30 Most Important Electrical Engineering Questions For SSC JE
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Preparing for the SSC JE exam in Electrical Engineering requires a strong grasp of core concepts and repeated practice with important questions. To help aspirants, we have compiled 30 Most Important Electrical Engineering Questions For SSC JE, covering both Machines and Power Systems. This carefully curated list includes frequently repeated questions from SSC JE, RRB JE, and state AE exams, ensuring you focus on the high-yield topics.
Each question comes with a detailed explanation and the correct answer, making it ideal for MCQs practice for students who want to strengthen their problem-solving skills and improve exam readiness. Whether itβs understanding crawling in induction motors, the function of damper windings, or transformer load sharing, this resource will give you the confidence to tackle high-frequency questions effectively.
Check: Important Topics for SSC JE
30 Most Important Electrical Engineering Questions For SSC JE
Practice these 30 Most Important Electrical Engineering Questions For SSC JE, with detailed answers and explanations provided to boost your MCQ-solving skills and exam readiness.
1. Why does crawling occur in an induction motor?
Answer:
Crawling occurs due to slot harmonics or space harmonics in an induction motor. The phenomenon is often observed at NSY7 frequency.
Right Answer: Harmonics developed in the motor.
2. Function of damper winding in the alternator.
Answer/Explanation:
-
In motors, it provides starting torque and prevents hunting.
-
In generators, it dampens oscillations in salient pole machines.
Check: SSC JE Electrical Subject Wise Weightage
3. Load sharing of transformers operating in parallel depends on:
Answer/Explanation:
Load sharing is based on per unit impedance. Two transformers can operate in parallel if they have the same phase sequence, polarity, and compatible per-unit impedance.
Right Answer: Per unit impedance.
4. Why is the core of a transformer laminated?
Answer/Explanation:
Lamination reduces eddy current losses in the core.
Right Answer: To reduce eddy current losses.
5. Purpose of open-circuit test in a transformer
Answer/Explanation:
-
Performed on the low-voltage side.
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Determines iron losses, shunt branch parameters, and turn ratio.
Right Answer: Iron losses.
6. Function of oil in a transformer
Answer/Explanation:
-
Provides cooling.
-
Provides insulation.
Right Answer: Insulation and cooling.
7. What happens if the field of a DC shunt motor opens while running?
Answer/Explanation:
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Field current β 0, flux β 0
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Speed β dangerously high (approaches infinity)
Right Answer: Field current zero, motor attains high speed.
8. How can the direction of rotation of a DC shunt motor be reversed?
Answer:
Reverse either the armature terminals or field terminals, not both.
9. DC series motor should always be started with load because:
Answer:
At no load, flux is very low β speed approaches infinity β dangerous.
10. DC series motor is best suitable for:
Answer:
Driving loads requiring high starting torque (e.g., traction).
11. Why is the armature of a DC machine laminated?
Answer:
To reduce eddy current losses.
12. Generator efficiency is maximum when:
Answer/Explanation:
-
Back EMF = half of supply voltage
-
Variable losses = constant losses
Right Answer: Constant losses = variable losses
13. DC generator brushes are made of:
Answer:
Carbon (or copper graphite in high-rating machines) for self-lubrication and polishing.
14. Rating of a fuse wire is expressed in:
Answer:
Amperes, as it protects against short-circuit currents.
15. Fuse wire diameter relation (fusing factor)
Answer:
Diameter power relation: d^3/2.
16. Function of protective relay in switchgear
Answer/Explanation:
-
Detects fault
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Closes the trip circuit when the quantity exceeds the preset value
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Works with the circuit breaker to isolate the faulty section
17. Most economical area of a conductor is based on:
Answer/Explanation:
Kelvinβs Law: balances material cost and power loss.
18. Purpose of sheets in a cable
Answer/Explanation:
Sheets made of lead and steel protect the cable from moisture and alkalies.
19. Basis of insulator design for modern EHV lines
Answer/Explanation:
Designed to withstand switching overvoltage.
20. Pin-type insulators are used for:
Answer:
Lines up to 33 kV.
21. Suspension-type insulators are used for:
Answer:
Lines up to 765 kV.
22. Strain-type insulators are used for:
Answer:
Locations with mechanical deviation or line crossings.
23. Disc-type insulators are used for:
Answer:
Lines of 132 kV.
24. Line insulators are made of:
Answer/Explanation:
Porcelain and mica, for excellent mechanical and electrical properties.
25. Function of steel wire in ACSR conductor
Answer/Explanation:
Increases mechanical strength of the conductor.
26. Ferranti effect occurs when:
Answer/Explanation:
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Long transmission line at light load/no load
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Receiving-end voltage exceeds sending-end voltage
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Power factor slightly leading
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Corona effect dominates
27. Demand factor of a power plant
Answer/Explanation:
Ratio of maximum demand to total installed capacity (as per video, detailed calculation left for comments).
28. Transformers operating in parallel must have:
Answer:
-
Same phase sequence
-
Same polarity
-
Compatible per-unit impedance
29. Open-circuit test gives:
Answer: The open-circuit test gives:
-
Iron losses
-
Shunt branch parameters
-
Turn ratio
30. Function of oil in a transformer
Answer:
-
Cooling, and
-
Insulation
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