transformers MCQs – Page 7

Practise focused transformers questions with marked answers for exam preparation and subject revision.

transformers Mcqs
121. If the supply frequency to the transformer is increased,the iron loss will__________?
comments icon0
A. increase

B. not change

C. any of the above

D. decrease

122. The value of flux involved m the e.m.f. equation of a transformer is____________?
comments icon0
A. maximum value

B. average value

C. instantaneous value

D. r.m.s. value

123. Which of the following statements regarding an idel single-phase transformer having a turn ratio of 1 : 2 and drawing a current of 10 A from 200 V A.C. supply is incorrect?
comments icon0

A. Its secondary voltage is 400 V

B. Its rating is 2 kVA

C. Its secondary current is 5 A

D. It is a step-up transformer

E. Its secondary current is 20 A
124. If a transformer is switched on to a voltage more than the rated voltage______________?
comments icon0

A. its power factor will be zero

B. its power factor will remain unaffected

C. its power factor will deteriorate

D. its power factor will increase

125. The function of breather in a transformer is___________?
comments icon0

A. to cool the transformer oil

B. to arrest flow of moisture when outside air enters the transformer

C. to provide oxygen inside the tank

D. to cool the coils during reduced load

126. Part of the transformer which is most subject to damage from overheating is_____________?
comments icon0

A. copper winding

B. transformer tank

C. winding insulation

D. frame or case

E. iron core

127. The transformer ratings are usually expressed in terms of______________?
comments icon0

A. kW

B. volts

C. amperes

D. kVA
128. Open circuit test on transformers is conducted to determine____________?
comments icon0
A. core losses

B. hysteresis losses

C. copper losses

D. eddy current losses

129. In a transformer the energy is conveyed from primary to secondary_________?
comments icon0

A. none of the above

B. by the flux

C. through cooling coil

D. through air

130. The chemical used in breather is_______________?
comments icon0

A. asbestos fiber

B. silica sand

C. silica gel

D. sodium chloride

131. When a given transformer is run at its rated voltage but reduced frequency, its____________?
comments icon0

A. core flux density is reduced

B. core flux density is increased

C. iron losses are reduced

D. flux density remains unaffected

132. The purpose of providing an iron core in a transformer is to_____________?
comments icon0

A. provide support to windings

B. decrease the reluctance of the magnetic path

C. reduce eddy current losses

D. reduce hysteresis loss

133. Buchholzs relay gives warning and protection against_________________?
comments icon0
A. electrical fault inside the transformer itself

B. electrical fault outside the transformer in outgoing feeder

C. for both outside and inside faults

D. none of the above

134. What will happen if the transformers working in parallel are not connected with regard to polarity ?
comments icon0

A. none of the above

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

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

D. Incorrect polarity will result in dead short circuit