Practical values of power factor
From Electrical Installation Guide
The calculations for the three-phase example above are as follows:
Pn = delivered shaft power = 51 kW
P = active power consumed
S = apparent power
So that, on referring to diagram Figure L5 or using a pocket calculator, the value of tan φ corresponding to a cos φ of 0.86 is found to be 0.59
Q = P tan φ = 56 x 0.59 = 33 kvar
Alternatively:
Fig. L5: Calculation power diagram
Average power factor values for the most commonly-used equipment and appliances
(see Fig. L6)
| Equipment and appliances | cos φ | tan φ | ||
| loaded at |
0% 25% 50% 75% 100% |
0.17 0.55 0.73 0.80 0.85 |
5.80 1.52 0.94 0.75 0.62 |
|
1.0 |
0 | ||
|
1.0 |
0 | ||
|
0.8 to 0.9 |
0.75 to 0.48 | ||
| 0.8 | 0.75 | ||
Fig. L6: Values of cos φ and tan φ for commonly-used equipment
