Transformers

81. The function of conservator in a transformer is

1. to project against'internal fault
2. to reduce copper as well as core losses
3. to cool the transformer oil
4. to take care of the expansion and contraction of transformer oil due to variation of temperature of surroundings

View answer

82. The highest voltage for transmitting electrical power in India is

1. 33 kV.
2. 66 kV
3. 132 kV
4. 400 kV

View answer

83. The hum in a transformer is mainly attributed to

1. load changes
2. oil in the transformer
3. magnetostriction
4. mechanical vibrations

View answer

84. The leakage flux in a transformer depends upon

1. load current
2. load current and voltage
3. load current, voltage and frequency
4. load current, voltage, frequency and power factor

View answer

85. The magnetising current of a transformer is usually small because it has

1. small air gap
2. large leakage flux
3. laminated silicon steel core
4. fewer rotating parts

View answer

86. The main reason for generation of harmonics in a transformer could be

1. fluctuating load
2. poor insulation
3. mechanical vibrations
4. saturation of core

View answer

87. The maximum efficiency of a distribution transformer is

1. at no load
2. at 50% full load
3. at 80% full load
4. at full load

View answer

88. The maximum load that a power transformer can carry is limited by its

1. temperature rise
2. dielectric strength of oil
3. voltage ratio
4. copper loss

View answer

89. The no load current in a transformer lags behind the applied voltage by an angle of about

1. 180°
2. 120"
3. 90°
4. 75°

View answer

90. The noise produced by a transformer is termed as

1. zoom
2. hum
3. ringing
4. buzz

View answer