| Post Name | ASSISTANT ENGINEER (ELECTRICAL) (Kerala Water Authority) |
|---|---|
| Question Paper Code | 103/2025 |
| Category Code | 126/2024 |
| Date of Test | 11 August 2025 |
| Medium of Question | ENGLISH |
| Exam Type | OMR Examination |
| Total Questions | 100 |
1
Use the superposition principle to find the current through Rβ in Fig. (1). The source circuit has Rβ = 1 kΞ©, Rβ = 3 kΞ©, an 8 mA current source and a 32 V voltage source.
Answer
B. 2 mA
2
A coil has an inductive reactance of 220 β¦ and a resistance of 220 β¦ connected in series
with the coil. If an AC voltage of 220V, 50Hz is applied to it; then the reactive current
is ______.
Answer
D. 0.5 A
3
A stable system is a dynamic system with a bounded input to a bounded output.
Answer
C. 2 and 3
4
If the current through capacitor is ic = β2eβt A, then find Vs βββββββ
1Ξ© 2H
ic
Vs i 1F
Answer
Question Cancelled
5
Two coupled coils are connected in series aiding as shown. If Lβ = 1 H, Lᡦ = 2 H and M = 0.5 H, the effective inductance is:
Answer
A. 4 H
6
An R-L-C series resonant circuit has R = 100 Ξ©, Q factor 20 and resonant frequency Οβ = 100 rad/s. The capacitance is:
Answer
A. 5 Β΅F
7
Find the current I flowing through the below circuit.
I
+ 2Ξ© 6Ξ©
9Vβ
6Ξ©
2Ξ©
2Ξ©
6Ξ©
Answer
C. 4.5 A
8
A series circuit has an impedance of (6 β j8) β¦. It is connected across 200 V supply. The
active power consumed by this circuit is _______.
Answer
A. 2400 W
9
An inductor of 3 H carries a current of i(t) = 0.5 t for 0 < t β€ 2sec. What is the energy
consumed by the inductor when time t = 2sec?
Answer
B. 1.5 Joules (J)
10
For the circuit shown below, what should be the value of the load resistance to be connected
across points 'A' and 'B' so that the maximum power will be transferred?
6Ξ©
1Ξ© 2Ξ©
A
15A
β 20V
+
B
Answer
Question Cancelled
11
Hysteresis loss in magnetic materials are primarily due to
Answer
B. flux density lagging behind magnetizing force
12
Air gaps are provided in magnetic circuits to
Answer
C. prevent saturation
13
In a parallel magnetic circuit with two branches, the net mmf required to create magnetic
flux is
Answer
C. sum of mmfs of both low and high reluctance paths
14
A coil of 1000 turns carrying a current of 'l' A produces a magnetic flux of 5 mWb. If the
current in the coil is reversed in 0.1s, then the average value of emf induced in the coil will
be
Answer
B. 100 V
15
A coil of 500 turns carrying 5A current produces 5mWb flux in an adjacent coil of 1000
turns. The mutual inductance between the coils is
Answer
B. 1 H
16
Two identical coils with 1000 turns and self inductance of 100 mH each are lying in parallel
planes. If current changing at the rate of 100 A/s in the first coil induces an emf of 5 V in
the second coil, then the coupling of coefficient between the coils will be
Answer
B. 0.5
17
A coil of 1000 turns has a resistance of 100 ohms. When excited with a DC source of 200 V,
the coil produces a magnetic flux of 10 mWb. The self inductance of the coil will be
Answer
A. 5 H
18
The mutual inductance M between two coupled inductors L1 and L2 will be
Answer
D. M β€ (LβLβ)ΒΉαΒ²
19
The hysteresis loop of a magnetic material has an area of 10 cmΒ² with axis scales 1 cm = 5 AT and 1 cm = 50 mWb. If the supply frequency is 50 Hz, the hysteresis loss is:
Answer
C. 125 W
20
Which of the following statements hold for the divergence of electric and magnetic flux
densities?
Answer
D. Divergence is zero for magnetic flux density
21
A 4-pole lap wound DC generator has 720 conductors, a flux of 40 mWb per pole is driven
at 400 rpm. Find the generated emf.
Answer
A. 192 V
22
A shunt generator running at 1000 rpm has generated emf as 220 V. If the speed increases
to 1200 rpm, then the generated emf will be
Answer
D. 264 V
23
The condition for maximum power in case of DC motor is
Answer
B. back emf = half of the supply voltage
24
A 20 kVA single phase transformer has 400 turns on the primary and 60 turns on the
secondary. The primary is connected to 2000 V, 50 Hz supply. The secondary voltage on
open circuit is
Answer
B. 300 V
25
If R2 is the secondary resistance and K is the transformation ratio, then the equivalent
secondary resistance referred to primary will be
Answer
B. R2 / K2
26
A 3-phase 400 V, 50 Hz induction motor has 5% slip. The frequency of rotor emf will be
Answer
C. 2.5 Hz
27
The power factor of a squirrel cage induction motor is
Answer
A. low at light loads only
28
The effective resistance of 2200 V, 50 Hz, 440 kVA, 1-phase alternator is 0.5 ohms. On
short circuit, a field current of 40 A gives the full load current of 200 A. The emf on open
circuit with same field excitation is 1160 V. The synchronous impedance is
Answer
A. 5.8 β¦
29
The frequency of voltage generated by an alternator having 6 poles and rotating at 1800
rpm is _____ Hz.
Answer
B. 90 Hz
30
The V-curves of a synchronous motor show the relationship between
Answer
C. D.C. field current and A.C. armature current
31
What is the minimum number of NAND gates required to realize an X-OR gate?
Answer
B. 4
32
Number of select lines m, required to select one out of n input lines is
Answer
A. m = logβ n
33
2421 code is
Answer
A. weighted self-complementing code
34
When an inverter is placed between the input of an S-R flip-flop, then the resulting
flip-flop is a
Answer
D. D flip-flop
35
The number of flip-flops required for a mod-12 Johnson counter is
Answer
B. 6
36
A certain 4-bit DAC uses binary weighted resistors. If the MSB resistor is 100 kβ¦, then the
LSB resistor will be
Answer
C. 800 kβ¦
37
The total memory capacity of 8085 processor is
Answer
A. 64 KB
38
The _____ instruction is used to store the accumulator content into memory pointed by
register pair DE in 8085 processors.
Answer
C. STAX D
39
The order of 8085 machine cycle executed in executing the instruction STA 1200H are
Answer
D. opcode fetch, memory read, memory read, memory write
103/2025 11
40
During which T-state of opcode fetch cycle, the higher order address/data lines are
de-multiplexed in 8085 processors?
Answer
A. T1
41
Calculate the inductance of each conductor of a transposed 3-phase, 3-wire transmission system arranged horizontally with Dββ = 4 m and Dββ = Dββ = 2 m. The conductor diameter is 3 cm.
Answer
A. 1.11 mH
42
A three-unit insulator string is fitted with a guard ring. The capacitance of the link pins to
metal work and guard ring can be assumed to be 15% and 5% of the capacitance of each
unit. Determine the string deficiency.
Answer
B. 86.5 %
43
In Newton-Raphson method of load flow analysis, what happens if the Q limit is violated
for a PV bus?
Answer
A. PV bus is changed to PQ bus and Q value is assigned to limit violated
44
At fault point Va2 = _____ and Z0 = ________
Answer
C. βZ2la2 and 3Zn + Zgo
45
For the shown power-transmission network, Xβ = 0.85 p.u., Xββ = Xββ = 0.157 p.u., Xββ = Xββ = 0.35 p.u., E = 1.5 p.u. and Vβ = 1.00 p.u. Calculate the maximum power limit and steady-state stability margin when the generator delivers 1.00 p.u.
Answer
C. 1.12 p.u. and 10.7 %
46
A 100 MVA, 50 Hz alternator operates at its rated speed. The H constant of the machine
is 5 kW sec per kVA. The load suddenly increases by 50 MW. Due to delay in governor
action, there is a delay of 0.6 sec in opening of steam valves. Find the frequency deviation.
Answer
C. 3.046 %
47
A generator-transformer unit feeds an infinite bus through a transmission line. The source network has generator E = 1.1 p.u. behind Xd = 0.7 p.u., transformer reactance j0.2 p.u., line reactance j0.2 p.u., a midpoint shunt inductor j0.5 p.u., and bus voltage 1 p.u. Find the steady-state power limits with the inductor open and closed.
Answer
B. 0.9167 p.u. and 0.6875 p.u.
48
In a short circuit test on a 3-pole, 132 kV circuit breaker, the following observations
are noted: p.f. of the fault is 0.4, the recovery voltage is 0.9 times the full line value, the
breaking current is symmetrical and the frequency of oscillations of re-striking voltage is
16 kHz. Assume that the neutral is grounded and the fault does not involve ground.
Determine the average rate of rise of re-striking voltage.
Answer
C. 8.566 kV/Β΅ sec
49
For the shown relay system, fault current is 2000 A, Relay 1 is set to 100%, Relay 2 to 125%, CT ratio is 200/1, grading margin is 0.5 s, and Relay 1 has time-multiplier setting 0.2. Determine the operating times using the shown characteristic.
Answer
A. 0.56 sec, 1.06 sec
50
A short circuit to earth occurs near the terminals of phase A of a three-phase alternator,
star connected with neutral point earthed. The current to earth is 1000 Amps. If the
alternator does not supply any normal current, then calculate the positive, negative and
zero sequence components of the currents of phase A.
Answer
A. 333.3 β 0Β° Amps, 333.3 β 0Β° Amps and 333.3 β 0Β° Amps
51
The open-loop transfer function of a unity-feedback control system is G(s) = 1/(s + 2)Β². The closed-loop transfer function will have poles at:
Answer
D. β2 Β± j1
52
For the signal flow graph shown below, which of the statement given are correct?
5. ' aa 1 1
Seid
-2
1. The number of loops are 2.
2. The number of loops are 3.
3. The number of forward paths are 3.
4.
5. β ratio is β.
R ratio is 37
Answer
B. 2, 3 and 4
53
The impulse response of a system is e*'sin 2t. The transfer function of the system is
1 2
Answer
B. β~ββ
( Frese
54
The open loop transfer function of a unity feedback system is . The value of gain K
for a damping ratio of is
Answer
D. 16
16 103/2025
55
Steady state error in response to a unit step input for a unity feedback system with forward
path transfer function is
Answer
D. 57%
56
Which of the following statements are correct?
1. Routh β Hurwitz criterion is a necessary and sufficient condition for stability. r
2. Relative stability is dictated by the location of roots of the characteristic equation.
3. A stable system is a dynamic system with a bounded input to a bounded output.
Answer
D. 1, 2 and 3
57
What will be the gain margin in dB of a system having open-loop transfer function G(s)H(s) = 2/[s(s + 1)]?
Answer
D. β
58
The transfer function of a linear control system is . The value of
gain in dB in its Bode plot corresponding to Ο = 0.1 rad/sec is
Answer
C. 60 dB
59
The Nyquist plot of a system is shown below
Im
Re
The open loop transfer function of this system will be
K K
A
Answer
D. s?(1+sT,)(1+sT,)(1+sT;)
60
A second-order control system has M(jΟ) = 100/(100 β ΟΒ² + 10β2 jΟ). Its peak magnitude is:
Answer
B. 1
61
The shown switch waveforms have current changing from 0 to 10 A while voltage changes from 200 V to 0 during rise time tα΅£ = 3 ΞΌs, and the reverse during fall time tκ° = 5 ΞΌs. At 50 kHz, determine the rise-time switching loss.
Answer
B. 50 W
62
Consider a single-phase half-wave rectifier with a free-wheeling diode feeding RL load
shown in the figure. Identify the waveform of voltage across the thyristor.
+ VV, -
> r
T,
{ R
Vv.
Answer
A. FDA Ve
Lg:
Y v,
63
A three-phase full-wave bridge rectifier feeds a resistive load. The input line voltage is 300 V, 50 Hz. Calculate the average output voltage for firing angle Ξ± = 90Β°.
Answer
C. (900β2/Ο)(1 β β3/2) V
64
A single-phase square wave inverter shown in the figure below feeds an RL load. Identify
the correct statement during the period when switches T3 and T4 are on, while T1 and T2
are off. The given polarity of load voltage and direction of load current in the figure shown
below is considered as positive.
Answer
C. The output voltage is equal to βVs, the output current is negative, and the power flows
from source to load.
65
Consider a three-phase inverter feeding a star-connected resistive load shown in the figure
below operated in 180Β° conduction mode. The magnitude of phase voltages Ξ½ao, Ξ½bo and
Ξ½co, when the switches S1, S2 and S6 are in conduction while other switches are in off state.
Answer
D. vββ = 2Vβ/3, vᡦβ = vκβ = βVβ/3
66
A boost converter connected to a resistive load (R = 10β¦) operates in continuous conduction
mode. The duty ratio and switching frequency are 0.6 and 10 kHz respectively. Determine
the value of the inductor under the condition il max = 1.5 (ilavg), where il max is the maximum
value of the inductor current and ilavg is the average value of inductor current.
Answer
A. 96 ΞΌH
67
Consider a class-A chopper (Vβ = 100 V) feeding an RLE load (R = 10 Ξ©, L = 10 ΞΌH and E = 120 V). The load current is continuous. Find the duty cycle Ξ± for which the average controlled-switch current is maximum.
Answer
B. 0.6
68
Calculate the value of V0 for the operational amplifier shown below.
Answer
A. 3 V
69
The input V, to an operational amplifier shown below is given in the graph. Identify its
output voltage.
10 kO.
V;
0.4 uF ne Bho
Yo 34-6 8 10 12 ?(ms)
V9 Ve
10 avrererasassoonen: 5 a anacneaarsnseees
() g i ba i? Gi
Answer
A. 9 L - + i
70
A differential amplifier has Vβ = 0.85 V, Vβ = 0.55 V and Vβ = 300.7 V. Its common-mode voltage gain is 1. What are the differential voltage gain Aα΄
and CMRR?
Answer
C. Aα΄
= 1000 and CMRR = 60 dB
71
The unknown resistance Rβ is measured with a Wheatstone bridge using Rβ = RβRβ/Rβ. Given Rβ = 10 Β± 0.5 Ξ©, Rβ = 20 Β± 0.2 Ξ© and Rβ = 30 Β± 0.6 Ξ©, the resulting error in Rβ is:
Answer
B. 60 Β± 8%
72
A PMMC voltmeter is connected across a series combination of Vβ = 5 V DC and Vβ(t) = 2 sin(314t) V AC. The meter reads:
Answer
D. 5 V
73
The deflection angle of the pointer of an ideal moving iron ammeter is 10Β° for 1.0 ampere
DC current. If a current of 3 sin (314 t) amperes is passed through the ammeter, then the
deflection angle is
Answer
C. 45Β°
74
Two voltmeters have the same range of 0 β 400 V and have sensitivity of 100 β¦/V and
150 β¦/V respectively. If they are connected in series and 600 V is applied across the series
circuit, then voltmeter readings are
Answer
B. 240 V and 360 V
75
A moving iron ammeter produces a full-scale torque of 250 Β΅N-m with a deflection of 125Β°
at a current of 20 A. The rate of change of self-inductance (Β΅H/rad) of the instrument at
full scale is
Answer
B. 1.25 Β΅H/rad
76
The voltage expression Ξ½(t) = E1sin(Οt) + E3sin(3Οt)V is applied to the pressure coil of a
wattmeter and current expression of i(t) = I1sin(Οt β Ο1) + I3sin(3Οt β Ο3) + I5sin(5Οt β Ο5) is
passed through current coil. The average power measured by the wattmeter is
Answer
C. 0.5(EβIβcosΟβ + EβIβcosΟβ)
77
Two wattmeter method is used for the measurement of power in a symmetrical three
phase system and load. One of the wattmeters reads half of the other. What will be the
power factor of the load if both are having positive readings?
Answer
D. 0.866
78
A single phase energy meter disc makes 2208 revolutions for a constant load of 230 V, 4 A
at unity power factor for 6 hours. What will be the energy consumption by the load if the
meter disc completes 1240 revolutions?
Answer
D. 3.1 kWh
24 103/2025
79
A sinusoidal waveform has peak - peak amplitude of 5 cm viewed on a CRO screen. The
vertical sensitivity is set to 4V/ cm. The RMS value of the signal is
Answer
A. 7.07V
80
The deflection sensitivity of a Cathode Ray Tube is
Answer
D. Independent of the deflection voltage
81
The fundamental period of the signal 10 sin9t + 20 cos5St is
Answer
A. 2Ο
82
Which one of the following is unbounded signal?
1\
Answer
C. nu (1)
83
Input output relationship of a system is given by y(t) = cos x(t). The system is
Answer
D. Nonlinear, time invariant, stable
84
Which one of the following is non causal system?
Answer
A. y(t) = x(sin t)
85
The energy and average power of the sequence x(n) = (1/3)βΏu(n) are respectively:
Answer
A. 9/8, 0
86
A signal x(t) = 10 sin(150Οt β 30) is sampled at 200 Hz. The fundamental period of the sampled sequence x(n) is:
Answer
C. 8
87
A discrete system is given by y(n) = [x(n) + 5]βΏ. The system is:
Answer
A. Memoryless, Causal system
88
The impulse response h[n] of a linear time-invariant system is given by
h[n] = u[n+2]+u[n β 3]β2u[n β 8], where u[n] is the unit step response.
The given system is
Answer
A. Stable but not causal
89
The fundamental period of x(n) = 8cos(0.1Οn) + 5sin(0.9Οn) β cos(0.8Οn) is:
Answer
D. 20
90
The source signal x(t) consists of unit-height rectangular pulses on [β4,β2] and [2,4]. Identify x(t/2 β 2).
Answer
B. Unit-height pulses on [β4,0] and [8,12]
91
The LVDT has
Answer
D. Movable core
103/2025 27
92
The sensitivity of an LVDT is 10V/Β΅m. What is the RMS value of output voltage for
displacement of 0.5 Β΅m?
Answer
Question Cancelled
93
Which instrument is used to measure the specific gravity of battery electrolyte?
Answer
B. Hydrometer
94
The maximum continuous discharge current of a 20Ah, LFP battery with a C rating
of 2C is
Answer
C. 40A for 0.5 hours
95
Four 2.5V cell each having internal resistance 5β¦ are connected in series. A 20 β¦ resistance
is connected to this battery. The current through the resistance is
Answer
D. 0.25A
96
As per the recommendation of ISI, the maximum load that can be connected in one
subcircuit is
Answer
A. 800 watts
97
What is the minimum required length of pipe in a pipe electrode earthing system?
Answer
D. 2.5.0m
98
What is the average intensity of illumination on a surface located 8 m from a 500 β candela
power lamp when the surface is inclined at an angle of 30 degrees to the rays?
Answer
C. 3.9 lux
99
What is the mean spherical candlepower of a lamp that emits 20000 lumens?
Answer
B. 5000/Ο
100
Which of the following is a discharge lamp?
Answer
A. Sodium vapour lamp
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