29. Transmission line are classified as short, medium and long depending on the
A. length of line
B. charging current or no load current
C. capacitance of line
D. both A and B above

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30. Corona is observed on
A. a.c. transmission lines only
B. d.c. transmission lines only
C. both a.c. and d.c. transmission lines
D. none of these

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31. An advantage of corona on transmission lines is that
A. it minimizes power loss
B. it reflects electrical surges
C. it works as a surge modifier during overloads
D. none of these

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32. As the moisture content in the air increases, the disruptive critical voltage
A. increases
B. decreases
C. remain constant
D. may increase or decrease

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33. Inductance in henries/metre of a single phase two parallel wire transmission line having conductor radius r and spacing D between conductors is equal to
A. 27E x lIn (D
B. 4 x 10-7 /n (1-1
C. 47cx 10-7 In (12D
D. 4 x

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34. For torque angle 8, the condition for maximum power transmission
A. 8 = 0
B. 8 = 90?R
C. 8 = tan-? ?
D. 8 = tan? rR43 X

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35. As per Indian Standards, the cross-sectional area of the neutral wire in a 3-phase 4 wire system is
A. twice that of a phase conductor
B. equal to that of a phase conductor
C. half that of a phase conductor
D. one-fourth that of a phase conductor

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