Power transformers are designed to have maximum efficiency at

Power transformers should be designed to have maximum efficiency

A

at one-fourth load

B

at one-half load

C

at or near full load

D

any of the above

Power transformers are generally designed to have maximum efficiency around

A

no-load

B

half-load

C

near full-load

D

10% overload

Distribution transformers are generally designed for maximum efficiency around

A

90% load

B

Zero load

C

25% load

D

50% load

Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in

A

short-circuiting of the secondaries

B

power factor of one of the transformers is leading while that of the other lagging

C

transformers having higher copper losses will have negligible core losses

D

loading of the transformers not in proportion to their kVA ratings

A single phase transformer has a maximum efficiency of 90% at full load and unity power factor. Efficiency at half load at the same power factor is -

A

87.8%

B

86.7%

C

88.26%

D

88.9%

The efficiency of two identical transformers under load conditions can be determined by

A

short-circuit test

B

back-to-back test

C

open circuit test

D

any of the above

Power transformers have rating

A

equal to 50 kVA

B

equal to 100 kVA

C

above 200 kVA

D

none of the above

Generators for peak load plants are usually designed for maximum efficiency at

A

25 to 50 percent full load

B

50 to 75 percent full load

C

full load

D

25 percent overload

D.C. generators are normally designed for maximum efficiency around

A

Full load

B

Rated r.p.m.

C

Rated voltage

D

All of the above

Efficiency of power transfer when maximum transfer of power c xerosis

A

100%

B

80%

C

75%

D

50%

Power transformers are designed to have maximum efficiency at

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