204.  Minimum voltage regulation occurs when the power factor of the load is
A. unity
B. lagging
C. leading
D. zero

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205.  In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of
A. less than 15 A
B. more than 15 A
C. 15 A
D. none of the above

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206.  Buchholz relay is used on
A. welding transformers
B. air-cooled transformers
C. furnace transformers
D. oil cooled transformers

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207.  The kVA rating ratio of transformers operating in parallel, as a general rule, should be within
A. 5 : 1
B. 4: 1
C. 3 : 1
D. 2: 1

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208.  Which value of flux is involved in the e.m.f. equation of the transformer?
A. R.M.S. value
B. Critical value
C. Average value
D. Maximum value

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209. In Scott connections the main transformer has centre tap on
A. primary winding
B. secondary windings
C. both primary and secondary windings
D. none of the above

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210.  In a transformer overcurrents affect
A. mechanical stress
B. temperature rise
C. insulation life
D. all of the above

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