For the parallel operation of single phase transformers it is necessary that they should have

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

The gypsys are a tribe of strange people. They do not have any fixed home but wander about from place to place and live in tents. they were originally natives of India. But as they reached England from Egypt ,the English took them from Egyptians. this is why they came to be called gypsys. they were beloved to possess strange powers. they could tell your fortune by reading the palm of your hand. it was thought they stole little children to train them in their way of life. whenever a child got lost it was thought that it has been carried away by gypsys so they were arrested and sent for trial. but this attitude towards the Gypsy has gradually changed.The gypsies are people who ---

A

have a settled way of life

B

came originally from Egypt to England

C

are always on the move

D

steal children to train them in the way of life

Why transformers connected in parallel should have same voltage ratio?

A

To avoid full load circulating current

B

To avoid no-load circulating current

C

To avoid other losses

D

To avoid all type of currents

For seccessful operation of two single phase transformer connected in parallel, the most essential condition is that their

A

Percentage impledances are equal

B

Polarities are properly connected

C

Turns ration are exactly equal

D

KVA rating are equal

দুটি সুসঙ্গত উৎস থেকে λ দৈর্ঘ্যের দুটি তরঙ্গ সমদশায় বের হয় । একটি বিন্দুতে যেখানে তরঙ্গ দুটি মিলিত হয় সেখানে তাদের দশা পার্থক্য 90° । তরঙ্গ দুটির অতিক্রান্ত পথ পার্থক্য তখন কত ? ( Two coherent sources emit waves of wavelength λ which are in phase. which are in phase. The two waves meet at a point where they have a phase difference of 90°. Which of the following could be the traversed path difference between the waves?)

A

2λ

B

λ

C

λ/2

D

λ/4

What will happen if the transformers working in parallel are not connected with regard to polarity?

A

The power factor of the two trans-formers will be different from the power factor of common load

B

Incorrect polarity will result in dead short circuit

C

The transformers will not share load in proportion to their kVA ratings

D

Cannot be determined

If the percentage impedances of the two transformers working in parallel are different, then

A

transformers will be overheated

B

power factors of both the transformers will be same

C

parallel operation will be not possible

D

parallel operation will still be possible, but the power factors at which the two transformers operate will be different from the power factor of the common load

Two transformers operating in parallel will share the load depending upon their

A

leakage reactance

B

per unit impedance

C

efficiencies

D

ratings

The essential condition for parallel operation of two D.C. generators is that they have

A

Same kW rating

B

The same operation r.p.m.

C

The same drooping voltage characteristics

D

Same percentage regulation

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

For the parallel operation of single phase transformers it is necessary that they should have

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