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Past Questions — 2026
Which of the following protective relays is most sensitive to ground faults in a power system?
A)
Overcurrent relay
B)
Under-voltage relay
C)
Thermal overload relay
D)
Earth fault relay
An earth fault relay is specifically designed to detect ground (earth) faults and is therefore the most sensitive relay for this purpose. It operates on small residual or zero-sequence currents that appear when insulation fails and current flows to earth.
Why others are incorrect: Overcurrent relay responds to excessive current in general but is not as sensitive specifically to ground faults. Under-voltage relay operates when voltage drops below a set value, not primarily for fault-to-ground detection. Thermal overload relay protects against overheating due to overload, mainly in motors and equipment, not ground faults.
The detention period of a septic tank is generally:
A)
2–4 hours
B)
5 days
C)
24–48 hours
D)
10 days
The detention period of a septic tank is the time sewage is retained in the tank for sedimentation and anaerobic digestion. In general design practice, it is about 24–48 hours.
Why others are incorrect:
- (a) 2–4 hours: too short for effective settling and digestion.
- (b) 5 days: much longer than the usual septic tank detention period.
- (d) 10 days: far too long for normal septic tank design.
In an electrical rotating machine, the primary mechanical necessity of providing an air gap between stator and rotor is to:
A)
Reduce copper loss
B)
Improve cooling
C)
Enable rotation
D)
Improve power factor
The air gap is the small physical clearance between the stator and rotor in a rotating electrical machine. Its primary mechanical purpose is to provide space so the rotor can rotate freely without rubbing against the stator. The other options are not the main mechanical reason: copper loss is an electrical loss, cooling is a secondary benefit in some designs, and power factor is an electrical performance issue, not the main purpose of the air gap.
For starting of an induction motor in a pump house, different starters are employed depending on starting current and system conditions. Which starter applies full line voltage directly to the motor?
A)
Star-Delta starter
B)
Auto-transformer starter
C)
Soft starter
D)
Direct On Line (DOL) starter
A Direct On Line (DOL) starter connects the induction motor directly to the supply, so it applies full line voltage at starting. This gives the highest starting current, so it is used only for small motors or where the supply system can tolerate the inrush current.
Why others are incorrect:
- Star-Delta starter: starts the motor at reduced voltage in star connection, then switches to delta.
- Auto-transformer starter: applies reduced voltage through a tapped autotransformer during starting.
- Soft starter: gradually increases the voltage using power electronics to limit starting current and mechanical stress.
The minimum residual chlorine recommended in drinking water is:
A)
0.01 mg/L
B)
1.5 mg/L
C)
0.2 mg/L
D)
5 mg/L
The recommended minimum residual chlorine in drinking water is about 0.2 mg/L to ensure disinfection safety in the distribution system. Option (a) 0.01 mg/L is too low to provide adequate protection, while (b) 1.5 mg/L and (d) 5 mg/L are excessively high for normal drinking water and may cause taste and health issues.
Segregation of solid waste means:
A)
Burning waste
B)
Separating waste at source
C)
Dumping waste
D)
Compacting waste
Segregation of solid waste means separating different types of waste, such as wet, dry, biodegradable, and non-biodegradable, at the point where it is generated. This is done to make collection, recycling, and disposal easier and more effective. Burning, dumping, and compacting are waste disposal or handling methods, not segregation.
In a pump house, an induction motor driving a water pump repeatedly trips on the thermal overload relay under normal operating conditions. Which of the following should be checked first during troubleshooting?
A)
Motor current
B)
Starter type
C)
Motor bearing
D)
Motor winding temperature
When an induction motor repeatedly trips on a thermal overload relay, the first thing to check is the motor current. The overload relay trips based on excess current drawn by the motor, so measuring current helps confirm whether the motor is actually overloaded, suffering from phase imbalance, low voltage, mechanical load issues, or other electrical faults. Starter type is not the immediate cause of thermal overload tripping, motor bearing problems are checked later if mechanical loading is suspected, and motor winding temperature is an effect rather than the first troubleshooting check.
Inadequate earthing in a pump house may result in:
A)
Low discharge
B)
High friction loss
C)
Pipe leakage
D)
Electric Shock
Inadequate earthing means faulty or insufficient connection of electrical equipment to the ground. In a pump house, this can cause leakage current to remain on metal parts of pumps, motors, or panels, creating a serious risk of electric shock. The other options are unrelated to earthing: low discharge and high friction loss are hydraulic issues, and pipe leakage is a plumbing/mechanical issue.
Which item is measured in cubic metres?
A)
Earthwork excavation
B)
Brick masonry
C)
Plastering
D)
Painting
Earthwork excavation is commonly measured in cubic metres (m³) because it involves volume. Brick masonry is also generally measured in cubic metres, but in standard single-answer MCQs of this type, earthwork excavation is the expected answer as the most typical volumetric item. Plastering and painting are measured in square metres (m²) because they involve surface area.
Analysis of rates is carried out to determine:
A)
Cost of construction
B)
Water quality
C)
Soil strength
D)
Population
Analysis of rates is used in estimation and costing to find the unit cost of an item of work by considering materials, labour, equipment, overheads, and profit. Therefore, its purpose is to determine the cost of construction. Water quality, soil strength, and population are unrelated to rate analysis.
Biodegradable waste includes:
A)
Plastic
B)
Glass
C)
Food waste
D)
Metal
Biodegradable waste is waste that can be broken down naturally by microorganisms, such as bacteria and fungi. Food waste decomposes easily, so it is biodegradable. Plastic, glass, and metal do not decompose naturally in this way, so they are non-biodegradable.
Hand Pump Tube Wells are mainly used for:
A)
Irrigation
B)
Hydropower
C)
Navigation
D)
Rural water supply
Hand pump tube wells are shallow or medium-depth wells fitted with a manual pump, mainly intended to supply drinking water in villages and small rural settlements where piped water systems may not be available. इसलिए the correct answer is rural water supply.
Why others are incorrect:
(a) Irrigation: Tube wells for irrigation usually require higher discharge and are generally power-operated, not hand pumps.
(b) Hydropower: Hand pump tube wells have no role in power generation.
(c) Navigation: They are unrelated to transport or waterways.
Power factor of an AC circuit is defined as the ratio of:
A)
Active power to apparent power
B)
Reactive power to apparent power
C)
Apparent power to active power
D)
Reactive power to active power
Option A is correct: Active power to apparent power.
For a given real power and voltage, if power factor decreases, the line current:
A)
Decreases
B)
Increases
C)
Remains same
D)
Becomes zero
For a single-phase AC load, real power P = VI cosφ, where cosφ is the power factor. For a given real power P and voltage V, line current I = P / (V × power factor). So if power factor decreases, the denominator becomes smaller and the current must increase. Hence, the correct answer is (b) Increases.
Which type of failure occurs when a footing rests on very soft clay?
A)
General shear failure
B)
Local shear failure
C)
Punching shear failure
D)
Tensile failure
Option C is correct: Punching shear failure.
The minimum thickness of RCC water tank wall is generally provided to:
A)
Improve appearance
B)
Reduce dead load
C)
Ensure water tightness and durability
D)
Reduce cement content
Option C is correct: Ensure water tightness and durability.
The process of removing entrapped air from fresh concrete is called:
A)
Mixing
B)
Transportation
C)
Compaction
D)
Finishing
Option C is correct: Compaction.
Hand Pump Tube Wells are mainly used for:
A)
Irrigation
B)
Hydropower
C)
Navigation
D)
Rural water supply
Option D is correct: Rural water supply.
The main purpose of a service reservoir is:
A)
Water treatment
B)
Storage and distribution
C)
Pumping
D)
Filtration
Option B is correct: Storage and distribution.
The structure used to collect water from a river is called:
A)
Reservoir
B)
Aqueduct
C)
Intake
D)
Weir
Option C is correct: Intake.
Which factor increases domestic water consumption?
A)
Low standard of living
B)
Dry climate only
C)
Improved sanitation facilities
D)
Small population
Option C is correct: Improved sanitation facilities.
Sullage water does NOT include:
A)
Bathroom waste water
B)
Kitchen waste water
C)
Wash basin discharge
D)
Human excreta
Option D is correct: Human excreta.
Water having pH less than 7 is considered:
A)
Neutral
B)
Alkaline
C)
Hard
D)
Acidic
Option D is correct: Acidic.
Rainwater harvesting is useful for:
A)
Increasing runoff
B)
Flooding roads
C)
Groundwater recharge and water conservation
D)
Soil erosion
Option C is correct: Groundwater recharge and water conservation.
Which reinforcement is mainly provided in a cantilever beam?
A)
Bottom reinforcement
B)
Side reinforcement
C)
Spiral reinforcement
D)
Top reinforcement
Option D is correct: Top reinforcement.