Part4— Electrical Engineering Interview Questions & Answers (MCQs)
Question 1. Why do we need symmetrical components?
a. To calculate balanced faults
b. To calculate unbalanced faults
c. To calculate bolted faults
Correct Answer: b. To calculate unbalanced faults (✓)
Explanation: No Explanation.
Question 2. Which conditions should be verified in order to find out whether a set of phasors is symmetrical or not?
a. Equal magnitude
b. Equal phase angle
c. Both
Correct Answer: c. Both (✓)
Explanation: No Explanation.
Question 3. Which sequence should be followed by phasors in order to assure symmetry?
a. ABC
b. ACB
c. Both
Correct Answer: c. Both (✓)
Explanation: No Explanation.
Question 4. What is the difference between ABC system and ACB system?
a. Phase sequence
b. Phasor magnitudes
c. Phase angles
Correct Answer: a. Phase sequence (✓)
Explanation: No Explanation.
Question 5. How many symmetrical components are generated from a single set of unbalanced phasors?
a. 1
b. 3 (✓)
c. 6
Correct Answer: b. 3 (✓)
Explanation: No Explanation.
Question 6. What is the sequence of symmetrical components when the unbalanced phasors have ACB phase sequence?
a. Positive= ACB; Negative=ACB; Zero=none
b. Positive= ACB; Negative=ABC; Zero=none
c. Positive= ABC; Negative=ACB; Zero=none
Correct Answer: b. Positive= ACB; Negative=ABC; Zero=none (✓)
Explanation: No Explanation.
Question 7. What would be the resultant when we add all three symmetrical components respectively?
a. A balanced set of phasors
b. The original unbalanced set of phasors
c. A different set of phasors
Correct Answer: b. The original unbalanced set of phasors (✓)
Explanation: No Explanation.
Question 8. How many symmetrical components are generated from a single set of balanced phasors?
a. 1
b. 3
c. 6
Correct Answer: a. 1 (✓)
Explanation: No Explanation.
Question 9. Why do we need ‘a’ operator?
a. To define all phasors in terms of one
b. It is present in the formula
c. No particular reason
Correct Answer: a. To define all phasors in terms of one (✓)
Explanation: No Explanation.
Question 10. Is the ‘a’ operator sequence specific? (Different for ABC and ACB phase sequence?)
a. Yes, in all cases
b. Yes, in some cases
c. No
Correct Answer: a. Yes, in all cases (✓)
Explanation: No Explanation.
Question 11. What is the benefit of using ‘a’ operator?
a. Decreases number of variables
b. Reduces equation complexity
c. Both
Correct Answer: c. Both (✓)
Explanation: No Explanation.
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Question 12. How can we find symmetrical components from System phasors?
a. Iₛᵧₘₘₑₜᵣᵢ꜀ₐₗ = A * Iₛᵧₛₜₑₘ
b. Iₛᵧₘₘₑₜᵣᵢ꜀ₐₗ = A-1 * Iₛᵧₛₜₑₘ
c. Iₛᵧₘₘₑₜᵣᵢ꜀ₐₗ = Iₛᵧₛₜₑₘ / A
Correct Answer: b. Iₛᵧₘₘₑₜᵣᵢ꜀ₐₗ = A-1 * Iₛᵧₛₜₑₘ (✓)
Explanation: No Explanation.
