Each question in this quiz is timed.

Which of the following formulas can calculate power in an ac circuit?

P = V x I x pf

P = V + I

P = V x I

P = V/R

What is the power produced by a 400v three phase system which delivers 25A at a power factor of 0.85

14.72kW

6.23kW

10kW

14kW

What is the power produced by a 400v three phase system which delivers 10A at a power factor of 0.7

4849.6W

4.7kW

5000W

4700W

The power factor of an installation can be calculated from

Cosθ = Z/X

Cosθ = X/Z

Cosθ = KVA/KW

Cosθ = KW/KVA

The power factor of an inductive load can be improved by?

Connecting a inductor across the load

Connecting a resistor in parallel with the load

Connecting a capacitor in series with the load

Connecting a capacitor across the load (parallel)

The power factor of a load consisting of inductance and resistance can be calculated from

Cosθ = True Power/Apparent Power

Cosθ = Apparent Power/ Reactive Power

Cosθ = Reactive Power/True Power

Cosθ = Apparent Power/True Power

The formula required to calculate the total power of a single phase inductive load supplied by an a.c. supply is

P = IV sinθ

P = IV

P = IV tanθ

P = IV cosθ

If the W is 100 and the VA is 120 what would the power factor be

0.75

0.2

0.85

0.83

If the kW is 200 and the KVA is 400 what would the power factor be?

0.6

0.7

0.8

0.5

A single phase circuit draws a current of 21.7A from a 230 V circuit at a power factor of 0.4 What is the current drawn if the power factor is corrected to 0.85

18.4 A

23.4 A

10.21 A

21.7 A

A circuit dissipates 2000 W at a power factor of 0.5 when connected to a 230 V ac supply. The current drawn from the supply is

17.8 A

17.39 A

4.3 A

8.7 A

A circuit dissipates 1.5 kW at a power factor of 0.75 when connected to a 230V ac supply. The current drawn from the supply is

7.8 A

9.2 A

6.5 A

A three phase system gives the following readings kVA =30 kW= 45 What is the power factor for the system

0.67

unity

1.5

A three phase system gives the following readings kW= 400 kVA = 500 What is the power factor for the system

1.25

What unit is reactive power measured in

kA

KVAr

kW

KVA

What unit is apparent power measured in

What unit is true power measured in

Which component would cause the current and voltage to behave as above

resistor

rectifier

capacitor

Inductor