MES Departmental • 2025 • Paper-II
What is the standard minimum ground clearance required for Low Tension (LT) and medium voltage lines crossing a street?
A)
4.5 meters
B)
5.8 meters
C)
6.1 meters
D)
7.2 meters
Option B is correct: 5.8 meters.
MES Departmental • 2025 • Paper-II
What is the fundamental operational need for incorporating power substations into an electrical grid network?
A)
To convert AC electrical power completely into DC power for domestic use.
B)
To store excess bulk power during off-peak operational hours.
C)
To shift, regulate, switch, and transform electrical parameters safely between generation and consumption.
D)
To increase the frequency of the power system for better long-distance transmission.
Option C is correct: To shift, regulate, switch, and transform electrical parameters safely between generation and consumption..
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
What critical maintenance activity prevents “contact welding” or local hotspots in outdoor isolator blades?
A)
Applying a thin layer of conductive, oxidation-inhibiting petroleum jelly or grease to the contacts.
B)
Painting the contact surfaces with anti-corrosive zinc paint.
C)
Increasing the spring tension until the blade cannot be moved manually.
D)
Washing the contacts thoroughly with high-pressure water while energized.
Option A is correct: Applying a thin layer of conductive, oxidation-inhibiting petroleum jelly or grease to the contacts..
MES Departmental • 2025 • Paper-II
100 cm length of a wire of cross-section A has a resistance of R ohms. The resistance of the wire of same material having length of 200 cm and cross-sectional area 2A will be:
A)
4R
B)
2R
C)
R
D)
R/4
Option C is correct: R.
MES Departmental • 2025 • Paper-II
Why is AC used instead of DC for measuring ground soil resistivity and earth resistance?
A)
AC travels faster in soil
B)
DC voltage cannot sink into deep earth
C)
AC prevents soil electrolytic polarization and stray DC bias interference
D)
AC instruments consume less battery power
Option C is correct: AC prevents soil electrolytic polarization and stray DC bias interference.
MES Departmental • 2025 • Paper-II
What is the most common cause of premature failure of pin insulators on 11kV lines?
A)
Accumulation of dust, salt, or industrial pollution causing leakage currents and flashovers
B)
Over-voltage in the system
C)
High ambient temperature in the summer
D)
High frequency AC transmission
Option A is correct: Accumulation of dust, salt, or industrial pollution causing leakage currents and flashovers.
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
In AC electrical networks, what is the key reason capacitors are used for power factor correction?
A)
to consume active power from the grid
B)
to provide reactive power to compensate for inductive loads
C)
to increase the frequency of the network
D)
to convert Alternating Current to Direct Current
Option B is correct: to provide reactive power to compensate for inductive loads.
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
From an economic and practical standpoint, what is the ideal location for a distribution substation?
A)
Far away from residential areas to avoid electromagnetic fields.
B)
Exactly at the geographical center of the city.
C)
At the load center.
D)
Right next to the primary generating station.
Option C is correct: At the load center..
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
If a 6-pole alternator is driven by a prime mover at 1000RPM, what is the frequency of the generated EMF?
A)
60Hz
B)
25Hz
C)
50Hz
D)
100Hz
Option C is correct: 50Hz.
MES Departmental • 2025 • Paper-II
Kirchhoff’s voltage law deals with:
A)
conservation of energy
B)
conservation of charge
C)
conservation of momentum
D)
conservation of angular momentum
Option A is correct: conservation of energy.
MES Departmental • 2025 • Paper-II
Which of the following best defines the relationship between horsepower and energy?
A)
1hp = 746Joules
B)
Energy is independent of horsepower
C)
1hp applied for 1 second equals 746 Joules of energy
D)
1hp = 746 Joules/second2
Option C is correct: 1hp applied for 1 second equals 746 Joules of energy.
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
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
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
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
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 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
What is the primary purpose of a Current Transformer (CT) in a substation?
A)
To step down voltage for energy meters.
B)
To step down current to a safe, measurable value (e.g., 5A or 1A).
C)
To interrupt fault currents.
D)
To measure the insulation resistance.
Option B is correct: To step down current to a safe, measurable value (e.g., 5A or 1A)..
MES Departmental • 2025 • Paper-II
What is the fundamental principle of a Percentage Differential Relay used in transformers?
A)
Measures the voltage drop across the line.
B)
Senses changes in ambient temperature.
C)
Operates based on the frequency of the system
D)
Compares currents entering and leaving the protected zone.
Option D is correct: Compares currents entering and leaving the protected zone..
MES Departmental • 2025 • Paper-II
What is the unit of measurement for apparent power (S) in an electrical circuit?
A)
Watts (W)
B)
Volt-Amperes Reactive (VAR)
C)
Volt-Amperes (VA)
D)
Joules (J)
Option C is correct: Volt-Amperes (VA).
