Electrical Engineering

What are the disadvantages of low power factor?



User Avatar
Wiki User

When you have a Power Factor less than 1 the voltage and current waveforms in an AC circuit are out of phase. Therefore at any given instant of time the work being done or energy being expended is calculated by multiplying the current x voltage. This reduces the wattage at any instant of time. When the Power Factor is one the instantaneous multiplication of the current and voltage would yield the maximum value with the waveforms in phase. This is much easier to see with a picture, but imagine a square wave for both voltage and current. Say for half the cycle the current is 2A and Voltage 3V and for the second half of the cycle both are zero. So for 1/2 the cycle the watts generated are 6 watts and zero for the second half of the cycle. Now if the two waveforms were 180 degrees out of phase the voltage would be zero when the current was 2A and the current would be zero when the voltage was 3V for zero watts. In this case the Power Factor would be zero.