Showing 71 to 80 out of 155 Questions