2. Example
Two single-phase motors are connected in
parallel across a 240 V, 50 Hz supply.
One motor draws 12 A at a power factor of 0.4
and the other draws 16 A at a power factor of
0.8

3. 12 A Motor
pf1 = cos Φ1 = 0.4
Φ1 = cos -1(0.4)
Therefore Φ1 = 66 ⁰

4. 16 A Motor
pf 2 = cos Φ2 = 0.8
Φ2 = cos -1(0.8)
Therefore Φ 2 = 37 ⁰

6. 49º
27 A

7. pf = cos Φ
∴ pf = cos 49⁰
pf = 0.66
Answer: Power factor is 0.66.

8. Refer to Electrical Trade
Principles p. 210 by
Hampson & Hanssen