Practice Switchgear & Protection Multiple Choice Questions with Answers Quiz-1

Q.1.

The under voltage relay can be used for

(a) generators,
(b) busbars,
(c) transformers,
all of the above

Q.2.

Resistance grounding is used for voltage between

33kVto66kV
3.3kVand ll kV
2.2 KV to 3.3 KV
above 11KV

Q.3.

Large internal faults are protected by

merz price percentage differential protection,
mho and ohm relays
horn gaps and temperature relays.
earth fault and positive sequence relays

Q.4.

Shunt capacitance is neglected while considering

short transmission line
medium transmission line
long transmission line
medium and long transmission lines

Q.5.

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

less than
same as,
more than,
not directly related with

Q.6.

Underground neutral transmission system is not recommended because of system

insulation being overstressed due to over voltages
insulation overstress may lead to failure and subsequent phase to phase faults,
being inadequately protected against ground fault
all of the above.

Q.7.

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

tapping,
load end,
sending end,
sending and other end

Q.8.

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

above 30 kVA.
equal to and above 5 MVA,
equal to and above 25 MVA,
none of the above

Q.9.

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

fault occurs on the bus itself,
fault occurs on neutral line
two or more faults occur simultaneously,
fault occurs with respect to earthing

Q.10.

Which of the following statements is incorrect?

Station batteries are used to operate relay only
The lightning arresters are basically surge diverters
An impedance relay has maximum fault current when fault occurs near the relay
A high speed relay has an operation of 1 to 2 cycles.

Q.11.

Wave trap is used to trap waves of

Power frequencies,
Higher frequencies entering generator or transformer units
Either of the above,
None of the above.

Q.12.

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

Generators,
Motors
Transmission line
Transformers

Q.13.

A voltage source can be converted into constant current source by adding

Low resistance in parallel with the voltage source
High resistance in parallel with the voltage source
Low resistance in series with the voltage source
High resistance in series with the voltage source

Q.14.

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

mechanical vibration,
insulation failure,
loose connection,
impulse voltage

Q.15.

Bus coupler is very essential in arrangement

single bus,
double bus, double breaker,
main and transfer bus,
all of the above.

Q.16.

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

(a) transposing transmission as well as communication lines.
(b) increasing the height of the trans-mission line tower
(c) increasing the distance between the two lines
(d) all of the above

Q.17.

Over fluxing protection is recommended for

(a) distribution transformer,
(b) generator transformer of the power plant
(c) auto-transformer of the power plant,
(d) station transformer of the power plant

Q.18.

The objective of a protection scheme is to keep the power system is

stable
safe
reliable
all of the above

Q.19.

What are the isolation requirements for an electric hot plate?

4.7.1
4.7.1 Note
4.8.1
8.3

Q.20.

Is an isolator required for an enclosed cooking appliance such as a wall oven?

4.7
2.10
4.7.1
4.19

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