| Post Name | ASSISTANT ELECTRICAL INSPECTOR (Kerala Electrical Inspectorate) |
|---|---|
| Question Paper Code | 148/2025 |
| Category Code | 096/2025 |
| Date of Test | 14 November 2025 |
| Medium of Question | ENGLISH |
| Exam Type | OMR Examination |
| Total Questions | 100 |
1
If the voltage across 2 Ω resistance is 18V as shown. Assuming ideal sources, what is the
strength of the current source :
Answer
D. None of the above
2
What is the phase of v(t) = 8√3 sin ωt + 8 sin(ωt + 90°) with respect to v₁(t) = 4 sin(ωt − π/4)?
Answer
B. 75° lead
3
An inductor with resistance of 10 ohm is connected in series with a pure capacitor across
an AC source of variable frequency. The Q factor of the coil when the circuit is
1
at resonance is 0.5. What is the reactance of the inductor at of the resonance
2
frequency?
Answer
A. 2.5 Ω
4
The line currents of a star connected load connected to a 3 Phase 4 wire balanced system are I_R = 42 + j0.55 A, I_Y = −20.7 − j8.8 A, I_B = −21.3 + j9.70 A. The current flowing from load neutral to source neutral is:
Answer
A. 1.45∠90°
5
What is the potential difference between points N and n (Vₙₙ) if Vₚ = 415 V? The source figure shows a balanced three-phase star-connected load with equal R + jXₗ branches and phase voltages Vₚ∠0°, Vₚ∠−120° and Vₚ∠120°.
Answer
C. 0 V
6
An electric stove with four burners and an oven is used in preparing a meal as follows.
Burner 1 : 10 minutes, Burner 2 : 50 minutes, Burner 3 : 25 minutes, Burner
4 : 35 minutes and Oven : 30 minutes
If each burner is rated at 1.8 kW and the oven at 1.2 kW, and electricity costs 6 rupees
per kWh,
What is the cost of electricity used in preparing the meal?
Answer
A. 25.2 rupees
7
If Rab is given to be 20Ω , what is the value of R :
Answer
D. 17Ω
148/2025 4 A
8
The Thevenin and Norton equivalents of circuit in Fig. 1 is given to be Fig. 2 and Fig. 3
respectively:
Fig. 1 Fig. 2 Fig. 3
Which of the statement is correct?
Answer
D. Vth is wrong and Ith is correct
9
The RMS value of the phase to neutral voltage of a 415V, 3Phase, 50 Hz, 4 wire
system is :
Answer
C. 239.6 V
10
Assuming ideal elements, Current through the inductor at steady state is :
Answer
B. 3.0 A
11
The reluctance, S of a magnetic circuit with flux, Φ and magneto motive force, F is :
Answer
A. S = F/Φ
12
The ability of a material to conduct magnetic flux through it is referred to as :
Answer
C. permeability
13
A particle of charge q and mass m moves in a circular orbit of radius r with angular
speed ω . The ratio of magnitude of its magnetic moment with its angular momentum
depends on :
Answer
C. q and m
14
A flat coil carrying current has a magnetic moment Pm . It is placed in a magnetic field B,
such that Pm is antiparallel to B. The coil is :
Answer
B. in unstable equilibrium
15
Consider an iron ring with a small air gap, with a coil wound on a portion of it. The
portion of the flux in the air gap that diverges outside the main air gap is referred to as :
Answer
B. Fringing flux
16
When placed in a non-uniform magnetic field, this material tends to move from high field
region to low field region. This material is :
(i) Diamagnetic
(ii) Paramagnetic
(iii) Ferromagnetic
Answer
A. (i)
17
A magnetic needle is kept in a non-uniform magnetic field. It experiences :
Answer
A. a force and a torque
18
A charged particle is released from rest in a region or steady and uniform electric and
magnetic field which are parallel to each other. The particle will move in
Answer
A. a straight line
19
Which among the following material have linear
Answer
A. (i) and (ii)
20
A magnetic saturation is observed by varying Voltage. Then current will be :
Answer
C. drastically varying
21
The load current corresponding to maximum efficiency of a 4 pole, 250 V, 10 kW dc shunt
generator with an armature resistance of 1 Ω and core loss of 900 W is :
Answer
B. 30 A
22
A 250 V dc shunt motor has full load armature current of 50 A at a speed of 1000 rpm.
The resistance of the armature is 0.2 Ω . Assuming constant field flux, the resistance that
must be added in series with the armature in order to reduce the speed by 25% for the
same load torque is :
Answer
C. 1.2 Ω
23
The phase sequence of a three phase alternator is reversed if :
Answer
B. the field current remains same but the direction of rotation is reversed
24
The range of slip for operation of an induction machine during plugging in motor mode is
from :
Answer
C. –1 to 0
25
A 3 phase, 500 hp, 440 V, 50 Hz, 6 pole induction motor is running at 950 rpm.
The frequency of rotor emf is :
Answer
C. 2.5 Hz
26
A 5 kVA, 50 V/100 V, single phase transformer has a secondary terminal voltage of
95 V when loaded. The regulation of the transformer is :
Answer
A. 5%
27
In Scott connected transformers, the voltage rating of primary winding of main
transformer is 100 V. Then the voltage rating of primary winding of teaser transformer
is :
Answer
D. 86.6 V
28
An over excited synchronous motor is called :
Answer
C. Synchronous condenser
29
In salient pole synchronous motor, the developed reluctance torque attains maximum
value when the load angle in electrical degree is :
Answer
B. 45º
30
The power delivered to the rotor of a 3-phase, 400 V, 50 Hz, 6 pole squirrel cage
induction motor running at 950 rpm is 2500 W. Then the rotor copper loss is :
Answer
A. 125 W
31
If (123)ₓ = (043)ᵧ, where x and y represent the bases of the corresponding numbers, then:
Answer
A. x = 4 and y = 6
32
For the 4 × 1 multiplexer shown in the figure, if the output is to be the AND of inputs at S₁ and S₀, the values of A₀, A₁, A₂ and A₃ are:
Answer
D. A₀ = 0, A₁ = 0, A₂ = 0 and A₃ = 1
33
To build a mod 8 counter, you need to cascade a mod 4 counter with another
Answer
C. mod 2 counter
34
An 8 bit DAC has a full scale voltage range from 0 V to 16 V. If the digital input is
1000 0000, the analog voltage output of the DAC (rounded to one decimal place is) is :
Answer
C. 8V
35
A decoder is used for addressing a 1024 K × 32 memory. If the decoder is realized using
AND gates, then the number of minimum AND gates required to implement the decoder
is :
Answer
B. 220
36
While executing a nested ‘CALL’ instruction, the address of the return instruction is
stored in :
Answer
C. Stack
37
In 8085 processor, the register contents are as follows A = 10H, B = 20H, C = 30H,
D = 40H, E = 50H, H = 60H, L = 70H, SP = 20 FAH. After execution of the following lines of
code
PUSH D
PUSH B
POP H
The contents of the HL pair will be
Answer
A. H = 20H, L = 30H
38
In 8085 microprocessor, let the register contents be A = 10H, B = 20H, C = 30H, D = 40H,
E = 50H, H = 60H, L = 70H. Executing the following code :
MVIA 88H
MVIB 38H
ADD B
will result in the following flags set
Answer
C. Sign, Auxiliary carry, Parity
39
The number of T states during the execution of LDA instruction in 8085 is :
Answer
D. 13 T states
40
Daisy chaining is
Answer
A. Bus arbitration technique for processing interrupts
41
For a 3 φ transmission line, the capacitance between two conductors is 3 μF. The
capacitance of each conductor to neutral is:
Answer
A. 6 μF
42
Shackle insulators are used as strain insulators for voltages :
Answer
B. < 11 kV
43
A 66 kV overhead transmission line having six units in the string of insulators. The
voltage across string is :
Answer
C. 38.1 kV
44
The rate of rise of restriking voltage is ______________ when the short circuit occurs near
the power station busbar.
Answer
A. high
45
The primary and secondary of current transformer used to protect delta
(primary)/star(secondary) transformer is :
Answer
D. star, delta
46
A 3 φ transmission line operating at 33 kV connected through a 500 kVA transformer
with 5% reactance to a generating station busbar 1000 kVA with 10% reactance. What
will be the reactance of transformer at 1000 kVA base?
Answer
A. 10%
47
In a 3 φ, 4 wire unbalanced system, the magnitude of current in the neutral wire is
______________ of the magnitude of zero sequence current.
Answer
D. 3 times
48
The steady state stability of a two machine system depends on :
Answer
C. per unit reactance of the system
49
The inertia constant H of a machine of 200 MVA is 2 pu. Its value corresponding to
400 MVA is ______________ pu.
Answer
C. 1
50
The corona effect is reduced when the spacing between conductors :
Answer
A. increased
51
For a third order type 1 system which of the following statement is correct?
Answer
B. Steady state error for unit ramp input is not zero
52
Identify the number of roots of the equation that are on the imaginary axis: s⁷ + 6s⁶ + 11s⁵ + 6s⁴ + s³ + 6s² + 11s + 6 = 0.
Answer
A. 0
53
Identify the transfer function of the system with the following asymptotic bode gain plot :
gy 40 Perri Pe PER pr
‘SS PoP PETER Pi tii of PEPE ONABE TE fi iil
10' ~—-10° 10" 10” 10°
freq --->rad/s
100(s +10 0.1s+1
Answer
C. y -_100(s+10)
54
Cascading the plant in a closed-loop system with a controller having transfer function C(s) = (1 + 0.1s)/s could cause:
Answer
B. reduction in the bandwidth of the closed-loop system
55
The Nyquist plot shown below represent a stable system in closed loop. Which of the
following statement is correct?
Answer
C. Open loop system has one pole to the right of imaginary axis
56
Identify the transfer function for the system Fs) :
S
x4 (0) X9(t)
fee] Nim FE
pee] Kg os pee] Ke es
ior en es coe rene cS
Frictionless
2
s't+s+l s+1
s’(s? +2842) 8 (s +23 +2)
s+1 s+s41
Answer
A. ~~ ___
57
Identify the transfer function for the system shown below :
R(s )
G1 (s )G3 (s )[1 + G2 (s )]
Answer
D. [1 + G2 (s)H 2 (s) + G1 (s)G2 (s)H1 (s)][1 + G3 (s )H 3 (s)]
C (s ) 1
58
The closed-loop transfer function of a system is C(s)/R(s) = 1/(s² + 0.8s + 1). Identify the correct statement:
Answer
B. Settling time is 10 s for unit step input
59
Identify the possible open loop transfer function of a system whose characteristic
equation have the root locus as shown below :
k(s +
Answer
C. (s + 4 )
60
Closed loop transfer function of a unity feedback system is 2
. Open loop
s +s+4
system is :
Answer
D. Type 0 and Order 2
61
An SCR with a latching current of 50mA is used to control an inductive RL load. If the
load inductance is increased, the minimum duration of the gate pulse necessary to
ensure turn on of the SCR:
Answer
B. Increases
62
The advantage of a half-controlled rectifier over a fully controller rectifier is that :
Answer
D. It has better power factor
63
The forward voltage drop of SCR during on-state :
Answer
A. Increases slightly with load current
64
The anode current through a conducting SCR is 10A. If its gate current is reduced to
half, the anode current will be :
Answer
D. 10A
65
For continuous conduction with a firing angle of alpha (α ) radian, in single phase full
converter, each pair of thyristor conducts for :
Answer
B. π
66
Forward break over voltage of a thyristor decreases with increase in :
Answer
C. Gate current
67
A DC motor with 100 A rated current is controlled by a two quadrant chopper fed from a
200V DC supply. The motor circuit has a resistance of 0.2 Ω and inductance of 0.2mH.
When operating at a particular speed, the motor develops a back emf of 100V. What is
the value of the duty cycle for rated motor current?
Answer
B. 0.6
68
Of the four characteristics given below, which is not a desirable property of differential
amplifier?
Answer
A. High output impedance
69
A single-phase half-bridge inverter is connected to a 400 V dc source which is feeding an
RL load. Determine the RMS output voltage :
Answer
C. 200 V
70
CMRR of an OP-AMP should be :
Answer
B. As large as possible
71
Specifications of three different ammeters are given in the table below. Which meter has
least error?
Ammeter Full scale value % accuracy of full scale
M1 20A ± 0.10
M2 10A ± 0.20
M3 1A ± 1.00
Answer
C. M3
72
Torque-weight ratio of an instrument indicates :
Answer
B. Sensitivity
73
Assertion (A) : Permanent magnet moving coil type of indicating instruments are
always critically damped.
Reason (R) : A critically damped system directly moves to its steady state without
oscillation.
Answer
D. is the correct explanation of (A)
(B) Both (A) and (R) are true and (R) is not the correct explanation of (A)
(C) (A) is true but (R) is false
(D) (A) is false but (R) is true
74
A 100 μ A ammeter has an internal resistance of 100 Ω . For extending the range to
measure 500 μ A, the shunt resistance required is :
Answer
A. 25 Ω
75
A water boiler is switched ON to the ac supply of 230 V at 50 Hz. The frequency of
instantaneous power consumed by the boiler is :
Answer
D. 100 Hz
76
Identify the correct statement :
(i) TOD meter is designed to track the demand, time and energy consumption of
electricity
(ii) TOD metering involves dividing the day into tariff slots with higher rates at peak
load periods and low tariff rates at off peak hours.
Answer
C. both (i) and (ii) are true
77
Power consumed by a balanced 3-phase, 3-wire load is measured by two wattmeter
method. One wattmeter reads twice the other. Then load impedance angle in radians is :
π π
Answer
A. ra
78
An energy meter having meter constant of 1200 rev/kWh makes 20 revolutions in
30 seconds for a constant load. Then the load is :
Answer
C. 2000 W
79
In an oscilloscope screen, linear sweep is applied at the :
Answer
C. horizontal axis
80
A CRO screen has ten divisions on the horizontal axis. If a voltage signal
5 sin (314t + 45 ) is measured with a time base setting of 5 ms/div. the number of cycles of
the signal displayed on the screen :
Answer
B. 2.5 cycles
81
A unit impulse response of a linear time invariant system is a unit step function u (t ) .
The response of the system to an excitation function e − at u (t ), a > 0 for a time t > 0 will
be :
1
Answer
A. (1 − e −at )
82
The condition for a system to be BIBO stable for an impulse response h(n) = aⁿu(n) is:
Answer
B. |a| < 1
83
Which of the following is true for the system represented by y (n) = x ( −n ) ?
Answer
A. Linear
84
A system characterized by the equation y (t ) = ax (t ) + b is :
Answer
D. Non Linear
148/2025 19 A
85
A LTI system has an impulse response e 2 t for t > 0 . If initial conditions are 0 and input
is e 3 t , the output for t > 0 is :
Answer
B. e3 t − e2 t
86
An aliasing effect is caused in s system when :
Answer
C. Sampling frequency less to the message signal
87
Which of the following statements is correct for a system with gain margin close to unity
or a phase margin close to zero?
Answer
C. The system is highly oscillators
88
How many minimum number of samples are required to exactly describe the signal x(t) = 10 cos(6πt) + 4 sin(8πt)?
Answer
C. 8 samples per second
89
The impulse response of a continuous time LTI system is H (t ) = 2 e −2 t − e 100 u (t ) .
Then the system is:
Answer
B. Causal but not stable
90
The impulse response of a LTI system is represented as h (n ) = u (n) , then the step
4
response of the system is :
1 −1 1 −1
n n
Answer
D. 4 +
4 4 5 4
91
The working principle of LVDT is based on :
Answer
B. Electromagnetic induction
92
A LVDT has a stroke length of ± 200 mm and provides a sensitivity of 50 mV per
millimetre of displacement. If the output voltage of the LVDT is 2.0 V, determine the
position of the core from its central (null) position :
Answer
C. 40 mm
93
The instrument which is used to measure the specific gravity of battery electrolyte?
Answer
B. Hydrometer
94
Determine the charging current for a 50 Ah battery when charged at a 0.2 C rate :
Answer
A. 10 A
95
A 24 V,60 Ah lead-acid battery is charged at a constant current of 0.1 C. If the battery is
fully discharged, estimate how long it will take to fully charge it, assuming the charging
efficiency is 80%?
Answer
A. 12.5 Hours
96
The main objective of earthing in an electrical installation is :
Answer
D. To ensure safety against electric shock
97
What is the minimum required length of pipe in a pipe electrode earthing system?
Answer
D. 2.5 m
98
The maximum permissible total connected load for a 15 A power sub-circuit in a
domestic installation, as per standard wiring practices, is :
Answer
D. 3000 W
99
In plate earthing, the copper plate used should not be less than :
Answer
A. 60 cm × 60 cm × 3.15 mm
100
A room of dimensions 5 m × 5 m is illuminated using four 100 W lamps. Each lamp has a
luminous efficiency of 80 lumens/W and the coefficient of utilization is 0.65. Calculate
the average illumination in the room :
Answer
C. 832 lux
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