Transformers

111. Two transformers operating in parallel will share the load depending upon their

1. leakage reactance
2. per unit impedance
3. efficiencies
4. ratings

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

1. The power factor of the two trans-formers will be different from the power factor of common load
2. Incorrect polarity will result in dead short circuit
3. The transformers will not share load in proportion to their kVA ratings
4. none of the above

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113. When a given transformer is run at its rated voltage but reduced frequency, its

1. flux density remains unaffected
2. iron losses are reduced
3. core flux density is reduced
4. core flux density is increased

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114. When secondary of a current transformer is open-circuited its iron core will be

1. hot because of heavy iron losses taking place in it due to high flux density
2. hot because primary will carry heavy current
3. cool as there is no secondary current
4. none of above will happen

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

1. Horn gaps
2. Thermal overload relays
3. Breather
4. Conservator

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116. Which of the following does not change in a transformer?

1. Current
2. Voltage
3. Frequency
4. All of the above

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117. Which of the following does not change in an ordinary transformer?

1. Frequency
2. Voltage
3. Current
4. Any of the above

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118. Which of the following insulating materials can withstand the highest temperature safely?

1. Cellulose
2. Asbestos
3. Mica
4. Glass fibre

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119. Which of the following is not a part of transformer installation?

1. Conservator
2. Breather
3. Buchholz relay
4. Exciter

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120. Which of the following is not a routine test on transformers?

1. Core insulation voltage test
2. Impedance test
3. Radio interference test
4. Polarity test

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