| Post Name | Assistant Engineer (Electrical) - Kerala State Electricity Board Ltd |
|---|---|
| Question Paper Code | 225/2023 |
| Category Code | 034/2023 |
| Date of Test | 14 November 2023 |
| Medium of Question | ENGLISH |
| Exam Type | OMR Examination |
| Total Questions | 100 |
1
A DC voltage source of 100 V with 1 ohm internal resistance is connected to a resistor load of
10 ohms. The current delivered to the load is:
Answer
A. 9.09 A
2
Two coils A and B are mutually coupled with mutual inductance of 0.5 henry. Coil A carries a
current of (20 sin 100 t) amperes. RMS value of induced voltage in coil B is :
Answer
C. 707 V
3
Two identical coupled inductors are connected in series. The measured inductances for the
two possible series connections are 300 ΞΌH and 200 ΞΌH. Their mutual inductance is :
Answer
B. 25 ΞΌH
4
What is the effective resistance between A and B in the circuit below?
Answer
C. 5Ξ©
5
An AC circuit has a source voltage of 80 V with internal impedance of (4 + j3) ohms. The load
impedance is adjusted such that maximum power is delivered to the load. Then the load
current is:
Answer
B. 10 A
6
A 100-microfarad capacitor is initially in the charged condition with a voltage of 10 V.
Another 100-microfarad capacitor without any charge in it is connected in parallel with the
first capacitor. What will be the voltage of the combination?
Answer
A. 5V
7
The average voltage of the given waveform is:
Answer
A. 4V
8
The current drawn (I) by the circuit below is:
Answer
C. 10 A
9
The power consumed by the circuit below is:
Answer
D. 16 W
225/2023 4 A
10
An amplifier has a maximum output of 10 V. The bandwidth of this amplifier is defined as
the frequency range over which the output is above:
Answer
C. 7.07 V
11
The relative permeability of a ferromagnetic material is 10000. Its absolute permeability will be:
Answer
B. 4Ο Γ 10β»Β³ H/m
12
The magnitude of magnetic field strength H is independent of:
Answer
C. Permeability of the medium
13
The magnetic potential difference in a magnetic circuit is given by :
Answer
C. Hl
14
The conductance of electrical circuit is analogous in magnetic circuit by :
Answer
C. Permeance
15
What is the value of the total electric flux coming out of the closed surface?
Answer
C. Equal to the total charge enclosed by the surface
16
In parallel magnetic circuit, the total ampere turn is equal to the :
Answer
D. Sum of Ampere-turn of each path
A 5 225/2023
17
As per Faradayβs laws of electromagnetic induction, an e.m.f. is induced in a conductor
whenever it:
Answer
C. Cuts magnetic flux
18
Principle of statically induced e.m.f is used in:
Answer
A. Transformer
19
The e.m.f induced in a coil of N turns is given by:
dΟ dΟ
Answer
C. βN
20
A conductor 0.8 m long lies at right angle to a uniform magnetic field of flux density 2 Wb/mΒ² and moves at 30 m/s. Calculate induced EMF, and the EMF if it moves at 30Β° to the field.
Answer
B. 48 V, 24 V
21
Which of the following is not a part of dc machines?
Answer
D. Damping winding
22
The load current and flux of a dc motor are held constant and voltage applied across it
armature is increased by 5%, the speed of motor will :
Answer
A. Increase by 5%
23
The core flux of a particular transformer with a resistive load:
Answer
A. Is strictly constant with the load changes
24
A transformer equivalent circuit has leakage reactances Xβ, Xββ² and magnetizing reactance X_M. Their magnitudes satisfy:
Answer
D. Xβ = Xββ² βͺ X_M
25
The winding used in a 3-phase shell type transformer is ______________ type:
Answer
C. Sandwich
26
In a power transformer:
Answer
C. Low voltage winding is always wound with lesser number of turns of thick wire
27
Which one of the following is the primary reason for placing field on rotor in an alternator?
Answer
B. Insulation of high voltage is made easy on stator than on rotor
28
Which of the following method is employed for starting a 3-phase synchronous motor?
Answer
D. Damper winding in conjunction with the star delta starter or an auto-transformer
starter
29
Which of the following material of slip ring in an induction machine?
Answer
C. Phosphor bronze
30
A 500 HP, 6 pole, 3-phase, 440 V, 50 Hz induction motor has a speed of 950 rpm on full load.
The full load slip and the number of cycles the rotor voltage makes per minute will be
respectively :
Answer
C. 5 % and 150
31
Convert binary number 100111.11 to equivalent decimal number:
Answer
D. 39.75
32
A mod β M counter and a Mod-N counter in cascade gives
Answer
A. Mod-MN counter
33
The condition normally avoided in the basic SR flip flop realized using NAND gate, is:
Answer
Question Cancelled
34
A 4 bit mod-16 ripple counter uses J-K flip flops. If the propagation delay of each flip flop is
20 ns, the maximum clock frequency that can be used is:
Answer
D. 12.5 MHz
35
Which of the following statement is correct about STA instruction of 8085?
Answer
C. It uses direct addressing mode
36
On a negative edge-triggered S-R flip-flop, the outputs reflect the input condition when :
Answer
D. The clock pulse transitions from HIGH to LOW
37
The Boolean expression AB + AC + BC simplifies to:
Answer
D. AB + BC
38
The number of T-states in INX instruction in 8085:
Answer
C. 6
39
The status flags of 8085 microprocessor that is not affected during the execution of DCR
instruction.
Answer
A. Carry Flag
40
The incrementer/decrementer address latch register in 8085 is:
Answer
D. 16 bit
41
If a transmission of characteristic impedance 200 Ξ© is terminated with a load impedance of
400 + j200 Ξ©, then the normalized impedance is:
Answer
D. 2+j
42
A 33 kV system has string insulator having 3 discs and the earth to disc capacitance ratio
of 0.10. The string efficiency will be:
Answer
Question Cancelled
43
Voltage at which corona glow occurs is known as:
Answer
C. Visual critical voltage
44
A three phase circuit breaker is rated 2000 MVA, 33 kV. What will be the making current?
Answer
D. 89 kA
45
The dielectric strength of SF6 circuit breaker is ______________ that of air.
Answer
B. 2 to 3 times
46
Which relay is used in protection of long transmission lines?
Answer
A. Mho relay
47
If for an IDMT relay with a plug setting of 50% and a CT ratio of 400/5, the current is 3000A,
then the plug setting multiplier would be:
Answer
B. 15.0
48
The per unit impedance of a line is X p.u. if the base voltage is increased 3 times and the base
MVA is doubled, the new per unit impedance is:
1
Answer
C. X
49
For a fully transposed transmission line:
Answer
B. Positive and negative sequence impedances are equal
50
In G-S method of power flow problem, the number of iterations:
Answer
C. Depends on number of buses
51
Consider SΒ² + 2ΞΆΟβS + ΟβΒ² = 0, where ΞΆ and Οβ are damping ratio and undamped natural frequency. Match: (a) ΞΆ=0; (b) 0<ΞΆ<1; (c) ΞΆ>1; (d) ΞΆ<0; (e) ΞΆ=1 with (i) underdamped; (ii) undamped; (iii) critically damped; (iv) overdamped; (v) negatively damped.
Answer
A. (a)-(ii), (b)-(i), (c)-(iv), (d)-(v), (e)-(iii)
52
A unity-feedback system has Y(s)/R(s) = ΟβΒ²/(sΒ² + 2ΞΆΟβs + ΟβΒ²). The steady-state error for a unit-ramp input is:
Answer
B. 2ΞΆ/Οβ
53
Consider the following statements:
(i) If an open-loop system is unstable, applying feedback will always improve its stability
(ii) If an open-loop system is subject to parameter variations, applying feedback will always
improve robustness.
Which of the following is correct answer?
Answer
C. Statement (ii) is true but statement (i) is false
54
Identify the number of forward paths for a system between source node and output node
whose SFG is shown in figure. Where the source node is a node with outgoing branches and
output node is a node with only incoming signals:
Answer
B. 9
55
(βa Β± jb) are complex conjugate roots of a second-order characteristic equation. Its damping coefficient and natural frequency respectively are:
Answer
C. a/β(aΒ²+bΒ²) and β(aΒ²+bΒ²)
56
For 0 < ΞΎ < , resonant peak βMrβ is equal to :
2
1 1
Answer
A. β =
57
The polynomial Ξ(S) = SΒ³ + 3SΒ² + 2S + 6 has:
Answer
D. Two roots on jΟ-axis and one root in left half
58
Polar plot of G ( jΟ ) = :
jΟ (1 + jΟΟ )
Answer
D. None of the answers in the
59
In control systems
(i) Reduction in bandwidth results in sluggish response
(ii) Reduction in bandwidth results in better signal/noise ratio
Which of the following is correct answer?
Answer
D. Both Statements are true
60
Occasionally in applying the Routh stability criterion, certain difficulties arise causing the
breakdown of Routh test. One of the difficulties is given as follows. βWhen all elements in any
one row of the Routh array are zeroβ. This condition is indicating:
Answer
A. Symmetrically located roots in the Complex plane
61
The holding current of an SCR is 20 mA. The latching current will be:
Answer
C. 22 mA
62
A line commutated single phase fully controlled rectifier operates as an inverter at firing
angles:
Answer
A. 90Β° β€ Ξ± β€ 180Β°
63
The prominent ripple frequency at the output of a three-phase fully controlled rectifier
operating at 50 Hz is:
Answer
D. 300 Hz
64
To eliminate the 5th harmonic from the output of a single pulse PWM inverter, the width of
pulse should be:
Answer
C. 72Β°
65
For a three-phase bridge inverter operating in 180Β° mode of conduction, a maximum of:
Answer
B. 3 power switches conduct simultaneously
66
The continuous or discontinuous mode of conduction of a chopper is influenced by :
Answer
D. All of these
67
For an ideal op-amp, which one is not applicable:
Answer
B. Infinite output resistance
68
The maximum frequency of operation of an Op-amp without distortion is decided by its:
Answer
B. Slew rate
69
The unit of Slew rate is:
Answer
C. V/ΞΌS
70
An op - amp operating at a high electromagnetically noisy environment should have:
Answer
A. High CMRR
71
Which of the following type of measuring instrument(s) have linear scale?
(i) PMMC
(ii) Moving Iron
(iii) Thermocouple
(iv) Rectifier type
Answer
D. Only (i)
72
Consider the following statement:
(i) The compensating coil of a low power factor wattmeter compensates the effect of the
impedance of the current coil.
(ii) The compensating coil of a low power factor wattmeter compensates the effect of the
impedance of the voltage coil circuit.
Answer
B. (i) is false but (ii) is true
73
VRN, VYN and VBN are the instantaneous line to neutral voltages and iR , iY and iB are
instantaneous line currents in a balanced three-phase circuit, the computation,
VRN ( iY β iB ) β (VYN β VBN) iR will yield a quantity proportional to:
Answer
D. Reactive Power
74
A stationary closed Lissajous pattern on an oscilloscope has 5 horizontal tangencies and
1 vertical tangencies for a horizontal input with frequency 3 kHz. The frequency of the
vertical input is:
Answer
A. 15 kHz
75
Moving Iron instruments can be used for:
(i) AC
(ii) DC
(iii) Complex AC
Answer
C. Both (i) and (ii)
76
A periodic voltage waveform observed on an oscilloscope across a load is shown. A permanent
magnet moving coil meter connected across the same load reads:
Answer
C. 4V
77
Match the following:
Instrument type Quantity measured
P. Permanent Magnet Moving Coil 1. AC
Q. Rectifier Type 2. DC
R. Electrodynamometer 3. Both AC and DC
S. Moving Coil connected through a
current transformer
Answer
A. P-2, Q-3, R-3, S-1
78
One Single phase energy meter operating on 230 V and 2 A for 5 hours makes
460 revolutions. Meter constant in revolution is 400. The power factor of the load will be:
Answer
D. 0.5
79
Two wattmeter method is used for measurement of power in a balanced three-phase load
supplied from a balanced three-phase system. If one of the Wattmeter reads half of the other
Answer
C. 0.866
80
A moving coil galvanometer is made into a D.C. ammeter by connecting:
Answer
B. A low resistance across the meter
81
A causal system is always:
Answer
C. Non-anticipative
82
Given the signal x(t), which of the following is true for signal x(3t + 6)?
Answer
B. x (t ) is compressed by a factor of 3 and then shifted left by two units
83
A system with x(t) and y(t) is defined by the input-output relation y(t) = β« from ββ to β4t of x(Ο) dΟ. The system will be:
Answer
D. Non-causal, time-variant
84
Which one of the following statements is not true?
Answer
B. The product of two odd signals will be an odd signal
85
Which one of the following systems is memoryless?
Answer
A. y(t) = tx(t) + 5xΒ³(t)
86
The output y(t ) of the following system is to be sampled, so as to reconstruct it from its
samples uniquely. The required minimum sampling rate is:
Answer
C. 2000 samples/s
87
The minimum Nyquist sampling rate is:
Οt
2 1
Answer
B. Ο Ο
88
The discrete-time system y(n) = x(n β 1) β 6x(n β 8) is
Answer
A. Dynamic system
89
Aliasing occurs when sampling frequency Οβ is (Οβ = band-limited signal frequency):
Answer
B. Οβ < 2Οβ
90
Consider the two continuous-time signals xβ(t) = |t| for β1 β€ t β€ 1 and 0 otherwise; xβ(t) = 1 β |t| for β1 β€ t β€ 1 and 0 otherwise. These signals are sampled with a sampling period T = 0.25 seconds to obtain discrete-time signals xβ[n] and xβ[n], respectively. Which statement is true?
Answer
A. The energy of xβ[n] is greater than the energy of xβ[n]
91
LVDT is an electrical transformer with ββββββββββββ type of core.
Answer
Question Cancelled
92
In domestic wiring the total lighting load in a sub-circuit should not be more than :
Answer
C. 800 W
93
Which among the following wiring system has large life span?
Answer
D. Conduct pipe wiring
94
The type of varnish used for the casing in capping wiring system :
Answer
D. Pure shellac varnish
95
According to Law of Illumination, the illumination of the surface is ββββββββββββ to the
spare of the distance of the surface from the source of light.
Answer
C. Inversely proportional
96
A hydrometer is used for checking the ββββββββββββ of the Electrolyte.
Answer
B. Specific gravity
97
The region for adding charcoal in earthing :
Answer
Question Cancelled
98
The current range that can cause lack of muscular control in human beings :
Answer
C. 10 mA to 30 mA
99
In control of light, absorption of rays of particular wave-length causes :
Answer
D. change of the color of light
100
The cell which is chemically irreversable in Battery :
Answer
A. Primary cell
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