MES Departmental • 2025 • Paper-II
Lenz’s law is a direct consequence of which fundamental physical law?
A)
The Law of Conservation of Mass
B)
The Law of Conservation of Energy
C)
Newton’s Third Law of Motion
D)
The Law of Conservation of Momentum
Option B is correct: The Law of Conservation of Energy.
MES Departmental • 2025 • Paper-II
What is the minimum standard vertical ground clearance required for 33 kV lines crossing over public roads?
A)
4.5 meters
B)
5.5 meters
C)
6.1 meters
D)
7.5 meters
Option C is correct: 6.1 meters.
MES Departmental • 2025 • Paper-II
What is the phase relationship between voltage and current in an R-C series AC circuit?
A)
Current lags the voltage by 90°.
B)
Current is in phase with voltage.
C)
Current leads the voltage by some angle φ between 0° and 90°.
D)
Voltage lags the current by 90°.
Option C is correct: Current leads the voltage by some angle φ between 0° and 90°..
MES Departmental • 2025 • Paper-II
How does an extremely low power factor affect the utility company?
A)
It decreases line losses.
B)
It increases I2R losses in the transmission and distribution lines.
C)
It generates power back into the grid.
D)
It improves system voltage stability.
Option B is correct: It increases I2R losses in the transmission and distribution lines..
MES Departmental • 2025 • Paper-II
The function of a conservator in a power transformer is to:
A)
protect against internal faults.
B)
cool the transformer oil.
C)
provide physical support to the core.
D)
take care of the expansion and contraction of transformer oil due to temperature variation.
Option D is correct: take care of the expansion and contraction of transformer oil due to temperature variation..
MES Departmental • 2025 • Paper-II
At higher operating voltages, which of the following additional losses becomes significant?
A)
Ohmic loss
B)
Leakage current loss
C)
Corona loss
D)
Eddy current loss
Option C is correct: Corona loss.
MES Departmental • 2025 • Paper-II
The specific resistance of a wire depends upon:
A)
its length
B)
its cross-sectional area
C)
its dimension
D)
its material
Option D is correct: its material.
MES Departmental • 2025 • Paper-II
Which type of distance relay is inherently directional and suited for long transmission lines?
A)
Impedance Relay
B)
Reactance Relay
C)
Mho Relay
D)
Plain Overcurrent Relay
Option C is correct: Mho Relay.
MES Departmental • 2025 • Paper-II
Is it dangerous to leave the secondary of a PT open-circuited?
A)
Yes, it will produce a high voltage and cause a flashover
B)
Yes, it will damage the primary winding
C)
No, a PT is a voltage source and is designed to operate with an open secondary (no load)
D)
No, it will only damage the core
Option C is correct: No, a PT is a voltage source and is designed to operate with an open secondary (no load).
MES Departmental • 2025 • Paper-II
If you increase the distance ‘a’ between the four test pins in a Wenner test setup, what practical change occurs?
A)
You measure soil resistivity at a deeper layer of the earth.
B)
The measured test voltage increases dramatically.
C)
You measure only the dry top soil layer.
D)
The meter automatically runs out of scale range.
Option A is correct: You measure soil resistivity at a deeper layer of the earth..
MES Departmental • 2025 • Paper-II
Which instrument is primarily used to measure the insulation resistance of a transformer?
A)
Megger
B)
Multimeter
C)
Voltmeter
D)
Ammeter
Option A is correct: Megger.
MES Departmental • 2025 • Paper-II
An essential condition for Ohm’s law to be applicable to a circuit is that:
A)
resistance must be at room temperature
B)
voltage should be only DC
C)
the current should flow in forward direction only
D)
the resistance must be uniform
Option D is correct: the resistance must be uniform.
MES Departmental • 2025 • Paper-II
In a standard symmetrical three-phase system, what is the phase difference between each phase voltage?
A)
90°
B)
180°
C)
120°
D)
360°
Option C is correct: 120°.
MES Departmental • 2025 • Paper-II
In a C&R panel, what is the standard secondary rating of a standard protection Current Transformer?
A)
500 A or 200 A
B)
5A or 1A
C)
110V or 220V
D)
50Hz or 60Hz
Option B is correct: 5A or 1A.
MES Departmental • 2025 • Paper-II
Which soil type consistently shows the lowest resistivity value, making it naturally ideal for electrical grounding?
A)
Dry sand
B)
Solid granite rock
C)
Clay or moist loamy soil
D)
Gravel beds
Option C is correct: Clay or moist loamy soil.
MES Departmental • 2025 • Paper-II
When two resistances are connected in parallel?
A)
the current through each must be the same.
B)
the voltage across each must be the same.
C)
their combined resistance value equals the sum of the individual values.
D)
each must have the same resistance value
Option B is correct: the voltage across each must be the same..
MES Departmental • 2025 • Paper-II
How is a power transformer protected from indirect lightning strikes or induced overvoltages?
A)
By using overhead ground wires (shield wires)
B)
By using overcurrent relays
C)
By using Differential protection
D)
By using conservator tanks
Option A is correct: By using overhead ground wires (shield wires).
MES Departmental • 2025 • Paper-II
Before energizing a power transformer for the first time during commissioning, what does a “BDV test” evaluate?
A)
Bulk Density Verification of the transformer core steel
B)
Balanced Direct Voltage of the control batteries
C)
Bushing Displacement Vector alignment
D)
Breakdown Voltage of the transformer insulating oil
Option D is correct: Breakdown Voltage of the transformer insulating oil.
MES Departmental • 2025 • Paper-II
How is an ammeter connected in a panel wiring circuit?
A)
In parallel with the load
B)
In series with the load
C)
Across the voltage transformer
D)
Through a high resistance multiplier
Option B is correct: In series with the load.
MES Departmental • 2025 • Paper-II
How does inductive reactance (XL) change if the frequency of the AC supply is increased?
A)
It decreases
B)
It increases
C)
It remains constant
D)
It drops to zero
Option B is correct: It increases.
MES Departmental • 2025 • Paper-II
What type of core transformer configuration is typically used in a grid distribution substation to provide a safe neutral wire for domestic consumer single-phase loads?
A)
Delta–Delta (Δ-Δ) connection.
B)
Star–Star (Y-Y) connection.
C)
Delta–Star (Δ-Y) step-down connection.
D)
Open-Delta (V-V) connection
Option C is correct: Delta–Star (Δ-Y) step-down connection..
MES Departmental • 2025 • Paper-II
Which of the following electrical network components utilizes Faraday’s law and Lenz’s law to function?
A)
Resistor
B)
Capacitor
C)
Inductor
D)
Diode
Option C is correct: Inductor.
MES Departmental • 2025 • Paper-II
What is the fundamental property of an inductor in alternating current (AC) networks?
A)
It dissipates electrical energy as heat.
B)
It causes the current to lead the voltage by 90 degrees.
C)
It produces an opposition to current flow known as inductive reactance.
D)
It consumes real power permanently.
Option C is correct: It produces an opposition to current flow known as inductive reactance..
MES Departmental • 2025 • Paper-II
If you double the voltage in a circuit while keeping the resistance constant, what happens to the power?
A)
It becomes half
B)
It stays the same
C)
It quadruples
D)
It doubles
Option C is correct: It quadruples.
MES Departmental • 2025 • Paper-II
Which protection scheme is generally recommended for Power transformers with a rating above 5MVA?
A)
Over-current protection
B)
Differential protection
C)
Restricted Earth Fault protection
D)
Buchholz relay
Option B is correct: Differential protection.
