Free Printable Switch gear & protection

1.

A transmission line is protected by

a)

inrush protection

b)

distance protection

c)

time graded and current graded over current protection

d)

both (b) and (c)

2.

Large internal faults are protected by

a)

(a) merz price percentage differential protection,

b)

(b) mho and ohm relays

c)

c) horn gaps and temperature relays.

d)

(d) earth fault and positive sequence relays

3.

When a transmission line is energized, the wave that propagates on it is

a)

(a) current wave only

b)

(b) voltage wave only

c)

(c) both (a) and (b)

d)

(d) power factor wave only.

4.

4. Shunt capacitance is neglected while considering

a)

(a) short transmission line,

b)

(b) medium transmission line,

c)

(c) long transmission line

d)

(d) medium and long transmission lines.

5.

The ground wire should not be smaller than No ______ copper.

a)

2

b)

4

c)

6

d)

10

6.

Resistance grounding is used for voltage between

a)

33kVto66kV

b)

3.3kVand ll kV

c)

2.2 KV to 3.3 KV

d)

above 11KV

7.

The contacts of high voltage switches used in power system are submerged in oil. The main purpose of the oil is to

a)

lubricate the contacts

b)

insulate the contacts from switch

c)

all of the above

d)

none of the above

8.

Wave trap is used to trap waves of

a)

(a) power frequencies,

b)

(b) higher frequencies entering generator or transformer units

c)

(c) either of the above,

d)

(d) none of the above.

9.

Underground neutral transmission system is not recommended because of system

a)

(a) insulation being overstressed due to over voltages

b)

insulation overstress may lead to failure and subsequent phase to phase faults,

c)

being inadequately protected against ground fault

d)

all of the above.

10.

The reflection co-efficient at the open circuited end of a transmission line.

a)

0

b)

infinity

c)

1

d)

none

11.

For the protection of power station buildings against direct strokes the requirements are

a)

(a) interception,

b)

(b) interception and conduction,

c)

(c) interception, conduction and dissipation

d)

(d) interception, conduction, dissipation and reflection

12.

The line insulation is the______ insulation level of the station equipment.

a)

(a) less than

b)

, (b) same as,

c)

(c) more than,

d)

d) not directly related with

13.

The interaction between a transmission line and communication line is minimized by

a)

(a) transposing transmission as well as communication lines

.

b)

(b) increasing the height of the trans-mission line tower

c)

(c) increasing the distance between the two lines

d)

(d) all of the above

14.

14. When a wave propagates on a transmission line, it suffers reflection several times at

a)

a) tapping,

b)

(b) load end,

c)

(c) sending end,

d)

(d) sending and other end

15.

15. Which of the following statements is incorrect?

a)

(a) Station batteries are used to operate relay only

b)

(b) The lightning arresters are basically surge diverters

c)

(c) An impedance relay has maximum fault current when fault occurs near the relay

d)

(d) A high speed relay has an operation of 1 to 2 cycles.

16.

16. Which of the following statements is incorrect ?

a)

(a) Lightning arrestors are used before the switchgear

b)

(b) Shunt reactors are used as compensation reactors

c)

(c) The peak short current is (1.8 xV2) times the A.C. component

d)

(d) The MVA at fault is equal to base MVA divided by per unit equivalent fault reactance.

17.

Bus coupler is very essential in arrangement

a)

(a) single bus,

b)

(b) double bus, double breaker,

c)

(c) main and transfer bus,

d)

(d) all of the above.

18.

For cost and safety, the outdoor substations are installed for voltages above

a)

11 KV

b)

33KV

c)

60KV

d)

110KV

19.

19. The short circuit in any winding of the transformer is the result of

a)

(a) mechanical vibration,

b)

(b) insulation failure,

c)

(c) loose connection,

d)

(d) impulse voltage

20.

Which type of relays are used for phase faults on long line.

a)

a) Impedance,

b)

(b) Reactance,

c)

(c) Either of the above,

d)

(d) None of the above

21.

For which of the following protection from negative sequence currents is provided ?

a)

(a) Generators,

b)

b) Motors,

c)

(c) Transmission line,

d)

(d) Transformers

22.

Which type of relay is preferred for phase fault on short transmission line.

a)

(a) Induction type,

b)

(b) Reluctance

c)

(c) Impedance

d)

(d) None of the above

23.

For which of the following ratings of the transformer differential protection is recommended ?

a)

(a) above 30 kVA.

b)

(b) equal to and above 5 MVA,

c)

(c) equal to and above 25 MVA,

d)

(d) none of the above

24.

The under voltage relay can be used for

a)

(a) generators,

b)

(b) busbars,

c)

(c) transformers,

d)

all of the above

25.

Which of the following devices will receive voltage surge first travelling on the transmission line ?

a)

(a) Lightning arresters,

b)

(b) Relays,

c)

(c) Step-down transformer,

d)

(d) Switchgear

26.

26. Which of the following parameter can be neglected for a short line ?

a)

(a) Inductance,

b)

(b) Capacitance,

c)

c) Resistance,

d)

(d) Reactance

27.

27. Over fluxing protection is recommended for

a)

(a) distribution transformer,

b)

(b) generator transformer of the power plant

c)

(c) auto-transformer of the power plant,

d)

(d) station transformer of the power plant

28.

28. The power loss is an important factor for the design of

a)

(a) transmission line,

b)

(b) motor,

c)

(c) generator,

d)

(d) feeder

29.

In a single bus-bar system there will be complete shut down when

a)

(a) fault occurs on the bus itself,

b)

(b) fault occurs on neutral line

c)

(c) two or more faults occur simultaneously,

d)

(d) fault occurs with respect to earthing

30.

Peterson coil is used for

a)

a) To reduce the fault current

b)

b) Grounding of system neutral

c)

c) Connecting two interconnected systems.

d)

d). For shunt compensation of transmission lines

31.

In substations, the most commonly used type of arrester is __________arrester.

a)

a) Thyrite

b)

b) Horngap

c)

c) Rod gap

d)

D) All of the above.

32.

Lightning arrester is made up of which material?

a)

a) Aluminium,

b)

b) silicon oxide,

c)

c) silver,

d)

d) copper.

33.

Earthing of the transformer neutral through reactance will improve its

a)

a) Transient stability

b)

b) Steady state stability

c)

c) dynamic stability,

d)

d) all of the above.

34.

The size of the earth wire is determined on the basis of

a)

a) Voltage of the service line,

b)

b) Current carrying capacity of the service line.

c)

c) Atmospheric conditions.

d)

d) none of the above.

35.

Ring main distribution is preferred to a radial system because

a)

(a) voltage drop in the feeder is less and supply is more reliable

b)

(b) voltage drop in the feeder is less and power factor is high

c)

(c) power factor is high and supply is more reliable

d)

(d) power factor is high and system is less expensive

36.

For reducing tower footing resistance it is better to use:

a)

(a) Chemical and ground rods only

b)

(b) Chemical and counterpoise only

c)

(c) Ground rod and counterpoise only

d)

(d) Chemical, ground rods and counterpoise

37.

37. The impulse ratio of a rod gap is:

a)

(a) Unity

b)

(b) Between 1.5 and 2.3

c)

(c) Between 1.6 and 1.8

d)

(d) Between 2 and 2.2.

38.

38. Standard impulse testing of a power transformer requires:

a)

(a) Two applications of chopped wave followed by one application of a full wave

b)

(b) One application of chopped wave followed by one application of a full wave

c)

(c) One application of chopped wave followed by two applications of a full wave

d)

(d) None of the above.

39.

The order of the lightning discharge current is:

a)

(a) 10,000 amp

b)

(b) 100 amp

c)

(c) 1 amp

d)

(d) 1 microampere.

40.

A Bucholz relay is used for

a)

(a) protection of a transformer against all internal faults

b)

(b) protection of a transformer against all external faults

c)

(c) protection of a transformer against both internal and external faults

d)

(d) protection of induction motors.

Switch gear & protection

Total questions: 40

Worksheet time: 40mins

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