(A) RMS value
(B) Average value
(C) instantaneous value
(D) peak value
Ans .- (C)
2. Which of the following statements is false for a 3∅ AC voltage produced in a 3∅ alternator?
(A) Difference 120 ° between phase R-Y
(B) Difference 120 degrees between phase Y-B
(C) Difference 120 degrees between phase R-B
(D) None of the above
Ans .- (C)
3. What is the difference between the line and phase voltage in the star connection?
(A) 0 degrees
(B) 30 degrees
(C) 45 degrees
(D) 120 degrees
Ans.-(B)
4. If a phase breaks in the star connection, what will be the output voltage?
(A) 25%
(B) 50%
(C) 58%
(D) 75%
Ans.-(B)
5. What is the relation between phase voltage and line voltage in star connection?
(A) 𝑉𝑝ℎ = 1.732VL
(B) 𝑉𝑝ℎ = VL
(C) 𝑉𝑝ℎ = VL / 1.732
(D) 𝑉𝑝ℎ = VL / 3
Ans .- (C)
6. If the phase voltage in a star connection is 240, what will be the line voltage?
(A) 240V
(B) 240 × 1.732
(C) 240 / 1.732
(D) 440V
Ans. (B)
7. What will be the line voltage in a delta connection if the phase connection of the same circuit has a phase voltage VL?
(A) VL
(B) 1.732 VL
(C) VL / 1.732
(D) 2VL
Ans. -(A)
8. Can use Star connection?
(A) lighting load
(B) power load
(C) lighting and power load
(D) None
Ans .- (C)
9. What will be the total power consumption in a 3∅ star connection balanced load?
(A) VP IP COS∅
(B) 1.732 VL IL COS∅
(C) 3 VL IL COS∅
(D) Both A and B
Ans. -(B)
10. Using the two watt meter method?
(A) Only in star combination
(B) only in delta combination
(C) star and delta combination
(D) None
Ans .- (C)
11. Can the method be used for balanced load?
(A) One wattmeter method and two wattmeter method
(B) Two wattmeter method and three wattmeter method
(C) One wattmeter method and three wattmeter method
(D) One wattmeter, two wattmeter and three wattmeter method
Ans .- (D)
12. What will be the reactive power of the circuit in the delta connection?
(A) 1.732 VL IL
(B) 1.732 VL IL cos∅
(C) 1.732 VL IL sin∅
(D) VL IL cos∅
Ans. -(A)
13. In two wattmeter method, if the wattmeter reads W1 and W2 respectively, what will be the idle power?
(A) 1.732 (W1 + W2)
(B) 1.732 (W1 - W2)
(C) (W1 - W2)
(D) (W1 + W2)
Ans. -(B)
14. What will happen in open delta circuit?
(A) 1/2
(B) 1 / 1.414
(C) 1/3
(D) 1 / 1.732
Ans .- (D)
15. If the star has circuit power P, what will happen in the delta?
(A) P
(B) 3P
(C) 𝑃 / 3
(D) 1.732P
Ans. -(B)
16. What will happen if a neutral wire breaks in a 3∅ star connection?
(A) Voltage of low load phase will increase
(B) The overloaded phase will have lower voltage
(C) Nothing will happen
(D) Both A and B
Ans .- (D)
17. In the delta connection, how are the line and phase current related?
(A) 𝐼phase = 1.732 × 𝐼Line
(B) 𝐼phase = 3 × 𝐼Line
(C) 𝐼phase = 𝐼Line / 1.732
(D) 𝐼phase = ILine / 3
Ans .- (C)
18. n The power of phase circuit can be measured by minimizing?
(A) up to n wattmeter
(B) up to 2n wattmeter
(C) (n-1) to wattmeter
(D) (n + 1) to wattmeter
Ans .- (C)
19. If the power factor of the circuit is 0.5 lag in the two wattmeter method, is it true?
(A) W1> W2
(B) W1 = W2
(C) W2 = 0
(D) W2> W1
Ans .- (C)
20. If the power factor is unit when measuring 3 kala power by 2 wattage method, what will be the reading of wattmeter W1 and W2?
(A) W1> W2
(B) W1 <W2
(C) W1 = W2
(D) W1 OR W2 = 0
Ans .- (C)