Power Factor Objective Questions Answers

1. The power factor of ac circuit lies between

a) 0 and 1

b) -1 and 1

c) 0 and -1

d) None of the above

A

2. A Circuit of zero lagging power factor behaves as:

a)  An inductive circuit

b) A capacitive circuit

c) R-L circuit

d) R-C circuit

A

3. In order to improve the power factor which device should be connected to the power system:

a) Series capacitor

b) Shunt capacitor

c) Series inductor

d) Shunt inductor

B

4. In an induction motor when the air gap field between rotor and stator increases power factor of the machine:

a) Increases

b) Decreases

c) Does not have any effect

d) None of the above

B

5. The power factor of an ac circuit is equal to:

a) Cosine of the phase angle

b) Sine of the phase angle

c) Tangent of the phase angle

d) Cotangent of the phase angle

A

6. In an ac circuit i x sin (Phi) is called the __ component of the current:

a) Watless

b) Reactive

c) Quadrature

d) All the above

D

7. The heat developed in an electric iron is attributed to __ power

a) Apparent

b) Reactive

c) True

d) True and reactive

C

8. When the power factor in the transmission line is leading, which device is employed at substation to reduce the power factor:

a) CVT

b) Reactor

c) Synchronous condenser

d) None of the above

B

9. In a circuit low reactive power compared to true power indicates:

a) Low power factor

b) High power factor

c) Low efficiency

d) High efficiency

B

10. The rating of given on the name plate of a transformer indicates the:

a) True power which it can supply

b) Apparent power which it can supply

c) Apparent power which it draws from the supply mains

d) True power which it draws from the supply mains 

B