Protection

#1. Mho relay is normally used for the protection of......?

short length lines

medium length lines

long length lines

all the above

incorrect

#2. Reactance relays are employed for phase fault in.....?

short line

medium line

long line

all the above

#3. Relays performs the function of.....?

decreasing current

increasing current

fault detection

fault interruption

#4. A thermal protection switch provide protection against.....?

temperature

over load

over voltage

over current

#5. Which circuit breaker works at lowest operating voltage?

air blast

air break

SF6

oil

#6. Buchholz relay is used on.....?

air cooled transformers

oil immersed power transformers

instrument transformers

distribution transformers

#7. which relay is used for ground fault protection?

direction relay

reactance relay

impedence relay

mho relay

#8. Differential relay is used for protection against....?

alternators

transformers

feeders

all the above

#9. A 2VA relay is ...... sensitive than 4VArelay?

less

more

#10. An over current relay having a current setting of 125% is connected to a supply circuit through a current transformer of ratio 400/5. the pick up value will be.....?

4 A

6 A

4.6 A

6.25A

#11. The pick up value of a relay is 7.5A and fault current in relay coil is 30A. its plug setting multiplier is.....?

2.5

4

6

23

#12. Back up protection used for protection against which fault?

no load fault

short circuit fault

internal fault

external fault

when primary protection fails back up protection works

#13. Most commonly used for the protection of stator winding faults of a alternator is.....?

over current protection

differential protection

earth fault protection

none of the above

#14. Buchholz relay is a........actuated relay?

oil

gas

SF6

coal

#15. Buchholz relay is installed between main tank and......?

mercury switch

trip circuit

conservator

float

#16. The ideal scheme of protection for lines is......?

distance protection

current protection

differential protection

#17. Which protection is used for very long high transmission lines?

differential protection

distance protection

reactance relay

#18. Differential protection of a alternator having ..... number of piolet wires?

1

2

3

4

#19. A sudden rise in voltage for a very short duration on the power system is known as.....?

restriking voltage

voltage surge

break down voltage

#20. Which of the following is not a cause of over voltages on a power system?

switching surges

insulation failure and arcing ground

resonance and lightning

all the above

#21. Transients on the power system due to current chopping are taken care of by.....?

resonance

lightninh

resistance switching

all the above

#22. Most commonly used arrester in substation is.....?

rod gap

thyrite

horn gap

#23. Arcing ground can be prevented by.....?

use of horn gap

use of rod gap

earthing the neutral

#24. The voltage rating of the transformer in a pole mounted substation is.....?

11kV/230V

11kV/400V

11kV/33kV

11kV/66kV

#25. Indoor substation used voltage upto.....?

11kV

22kV

33kV

66kV

#26. Outdoor substation used voltage beyond.....?

11kV

22kV

33kV

66kV

#27. An indoor substation is ..... expensive than outdoor substation?

less

more

#28. The advantage of neutral earthing is.....?

saftey of personel

reduction of the earth fault current

elimination of arcing ground

none of the above

#29. The size of the earth wire is determined on the basis of....?

current carrying capacity of service line

voltage of the service line

atmospheric condition

temperature

#30. The best location for use of a booster transformer in a transmission line is.....?

at the sending end

at the receiving end

at the intermediate point

any of the above

#31. Earthing is necessary to give protection against....?

over loading

short circuit

electric shock

electric fire

#32. Which circuit breaker is used for 1.5 T air conditioner?

2A

5A

15 A

20A

#33. ELCB is protect circuit from....?

over load

short circuit

leakage current

over current

#1. Mho relay is normally used for the protection of......?

#2. Reactance relays are employed for phase fault in.....?

#3. Relays performs the function of.....?

#4. A thermal protection switch provide protection against.....?

#5. Which circuit breaker works at lowest operating voltage?

#6. Buchholz relay is used on.....?

#7. which relay is used for ground fault protection?

#8. Differential relay is used for protection against....?

#9. A 2VA relay is ...... sensitive than 4VArelay?

#10. An over current relay having a current setting of 125% is connected to a supply circuit through a current transformer of ratio 400/5. the pick up value will be.....?

#11. The pick up value of a relay is 7.5A and fault current in relay coil is 30A. its plug setting multiplier is.....?

#12. Back up protection used for protection against which fault?

#13. Most commonly used for the protection of stator winding faults of a alternator is.....?

#14. Buchholz relay is a........actuated relay?

#15. Buchholz relay is installed between main tank and......?

#16. The ideal scheme of protection for lines is......?

#17. Which protection is used for very long high transmission lines?

#18. Differential protection of a alternator having ..... number of piolet wires?

#19. A sudden rise in voltage for a very short duration on the power system is known as.....?

#20. Which of the following is not a cause of over voltages on a power system?

#21. Transients on the power system due to current chopping are taken care of by.....?

#22. Most commonly used arrester in substation is.....?

#23. Arcing ground can be prevented by.....?

#24. The voltage rating of the transformer in a pole mounted substation is.....?

#25. Indoor substation used voltage upto.....?

#26. Outdoor substation used voltage beyond.....?

#27. An indoor substation is ..... expensive than outdoor substation?

#28. The advantage of neutral earthing is.....?

#29. The size of the earth wire is determined on the basis of....?

#30. The best location for use of a booster transformer in a transmission line is.....?

#31. Earthing is necessary to give protection against....?

#32. Which circuit breaker is used for 1.5 T air conditioner?

#33. ELCB is protect circuit from....?

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