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 Vload24.5 kW, 18 kvarI = ?

A single-phase load connected to a 230 V supply takes 24.5 kW and 18 kvar. Find the current I drawn from the supply.

V = 230 VP = 24.5 kWQ = 18 kvar
I = A
2.Easy
240 VloadP = 3072 W16 A

A voltmeter, an ammeter and a wattmeter connected to a single-phase inductive load read 240 V, 16 A and 3072 W. Find the reactive power Q taken by the load.

V = 240 VI = 16 AP = 3072 W
Q = var
3.Medium
230 VR + jXP = 1380 W8 A

An inductive load takes 8 A and 1380 W from a 230 V (rms) single-phase supply. Model it as a resistance R in series with a reactance X. Find R.

V = 230 VI = 8 AP = 1380 W
R = Ω
4.Medium
230 V16 kW, 0.623 kW, 0.7I = ?

Two loads are connected in parallel to a 230 V single-phase supply: a 6 kW load at a power factor of 0.6 lagging and a 3 kW load at a power factor of 0.7 lagging. Find the total current I drawn from the supply.

V = 230 VP1 = 6 kW, pf1 = 0.6 laggingP2 = 3 kW, pf2 = 0.7 lagging
I = A
5.Hard
P = 40 kWQ1​S1​φ1​QC​

A single-phase load takes 40 kW at a power factor of 0.65 lagging from a 240 V, 50 Hz supply. A capacitor connected in parallel raises the power factor to 0.95. Find the new line current Inew.

P = 40 kWpf1 = 0.65pf2 = 0.95V = 240 Vf = 50 Hz
Inew = A
6.Hard
P = 10 kWQ1​S1​φ1​QC​

A single-phase load takes 10 kW at a power factor of 0.6 lagging from a 230 V, 60 Hz supply. A capacitor connected in parallel raises the power factor to 0.98. Find the reactive power QC the capacitor must supply.

P = 10 kWpf1 = 0.6pf2 = 0.98V = 230 Vf = 60 Hz
QC = kvar

Answer key

  1. 1. I = 132.2 A
  2. 2. Q = 2304 var
  3. 3. R = 21.56 Ω
  4. 4. I = 62 A
  5. 5. Inew = 175.4 A
  6. 6. QC = 11.3 kvar

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