Electrical Engg (EEE) — MCQ Practice Questions & Answers

Question 1

What is the primary function of a transformer in a power system?

Accepted Answer

Correct answer: A. To convert voltage levels for efficient power transmission and distribution — Transformers step up voltage for transmission (reducing current and losses) and step down voltage for distribution to consumers.

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B. To increase the frequency of AC supply

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C. To convert AC to DC power

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D. To reduce power losses completely

Question 2

The per unit system in power system analysis is based on:

Accepted Answer

Correct answer: B. Base values chosen arbitrarily for the system — Per unit system uses selected base values for voltage, power, and impedance to normalize calculations across different system parts.

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A. Actual values of voltage, current, and impedance

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C. International standard fixed values

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D. Percentage of maximum load

Question 3

Which of the following represents the power factor in a three-phase AC circuit?

Accepted Answer

Correct answer: A. cos(φ) where φ is the angle between voltage and current — Power factor is defined as cos(φ), the cosine of the phase angle between voltage and current waveforms.

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B. sin(φ) where φ is the phase angle

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C. tan(φ) where φ is the impedance angle

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D. The ratio of reactive power to apparent power

Question 4

In the Indian power system (2024-25), what is the nominal frequency?

Accepted Answer

Correct answer: C. 50 Hz with ±2% frequency band — Indian power system operates at 50 Hz nominal frequency with allowed frequency variation of ±2% (49-51 Hz) as per grid code standards.

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A. 50 Hz with ±3% frequency band

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B. 60 Hz with ±5% frequency band

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D. 60 Hz with ±2% frequency band

Question 5

What is the primary role of a circuit breaker in a power system?

Accepted Answer

Correct answer: A. To continuously conduct normal operating current and interrupt fault current automatically — Circuit breakers carry normal load current and automatically open when fault current exceeds preset relay settings, isolating the faulty section.

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B. To step up voltage for transmission

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C. To measure power consumption

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D. To regulate frequency

Question 6

What is the primary purpose of shunt capacitors in power systems?

Accepted Answer

Correct answer: B. To improve voltage profile and reduce reactive power demand — Shunt capacitors supply reactive power locally, improving voltage profile and reducing the burden on generators and transmission lines to supply reactive power.

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A. To reduce transmission line losses only

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C. To increase current capacity of lines

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D. To prevent harmonic distortion exclusively

Question 7

Which type of fault in power system requires the fastest clearance to maintain stability?

Accepted Answer

Correct answer: B. Three-phase fault — Three-phase faults cause maximum current and power imbalance, requiring fastest clearance (typically 100-150 ms) to maintain transient stability.

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A. Single line-to-ground fault

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C. Line-to-line fault

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D. Double line-to-ground fault

Question 8

In Indian grid operation, what is the nominal frequency specification?

Accepted Answer

Correct answer: C. 50.00 ± 0.10 Hz — As per Indian Grid Code 2024 and POSOCO standards, the nominal frequency is 50 Hz with a normal operating range of ±0.10 Hz (49.90-50.10 Hz).

Answer

A. 49.50 ± 0.20 Hz

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B. 50.00 ± 0.05 Hz

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D. 49.80 ± 0.15 Hz

Electrical Engg (EEE) - MCQ Practice Questions