One of my friend told me about that the power factor of a 3 phase balanced system is 1. I don't get any book reference for it. Is it true?

If true, then why? If I assume the 3 loads are equal 4+j3 ohm in the balanced system. Then there should a phase difference between the current and voltages. Can anyone plz explain?

  • \$\begingroup\$ Your friend is wrong. If the load has a reactive component, the power factor can't be 1. Remember that it is the cosine of the phase angle between voltage and current. I'll leave a proper answer to someone that is more familiar with power than myself. \$\endgroup\$
    – Matt Young
    Nov 19, 2014 at 14:12
  • \$\begingroup\$ yes, it should be.. :) \$\endgroup\$ Nov 19, 2014 at 14:13
  • \$\begingroup\$ @Matt Young. The power factor isnt the phase angle between voltage and current. It is a combination of harmonic distortion and the phase angle between voltage and current. For purely passive loads the Displacement Power Factor (DPF) equals power factor PF) \$\endgroup\$
    – user16222
    Nov 19, 2014 at 14:25

2 Answers 2


Power factor is equal to

$$ \frac{P}{S} $$

and it's not determined by if the 3 phase are balanced or not, any reactive power on any phase may result a non-unity power factor, whether 3-phase or single phase system, whether the system balanced or not.


You can imbalance a 3 phase system with purely resistive loads. Imagine taking 10kW on one phase and 20kW on the other two. This is called imbalanced because the phase currents don't have equal magnitude. Yet, the power factor of each phase is unity.

A balanced system (balanced reactive loads) will not have a power factor of unity.


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