| Post Name | Assistant Electrical Inspector |
|---|---|
| Department | Kerala Electrical Inspectorate |
| Question Paper Code | 117/2014 |
| Date of Test | 7 August 2014 |
| Medium of Question | ENGLISH |
| Exam Type | OMR Examination |
| Total Questions | 100 |
1
Zero voltage regulation in a transformer occurs at :
Answer
C. leading p-f.
2
A parallel plate capacitor has 15 pF capacitance. If the linear dimensions of the plate are
doubled and the distance between the plates are also doubled, then new value of
capacitance would be :
Answer
B. 30 uF
3
Resistance of a 230 V 100 W bulb is R, and that of a 230 V 75 W is R5. Then,
Answer
C. RK, «ks
4
‘The current in a series RL circuit with R=10 9) and L.=0.05 H is suddenly connected to a DC
voltage source of 200 V. The current in the series circuit, just after the switch is closed is
equal to:
Answer
D. zero
5
A 230/115 V transformer has its LV-side resistance of 0.06 p.u. The resistance referred to the HV side is:
Answer
Question Cancelled
6
Laplace transform of the function te~* is :
eine: eee Bit Se oh
Answer
B. (s +a)"
7
The effect of addition of zero to the open loop transfer function is :
Answer
C. pulling the root locus to the left and to speed up the settling of response
8
Polar plot of a sinusoidal transfer function is a plot of :
Answer
A. magnitude and phase angle
9
Gain margin is the:
Answer
D. reciprocal of the magnitude of |G(jw)| at the frequency at which the phase angle
| is —180°
10
A bipolar transistor is specified to have forward current gain in the range of 8 to 40, The
load resistance is 11 2. The de supply voltage V..=200 V and input voltage to the base
circuit is 10 V. If Ve-p.,,=1.0 V and Vop.,.=1.5 V, what is the collector saturation current ?
|
Answer
B. 18.09 A
11
The current rating of a relay is 5 A and it is set at 150%. C.T. ratio is a Fault current is
6000 A. PSM is :
Answer
C. c) 10
12
A11kV 100 MVA alternator is grounded through a resistance of 4.9, The
Answer
Question Cancelled
13
A generating station has a connected load of 500 MW and a maximum demand of 300 MW.
The units generated being 600 10° per annum. The load factor is :
Answer
D. 22.83%
14
A 132 kV, 200 km long transmission line has a reactance of 0.2 0/phase/km. What is its
reactance/ phase in p.u. on 100 MVA base ? |
Answer
B. 0.23
15
Which of the following is not true for a fault limiting reactor ?
Answer
C. they improve the voltage regulation
16
Positive sequence impedance of a transformer is
Answer
B. equal to negative sequence impedance
17
Two parallel alternators each rated 11 kV 50 MVA and each having a subtransient reactance
of 15% are connected to a bus bar, What is the fault level for a fault on one of the feeders
near the bus bar ?
Answer
A. 666.67 MVA
18
The positive sequence and zero sequence impedance of a generator are X, and X, respectively
and its neutral is grounded through a reactance Xn. A single line to ground fault is more
severe than a three phase fault at its terminals when ?
Answer
D. Xn < (1/3)(X1 - X0)
19
A schedule speed of 45 km/h is required between two stops 1.5 km apart. If the stop is 20s
duration, what is the actual time of run for the train ?
Answer
C. 100s
20
What is the supply voltage of electric traction in Kerala ?
Answer
D. 25 kV AC
21
What is the decimal number for 10101 ?
Answer
A. 21
22
Which gate is known as inverter gate ?
Answer
C. NOT
23
Which of the following is a binary storage device ?
Answer
B. flipflop
24
The address of a memory location of Intel 8085 microprocessor is :
Answer
B. 16 bit
25
A voltage of V is applied across an RLC series circuit. A voltmeter is connected across
Land C, What will be the reading of voltmeter at resonance ?
Answer
A. zero
26
The mechanical power developed by a shunt motor will be maximum when the ratio of back
e.m.f, to applied voltage is : |
Answer
D. 0.5
27
The e.m.f. induced in the armature of a shunt generator is 240 V. The armature resistance is
0.8 (2. If the armature current is 10 A, the terminal voltage will be :
Answer
C. 232 V
28
The speed of a DC shunt motor can be increased by :
Answer
A. Increasing the resistance in the field circuit
29
At full load, the copper loss and iron loss in a 100 kVA transformer is each equal to 3 kW.
What is the efficiency at a load of 60 KVA, 0.8 power factor ?
Answer
D. 92.16%
30
An 8 pole DC generator has 500 armature conductors and has a useful flux/ pole of
0,065 Wb. What will be the e.m.f. generated it is lap connected and runs at 1000 r.p.m. ?
3
Answer
A. 541.67 V
31
An over excited synchronous motor will take current at :
Answer
B. leading p-f.
32
The V curves of a synchronous motor show relationship between :
Answer
D. de field current and ac armature current
33
If ina 3 phase 3.5 MVA, 4160 V star connected alternator, a field current of 200 A produces |
full load current on short circuit and 4750 V on open circuit, its synchronous impedance is :
Answer
C. 5.64 2
34
What is the rms. value of the induced e.m.f. per phase of a 10 pole, 3 phase, 50 Hz alternator
with 2 slots per pole per phase and 4 conductors per slot in two layers ? The coil span is 150°. |
Flux per pole is 0.12 Wb. |
Answer
B. 995 V
35
Which of the following devices convert fixed DC to variable DC ?
Answer
C. chopper
36
If V_ is the peak value of carrier signal and V, is that of reference signal, modulation index of
a sinusoidal PWM is:
Answer
A. Vr/Vc
37
Which of the following possess bidirectional current capability ?
Answer
B. Triac
38
What is the approximate value of an alternating current producing 4 times the heat produced
per second by a steady current of 2 A in a resistor ?
Answer
D. 4A
39
40
A50 Hz AC current of peak value 1 A flows through the primary coil of a transformer. If the
mutual inductance between primary and secondary is 1.5 H, the mean value of induced
voltage is :
Answer
A. 300 V
41
Ther.m.s. value of the e.m-f. given by E=8 sinwt +6 sin2wt volt is :
Answer
B. 5 sqrt(2) V
42
A22cm long solenoid having total number of turns 1000, consists of a core of cross sectional
area 4 cm?. Half portion of the core consists of air and other half is made of iron of relative
permeability 500. The self inductance of the solenoid is :
Answer
C. 0.57H
43
Which of the following is a solution to Ferranti effect ?
Answer
B. shunt reactor
44
FACTS device is used for :
Answer
D. all of the above
A 7 117/2014
IP.T.O.}
45
Pijay 18 the maximum power that can be transferred through a transmission line, What is the
1
maximum power transfer if a series capacitor with a degree of compensation k= 3 is
connected in the line ?
2
= 1
Answer
A. 1.5 Pmax
46
STATCOM isa:
Answer
C. switched converter type shunt compensator
47
A static synchronous series compensator injects :
Answer
B. a voltage in quadrature with the line current
48
The operation of a TCSC is prohibited for firing angles in the resonance region, since it offers
to the network :
Answer
D. a high impedance
49
Which of the following scheme is used for coupling ac systems of different frequencies ?
Answer
C. back to back de link
50
Under normal conditions, an HVDC link operates with :
Answer
A. CC control at rectifier station and CEA control at inverter station
51
What is the penalty factor of a plant if its incremental loss is 0.2 ?
Answer
D. 1.25
117/2014 8 A
52
What is the new steady state frequency, if a 10 MW load increase occurs in an area with
frequency 50 Hz, governor regulation R=0.1 p.u. and frequency dependent component of
load change D=0.8 p.u. on 100 MVA base 7
Answer
B. 49.537 Hz
53
Acircuit breaker is connected to a 132 kV bus bar. What is the maximum value of restriking
voltage across the contacts of the circuit breaker ?
Answer
Question Cancelled
54
Current chopping occurs during :
Answer
C. disconnection of transformer on no load
55
A 400 kV surge travels on an overhead line of surge impedance 400 0 towards its junction
with a cable which has a surge impedance of 40 0. What is the transmitted voltage ?
Answer
B. 7273 kV
56
Which of the following is an example of high frequency electric heating ?
Answer
B. induction furnace
57
An illumination on the working plane of 32 lux is required ina room 80m X 15m. Assuming
a utilization factor of 0.5, lamp efficacy of 14 lumen/ watt and candle power depreciation of
0.2, estimate the number of 200 W lamps required. |
Answer
D. 36 |
58
The specified parameters for a slack bus in load flow analysis are :
Answer
C. voltage magnitude and phase angle
59
Which of the following is true for a suburban electric traction service ?
Answer
A. coasting period is longer
60
The dead weight of an electric train is 200 tonnes. The distance between station is 1.6 kms
and there is a uniform gradient of 1 in 80 between the stations. The tractive effort due to
gradient is :
Answer
B. 2500 kg
61
Fora given schedule speed, the specific energy consumption for an electric train is :
Answer
A. larger for suburban service
62
Which of the following material is used as a moderator in nuclear reactors ?
Answer
D. Graphite
63
Choke is provided in a fluorescent lamp to :
Answer
C. provide stability to the arc in the tube
64
Which of the following use a resonant converter for its operation ?
Answer
Question Cancelled
65
What will happen if the field of a DC motor opened while running ?
Answer
B. motor will attain dangerously high speed
66
Which of the following motor has highest no load speed ?
Answer
A. series
67
The resistance of a moving coil instrument is 10 Ω which gives full scale deflection when carrying a current of 50 mA. What should be the value of shunt to be connected to extend its range to 100 A ?
Answer
D. 0.005 Ω
68
What will be the load power factor, if one wattmeter read positive and the other zero in a two wattmeter method for power measurement ?
Answer
Question Cancelled
69
A dynamometer moving coil instrument can measure :
Answer
C. both a.c and d.c.
70
Which of the following bridge rectifiers has highest harmonic content in output voltage ?
Answer
A. 1-phase half wave
71
The rotor copper loss for a 4 pole 3-phase 50 Hz induction motor running at 1495 rpm is 50 W. Its rotor input is :
Answer
B. 15 kW
72
The electrical representation of the variable mechanical load of a 3-phase induction motor is the resistance given by :
Answer
D. r₂[(1/s) − 1]
73
If V is the voltage applied to the stator of an induction motor, the electrical torque Te is proportional to :
Answer
C. V²
74
The rotor slots of squirrel cage induction motor are given a slight skew in order to :
Answer
B. reduce magnetic hum
75
The speed of a 3-phase, 4 pole, 440 V 50 Hz induction motor is 1440 rpm. What is the frequency of rotor emf ?
Answer
C. 2 Hz
76
The cogging in an induction motor is caused by :
Answer
Question Cancelled
77
Rotor rheostatic method of speed control is used for :
Answer
A. slip ring induction motor
78
What is meant by plugging in the case of a 3-phase induction motor ?
Answer
B. interchanging two supply phases for quick stopping
79
What is the condition for maximum torque under running conditions for a 3-phase induction motor, if R₂ is the rotor resistance, X₂ is the rotor reactance and ‘s’ is the slip ?
Answer
C. R₂ = sX₂
80
The torque developed by a single phase induction motor at starting is :
Answer
D. zero
81
A reluctance motor is preferable for :
Answer
B. timing and control devices
82
The phase displacement between starting and running winding of a capacitor start motor is
nearly :
Answer
A. 90°
83
Which of the following does not change in a transformer ?
Answer
B. frequency
84
The highest transmission voltage in India is :
Answer
C. 765 kV
85
Which of the following transformers has its secondary always kept closed ?
Answer
D. current transformer
86
A40 kVA, 1-phase transformer has an iron loss of 400 W and full load copper loss of 600 W.
Maximum efficiency occurs at a load of ;
Answer
C. 32.66 kVA
87
Which winding of the transformer has large cross sectional area ?
Answer
D. low voltage winding
88
During short circuit test, iron losses are negligible because :
Answer
B. voltage applied on primary side is low
89
If the input to the primemover of an alternator is constant but the excitation is changed,
then :
Answer
A. reactive power output changed
90
Fora sine wave oscillator, total phase shift around the loop and magnitude of loop gain must
be :
Answer
A. zero and unity
91
The first column of Routh table contains the following; 1, 2, 4, 3.5, 1. The system is :
Answer
B. stable
92
The effect of a phase lag network is :
Answer
A. phase margin increased and bandwidth reduced
93
If the bandwidth of a control system is increased, the result will be : :
Answer
A. slower response
94
‘The settling time of the second order linear system is :
1 th
Answer
Question Cancelled
95
In force-current analogy, electrical capacitance is analogous to :
Answer
B. mass
96
Which of the following is not in frequency domain ?
Answer
B. Root locus
97
If the characteristic equation of a system is s?+8s +25=0, value of w, is :
Answer
D. 5 rad/s
98
The phase shift of G(s)= = is :
Answer
A. —180°
99
The open-loop transfer function of a unity-feedback system is G(s) = 50/[(1 + 0.1s)(s + 10)]. What is the static position error coefficient Kp?
Answer
A. 5
100
Schmidt trigger is an example of :
Answer
C. bistable multivibrator
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