183. The secondary ofa current transformer is always short-circuited under operating conditions because it
A. avoids core saturation and high voltage induction
B. is safe to human beings
C. protects the primary circuit
D. none of the above

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184.  In a transformer the resistance between its primary and secondary should be
A. zero
B.10
C.1000
D. infinity

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185.  A good voltage regulation of a transformer means
A. output voltage fluctuation from no load to full load is least
B. output voltage fluctuation with power factor is least
C. difference between primary and secondary voltage is least
D. difference between primary and secondary voltage is maximum

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186.  For a transformer, operating at constant load current, maximum efficiency will occur at
A. 0.8 leading power factor
B. 0.8 lagging power factor
C. zero power factor
D. unity power factor

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187.  Which of the following protection is normally not provided on small distribution transformers?
A. Overfluxing protection
B. Buchholz relay
C. Overcurrent protection
D. All of the above

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188.  Which of the following acts as a protection against high voltage surges due to lightning and switching?
A. Horn gaps
B. Thermal overload relays
C. Breather
D. Conservator

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189.  The efficiency of two identical transformers under load conditions can be determined by
A. short-circuit test
B. back-to-back test
C. open circuit test
D. any of the above

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