Power Systems Mcqs

01. In order to reduce skin effect at UHF

Conductors are painted

Conductors are anodised

Copper tubes with silver plating are used

Copper rods with silver plating are used


02. Shunt capacitance is usually neglected in the analysis of

Short transmission lines

Medium transmission lines

Long transmission lines

Medium as well as long transmission lines


03. The chances of corona are maximum during

Summer heat

Winter

Dry weather

Humid weather


04. The power transmitted will be maximum when

Sending end voltage is more

Recieving end voltage is more

Reactance is high

Corona losses are least


05. Neglecting losses in a transmission system, if the voltage is doubled, for the same power transmission, the weight of conductor material require will be

Four times

Double

Half

One forth


06. A relay used on short transmission lines is

Reactance relay

Mho’s relay

Impedance relay

None


07. In case of characteristic impedance of the line is equal to the load impedance

All the energy will pass to the earth

All the energy will be lost in transmission losses

The system will resonate badly

All the energy sent will be absorbed by the load


08. For a properly terminated line

ZR = ZO

ZR > ZO

ZR < ZO

ZR = ZO = 0


09. The dielectric strength of air at 25 C and 76 cm/Hg is

1 point

1 kV/cm

1 kV/mm

3 kV/cm

30 kV/cm


10. The chances of corona are maximum in

Domestic wiring

Distribution lines

Transmission lines

All of the above


11. Transmission lines link

Service point to consumer premises

Distribution transformer to consumer premises

Recieving end station to distribution tranformer

Generating station to recieving end station


12. In case of open circuit transmission lines the reflection coefficient is

1

0.5

-1

0


13. Impedance relay is used on

Short transmission lines

Medium transmission lines

Long transmission lines

All the transmission lines


14. Which type of insulator are used on 132 kV transmission lines ?

Pin type

Disc type

Shackle type

Pin and shackle type


15. String efficiency can be improved by

Using longer cross arm

Grading the insulator

Using guard ring

Any of the above


16. If a 66 kV lines passes over a residential building, the minimum vertical clearance from the roof of the building must be

8 feet

12 feet

13 feet

16 feet


17. Alternating current power is transmitted at high voltage

To safeguard against pilferage

To minimize transmission losses

To reduce cost of generation

To make the system relaible


18. Stranded conductors are used for transmitting power at high voltage because of

Increased tensile strength

Better wind resistance

Ease in handling

Low cost


19. The function of steel wire in a ACSR conductor is

To take care of surges

To prevent corona

To reduce inductance and hence improve power factor

To provide additional mechanical strength


20. In high voltage transmission lines, the top most conductor is

R- phase conductor

Y- phase conductor

B- phase conductor

Earth Conductor

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