Transformers Archives

111. The transformer laminations are insulated from each other by

mica strip

thin coat of varnish

paper

any of the above

Detailed SolutionThe transformer laminations are insulated from each other by

112. No-load current of a transformer has

has high magnitude and low power factor

has high magnitude and high power factor

has small magnitude and high power factor

has small magnitude and low power factor

Detailed SolutionNo-load current of a transformer has

113. In a given transformer for given applied voltage, losses which remain constant irrespective of load changes are

friction and windage losses

copper losses

hysteresis and eddy current losses

none of the above

Detailed SolutionIn a given transformer for given applied voltage, losses which remain constant irrespective of load changes are

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

short-circuiting of the secondaries

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

transformers having higher copper losses will have negligible core losses

loading of the transformers not in proportion to their kVA ratings

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

115. Which of the following acts as a protection against high voltage surges due to lightning and switching?

Horn gaps

Thermal overload relays

Breather

Conservator

Detailed SolutionWhich of the following acts as a protection against high voltage surges due to lightning and switching?

116. In a transformer the resistance between its primary and secondary is

zero

1 ohm

1000 ohms

infinite

Detailed SolutionIn a transformer the resistance between its primary and secondary is

117. Which of the following parts of a transformer is visible from outside?

Bushings

Core

Primary winding

Secondary winding

Detailed SolutionWhich of the following parts of a transformer is visible from outside?

118. Gas is usually not liberated due to dissociation of transformer oil unless the oil temperature exceeds

50Â°C

80Â°C

100Â°C

150Â°C

Detailed SolutionGas is usually not liberated due to dissociation of transformer oil unless the oil temperature exceeds

119. Primary winding of a transformer

is always a low voltage winding

is always a high voltage winding

could either be a low voltage or high voltage winding

none of the above

Detailed SolutionPrimary winding of a transformer

120. The core used in high frequency transformer is usually

copper core

cost iron core

air core

mild steel core

Detailed SolutionThe core used in high frequency transformer is usually

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