69) If the current rating of the installation is high, a current transformer is used in the energy meter circuit. If a current transformer of 100A/5A is connected with an energy meter, the multiplying factor for the recorded energy is

105

Answer is:

20

Transformers MCQ - Electrician (Set-1) with Answers

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70) In constant voltage transformer at certain induced secondary voltage, the impedance of secondary winding will become equal to impedance of the capcitor across it. What is this condition of circuit known as ?

Saturation

Equality

Good

Resonance

Answer is:

Resonance

71) What may be the cause for over heating of a transformer ?

High ambient temperature

Input voltage is too low

Load is too high

Arc from the transformer primary to the secondary

Answer is:

Load is too high

72) In which part of the distribution transformer, maximum heat occurs ?

Transformer core

Transformer tank

Transformer oil

L.V. and H.V. winding

Answer is:

L.V. and H.V. winding

Explanation:

Assuming that the transformer is working at its rated capacity, the maximum heating occurs in the winding. The transformer core is made using low loss materials to make it more efficient and thus the core loss at rated load is a fraction of the winding loss.

73) What principle makes the instrument transformer working ?

Self induction

Lenz's law

Mutual induction

Fleming's right hand rule

Answer is:

Mutual induction

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