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 VloadP = 1530 W9.5 A

A voltmeter, an ammeter and a wattmeter connected to a single-phase inductive load read 230 V, 9.5 A and 1530 W. Find the reactive power Q taken by the load.

V = 230 VI = 9.5 AP = 1530 W
Q = var
2.Easy
230 VloadP = 322 W2 A

A voltmeter, an ammeter and a wattmeter connected to a single-phase inductive load read 230 V, 2 A and 322 W. Find the reactive power Q taken by the load.

V = 230 VI = 2 AP = 322 W
Q = var
3.Medium
240 VZ15 + j20 ΩI

A load with impedance Z = 15 + j20 Ω is connected to a 240 V (rms) single-phase supply. Find the apparent power S.

V = 240 VZ = 15 + j20 Ω
S = VA
4.Medium
P = 11 kWQ = ?Sφ

A single-phase motor takes 11 kW at a power factor of 0.9 lagging from a 240 V supply. Find the reactive power Q it draws.

P = 11 kWpf = 0.9V = 240 V
Q = kvar
5.Hard
240 V60 Hzload18 kW, 0.75C330 µFI = ?

A single-phase load takes 18 kW at a power factor of 0.75 lagging from a 240 V, 60 Hz supply. A 330 µF capacitor is connected in parallel with the load. Find the new line current I.

P = 18 kWpf1 = 0.75V = 240 Vf = 60 HzC = 330 µF
I = A
6.Hard
400 V60 Hzload25 kW, 0.65C220 µFI = ?

A single-phase load takes 25 kW at a power factor of 0.65 lagging from a 400 V, 60 Hz supply. A 220 µF capacitor is connected in parallel with the load. Find the new line current I.

P = 25 kWpf1 = 0.65V = 400 Vf = 60 HzC = 220 µF
I = A

Answer key

  1. 1. Q = 1560 var
  2. 2. Q = 328.5 var
  3. 3. S = 2304 VA
  4. 4. Q = 5.328 kvar
  5. 5. I = 83.32 A
  6. 6. I = 74.15 A

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