The cosine of the angle between the voltage and current in an A.C. circuit is known as power factor. If the circuit is inductive, the current lags behind the voltage and the power factor is referred to as lagging, whereas in a capacitive circuit, current leads the voltage and the power factor is said to be leading.
Power Factor Sensing Unit
The primary of a 440/5V step down transformer is connected across the lines. The voltage is proportional to the load current which is dropped across the resistance connected in series with the line. These activating signals are given to operational amplifier which converts it to square waves. It is further converted into pulses using transistor as a switch. These waveforms are given to the input terminals of the AND gate. The output of the AND gate is proportional to the power factor angle.
