1 Power Factor Principles

 Impact of Low Power Factor

Low PF causes an inefficient utilization of electric power.  In other words, you are using more current to do the same amount of work when the PF is low.  If we take the basic equation for single phase power:

                  Power (watts) = Volts x Amps x PF

and solve for current we get:

                  Amps = Power (watts)

                        Volts x PF

Voltage is assumed to remain constant in this example.  If power is to be maintained, current must go up when PF decreases.  This increased requirement for current is where the electrical inefficiency occurs.

Lets look at it graphically with two power triangles:

In the example on the left the PF was measured at 70 percent. If our goal is to produce 100 kilowatts of real power we find that 141 KVA are required.  The power triangle on the right shows a PF of 95 percent.  In this instance only 105 KVA are required to produce the same amount of real power.  Since voltage remains constant, the current must increase by 35 percent to deliver the desired power when the PF is at 70 percent.