A entire current passes through the core of the conductor
B portion of conductor near the surface carries more current in comparison to the core
C Current remains uniformly distributed over the whole x-section of the conductor
D portion of conductor near the surface carries less current in comparison to the core
Answer: B portion of conductor near the surface carries more current in comparison to the core
2 Increase in frequency of transmission line causes
A no change in line resistance
B Increase in line resistance
C Decrease in line resistance
D Decrease in line series reactance
Answer: B Increase in line resistance
3. Transposition of transmission line is done to reduce the
A Line losses
B capacitive effect
C distrubances to nearby communication circuits
D effect of surge voltage induced on the line
Answer: C distrubances to nearby communication circuits
3. Which of the following is neglected while analyzing a short transmission line?
A shunt admittances
B power losses
C series impedance
D none of above
Answer: A shunt admittances
4. The phenomenon of rise in receiving end voltage of the open circuited or lightly load line is called the
A Proximity effect
B Skin effect
C Ferrranti effect
D Seebeck effect
Answer: C Ferrranti effect
5. Series capacitor is used in a transmission line to
A compensate the voltage drop
B reduce line loss
C limit short circuit current
D improve load power factor
Answer: A compensate the voltage drop
6. The material commonly used for sheaths of underground cable is
A copper
B lead
C steel
D rubber
Answer: B lead
7. The insulation resistance of a cable of length 10 km is 10 km; its resistance for 50 km length will be
Α 1 ΜΩ
Β 5 ΜΩ
С 0.2 MΩ
D none of above
Answer: С 0.2 MΩ
8. Back-to-Back HVDC is used to
A increase the transmission capability
B decrease line losses
C provide stable interconnection
D reduce voltage drop
Answer: C provide stable interconnection
9. The power transmission capability of bipolar lines is approximately ____________
A same as that of 3-ph single circuit lineB same as that of 3-ph double circuit line
C twice to that of 3-ph single circuit line
D half to that of 3-ph single circuit line
Answer: A same as that of 3-ph single circuit line
10. A dc line carries as compared to ac line _____________
A more power
B less power
C same power
D can’t be decided
A more power
B less power
C same power
D can’t be decided
Answer: A more power
11. As compared with the HVAC lines, dc transmission system is free from ___________
A inductance
B capacitance
C phase displacement
D all of the mentioned
A inductance
B capacitance
C phase displacement
D all of the mentioned
Answer: D all of the mentioned
B low losses
C easy installation
D all of the mentioned
12. Mostly the high voltage transmission is provided by overhead lines due to _____________
A low costB low losses
C easy installation
D all of the mentioned
Answer: A low cost
13. Skin effect in conductor is proportional to
A root of (diameter of conductor)
B diameter of conductor
C (diameter of conductor)2
D (diameter of conductor)4
Answer: C (diameter of conductor)2
14. Compared with a solid conductor of the same radius, corona appears on a stranded on a stranded conductor lower voltage, because stranding
A assists ionization
B makes the current flow spirally the axis of the conductor
C produces oblique sections to a plane perpendicular to the axis of the conductor
D produces surfaces of smaller radius
Answer: D produces surfaces of smaller radius
15. Which of the following distribution system is preferred for good efficiency and high economy?
A single phase, 2-wire system
B 2-phase, 3-wire system
C 3-phase, 3-wire system
D 3-phase, 4-wire system
Answer: D 3-phase, 4-wire system
16. In transmission lines we usually use cross-arms made of
A aluminium
B copper
C steel
D RCC
Answer: C steel
17. Insulators used on EHT transmission lines are made of
A PVC
B porcelain
C glass
D steatite
Answer: B porcelain
18. Which of the following material is not used for overhead line insulators?
A PorcelainB Glass
C PVC
D Steatite
Answer: C PVC
19. Pin type insulator are mostly subjected to which type of mechanical stress?
A Compressive stress
B Tensile stress
C Both tensile and compressive stress
D Twisting stress
A Compressive stress
B Tensile stress
C Both tensile and compressive stress
D Twisting stress
Answer: D Twisting stress
20. Which of the following is the main field of application of pin type insulator?
A Distribution system
B Transmission system
C Transmission and distribution system
D EHV transmission system
A Distribution system
B Transmission system
C Transmission and distribution system
D EHV transmission system
Answer: A Distribution system
21. Suspension type insulator are subjected to ______________
A tensile stress
B compressive stress
C tensile and compressive stress
D depends on its use
A tensile stress
B compressive stress
C tensile and compressive stress
D depends on its use
Answer: A tensile stress
22. A transmission line consists of 9 discs of suspension insulator in each string. What is the operating voltage of the transmission line?
A 11 KV
B 33 KV
C 66 KV
D 132 KV
A 11 KV
B 33 KV
C 66 KV
D 132 KV
Answer: D 132 KV
23. Suspension insulator are made up of _____________
A glass
B porcelain
C steatite
D epoxy resin
A glass
B porcelain
C steatite
D epoxy resin
Answer: B porcelain
24. Which of the following insulator is similar to pin type insulators?
A Suspension insulatorB Post insulator
C Strain insulator
D Shackle insulator
Answer: B Post insulator
25. Which type of insulator is used where there is dead end of the line or there is a corner or a sharp curve, for high voltage line?
A Pin type insulator
B Shackle insulator
C Strain insulator
D Stay insulator
B Mechanical stress
C Porosity of materials
D Improper vitrification
A Pin type insulator
B Shackle insulator
C Strain insulator
D Stay insulator
Answer: C Strain insulator
26. What is the most common cause of failure of overhead line insulators?
A FlashoverB Mechanical stress
C Porosity of materials
D Improper vitrification
Answer: A Flashover
27. Voltage distribution across disc of strings of suspension insulator assembly is ______
A same for all disks
B maximum for unit nearest to the line
C maximum for unit nearest to the tower
D equal to transmission line voltage rating
A same for all disks
B maximum for unit nearest to the line
C maximum for unit nearest to the tower
D equal to transmission line voltage rating
Answer: B maximum for unit nearest to the line
28. The unequal voltage distribution across individual unit of string of suspension insulator is __________
A desirable and expressed by string efficiencyB undesirable and expressed by string efficiency
C desirable and expressed by impulse ratio
D undesirable and expressed by impulse ratio
Answer: B undesirable and expressed by string efficiency
29. Capacitance in equivalent circuit of a transmission line is due to
A current in the line
B difference in potential of line
C leakage of current
D presence of magnetic Flux
Answer: B difference in potential of line
30. In a distribution system, which of the following items shares the major cost?
A Conductors
B Earthing system
C Distribution transformer
D Insulators
Answer: C Distribution transformer
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