25 Most important Power factor MCQ - E Tips BD

## Friday, February 9, 2018

25 Most important Power factor MCQ. ২৫টি Very Important পাওয়ার ফ্যাক্টর এর MCQ.

Answer লেখা ইমেজে ক্লিক করলেই, উত্তর পাওয়া যাবে
1) Power factor is the ratio of __ and apparent power.
A. Reactive power
C. Active power
D. Maximum demand>

2) The power factor of an AC circuit is given by—
A. cos φ
B. sin φ
C. tan φ
D. all of above

3) In a R-L series circuit, power factor—
A. lag
C. zero
D. unity

4) In a R-C series circuit, power factor—
A. lag
C. zero
D. unity

5) 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

6) The power factor of ordinary bulb is—
A. unity
B. zero
C. lagging

7) What is maximum value of power factor?
A. 0.5
B. 1
C. 1.5
D. 0.95

8) In an ac circuit i sin φ is called the __ component of the current
A. Watless>
B. Reactive
D. All the above

9) If the power factor is unity, its reactive power is —
A. zero
B. equal to aparant power
C. equal to real power
D. none of above

10) Which among the following happens in a low power factor?
A. Large kVA rating of the equipment.
B. Greater conductor size.
C. Reduced handling capacity of the system.
D. All of the above.

11) Lower power factor is usually not due to
A. Discharge lamp.
B. Arc lamps.
C. Incandescent lamps.
D. Induction furnace

12) For a consumer what is the most economical power factor?
A. 0.25 – 0.5 lagging
C. 0.85 – 0.95 lagging.

13) 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

14) Commonly Power factor improve by——
A. Resistor bank
B. Capacitor Bank
C. Transformer Bank
D. Inductor bank

15) The primary reason for the low power factor is due to the installation of
A. Induction motors
B. DC motors
C. Synchronous motors.
D. Commutator motors

16) For which among the following consumers is penalty imposed for low power factor in Bangladesh?
A. Residential and commercial consumers.
B. Industrial consumers.
C. Agricultural consumers.
D. All of the above.

17) A transformer has negative voltage regulation when its load power factor is–
A. lagging
C. unity
D. zero

18) In resonance condition (XL = XC) power factro–
A. unity
B. zero
D. lagging

19) Power factor can be improved by connecting which among these?
A. Static capacitors.
C. Synchronous condensers.
D. All of above

20) 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

21) What is the advantage of the static capacitors?
A. Low losses.
B. Easy installation.
C. Lower maintenance.
D. All of the above.

22) Phase advancers are used for which among the following machines?
A. Transformers
B. Synchronous machines.
C. Induction motors.
D. None of above

23) The most suitable location for the power factor improvement device is
A. Near the electrical appliance which is responsible for the poor power factor.
B. At the receiving end in case of transmission lines.
C. Both (A) and (B).
D. At the sending end.

24) 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

25) 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

Most important Power factor MCQ, ই টিপস বিডি, পাওয়ার ফ্যক্টর