MES Departmental • 2025 • Paper-II
A major constraint for substation location is proximity to:
A)
River crossings
B)
Industrial zones
C)
Airports & defense establishments
D)
Agricultural lands
Option C is correct: Airports & defense establishments.
MES Departmental • 2025 • Paper-II
The function of a protective relay is to:
A)
Detect the fault and initiate the operation of the circuit breaker
B)
Absorb the fault current
C)
Step down the voltage for metering
D)
Provide an alarm only during a fault
Option A is correct: Detect the fault and initiate the operation of the circuit breaker.
MES Departmental • 2025 • Paper-II
In a power triangle, what is the relationship between active power (P), reactive power (Q), and apparent power (S)?
A)
P + Q = S
B)
P² + Q² = S²
C)
P = Q + S
D)
S² + Q² = P
Option B is correct: P² + Q² = S².
MES Departmental • 2025 • Paper-II
What is the primary instrument used specifically for measuring earth resistance?
A)
Ammeter
B)
Voltmeter
C)
Earth Tester (or Ground Resistance Tester)
D)
Frequency Meter
Option C is correct: Earth Tester (or Ground Resistance Tester).
MES Departmental • 2025 • Paper-II
What is a common maintenance task for Power Transformers in outdoor substations?
A)
Changing the tank paint every year.
B)
Checking oil level, colour, and moisture content, plus oil testing.
C)
Removing all bushings for cleaning.
D)
Reducing the load to below 50%.
Option B is correct: Checking oil level, colour, and moisture content, plus oil testing..
MES Departmental • 2025 • Paper-II
What is the benefit of proper grounding for lightning protection?
A)
It attracts more lightning strikes.
B)
It stores the lightning energy.
C)
It provides a low-resistance path for surge current to dissipate into the earth safely.
D)
It creates a magnetic field to deflect strikes
Option C is correct: It provides a low-resistance path for surge current to dissipate into the earth safely..
MES Departmental • 2025 • Paper-II
In a series connection of resistors, what happens to the current across each resistor?
A)
Increases
B)
Decreases
C)
Remains the same
D)
Initially increases and then decreases
Option C is correct: Remains the same.
MES Departmental • 2025 • Paper-II
How does earthing contribute to system stability?
A)
By introducing resistance in the neutral
B)
By providing a stable reference point (zero potential) for the system
C)
By increasing system impedance
D)
By creating an isolated neutral
Option B is correct: By providing a stable reference point (zero potential) for the system.
MES Departmental • 2025 • Paper-II
Why are off-load tap changers operated only when the transformer is de-energized?
A)
To prevent sparking
B)
To avoid damaging the mechanism
C)
To ensure safety and proper contact engagement
D)
They don’t require power
Option C is correct: To ensure safety and proper contact engagement.
MES Departmental • 2025 • Paper-II
Where should lightning arresters be installed for optimal transformer protection?
A)
Inside the transformer tank
B)
At the termination point of overhead lines leading to the transformer
C)
On the ground below the transformer
D)
Only on the low-voltage side
Option B is correct: At the termination point of overhead lines leading to the transformer.
MES Departmental • 2025 • Paper-II
A freewheeling diode in a phase-controlled rectifier is used to:
A)
Improve the power factor
B)
Provide a path for inductive load current
C)
Reduce the reverse breakdown voltage requirement
D)
Increase the output voltage
Option B is correct: Provide a path for inductive load current.
MES Departmental • 2025 • Paper-II
What is the primary purpose of switchgear in an electrical power system?
A)
To generate electricity
B)
To step up or step down voltage levels
C)
To protect, control, and isolate electrical equipment
D)
To measure power consumption
Option C is correct: To protect, control, and isolate electrical equipment.
MES Departmental • 2025 • Paper-II
The algebraic sum of voltages (potential differences) around any closed path in a network is equal to:
A)
Infinity
B)
1
C)
0
D)
Negative polarity
Option C is correct: 0.
MES Departmental • 2025 • Paper-II
Which of the following power semiconductor devices has the highest switching speed?
A)
BJT
B)
IGBT
C)
Power MOSFET
D)
SCR
Option C is correct: Power MOSFET.
MES Departmental • 2025 • Paper-II
Which relay protects the transformer from external short circuits and overloads?
A)
Differential Relay
B)
Buchholz Relay
C)
Overcurrent Relay
D)
Thermal Relay
Option C is correct: Overcurrent Relay.
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.
MES Departmental • 2025 • Engineering Paper-II
What is a circuit diagram also known as?
A)
A blueprint
B)
An elementary diagram
C)
A blueprint of a building
D)
A schematic diagram
Option D is correct: A schematic diagram.
MES Departmental • 2025 • Engineering Paper-II
Which of the following process is used in winter air conditioning?
A)
Cooling and Dehumidification
B)
Heating and Humidification
C)
Dehumidification
D)
Humidification
Option B is correct: Heating and Humidification.
MES Departmental • 2025 • Engineering Paper-II
Which of the following devices detects and interrupts ground faults?
A)
Fuse
B)
ELCB
C)
MCB
D)
Isolator
Option B is correct: ELCB.
MES Departmental • 2025 • Engineering Paper-II
What is the purpose of using a diffuser in a lighting fixture?
A)
To increase the luminous flux
B)
To improve the color rendering index (CRI)
C)
To reduce glare and reflections
D)
To increase the energy efficiency of the fixture
Option C is correct: To reduce glare and reflections.
MES Departmental • 2025 • Engineering Paper-II
Which of the following process is used in summer air conditioning?
A)
Heating and Humidification
B)
Cooling and Dehumidification
C)
Humidification
D)
Dehumidification
Option B is correct: Cooling and Dehumidification.
MES Departmental • 2025 • Engineering Paper-II
What is Refrigeration?
A)
Refrigeration is the process of removing heat from a substance and cooling it to a temperature or below the actual temperature
B)
Refrigeration is the process of adding heat from a substance and cooling it to a Temperature
C)
Refrigeration is used to increase the level of humidity in the air by adding heat
D)
None of the mentioned
Option A is correct: Refrigeration is the process of removing heat from a substance and cooling it to a temperature or below the actual temperature.
MES Departmental • 2025 • Engineering Paper-II
Which of the following instruments is NOT used for linear measurement?
A)
Calipers
B)
Micrometers
C)
Height gauge
D)
Pressure gauge
Option D is correct: Pressure gauge.
MES Departmental • 2025 • Engineering Paper-II
Which of the following is a critical aspect of D G set maintenance?
A)
Regular oil changes.
B)
Monitoring voltage.
C)
Checking battery levels.
D)
All of the above.
Option D is correct: All of the above..
MES Departmental • 2025 • Engineering Paper-II
What is free Maintenance Earthing and advantages over conventional Earthing ?
