1.

  Outdoor switchgear is generally used for voltage beyond

   A. 11 KV
   B. 33 KV
   C. 66 KV
   D. 132 KV
Answer
C. 66 KV

2.  The least expensive protection for over current in low-voltage system is
   A. Rewirable fuse
   B. Isolator
   C. Circuit breaker
   D. Air-break switch
Answer
A. Rewirable fuse

3.  Purpose of backup protection is

   A. To increase the speed
   B. To increase a reach
   C. To leave no blind spot
   D. To guard against failure of primary
Answer
D. To guard against failure of primary

4.  We do not require any protection against prime mover failure in case of
   A. Turbo generator sets
   B. Hydro generator sets
   C. Diesel engine driven alternators
   D. Back pressure turbo generators
Answer
A. Turbo generator sets
5.  For the protection of stator winding of an alternate against internal fault involving ground
the relay used is a
   A. Biased differential relay
   B. Directional over-current relay
   C. Plain impedance relay
   D. Buchholz relay
Answer
A. Biased differential relay

6.  For the protection of a large squirrel cage induction motor against single phase normally
   A. An over-current relay is used
   B. Differential relay is used
   C. Directional relay is used
   D. Negative sequence current sensitive relay is used
Answer
D. Negative sequence current sensitive relay is used

7.  The most commonly used method for the protection of three phase feeder is
   A. Time graded protection
   B. Differential protection
   C. Reverse power protection
   D. None of the above
Answer
B. Differential protection

8.  Which is the pilotless protection method for feeder line ?

   A. Differential protection
   B. Carrier current protection
   C. Time credit protection
   D. None of the above
Answer
B. Carrier current protection
9.  Time graded protection of a radial feeder can be achieved by using
   A. Definite time relay
   B. Inverse time relay
   C. Both definite and inverse time relays
   D. None of the above
Answer
C. Both definite and inverse time relays

10.  Pilot-wire protection scheme is the most economical and provides high speed relaying
for
   A. Short length of lines upto 15 km
   B. Medium length of lives up to 60 km
   C. Long length of lines up to 200 km
   D. All of the above
Answer
A. Short length of lines upto 15 km

11.  Problems associated with differential protection is/are

 A. Magnetising inrush current
   B. Mismatching characteristics of CTs
   C. Charge of ratio as a result of tapping
   D. All of the above
Answer
D. All of the above

12.  For the protection of transformers, harmonic restraint is used to guard against
   A. Magnetising inrush current
   B. Unbalanced operation
   C. Lightning
   D. Switching over-voltage
Answer
A. Magnetising inrush current
13.  The types of faults that occur in electric motors are
   A. Stator
   B. Rotor
   C. Overload
   D. All of the above
Answer
D. All of the above

14.  The main function of under voltage protective device generally employed with a motor
starter is to
   A. Open the supply circuit on failure of power supply
   B. Control the motor voltage
   C. Prevent the opening of supply circuit
   D. None of the above
Answer
A. Open the supply circuit on failure of power supply

15.  The bias factor S in unit protection synchronous generators

   A. Lies between .05 and .1 pu
   B. Is less than .05 pu
   C. Lies between .1 to .25 pu
   D. Is greater than .025 pu
Answer
A. Lies between .05 and .1 pu

16.  In a balanced voltage pilot wire protection scheme if the pilot circuit gets opened, the
relay will
   A. Fail to trip on internal faults
   B. Trip on full load
   C. Trip instantaneously on external faults
   D. None of the above
Answer
A. Fail to trip on internal faults
17.  In a balanced voltage pilot-wire protection scheme, if the pilot circuit gets short-
circuited, the relay will
   A. Fail to trip on internal faults
   B. Fail to trip on external faults
   C. Trip on full load
   D. Trip instantaneously
Answer
C. Trip on full load

18.  The frequency of carrier in the carrier current pilot scheme is in the range of
 A. 1 kHz to 10 kHz
   B. 10 kHz to 25 kHz
   C. 25 kHz to 50 kHz
   D. 50 kHz to 500 kHz
Answer
D. 50 kHz to 500 kHz

19.  The frequency of carrier transmitted by microwave pilot is in the range of

   A. 1000 kHz to 1500 kHz
   B. 2000 kHz to 5000 kHz
   C. 900 kHz to 6000 kHz
   D. 10000 kHz to 15000 kHz
Answer
C. 900 kHz to 6000 kHz

20.  In carrier current protection the purpose of the wave trap is for
   A. Trapping power frequency waves
   B. Trapping high frequency waves entering into generators/ transformer unit
   C. Both a and b
   D. None of the above
Answer
B. Trapping high frequency waves entering into generators/ transformer unit
21.  As soon as a fault develops in a generator stator, it is essential to suppress field
excitation, otherwise
   A. Terminal voltage will drop
   B. It may lead to loss of synchronism
   C. It will continue to supply power to the stator winding fault
   D. All of the above
Answer
C. It will continue to supply power to the stator winding fault

22.  Distance protection scheme is preferred over graded lime-lag over-current protection in
HV and EHV lines because
   A. It is faster in operation
   B. It is simple
   C. It is cheaper in cost
   D. All of the above
Answer
A. It is faster in operation

23.  Requirements of protection power station buildings against direct strokes are
   A. Interception
   B. Conduction
   C.. Dissipation
   D. All of the above
Answer
D. All of the above

24.  The protection against direct lighting strokes and a high-voltage steep waves is provided
by
   A. Ground wires
   B. Lightning arresters
   C. Lightning arresters and ground wires
   D. Earthing of neutral
Answer
C. Lightning arresters and ground wires
25.  For protection of rotating machines against lightning surge .............is used
   A. Lightning arrester
   B. Capacitor
   C. Combination of lightning arrester and a capacitor
   D. Lightning conductor and arrester
Answer
B. Combination of lightning arrester and a capacitor

26.  In between the generating station and consumers a number of transformation and
switching stations exist, these are called the
   A. Switchgears
   B. Substations
   C. Intermediate substations
   D. Transformation stations
Answer
C. Sub-stations

27.  With large reactance interconnector between two power stations

   A. The power stations may fall out of step due to large angular displacement between the
power stations
   B. Power will be transferred with minimum power losses
   C. Power will be transferred with voltage fluctuations and noise
   D. None of the above
Answer
A. The power stations may fall out of step due to large angular displacement between the
power stations

28.  In a isolated neutral system, when a single line to ground fault occurs
   A. Persistent arcing grounds will be developed
   B. Voltage in the healthy phases rise to full line value causing isolation breakdown
   C. The capacitive current in the faulty phase rises to 3 times its normal value
   D. All of the above
Answer
D. All of the above
29.  Tap changing transformers are employed for
   A. Stepping down the voltage
   B. Stepping up the voltage
   C. Supplying low-voltage current to instruments
   D. Both stepping up and stepping down the voltage
Answer
D. Both stepping up and stepping down the voltage.

30.  Field failure in an alternator occurs due to

   A. Failure of exciter
   B. Faulty field circuit breaker
   C. In rush of large currents
   D. Both A and B
Answer
D. Both A and B

31.  Large internal faults are protected by

   A. Merz price percentage differential protection
   B. Mho and ohm relays
   C. Horan gaps and temperature relays
   D. Earth fault and positive sequence relays
Answer
A. Merz price percentage differential protection

32.  Which of the following is the least expensive protection for over current in low-voltage
system ?
   A. Rewireable fuse
   B. Isolator
   C. Oil circuit breaker
   D. Air break circuit breaker
Answer
A. Rewireable fuse
33.  For the protection of power station buildings against direct strokes the requirements are
   A. Interception
   B. Interception and conduction
   C. Interception, conduction and dissipation
   D. Interception,conduction,dissipation and reflection
Answer
C. Interception, conduction and dissipation

34.  The line insulation is............. the insulation level at the station equipment
   A. Less than
   B. Same as
   C. More than
   D. Not directly related with
Answer
D. Not directly related with

35.  Discrimination between main and back up protection is provided by the use of relays
which are
   A. Fact
   B. Sensitive
   C. Slow
   D. None of the above
Answer
C. Slow

36.  Short-circuit currents are due to

   A. Single phase to ground faults
   B. Phase to phase faults
   C. Three phase faults
   D. Any of these
Answer
D. Any of these
37.  For which of the following protection from negative sequence current is provided?
   A. Generators
   B. Motors
   C. Transmission line
   D. Transformers
Answer
A. Generators

38.  For which of the following ratings of the transformer differential protection is
recommended?
   A. Above 30 KVA
   B. Equal to and above 5 MVA
   C. Equal two and above 25 MVA
   D. None of the above
Answer
B. Equal to and above 5 MVA

39.  Over voltage protection is recommended for

   A. Hydro electric generators
   B. Steam turbine generators
   C. Gasturbine generators
   D. All of the above
Answer
D. All of the above

40.  Overfluxing 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
Answer
B. Generator transformer of the power plant
41.  Hey switchgear is device used for
   A. Interrupting an electrical circuit
   B. Switching an electrical circuit
   C. Reaching and controlling an electrical circuit
   D. Switching, controlling and protecting the electrical circuit and equipment
Answer
D. Switching, controlling and protecting the electrical circuit and equipment

42.  Switching over voltage arc are more hazardous than lighting surges in case of
   A. Unbalanced systems
   B. Low-voltages
   C. 11 KV systems
   D. EHV and UHV systems
Answer
D. EHV and UHV systems

43.  Least number of faults are generally reported for

   A. Transmission lines
   B. Cables
   C. Switchgears
   D. Transformers
Answer
B. Cables

44.  Minimum working voltage will be least in case of

   A. Silver
   B. Graphite
   C. Carbon
   D. Tungsten
Answer
A. Silver
45.  In a contactor, interrupting medium may be
   A. Air
   B. Oil
   C. Sf6 gas
   D. Any of the above
Answer
D. Any of the above

46.  The transient voltages that appears across the contacts at the instant of arc extinction is
called ..............voltage
   A. Supply
   B. Recovery
   C. Restriking
   D. Peak
Answer
C. Restriking

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

   A. Transmission line
   B. Motor
   C. Generator
   D. Feeder
Answer
B. Motor

48.  SF6 gas
   A. Is yellow in colour
   B. Is lighter than air
   C. Is non-toxic
   D. Has pungent small
Answer
C. Is non-toxic
49.  SF6 gas is transported in
   A. Air cylinders
   B. Gas cylinders
   C. Liquid from in cylinders
   D. Solid form in boxes
Answer
C. Liquid from in cylinders

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

   A. Mechanical vibration
   B. Insulation failure
   C. Loose connection
   D. Impulse voltage
Answer
D. Loose connection

51.  The actuating quantity for the relays may be

   A. Magnitude
   B. Frequency
   C. Phase angle
   D. Any of the above
Answer
D. Any of the above

52.  The operating speed of a relay depends upon the

   A. Rate of flux built up
   B. Armature core air gap
   C. Spring tension
   D. All of these
Answer
D. All of these
53.  Inverse time current relays are used for the protection of
   A. Feeders
   B. Transformers
   C. Alternators
   D. Both A and B
Answer
D. Both A and B

54.  IDMT relays are used to protect the power transformers against
   A. External short-circuit
   B. Over loads
   C. Internal short-circuits
   D. Both A and B
Answer
D. Both A and B

55.  In distance protection, the relay measures

   A. Negative sequence impedance of the light from relay up to the fault point
   B. Positive sequence impedance of the line from relay up to the fault point
   C. Self impedance of the line from relay up to the fault point
   D. Zero sequence impedance of the line from relay up to the fault point
Answer
B. Positive sequence impedance of the line from relay up to the fault point

56.  The relay used for phase fault protection of short transmission lines is
   A. Reactance relay
   B. Impedance relay
   C. Mho relay
   D. IDMT relay
Answer
A. Reactance relay
57.  Where severe synchronising swing occur, the relay employed is
   A. Impedance relay
   B. Mho relay
   C. Reactance relay
   D. Induction relay
Answer
B. Mho relay

58.  For the protection of lines against faults involving variable fault resistance, the preferred
relaying scheme is a
   A. Plain impedance relay
   B. Directional over-current relay
   C. Mho relay
   D. Reactance relay
Answer
D. Reactance relay

59.  For ground fault we prefer

   A. Plain impedance relay
   B. Directional over current relay
   C. Mho relay
   D. Reactance relay
Answer
D. Reactance relay

60.  Admittance relay

   A. Nondirectional relay
   B. Directional relay
   C. Differential relay
   D. None of the above
Answer
B. Directional relay
61.  The relay used for feeder protection is
   A. Under voltage relay
   B. Translay relay
   C. Thermal relay
   D. Buchholz relay
Answer
B. Translay relay

62.  Which relay is used to detect and protect internal fault in a transformer ?
   A. Buchholz relay
   B. Directional relay
   C. Thermal relay
   D. Distance relay
Answer
A. Buchholz relay

63.  Which one of the following relay has the capability of anticipating the possible major
fault in a transformer ?
   A. Over-current relay
   B. Differential relay
   C. Buchholz relay
   D. Over fluxing relay
Answer
C. Buchholz relay

64.  Zero sequence current is used for relaying purpose only in the case of
   A. Phase over current really
   B.Phase impedance relay
   C. Ground over current relay
   D. Ground impedance relay
Answer
C. Ground over current relay
65.  To prevent mal operation of differentially connected relay while energising a
transformer, the relay restraining coil is biased with
   A. Second harmonic current
   B. Third harmonic current
   C. Fifth harmonic current
   D. Seventh harmonic current
Answer
A. Second harmonic current

66.  How many relays are used to detect interphase fault of a three line system?
   A. One
   B. Two
   C. Three
   D. Six
Answer
C. Three

67.  Which is the main relay for protecting up to 90% of the transmission line-length in the
forward direction?
   A. Directional over current relay
   B. Mho relay
   C. Carrier current protective relay
   D. Impedance relay
Answer
B. Mho relay

68.  For protection of parallel feeders fed from one end, the relays required are
   A. Nondirectional relays at the source end and directional relay at the load end
   B. Nondirectional relay at both ends
   C. Directional relay at source end and nondirectional relay at load end
   D. Directional relay at both ends
Answer
A. Nondirectional relays at the source end and directional relay at the load end
69.  Relays can be designed to respond to changes in
   A. Resistance, reactance or impedance
   B. Voltage and current
   C. Light intensity
   D. All of the above
Answer
D. All of the above

70.  DC shunt relays are made of

   A. Few turns of thin wire
   B. Few turns of thick wire
   C. Many turns of thin wire
   D. Many turns of thick wire
Answer
C. Many turns of thin wire

71.  The relay operating speed depends upon

   A. The spring tension
   B. The rate of flux built up
   C. Armature core air gap
   D. All of the above
Answer
D. All of the above

72.  In order that current should flow without causing excessive heating or voltage drop, the
relay contacts should
   A. Have low contact resistance
   B. Be clean and smooth
   C. Be of sufficient size and proper shape
   D. Have all above properties
Answer
D. Have all above properties
73.  Interruption of large currents by relay requires
   A. Arc suppressing blow out coils
   B. Wide separation of the open contacts
   C. High speed opening of contacts
   D. All of the above
Answer
D. All of the above

74.  To protect most of the electrical equipment handling low power, the types of relays used
are
   A. Thermocouple
   B. Electronic and bimetallic
   C. Both A and B
   D. None of the above
Answer
C. Both A and B

75.  ............. Relays are used for phase faults on long line
   A. Impedance
   B. Reactance
   C. Either of the above
   D. None of the above
Answer
A. Impedance
76.  ........ Relays is preferred for phase fault on short transmission line
   A. Induction type
   B. Reactance
   C. Impedance
   D. None of the above
Answer
B. Reactance
77.  The under voltage relay can be used for
   A. Generators
   B. Bus bars
   C. Transformers
   D. All of the above
Answer
D. All of the above

78.  The relay with inverse time characteristic will operate within
   A. 1.5 sec
   B. 5 to 10 sec
   C. 5 to 20 sec
   D. 20 to 30 sec
Answer
B.5 to 10 sec

79.  The single phasing relays are used for the protection of
   A. Single phase motors only
   B. Two phase motors only
   C. Two single phase motor running in parallel
   D. Three phase motors
Answer
D. Three phase motors

80.  The inverse definite mean time relays are used for over current and earth fault protection
of transformer against
   A. Heavy loads
   B. Internal short circuits
   C. External short circuits
   D. All of the above
Answer
B. Internal short circuits
81.  In a static over current relay, inverse time characteristics are obtained by
   A. A transistor amplifier
   B. An integrating circuit
   C. A transistor switch
   D. A differentiating circuit
Answer
B. An integrating circuit

82.  In the case of transmission line protection, over current relay is used
   A. Only up to 110 KV
   B. Only up to 220 KV
   C. Only up to 50 KV
   D. Only up to 1100 KV
Answer
C. Only up to 50 KV

83.  Directional over current relays have two exciting coils connected across
   A. CT secondaries of two different phases
   B. VT secondaries of two different phases
   C. CT and VT secondaries of same phases
   D. CT and VT secondaries of two different phases
Answer
C. CT and VT secondaries of same phases

84.  The domains of power system where directional over current relay is indispensable are
   A. In case of parallel feeder protection
   B. In case of ring main feeder protection
   C. Both A and B
   D. None of the above
Answer
C. Both A and B
85.  In an inverse definite minimum time, electromagnetic type over current relay, the
minimum time feature is achieved because of
   A. Saturation of the magnetic circuit
   B. Proper mechanical design
   C. Appropriate time delay element
   D. Electromagnetic damping
Answer
A. Saturation of the magnetic circuit

86.  Impedance relay can be used for

   A. Phase faults only
   B. Earth faults only
   C. Both earth and phase faults
   D. None of the above
Answer
A. Phase faults only

87.  Impedance relay may use

   A. Balance beam structure
   B. Induction cup structure
   C. Shaded pole structure
   D. Either A or B
Answer
D. Either A or B

88.  An impedance is relay is a

   A. Voltage restrained over current relay
   B. Voltage restrained directional relay
   C. Directional restrained over current relay
   D. Directional restrained over voltage relay
Answer
A. Voltage restrained over current relay
89.  On transient fault OC and impedance relay
   A. Under reaches
   B. Over reaches
   C. Reach unaffected
   D. None of the above
Answer
A. Under reaches

90.  Threshold characteristics of a plain impedance relay in a complex Z plane is a

   A. Circle passing through origin
   B. Circle with the centre at the origin
   C. Straight line passing through origin
   D. Straight line offset from the origin
Answer
B. Circle with the centre at the origin

91.  The structure used in reactance relay is

   A. Induction cup
   B. Double induction loop
   C. Single induction loop
   D. Either A or B
Answer
D. Either A or B

92.  Reactance relay is normally used for protection against

   A. Earth fault only
   B. Phase fault only
   C. Both earth and phase faults
   D. None of the above
Answer
A. Earth fault only
93.  The operating characteristics of the reactance relay in the complex impedance plane is a
   A. Circle with its origin at the centre of the R-X plane
   B. Circle passing through the origin
   C. Straight line passing through the origin
   D. Straight line parallel to the X axis
Answer
D. Straight line parallel to the X axis

94.  A reactance relay is

 A. Voltage restrained overcurrent relay
   B. Voltage restrained directional relay
   C. Directional restrained overcurrent relay
   D. Directional restrained over voltage relay
Answer
C. Directional restrained overcurrent relay

95.  Reactance relays are used for phase fault in.......line

   A. Short
   B. Medium
   C. Long
   D. All of the above
Answer
A. Short

96.  A differential relay response to

   A. Algebraic difference of two or more similar electrical quantities
   B. Phasor difference of two or more similar electrical quantities
   C. Algebraic difference between two currents
   D. Algebraic difference between two voltages
Answer
B. Phasor difference of two or more similar electrical quantities
97.  Differential relays are used for protection of
   A. Feeders
   B. Alternators
   C. Transformers
   D. All of the above
Answer
D. All of the above

98.  Differential relays are used for protection of equipments against

   A. Internal faults
   B. Over current
   C. Reverse current
   D. Reverse power
Answer
A. Internal faults

99.  In a biased differential relay the bias is defined as a ratio of

   A. Number of turns of restraining and operating coil
   B. Operating coil current and restraining coil current
   C. Fault current and operating coil current
   D. Fault current and restraining coil current
Answer
B. Fault current and operating coil current

100.  Both voltage and current signals are required for

   A. A plain over current relay
   B. A differential relay
   C. A directional relay
   D. A biased directional relay
Answer
C. A directional relay
101.  Protective relays can be designed to respond to
   A. Light intensity
   B. Temperature
   C. Resistance, reactance or impedance
   D. All of the above
Answer
D. All of the above

102.  Protective relays are the devices that detect abnormal conditions in electrical circuits by
measuring
 A. Voltage
   B. Current
   C. Constantly the electrical quantities which differ during normal and abnormal conditions
   D. Note the above
Answer
C. Constantly the electrical quantities which differ during normal and abnormal conditions

103.  The protective relays is provided to

   A. Provide additional safety to the circuit breaker in its operation
   B. Close the contacts when the actuating quantity attains a certain predetermined value
   C. Limit the arcing current during the circuit breaker operation
   D. Earth any stray voltage
Answer
B. Close the contacts when the actuating quantity attains a certain predetermined value

104.  For the protection of a very long extra high-voltage lines, the productive relay used is
   A. Over currently with extremely inverse characteristics
   B. Percentage differential relay
   C. Reactance type distance relay
   D. Mho type distance relay
Answer
D. Mho type distance relay
105.  Burden of a protective relay is the power
   A. Required to operate the circuit breaker
   B. Absorbed by the circuit of relay
   C. Developed by the relay circuit
   D. None of the above
Answer
B. Absorbed by the circuit of relay

106.  Buchholz relay is

   A. Located in the conservator tank
   B.Located in the transformer tank itself
   C. Connected in the pipe connecting main tank of transformer and conservator
   D. Installed in the circuit breaker
Answer
C. Connected in the pipe connecting main tank of transformer and conservator

107.  Buchholz relays are used on

   A. Air cooled Transformers
   B. Instrument Transformers
   C. Distribution transformers
   D. Oil immersed power transformers of ratings above 500 kVA
Answer
D. Oil immersed power transformers of ratings above 500 kVA

108.  Buchholz relay cannot be used on

   A. Three-phase transformers
   B. Air cooled transformers
   C. 500 KV transformers
   D.1000 kV transformers
Answer
B. Air cooled transformers
109.  Buchholz relay is a.......relay
   A. Oil immersed
   B. Arc quenching
   C. Gas actuated
   D. None of the above
Answer
C. Gas actuated

110.  Buchholz relay can detect faults..........oil level in the transformer.

   A. Upper
   B. Below
   C. Same
   D. None of the above
Answer
B. Below

111.  Distance relays are generally

   A. Split phase relays
   B. Reactance relays
   C. Impedance relays
   D. None of the above
Answer
D. None of the above

112.  Three step time distance characteristic of distance relay can be had by
   A. Changing taps on voltage transformer
   B. Separate measuring elements for zones 2 and 3
   C. Switching resistance in relay restrain circuit at pre-set time interval by means of a timer
element
   D. Any of the above
Answer
D. Any of the above
113.  Distance protection scheme is preferred over graded lime-lag over-current protection in
HV and EHV lines because
   A. It is faster in operation
   B. It is simple
   C. It is cheaper in cost
   D. All of the above
Answer
A. It is faster in operation

114.  In a three-step distance protection the reach of the three zones of the relay at the
beginning of the first line typically extends into
   A. 100% of the first line, 50% of the second line and 20% of the third line
   B. 80% of the first line, of 50% of the second line and 20% of the third line
   C. 80% of the first line, 50% of the second line and 10% of the third line
   D. 50% of the first line, 50% of the second line and 20% of the third line
Answer
B. 80% of the first line, of 50% of the second line and 20% of the third line

115.  Which of the following relay is/are overload relays?

   A. Thermal
   B. Electromagnetic
   C. Induction
   D. All of the above
Answer
D. All of the above

116.  A Mho relay is a

   A. Voltage restrained directional relay
   B. Voltage restrained over current relay
   C.. Directional restrained over-current relay
   D. Directional restrained over voltage relay
Answer
A. Voltage restrained directional relay
117.  Mho relay is usually employed for the protection of
   A. Short lines only
   B. Medium lines only
   C. Long lines only
   D. Any line
Answer
C. Long lines only

118.  Which of the following relay has inherent directional characteristic?

   A. Mho
   B. Reactance
   C. Impedance
   D. None of the above
Answer
A. Mho

119.  For the protection of a very long extra high voltage line, the protective relay used is
   A. Over current with extremely inverse characteristics
   B. Percentage differential relay
   C. Reactance type distance relay
   D. Mho type distance relay
Answer
D. Mho type distance relay

120.  Relay used for feeder protection is

   A. Under voltage relay
   B. Translay relay
   C.Thermal relay
   D. Buchholz relay
Answer
B. Translay relay
121.  The torque produced in shaded pole structure induction type relay is
   A. Proportional to the square of the current
   B. Proportional to the current
   C. Inversely proportional to the current
   D. Inversely proportional to the square of the current
Answer
A. Proportional to the square of the current

122.  The most efficient torque producing actuating structure for induction type relays is
   A. Shaded pole structure
   B. Watt hour meter structure
   C. Induction type structure
   D. Single induction loop structure
Answer
C. Induction type structure

123.  Admittance relay is.......relay

   A. Impedance
   B. Directional
   C. Nondirectional
   D. None of the above
Answer
B. Directional

124.  If the fault occurs near the impedance relay, the V/I ratio will be
   A. Constant for all distances
   B. Lower than that of if fault occurs away from the relay
   C. Higher than that of if fault occurs away from the relay
   D. None of the above
Answer
B. Lower than that of if fault occurs away from the relay
125.  The power loss is an important factor for the design of
   A. Transmission line
   B. Motor
   C. Generator
   D. Feeder
Answer
A. Transmission line

126.  In an over current protection the setting of the earth fault relay is
   A. More than the phase fault relay
   B. Equal to the phase fault relay
   C. Less than the phase fault relay
   D. The two settings are unrelated to each other
Answer
C. Less than the phase fault relay

127.  Earth fault relays are

   A. Directional relays
   B. Nondirectional relays
   C. Short update Time relays
   D. None of the above
Answer
A. Directional relays

128.  The earth fault in stator causes

   A. Arcing to core
   B. Severe heating in conductors and thereby damaging the insulation
   C. Open circuit in the stator
   D. Both A and B
Answer
D. Both A and B
129.  Earth fault protection for an electric motor is provided by means of
   A. Instantaneous over-current relay
   B. Instantaneous relay having a setting of approximately 30% of motor rated current in the
residual circuits of two CTs
   C. Ground wire
   D. Both B and C
Answer
D. Both B and C

130.  The magnitude of earth fault current for a given fault position within a winding depends
upon
   A. The winding connections
   B. The method of neutral grounding
   C. Unmatched characteristics of CTs
   D. Both A and B
Answer
D. Both A and B

131.  Merz-Price protection is employed for protection of

   A. Alternators
   B. Transformers
   C. Transmission lines
   D. Both A and B
Answer
D. Both A and B

132.  In Merz-Price differential protection of a delta star transformer, the CT secondaries

connection in the primary and secondary winding of the transformer would be in the form of
   A. Delta star
   B. Star delta
   C. Delta delta
   D. Star star
Answer B. Star delta
133.  For preventing the maloperation of Merz-Price protection scheme on inrush of
magnetising current
   A. The relay restraining coil is biased with second harmonic current
   B. Time lag is provided in the relay
   C. Relay sensitivity is reduced by employing a shunt
   D. All of the above
Answer
D. All of the above

134.  To protect the power transformer ( star-star with neutral grounded) against fault, what
type of connection do the CTs have?
   A. Delta star connection
   B. Delta delta connection
   C. Star star connection
   D. Star delta connection
Answer
B. Delta delta connection

135.  Magnetising in Russian phenomena occur in

   A. Large transformer primary only when the transformer is switched on
   B. Large transformer primary when a three-phase a fault occurs in the secondary
   C. Large transformer secondary only when the transformer is switched on in the primary
   D. None of the above
Answer
A. Large transformer primary only when the transformer is switched on

136.  A bimetal strip, in a thermal relay, consist of two metal strips of different
   A. Specific heat
   B. Thermal conductivity
   C. Coefficients of expansion
   D. All of the above
Answer
C. Coefficients of expansion
137.  Thermal relays are used for protection of motors against over current owing to
   A. Short circuits
   B. Heavy loads
   C. Earth fault
   D. All of the above
Answer
B. Heavy loads

138.  Thermal relay are often employed in

   A. Motor starters
   B. Transformer protection
   C. Generator protection
   D. None of the above
Answer
A. Motor starters

139.  Two input phase comparator in a static relay is made up of a

   A. transformer amplifier
   B. Transistor logic circuit
   C. Rectifier Bridge
   D. Thyristor Bridge
Answer
C. Rectifier Bridge

140.  The phase comparators in case of static relays and electromechanical relays normally
are
   A.. Cosine and sine comparators respectively
   B. Sine and cosine comparators respectively
   C. Both are sine comparators
   D. Both are cosine comparators
Answer
A. Cosine and sine comparators respectively
141.  Lightning arresters are used in power system to protect electrical equipments against
   A. Direct strokes of lightning
   B. over voltages due to indirect lightning stroke
   C. Power frequency over-voltages
   D. Over currents due to lightning
Answer
C. Power frequency over-voltages

142.  A lightning arrester provides

   A. Low impedance path
   B. High impedance path
   C. Low resistance path
   D. High resistance path between line and earth during operation
Answer
A. Low impedance path

143.  A lightning arrester connected between the line and earth in a power system
   A. Protects the terminal equipment against travelling surges
   B. Protects the terminal equipment against direct lightning stroke
   C. Suppresses high-frequency oscillations in the line
   D. Reflects back the travelling waves approaching it
Answer
A. Protects the terminal equipment against travelling surges

144.  Basically a lightning arrester is a

   A. Surge diverter
   B. Surge alternator
   C. Surge reflector
   D. Surge absorber
Answer
A. Surge diverter
145.  Which system will need the lightning arrester of least voltage rating?
   A. Solid ground neutral system
   B. Insulated neutral system
   C. Resistance grounded neutral system
   D. Reactance grounded neutral system
Answer
A. Solid ground neutral system

146.  Impulse ratios of insulators and lightning arresters should be

   A. Both low
   B. High and low respectively
   C. Low and high respectively
   D. Both high
Answer
B. High and low respectively

147.  In a thyrite lightning arrester the resistance

   A. Varies linearly with the applied voltage
   B. Increases with the applied voltage
   C. Decreases linearly with the applied voltage
   D. Is high at low current and low at high current
Answer
D. Is high at low current and low at high current

148.  A thyrite type lightning arrester

   A. Blocks the search voltage appearing in a line
   B. Absorbs the surgery voltage appearing in a line
   C. Offers a low resistance path to the surge appearing in a line
   D. Returns the surge back to the source
Answer
C. Offers a low resistance path to the surge appearing in a line
149.  Which of the following is the protective device against lightning over voltages?
   A. Rod gaps
   B. Surge absorbers
   C. Horn gaps
   D. All of the above
Answer
D. All of the above

150.  A lightning arrester provides

   A. A low impedance path between line and ground, during operation
   B. A high impedance path between line and ground, during operation
   C. A low resistance path between line and ground, during operation
   D. A high resistance path between line and ground, during operation
Answer
A. A low impedance path between line and ground, during operation

151.  Which of the following sections can be employed for bus-bars ?

   A. Bars
   B.Rods
   C. Tubes
   D. Any of the above
Answer
D. Any of the above

152.  A bus-bar is rated by

   A. Current only
   B. Voltage only
   C. Current , voltage and frequency
   D. Current, voltage, frequency and short circuit current
Answer
D. Current, voltage, frequency and short circuit current
153.  The material used for bus-bar should have
   A. Low resistivity
   B. Low-cost
   C. High Softening temperature
   D. All of the above
Answer
D. All of the above

154.  Which of the following bus-bar schemes has the lowest cost?
   A. Ring bus-bar scheme
   B. Single bus-bar scheme
   C. Breaker and a half scheme
   D. Main and transfer scheme
Answer
B. Single bus-bar scheme

155.  Which of the following can be used for bus-bars?

  A. Tubes
   B. Rods
   C. Bars
   D. Any of the above
Answer
D. Any of the above

156.  Due to which of the following reasons aluminium is being favoured as bus-bar
material?
   A. Low-density
   B. Low-cost
   C. Ease of fabrication
   D. None of the above
Answer
B. Low-cost
157.  Which of the following bar schemes is the most expensive?
   A. Double bus-bar double breaker
   B. Ring bus-bar scheme
   C. Single bus-bar scheme
   D. Main and transfer scheme
Answer
A. Double bus-bar double breaker

158.  When an alternator connected to the bus-bar is shut down the bus-bar voltage will
   A. Fall
   B. Rise
   C. Remain unchanged
   D. none of the above
Answer
C. Remain unchanged

159.  The bus-bar zone, the purpose of protection includes .............., ............and .............
   A. Bus-bars, isolating switches, circuit breakers
   B. Transformers, relays, circuit breakers
   C. Transformers, conductors and relays
   D. None of the above
Answer
A. Bus-bars, isolating switches, circuit breakers

160.  If a voltage controlled bus is treated as a load bus, then which one of the following
limits would be violated ?
   A. Voltage
   B. Active power
   C. Reactive power
   D. Phase angle
Answer
A. Voltage
161.  Single bus-bar arrangement
   A. Is cheapest in initial as well as maintenance cost
   B. Provide simple operation and relaying system
   C. Has the drawback that there will be complete shut down when a fault occurs on the bus
itself
   D. All of the above
Answer
D. All of the above

162.  In a single bus bar system there will be complete shutdown when
   A. Fault occurs on the bus itself
   B. Fault occurs on neutral line
   C. Two or more faults occur simultaneously
   D. Fault occurs with respect to earthing
Answer
A. Fault occurs on the bus itself

163.  The main factor in favour of the use of aluminium as bus bar material is its
   A. Low-cost
   B. Low-density
   C. Low melting point
   D. High resistivity
Answer
A. Low-cost

164.  Double bus bar arrangement makes use of two identical bus bus and has the advantages
that
   A. It does not require any bus coupler and permits switchover from one bus to another
whenever desired
   B. It provides maximum flexibility and reliability
   C. Either bus bar may be taken up for maintenance
   D. All of the above
Answer
D. All of the above
165.  The voltage of a particular bus is regulated by controlling the
   A. Active power of the bus
   B. Reactive power of the bus
   C. Phase angle
   D. Phase angle and reactive power
Answer
D. Phase angle and reactive power

166.  The voltage of a particular bus can be controlled by controlling the

   A. Active power of the bus
   B. Reactive power of the bus
   C. Phase angle
   D. Both A and B
Answer
B. Reactive power of the bus

167.  In a power system the maximum number of buses are

   A. Generator buses
   B. Load buses
   C. Slack buses
   D. P-V buses
Answer
B. Load buses

168.  Load bus is specified by

   A. P and V
   B. P and δ
   C. P and |V|
   D. P and Q
Answer
D. P and Q
169.  At slacks bus, which one of the following combinations of variables is specified?
   A. |V|, δ
   B. P, Q
   C. P, |V|
   D. Q, |V|
Answer
A. |V|, δ

170.  YBUS as used in load flow study, and ZBUS as used for short circuit study are:
   A. The same
   B. Inverse of each other
   C. Are not related to each other
   D. None of the above
Answer
C.Are not related to each other

171.  Surge absorbers are used for protection against

   A. High-voltage low-frequency oscillations
   B. High-voltage high-frequency oscillations
   C. Low-voltage high frequency oscillations
   D. Low-voltage low-frequency oscillations
Answer
C. Low-voltage high frequency oscillations

172.  Surge absorber........... the energy of travelling waves

   A. Absorbs
   B. Reflects
   C. Diverts
   D. Partly absorbs and partly diverts
Answer
D. Partly absorbs and partly diverts
173.  Surge modifiers are employed for
   A. Reducing the steepness of wave front
   B. Reducing the current of wavefront
   C. Reducing the voltage of wavefront
   D. Modify the shape of the wave front
Answer
A. Reducing the steepness of wavefront

174.  Switching over voltages are more hazards than lightning surges in case of
   A. Low-voltage system
   B. 33KV system
   C. EHV and UHV system
   D. All of the above
Answer
C. EHV and UHV system

175.  The over voltage surge in power systems may be caused by

   A. Lightning
   B. Resonance
   C. Switching
   D. All of the above
Answer
D. All of the above

176.  In a substation the following equipment is not installed

   A. Exciters
   B. Series capacitors
   C. Shunt reactors
   D. Voltage transformers
Answer
A. Exciters
177.  With which of the following are step-up substations associated
   A. Concentrated load
   B. Consumer location
   C. Distributors
   D. Generating stations
Answer
D. Generating stations

178.  Which of the following equipment is used to limit short circuit current level in a Sub
Station?
   A. Isolator
   B. Lightning switch
   C. Coupling capacitor
   D. Series reactor
Answer
D. Series reactor

179.  Most of the substations in the power system change .................of electric supply.
   A. Current level
   B. Voltage level
   C. Both A and B
   D. None of the above
Answer
B. Voltage level

180.  An ideal location for the substation would be at the ............of load
   A. Centre of gravity
   B. Load centre
   C. Nearer to consumer
   D. None of the above
Answer
A. Centre of gravity
181.  Outdoor Sub Station requires ..........space
   A. Less
   B. More
   C. Medium
   D. Any of the above
Answer
B. More

182.  Majority of distribution substations are of .......... type.

   A. Pole mounted
   B. Indoor
   C. Outdoor
   D. All of the above
Answer
C. Outdoor

183.  Power factor correction substations are generally located at the ................end of a
transmission line
   A. Sending
   B. Receiving
   C. Both sending and receiving
   D. None of the above
Answer
B. Receiving

184.  Underground sub stations are generally located in .........

   A. Thickly polluted area
   B. Villages
   C. Cities
   D. Any of the above
Answer
A. Thickly polluted area
185.  An indoor Sub Station is ...............expensive than outdoor Sub Station
   A. More
   B. Less
   C. Almost equal
   D. None of the above
Answer
A. More

186.  Pole mounted sub stations are used for............ distribution

   A. Primary
   B. Secondary
   C. Both A and B
   D. None of the above
Answer
B. Secondary

187.  The voltage rating of the transformer in a pole-mounted Sub Station is.............
   A. 11 KV / 400 V
   B. 11 KV / 240 V
   C. 33 KV / 400 V
   D. None of the above
Answer
A. 11 KV / 400 V

188.  Single bus-bar arrangement in substations is used for voltage is less than............
   A. 11 KV
   B.33 KV
   C. 132 KV
   D. 220 KV
Answer
B. 33 KV
189.  For voltage is greater than 33 KV, ..............Busbar arrangement is employed
   A. Single
   B. Double
   C. Duplicate
   D. None of the above
Answer
C. Duplicate

190.  For cost and safety the outdoor substations are installed for voltages above
   A. 11 KV
   B. 33 KV
   C. 66 KV
   D. 132 KV
Answer
B. 33 KV

191.  The neutral wire is coloured

   A. Black
   B. Blue
   C. Red
   D. Yellow
Answer
A. Black

192.  In case of earth fault, the underground neutral system ..........lead to arcing ground
   A. Does
   B. Does not
   C. Any of the above
   D. None of the alarm
Answer
A. Does
193.  Grounding transformer is used where neutral .........available
   A. Is
   B. Is not
   C. Either A or B
   D. None of the above
Answer
B. Is not

194.  The ground wire is coloured

   A. Green
   B. Black
   C. Yellow
   D. Red
Answer
A. Green

195.  In equipment grounding, the enclosure is connected to ...........wire

   A. Ground
   B. Neutral
   C. Phase
   D. Either A or B
Answer
A. Ground

196.  Earthing is necessary to give protection against

   A. Danger of electric shock
   B. Voltage fluctuation
   C. Overloading
   D. High temperature of the conductors
Answer
A. Danger of electric shock
197.  Solid grounding is addopted for voltages below
   A. 100 V
   B. 200 V
   C. 400 V
   D. 660 V
Answer
D. 660 V

198.  The advantage of neutral earthing is

   A. Freedom from persistent arcing grounds
   B. Over voltages due to lightning can be discharged to earth
   C. Simplified design earth fault protection
   D. All of the above
Answer
D. All of the above

199.  In a star connected system without neutral grounding, zero sequence currents are
   A. Zero
   B. Phaser sum of phase currents
   C. Same as r.m.s. value of phase currents
   D. Same as peak value of phase currents
Answer
A. Zero

200.  The advantage of neutral earthing

   A. Safety of personnel
   B. Reduction of earth fault current
   C. Elemination of arcing ground
   D. None of the above
Answer
C. Elemination of arcing ground