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Section 1 -Lect Electrical Engg

No. of Questions: 100
Duration in Minutes: 120

The stator of a 415V, 50 Hz, 4-pole slip ring Induction Motor is excited by rated frequency with
slip rings open circuited. The rotor is made to rotate at a speed of 600 rpm in the opposite direction
to the normal direction, The frequency of induced voltage across slip ring is

30Hz
70Hz
20 Hz
35 Hz

A DC shunt motor has rated rpm of 480. Certain industrial application requires this motor to run
at 540 rpm for some time. Which speed control will be desirable?

Ward Leonard control
Armature current control
Field resistance control
It is not possible to run the motor at more than the rated rpm

A single phase transmission line consists of two parallel conductors one meter apart and 1.25 cm
in diameter. The loop inductance per km of the line is:

21.3 x 10-4 Henry/ km
34.3 x 10-7 Henry/ km
11.5 x 10-7 Henry/ km
19.5 x 10-7 Henry/ km

Capacitance grading of cable implies

grading according to capacitance of cables per kilometer length
cables using single dielectric in different concentrations
use of dielectrics of different permeabilities
capacitance required to be introduced at different length to counter the effect of inductance

One out of the following statements is not true:

The curl of gradient of any scalar field is identically zero
The divergence of curl of any vector field is identically zero
A field, which has zero divergence, is said to be solenoidal
A field, whose curl is zero, is said to be rotational

In a loss-free circuit the transient current will be:

Oscillating
Non-oscillating
Sinusoidal wave
Square wave

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Which statement out of the following is a wrong statement with regard to Induction motor?
Auto-transformer starter is costlier to "direct on line" starter
DOL starter is used for motors up to 5 horse power only
Auto transformer starter is used for motors up to 20 horse power only
Star delta starter connects the motor first in delta at the time of starting then in star for
running
In the measurement of power of balanced load by two wattmeter method in a 3-phase circuit, The
readings of the wattmeters are 4 kW and 2 kW respectively, the later is being taken after reversing
the connections of current coil. the power factor and reactive power of the load is
0.2 6 kVAR
0.2 6 v3 kVAR
0.32 2 kVAR
0.32 2 v3 kVAR
The RMS value of a half-wave rectified current is 10 Ampere. Its value for full-wave rectification
would be:
10 Ampere
14.14 Ampere
31.4 Ampere
20 Ampere
10) One of the following does not represent a valid combination of of insulating material and
its limiting temperature in 'Degree Centigrade'.
'Class- 1050C
'Class- 1550C
'Class- 1800C
'Class- 1200C
11) On a base of 132 kV, 100 MVA, a transmission line has 0.2 per unit impedance. On a base of
220 kV, 50 MVA, it will have a per unit impedance of:





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12) In which of the following power plants the availability of power is least reliable?

Solar power plant
Wind energy
Tidal power plant
Geothermal power plant

13) Overall thermal efficiency of a steam power station in India is in the range:

18-24 percent
30-40 percent
44-62 percent
68-79 percent

14) A system having T.F. is excited by a step function of magnitude The time
required by output to reach upto 96% of its steady state value is

0.54 sec
1.23 sec
2.08 sec
3.22 sec

15) The burden value in Potential Transformer should be to achieve low errors in PT:

low
high
medium
infinite

16) For complete protection of a three-phase line:

three Phase relays and three Earth fault relays are required
three Phase relays and two Earth fault relays are required
two Phase relays and two Earth fault relays are required
two Phase relays and one Earth fault relay are required

17) For a waveform to be expressed in Fourier series, which of the following conditions must be
satisfied?

I. Maxwell's conditions,
II. Drichlet conditions,
III. Sampling Theorem
I only
II only
II and III only
II and III

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18) Which one is not a valid condition for the wave winding?

Back pitch and front pitch are of the same sign
Back pitch and front pitch are odd numbers
Back pitch and front pitch may differ by two and may be equal also
Commutator pitch is always unity

19) For rural electrification in a country like India with complex networks, it is preferable to use:

Air circuit breaker
Oil circuit breaker
Vacuum circuit breaker
Minimum oil circuit breaker

20) Which of the following statements is incorrect?

During parallel resonance impedance at resonance is minimum
During parallel resonance current is magnified
During series resonance current at resonance is maximum
During series as well as parallel resonance, the power factor is unity

21) One of the following is not the Maxwell's equation:





22) One of the following is not a valid statement:

Fleming's right hand rule is used to find out the direction of current in the conductor of a
generator
Fleming's left hand rule is used to find out the direction of rotation of the armature of DC
motor
Ampere's rule is used to find out the direction of lines of force around the wire carrying
current
Right hand thumb rule is used to find out the direction of counter current produced in the
armature magnetic field

23) The number of electrical degrees 'passed through' in one revolution of a 6-pole synchronous
alternator is:

360 degree

720 degree

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1080 degree
2160 degree

24) Following is not the property of a complete incidence matrix:

Algebraic sum of the column entries of an incidence matrix is zero
The rank of a complete incidence matrix of a connected graph is where n is total
number of nodes


Order of a complete incidence matrix will be where b is total number of branches
and n is total number of nodes
Determinant of the incidence matrix of a closed loop is not zero.

25) An ideal current source has zero:

internal resistance

internal conductance

voltage at no-load

ripples

26) If the frequency of input voltage of a transformer is increased keeping the magnitude of voltage
unchanged, then:

both hysteresis loss and eddy current loss in the core will increase
hysteresis loss will increase but eddy current loss will decrease
hysteresis loss will decrease but eddy current loss will increase
hysteresis loss will decrease but eddy current loss will remain unchanged

27) The superposition theorem is applicable to:

linear response only
linear and non-linear response
non-linear and time-variant response
linear, non-linear and time-variant response

28) Which motor is generally used in Tap Recorders?

universal motor

reluctance motor

split phase motor

hysteresis motor

29) A gas turbine works on:

Carnot cycle
Brayton cycle
Dual cycle
Rankine cycle

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30) In practice, a current source inverter consists of an AC/ DC converter with a large inductance
in the output. This inductance maintains a ……… …………through the switching devices over
short interval of time.

constant current
constant voltage
constant power
none of the

31) If the input to a differentiating circuit is a saw-tooth wave, then output will be …………….. wave:

square
rectangular wave
triangular wave
rectified sine wave

32) A unit ramp function when integrated yields:

unit parabolic function
unit ramp function
unit doublet
unit impulse function

33) Which of the following statements is not valid in case of conductors in electrostatic fields?

The static electric field intensity inside a conductor is zero
The static electric field intensity at the surface of a conductor is everywhere directed normal

to the surface
The conductor surface is an equivalent potential surface
None of the above

34) The leakage flux in a transformer depends upon:

load current
load current and voltage
load current, voltage and frequency
load current, voltage, frequency and power factor

35) Which of the following company is associated with manufacture of high capacity transformers in
India?

M/S National Thermal Power Corporation Limited
M/S Bharat Heavy Electricals Limited
M/S Heavy Engineering Corporation Limited
M/S Electricity Authority of India

36) In case of semi-conductors, the ratio of conduction current to displacement current is:

more than 200 and less than 1000

less than 100 but greater than 1/100

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less than 1/100
more than 1000


37) A large hydropower station has a head of 324 metre and an average flow of 1370 metre3/
second. The available hydraulic power from this station will be:

4.35 MW
4.15 MW
4.47 MW
4.73 MW

38) Which among the given statement is/are CORRECT.

Avalanche breakdown voltage increases with temperature
Zener breakdown voltage decreases with temperature
Only
Only
Both
None of


39) The operation of the relay which is most affected due to arc resistance is

Mho relay
Reactance relay
Impedance relay
All are equally affected

40) The reactance relay is essentially:

an over-voltage relay with current restraint
an over-voltage relay with directional restraint
a directional relay with voltage restraint
a directional relay with current restraint

41) An 8-pole alternator runs at 750 rpm and supplies power to a 6-pole induction motor which has
a full load slip of 3 percent. The full load speed of the induction motor will be:

1000 rpm

920 rpm

950 rpm

970 rpm

42) For AC networks, as per maximum power transfer theorem, for maximum power transfer, the
source impedance should be equal to:

twice the load impedance
complex conjugate of load impedance

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twice the complex conjugate of load impedance
none of these

43) In power station practice "spinning reserve" is:

reserve generating capacity that is in operation but not in service
reserve generating capacity that is connected to bus and ready to take the load
reserve generating capacity that is available for service but not in operation
capacity of the part of the plant that remains under maintenance

is
44) An open loop system represented by the transfer function

Stable and of the minimum phase type
Stable and of the non -minimum phase type
Unstable and of the minimum phase type
Unstable and of non-minimum phase type

45) The bridge circuit shown in the figure below is used for the measurement of an unknown
element ZX.

The bridge circuit is best suited when ZX is a


low resistance
high resistance
low Q inductor
lossy capacitor


46) Which of the following plants will take least time in starting from cold conditions to full-load
operation?

Nuclear power plant
Steam power plant
Hydro-electric power plant
Gas turbine plant

47) Which of the following are the basic elements in a 555 timer IC?

Two comparators
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A flip-flop
A discharge transistor
A resistive voltage divider
and
only and
only and
only and


48) Which waveform out of the following waves has the least value of form-factor:

Triangular wave
Square wave
Rectangular wave
Sine wave

49) Which type of protection is provided on a generator to protect against stator insulation failure?

Differential protection
Overcurrent relay
Thermocouple actuated alarm
Reverse power relay

50) In an alternator if the winding is short pitched by 60 electrical degrees, its pitch factor will be:

1.0

0.866

0.75

0.50

51) The inertia constant of a 100 MVA, 11 kV water wheel generator is 4. The energy stored in the
rotor at the synchronous speed is:

400 Mega Joule

400 Kilo Joule

25 Mega Joule

25 Kilo Joule

52)
positive, positive
negative, negative
negative, positive
positive, negative


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53) The reflection coefficient of a short-circuited line for voltage is:


0.5
zero
54) The typical ratio of latching current to holding current in a 20A thyristor is
5.0
2.0
1.0
0.5
55) If the primary fault current is 2000 ampere, the relay setting current is 50 percent and the CT
ratio is 400/5, then the plug-setting multiplier is:
25
15
50
None of the above
56) Highest flux density exists inside which of the following instruments?
Electrodynamic instruments
Hot wire instruments
Moving iron instruments
Moving coil instruments
57) The current gain of emitter follower is:
less than one
more than one
zero
unpredictable
58) A half-controlled single-phase bridge rectifier is supplying an R-L load. It is
operated at a firing angle a and the load current is continuous. The fraction of cycle that the
freewheeling diode conducts is




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59) Which statement out of the following statements about 'corona' is incorrect?
Corona gives rise to radio interference
Corona results in loss of power in transmission
Corona discharge can be observed as red luminescence
Corona is always accompanied by a hissing voice
60) A three-phase transformer, connected in star-delta, is composed of three single-phase
transformers, each rated 127/ 13.2 kV. The line-to-line voltage ratio for the three-phase transformer
is:
220 13.2 kV
127 13.2 kV
127 220 kV
220 220 kV
61) Synchronous wattage of induction motor means:
rotor input in watts
stator input in watts
combined stator and rotor input in watts
shaft output in watts
62) The average power delivered to an impedance 4 j 3 O by a current 5Cos(100pt
100) Ampere is
44.2 W
50 W
62.5 W
125 W
63) Two 220 volt lamps, one of 60 watt and the other of 75 watt are connected in series across a
440 volt supply. The potential difference across 60 watt lamp will be:
195 volt
220 volt
245 volt
440 volt
64) lumen watt is the unit of:
light flux
luminous intensity
brightness
luminous efficiency

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65) The load-flow solution is always assured in case of:

Newon-Raphson method
Gauss-Seidal method
Fast Decoupled method
None of these methods guarantee

66) Full load current of an Induction motor is 20 Ampere. The no-load current may be expected to
be:

25 Ampere to 28 Ampere
15 Ampere to 18 Ampere
11 Ampere to 14 Ampere
6 Ampere to 10 Ampere

67) Which of the following relation is incorrect?

capacity factor utilization factor x load factor
load factor x maximum load average load
demand factor x connected load maximum demand
none of these

68) The inrush current of a transformer at no-load is maximum, if it is switched-on when the supply
voltage is at:

zero voltage value
at peak voltage value
at half of the peak voltage value
at 0.866 of the peak voltage value

69) A generating station has a maximum demand of 500 MW. The annual load factor is 50 percent.
The energy generated per annum will be:

2.19 x 106 MWhr
600 MWhr
250 MWhr
7.50 x 106 MWhr

70) A DC reactor is connected in series with each pole of a converter station in order to:

prevent commutation failures in the inverter
supply reactive power to the converter
improve system stability
increase the power transfer capability

71) The total inductance of two coupled coils in the 'series aiding' and 'series opposing' connections
are 1.4 x 10-3 Henry and 0.6 x 10-3 Henry, respectively. The value of mutual inductance will be:

0.8 x 10-3 Henry

10-3 Henry

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0.2 x 10-3 Henry
0.5 x 10-3 Henry
72) Two stator windings of AC servomotors are oriented:
90 degree (mechanical) apart
90 degree (electrical) apart
180 degree (mechanical) apart
180 degree (electrical) apart
73) A 10A DC Ammeter has a resistance of 0.1 O is to be extended to 50 the required shunt wire
is
Manganin wire of 20 m O
Constantan wire of 20 m O
Manganin wire of 25 m O
Constantan wire of 25 m O
74) Two single-phase 150 kVA, 7200/ 600 volt transformers are connected in open-delta. The
maximum three-phase load that they can carry is:
300 kVA
75 kVA
259 kVA
249 kVA
75) A DC Motor develops a torque of 150 N-m. A 10 percent reduction in the field flux causes a 50
percent increase in armature current. The new value of torque is:
102.5 N-m
202.5 N-m
172.5 N-m
232.5 N-m
76) Natural commutation means:
reducing the thyristor current to zero
reducing the thyristor current below "holding current"
reducing the current to zero and allowing time to recover thristor junctions
none of and
77) The characteristic equation of a simple servo system is s2+6s+25=0. Damping factor of the
system is:
3.2
2.4
1.8
2.9

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78) The property of materials by which they can be drawn into wires is known as:

malleability
elasticity
creep
ductility

79) Full load cupper loss in a transformer is 1600 watts. At half load the cupper loss will be:

6400 watt

1600 watt

800 watt

400 watt

80) Which braking system on the locomotives is the costliest among the following?

Vacuum braking on diesel locomotives
Vacuum braking on steam locomotives
Regenerative braking on electric locomotives
All braking systems are equally costly

81) In a microprocessor, the address of the next instruction to be executed, is stored in

Stack pointer
Address latch
Program counter
General purpose register

82) vx in the network below is:


1 Volt
Volt
Volt
2 Volt

83) A system is critically damped. If the gain of the system is increased, the system will behave as:
overdamped

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underdamped
oscillatory
critically damped
84) An ideal voltage source will charge an ideal capacitor
in infinite time
exponentially
instantaneously
cannot be guessed
85) For the circuit given below, the Thevenin's resistance across the terminals A and B is
2 kO
0.2 kO
5 kO
0.5 kO
86) A high-pass filter has a resistance R 2 kO The lowest input frequency to be passed is 7.5 kHz.
The value of suitable coupling capacitor must be:
0.001 pico Farad
0.01 pico Farad
0.1 pico Farad
1 pico Farad
87) A long transmission line has considerable ……………….. effect.
series capacitance
shunt capacitance
series inductance
shunt inductance
88) For the protection of parallel feeders fed from one end, the relays used are:
non-directional relays at the source-end and directional relays at the load-end
non-directional relays at both the ends
directional relays at the source-end and non-directional at the load-end
directional relays at both the ends

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89) The bridge used to measure the dielectric loss of an insulator is:

Anderson bridge

Wien's bridge

Schering bridge

Any of the above

90) In a series RLC circuit at resonance, the magnitude of the voltage developed across the
capacitor

is always zero
can never be greater than the input voltage
can be greater than the input voltage, however, it is 90° out of phase with the input voltage
can be greater than the input voltage, and is in phase with the input voltage.

91) A 200 milli-Ampere meter has accuracy of


0.5 percent. Its accuracy while reading 100 milli-
Ampere will be:





92) In air-blast circuit breakers, the pressure of the air is of the order of:

100mm Hg
1kg/cm2
20 kg cm2 to 30 kg/ cm2
200 kg cm2 to 300 kg/ cm2

93) A passive 2-port network is in a steady-state compared to its input, the steady state output can
never offer

higher voltage

lower impedance

greater power

better regulation

94) Decimal equivalent of Hexadecimal number (C3B1)16 is:

12197
32097
52097
50097

95) The driving power from the prime-mover driving the alternator is lost but the alternator remains
connected to the supply network; the field supply also remains on. The alternator will:

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get burnt
behave as an induction motor but will rotate in the opposite direction
behave as a synchronous motor and will rotate in the same direction
behave as a synchronous motor but will rotate in a reverse direction to that corresponding to

generator action

96) Impulse testing of transformers is done to determine the ability of:

bushings to withstand vibrations
insulation to withstand transient voltages
windings to withstand voltage fluctuations
all of the above

97) The 8O85 assembly language instruction that stores the contents of H and L registers into
the memory locations 2050H and 2051H, respectively, is:

SPHL 2050H

SPHL 2051H

SHLD 2050H

STAX 2050H

98) In an 8085 microprocessor, after the execution of XRA A instruction

the carry flag is set
the accumulator contains FFH
the zero flag is set
the accumulator contents are shifted left by one bit

99) The melting point of carbon is:

1800 degree Centigrade
2200 degree Centigrade
3500 degree Centigrade
5500 degree Centigrade

100) A power system is subjected to a fault which makes the zero sequence component of current
equal to zero. The nature of fault current is:

Double line to ground fault
Line to line fault
Line to ground fault
Three-phase to ground fault

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