AC power & power factor worksheet with answers

Free printable AC power & power factor worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
230 Vload17.5 kW, 6 kvarI = ?

A single-phase load connected to a 230 V supply takes 17.5 kW and 6 kvar. Find the current I drawn from the supply.

V = 230 VP = 17.5 kWQ = 6 kvar
I = A
2.Easy
PQ = ?S = V·Iφ

A single-phase load draws 16 A (rms) from a 120 V (rms) supply at a power factor of 0.95 lagging. Find the reactive power Q it takes.

V = 120 VI = 16 Apf = cos φ = 0.95
Q = var
3.Medium
P = 40 kWQSφ

A single-phase motor takes 40 kW at a power factor of 0.8 lagging from a 230 V supply. Find the line current I.

P = 40 kWpf = 0.8V = 230 V
I = A
4.Medium
P = 33 kWQ = ?Sφ

A single-phase motor takes 33 kW at a power factor of 0.75 lagging from a 230 V supply. Find the reactive power Q it draws.

P = 33 kWpf = 0.75V = 230 V
Q = kvar
5.Hard
230 V50 Hzload22 kW, 0.7C330 µFI = ?

A single-phase load takes 22 kW at a power factor of 0.7 lagging from a 230 V, 50 Hz supply. A 330 µF capacitor is connected in parallel with the load. Find the new line current I.

P = 22 kWpf1 = 0.7V = 230 Vf = 50 HzC = 330 µF
I = A
6.Hard
400 V50 Hzload8 kW, 0.8C47 µFI = ?

A single-phase load takes 8 kW at a power factor of 0.8 lagging from a 400 V, 50 Hz supply. A 47 µF capacitor is connected in parallel with the load. Find the new line current I.

P = 8 kWpf1 = 0.8V = 400 Vf = 50 HzC = 47 µF
I = A

Answer key

  1. 1. I = 80.43 A
  2. 2. Q = 599.5 var
  3. 3. I = 217.4 A
  4. 4. Q = 29.1 kvar
  5. 5. I = 120.8 A
  6. 6. I = 21.97 A

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