Power factor
It is the magnitude of the difference between the voltage and current waveform. This difference between voltage and current waveform denoted by ф.
Power in A.C circuit is given by
P = V*I*cosф
in the above equation, cosф is called power factor.
Resistive Load -
In a resistive load, there is no phase difference between the voltage and the current wave because resistance only opposes current but it doesn't oppose a change in voltage or current. hence, ф will be zero. which represents a unity power factor.
Inductive Load -
Inductor has a property to oppose the change in current. when the power supply is given to the inductive circuit or inductive load it will start opposing the change in current. so current lags behind the voltage.which will create a magnitude of the difference ф between voltage and current wave. which represents a lagging power factor.The value of ф will depend on how much load or circuit is inductive.
Capacitive Load -
Capacitor has a property to oppose the change in Voltage. when the power supply is given to the Capacitive circuit or Capacitive load it will start opposing the change in Voltage. so voltage lags behind the current.which will create a magnitude of the difference ф between voltage and current wave. which represents a leading power factor. The value of ф will depend on how much load or circuit is capacitive.
Another Explanation-
Power factor is a measure of how efficiently electricity is used in the electrical system or we can say Power factor is a measure of electrical system efficiency. It is defined as the ratio of useful power (Real power) to Total power (Apparent power).
Real power (kW) is the power that actually gives power to the equipment and does useful, productive work. It is also known as Active power or Actual power or Useful power.
Reactive power (kVAR) is the necessary power by some devices (such as transformers, motors, and relays) that produce a magnetic field to enable the actual work.
Apparent Power (kVA) is the vector sum of Real Power (kW) and Reactive Power (kVAR) and is the total power to be supplied through Power Supply Company, which is necessary to produce the appropriate amount of actual power for the load.
Let's take a simple example of a cold drink to better understand this term. Let's say you ordered a glass of cold drink. The liquid part of your cold drink which you can drink represents the Real Power (kW). Unfortunately, a little bit of foam comes along with your cold drink which you cannot drink represented by Reactive Power (kVAR). The total content of your glass which is the sum of Real Power (KW) (the liquid portion which your cold drink) and Reactive Power (KVAR)(foam which you cannot drink) is represented by Apparent Power(KVA)(cold drink + foam).
Power Factor = Real Power (Kw) (Cold drink)/Apparent Power (KVA) (Cold drink + Foam)
- The more foam you have (the percentage of kVAR is more), the ratio of kW (cold drink) to kVA (cold drink + foam) will be less. So, poor power factor.— lagging power factor
- If you have a small portion of foam (the percentage of kVAR is less) then the ratio of kW (cold drink) to kVA (cold drink + foam) will be high. So, better power factor.— leading power factor
- As foam approaches to zero (the percentage of kVAR is zero) then the ratio of kW (cold drink) to kVA (cold drink + foam) will be unity. So, unity power factor.— unity power factor
