TRANSFORMERS QUIZ

Cores of large transformers are built upto nearly circular cross section in order to reduce

Eddy current loss

Leakage reactance

Iron losses

Copper loss

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Which of the following protection is normally not provided on small distribution transformers?

Buchholz relay

Overcurrent protection

All of these

Overfluxing protection

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Transformer having ratings less than 5kVA are generally ______

Natural air cooled

Oil cooled

None of the listed here

Water cooled

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The path of the magnetic flux in transformer should have

low resistance

low reactance

high resistance

high reluctance

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When load on a transformer is decreased, ______loss is decreased

Hysteresis

Eddy current

Friction

Copper

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A transformer has a 1:6 turns ratio and a secondary coil load resistance of 470 . The load resistance as seen by the source is

7.8 Ω

1.3 Ω

78 Ω

13 Ω

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If a power transformer is operated at very high frequencies, then ______

Core losses will be excessive

Primary reactance is too much increased

Primary will draw large power

None of the listed here

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A transformer has full load copper loss of 400 W. The copper loss at half full load will be _____.

100 W

400 W

200 W

None of the listed here

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The leakage flux in a transformer depends upon

load current

load current, voltage, frequency and power factor

load current, voltage and frequency

load current and voltage

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A transformer with a 110 V primary has a 15:1 turns ratio. The load resistance, RL, is 120 . What is the approximate voltage across the load?

880 V

73 V

88 V

7.3 V

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