Transmission and distribution

11. Which of the following characteristics should the line supports for transmission lines possess?

Low cost
High mechanical strength
Longer life
All of the above

Detailed SolutionWhich of the following characteristics should the line supports for transmission lines possess?

12. Which of the following relays is used on long transmission lines?

Impedance relay
Mho's relay
Reactance relay
None of the above

Detailed SolutionWhich of the following relays is used on long transmission lines?

13. In transmission lines the cross-arms are made of

Copper
Wood
R.C.C.
Steel

Detailed SolutionIn transmission lines the cross-arms are made of

14. Due to which of the following reasons the cables should not be operated too hot?

The oil may loose its viscosity and it may start drawing off from higher levels
Expansion of the oil may cause the sheath to burst
Unequal expansion may create voids in the insulation which will lead to ionization
All of the above

Detailed SolutionDue to which of the following reasons the cables should not be operated too hot?

15. The loads on distributors systems are generally

Balanced
Unbalanced
Either of the above
None of the above

Detailed SolutionThe loads on distributors systems are generally

16. If variable part of annual cost on account of interest and depreciation on the capital outlay is equal to the annual cost of electrical energy wasted in the conductors, the total annual cost will be minimum and the corresponding size of conductor will be most economical. This statement is known as

Kelvin's law
Ohm's law
Kirchhoff's law
Faraday's law

Detailed SolutionIf variable part of annual cost on account of interest and depreciation on the capital outlay is equal to the annual cost of electrical energy wasted in the conductors, the total annual cost will be minimum and the corresponding size of conductor will be most economical. This statement is known as

17. The distributors for residential areas are

Single phase
Three-phase three wire
Three-phase four wire
None of the above

Detailed SolutionThe distributors for residential areas are

18. In a substation the following equipment is not installed

Exciters
Series capacitors
Shunt reactors
Voltaire transformers

Detailed SolutionIn a substation the following equipment is not installed

19. Overhead lines generally use

Copper conductors
All aluminium conductors
A.C.S.R. conductors
None of these

Detailed SolutionOverhead lines generally use

20. Aluminium has a specific gravity of

1.5
2.7
4.2
7.8

Detailed SolutionAluminium has a specific gravity of

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