Electrical Substation MCQ

November 12, 2025

581

Electrical substations are the heart of power distribution systems acting as vital nodes that step up (or) step down voltage levels for efficient transmission and safe distribution of electricity. Understanding their layout, components and protection mechanisms is essential for engineers, operators and technicians in the power sector.

This Electrical Substation 25 MCQ set is designed to test and strengthen your knowledge of substation equipment, protection systems, maintenance procedures and operational safety. Each question focuses on real-world concepts used in 110/33 kV and 33/11 kV substations including:
• Transformer working principles and testing
• Circuit breakers (Oil, SF₆, and Vacuum types)
• Current Transformers (CT) and Voltage Transformers (VT) functions
• Busbar configurations and isolator operations
• Lightning arresters, grounding systems, and protection relays
• Load management, safety permits and maintenance protocols

Electrical Substation MCQ

These objective questions are ideal for ITI, Diploma, AE/JE and Lineman Exam preparation (or) anyone working in power transmission and distribution sectors.

1 / 25

1. Equipment not installed in substation

A. Shunt reactor

B. Voltage transformer

C. Exciter

D. Series capacitor

2 / 25

2. Instrument used to measure insulation resistance

A. Kelvin’s bridge

B. Wheatstone bridge

C. Megger

D. Both (b) & (c)

3 / 25

3. Test performed to verify equipment readiness for energizing

A. Maintenance test

B. Type test

C. Reliability test

D. Commissioning test

4 / 25

4. Load shedding is carried out at

A. Distribution level

B. Transmission

C. Both

D. Depends on load

5 / 25

5. Step potential and touch potential are associated with

A. High voltage distribution

B. Voltage rise

C. Substation earthing

D. Communication system

6 / 25

6. Lightning arrester in 11/0.433 kV substation is installed on

A. LT side

B. HT side

C. Both

D. None

7 / 25

7. Relays can respond to changes in

A. Resistance, reactance, impedance

B. Voltage and current

C. Light intensity and temperature

D. All of the above

8 / 25

8. Arcing contacts of circuit breaker are made of

A. Copper-tungsten alloy

B. Porcelain

C. Copper

D. Aluminium

9 / 25

9. A thermal protection switch can protect against

A. Short-circuit

B. Temperature

C. Overload

D. Over-voltage

10 / 25

10. Color of silica gel in dry state is

A. White

B. Yellow

C. Pink

D. Blue

11 / 25

11. Buchholz relay is connected between

A. Conservator and oil tank

B. Pressure release valve and conservator

C. Oil tank and pressure valve

D. Explosion vent pipe and oil tank

12 / 25

12. Buchholz relay is provided on transformer to

A. Indicate minor fault

B. Indicate and isolate during internal major faults

C. Isolate during minor faults

D. Indicate major fault only

13 / 25

13. Which of the following does not change in a transformer?

A. Current

B. Voltage

C. Frequency

D. All

14 / 25

14. A transformer works on

A. Lenz’s law

B. Faraday’s law of electromagnetic induction

C. Gauss law

D. Biot-Savart law

15 / 25

15. Stone is provided in the substation to

A. Drain transformer oil if leakage

B. Avoid weed growth

C. Provide insulation

D. All of the above

16 / 25

16. In GIS substation, insulating medium is

A. Air

B. CO₂

C. Methane

D. SF₆

17 / 25

17. Hazards occur due to

A. Inadequate wiring

B. Exposed electrical ports

C. Wires with bad insulation

D. All of the above

18 / 25

18. Basic fundamentals of safety are

A. Accidents result from unsafe conditions/work

B. Cooperation of coworkers

C. Incomplete knowledge invites accidents

D. All of the above

19 / 25

19. Delta connection is preferred for ______ due to unbalanced current problems.

A. Short distance power transmission

B. Long distance power transmission

C. Both (a) and (b)

D. None of the above

20 / 25

20. Unduly long feeders lead to

A. High voltage and high losses

B. Low voltage and high technical losses

C. Low voltage and low losses

D. High voltage and low losses

21 / 25

21. In rural areas, which type of feeder system is used?

A. Radial system

B. Interconnected

C. Ring main

D. None

22 / 25

22. Star connection is preferred for ______ because it has a neutral point.

A. Short distance power transmission

B. Long distance power transmission

C. Both (a) and (b)

D. None of the above

23 / 25

23. Load Factor is defined as the ratio of

A. The average power to the maximum demand

B. The maximum demand to the average power

C. The connected load to maximum demand

D. The maximum demand to connected load

24 / 25

24. Primary distribution network connects the transmission system with secondary distribution network at a voltage level of

A. 66 kV

B. 415 V

C. 240 V

D. 33 kV or 11 kV

25 / 25

25. Voltage level to the end consumer is

A. 260/460 V

B. 110/240 V

C. 310/350 V

D. 240/415 V

Your score is

The average score is 64%

Electrical Substation MCQ

These objective questions are ideal for ITI, Diploma, AE/JE and Lineman Exam preparation (or) anyone working in power transmission and distribution sectors.

Menu List

Popular Categories