Transmission And Distribution

1. Which of the following is not the trans­mission voltage in America ?

(A) 66 kV

(B) l32kV

(C) 264 kV

(D) 400 kV

Answer: (c) 264 Kv

2. Which of the following is usually not the generating voltage ?

(A) 6.6 kV

(B) 9.9 kV

(C) 11kV

(D) 13.2 kV.

Answer: (B) 9.9 kV

3.Boosters are basically

(A) inductors

(B) capacitors

(C) transformers

(D) synchronous motors.

Answer: (C) transformers

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.

Answer: (D) Single phase -4 wire.

5. 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.

 Answer: (B) to increase clearance from ground

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.

Answer: (A) voltage and power factor both increase

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).

 Answer: (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.

Answer: (B) portion of conductor near the surface carries more current as compared to the core

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.

Answer: (A) skin effect

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.

Answer: (D) Current is uniformly distributed in the conductor cross-section.

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