1. Strain type insulator arc used where the conductors arc
(A) dead ended
(B) at intermediate anchor towers
(C) any of the above
(D) none of the above.
2. Conductors for high voltage transmission lines are suspended from towers
(A) to reduce clearance from ground
(B) to increase clearance from ground
(C) to reduce wind and snow loads
(D) to take care of extension in length during summer.
3. Boosters are basically
(A) inductors
(B) capacitors
(C) transformers
(D) synchronous motors.
4. Which of the following is not the distribution system normally used
(A) 3 phase-4 wire
(B) 3 phase-3 wire
(C) Single phase - 3 wire
(D) Single phase -4 wire.
5. Skin effect results in
(A) reduced effective resistance but increased effective internal reactance of the conductor
(B) increased effective resistance but reduced effective internal reactance of. the conductor
(C) reduced effective resistance as well as effective internal reactance
(D) increased effective resistance as well as effective internal reactance.
6. Transmission efficiency increases as
(A) voltage and power factor both increase
(B) voltage and power factor both decrease
(C) voltage increases but power factor decreases
(D) voltage decreases but power factor increases.
7. With same maximum voltage to earth, which ac system (with p.f. 0.8) will require more copper as compared to dc 2 wire system
(A) single phase. 2 wire (mid point earthed)
(B) single phase. 3 wire (neutral=1/2 outer)
(C) three phase three wire
(D) three phase-four wire (neutral = outer).
8. When alternating current passes through a conductor
(A) it remains uniformly distributed throughout the section of conductor
(B) portion of conductor near the surface carries more current as compared to the core
(C) portion of conductor near the surface carries less current as compared to the core
(D) entire current passes through the core of the conductor.
9. The fact that a conductor carries more current on the surface as compared to core, is known as
(A) skin effect
(B) corona
(C) permeability
(D) unsymmetrical fault.
10. The effective resistance of a conductor will be the same as ohmic resistance when
(A) current is in true sine wave form
(B) voltage is low
(C) power factor is unity
(D) Current is uniformly distributed in the conductor cross-section.
11. Which of the following is usually not the generating voltage ?
(A) 6.6 kV
(B) 9.9 kV
(C) 11kV
(D) 13.2 kV.
12. Skin effect depends on
(A) size of the conductor
(B) frequency of the current
(C) resistivity of the conductor material
(D) all of the above.
13. The skin effect of a conductor will reduce as the
(A) diameter increases
(B) frequency increases
(C) permeability of conductor material increases
(D) resistivity of conductor material increases.
14. Skin effect is proportional to
(A) diameter of conductor
(B) (diameter of conductor)1/2
(C) (diameter of conductor )2
(D) (diameter of conductor )2.
15. In overhead transmission lines the effect of capacitance can be neglected when the length of line is less than
(A) 200 km
(B) 160 km
(C) 100 km
(D) 80 km.
16. The effect of wind pressure is more predominant on
(A) transmission lines
(B) neutral wires
(C) insulator
(D) supporting towers.
17. The disadvantage of constant voltage transmission is
(A) short circuit current of the system is increased
(B) load power factor in heavy loads
(C) large conductor area is required for same power transmission
(D) air of the above.
18. For constant voltage transmission the voltage drop is compensated by installing
(A) synchronous motors
(B) capacitors
(C) inductors
(D) all of the above.
19. Pin insulators are normally used up to voltage of about
(A)100kV
(B) 66 kV
(C) 33 kV
(D) 25 kV.
20. The surge impedance for over head line is taken as
(A) 10-20 ohms
(B) 50-60 ohms
(C) 100-200 ohms
(D) 1000-2000 ohms.
Answers:
1.C ----- 2.B ----- 3.C ----- 4.D ----- 5.B ----- 6.A ----- 7.D ----- 8.B -----9.A -----10.D -----11.B ----- 12.D -----13.D -----14.C ----- 15.D -----16.D ----- 17.A ----- 18.A ----- 19.D ----- 20.C -----
(A) dead ended
(B) at intermediate anchor towers
(C) any of the above
(D) none of the above.
2. Conductors for high voltage transmission lines are suspended from towers(A) to reduce clearance from ground
(B) to increase clearance from ground
(C) to reduce wind and snow loads
(D) to take care of extension in length during summer.
3. Boosters are basically
(A) inductors
(B) capacitors
(C) transformers
(D) synchronous motors.
4. Which of the following is not the distribution system normally used
(A) 3 phase-4 wire
(B) 3 phase-3 wire
(C) Single phase - 3 wire
(D) Single phase -4 wire.
5. Skin effect results in
(A) reduced effective resistance but increased effective internal reactance of the conductor
(B) increased effective resistance but reduced effective internal reactance of. the conductor
(C) reduced effective resistance as well as effective internal reactance
(D) increased effective resistance as well as effective internal reactance.
6. Transmission efficiency increases as
(A) voltage and power factor both increase
(B) voltage and power factor both decrease
(C) voltage increases but power factor decreases
(D) voltage decreases but power factor increases.
7. With same maximum voltage to earth, which ac system (with p.f. 0.8) will require more copper as compared to dc 2 wire system
(A) single phase. 2 wire (mid point earthed)
(B) single phase. 3 wire (neutral=1/2 outer)
(C) three phase three wire
(D) three phase-four wire (neutral = outer).
8. When alternating current passes through a conductor
(A) it remains uniformly distributed throughout the section of conductor
(B) portion of conductor near the surface carries more current as compared to the core
(C) portion of conductor near the surface carries less current as compared to the core
(D) entire current passes through the core of the conductor.
9. The fact that a conductor carries more current on the surface as compared to core, is known as
(A) skin effect
(B) corona
(C) permeability
(D) unsymmetrical fault.
10. The effective resistance of a conductor will be the same as ohmic resistance when
(A) current is in true sine wave form
(B) voltage is low
(C) power factor is unity
(D) Current is uniformly distributed in the conductor cross-section.
11. Which of the following is usually not the generating voltage ?
(A) 6.6 kV
(B) 9.9 kV
(C) 11kV
(D) 13.2 kV.
12. Skin effect depends on
(A) size of the conductor
(B) frequency of the current
(C) resistivity of the conductor material
(D) all of the above.
13. The skin effect of a conductor will reduce as the
(A) diameter increases
(B) frequency increases
(C) permeability of conductor material increases
(D) resistivity of conductor material increases.
14. Skin effect is proportional to
(A) diameter of conductor
(B) (diameter of conductor)1/2
(C) (diameter of conductor )2
(D) (diameter of conductor )2.
15. In overhead transmission lines the effect of capacitance can be neglected when the length of line is less than
(A) 200 km
(B) 160 km
(C) 100 km
(D) 80 km.
16. The effect of wind pressure is more predominant on
(A) transmission lines
(B) neutral wires
(C) insulator
(D) supporting towers.
17. The disadvantage of constant voltage transmission is
(A) short circuit current of the system is increased
(B) load power factor in heavy loads
(C) large conductor area is required for same power transmission
(D) air of the above.
18. For constant voltage transmission the voltage drop is compensated by installing
(A) synchronous motors
(B) capacitors
(C) inductors
(D) all of the above.
19. Pin insulators are normally used up to voltage of about
(A)100kV
(B) 66 kV
(C) 33 kV
(D) 25 kV.
20. The surge impedance for over head line is taken as
(A) 10-20 ohms
(B) 50-60 ohms
(C) 100-200 ohms
(D) 1000-2000 ohms.
Answers:
1.C ----- 2.B ----- 3.C ----- 4.D ----- 5.B ----- 6.A ----- 7.D ----- 8.B -----9.A -----10.D -----11.B ----- 12.D -----13.D -----14.C ----- 15.D -----16.D ----- 17.A ----- 18.A ----- 19.D ----- 20.C -----
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