Power factor is the measure of evaluating how effectively the incoming electrical power is used in an electrical system. It is defined as the ratio of Active Power (kW) to Apparent Power (kVA).
In this article, We are going to discuss: what is power factor and why it is important in electrical system. Also what is the physical significance of power factor in power system. But before that, we have to understand the basic concepts of Electrical power and brief analysis of Active, Reactive and Apparent Power, so that it will be easy to understand the concepts of Power Factor.
Because the concepts of power factor are derived from Electrical power concepts. We have already discussed the concepts of Electrical power (Active, Reactive and Apparent Power) in our previous Article. So please follow my previous Article about Electrical Power titled as: Electrical Power- Active, Reactive and Apparent Power.
Well, now coming to our main topic which has mainly two parts. First, what is power factor? And other is why it is important?
What is Power Factor?
If the power factor is high, then we can say that more effectively the electric power is being used in an electrical system.
A load with power factor of 1 (maximum) results most efficient loading of the system.
But if the power factor is poor (say less than 0.8), then the effectiveness of usage of electrical power reduces, that results in higher losses in the supply system and a higher bill for consumers.
Power factor represents the fraction of the total power that is used to do the useful work. The other fraction of electrical power is stored in the form of magnetic energy in an inductor or electrostatic energy in the capacitor.
A high power factor benefits consumers and Power Company both. Whereas Low power factor indicates poor utilization of Electrical Power and it penalizes consumers.
In Electrical Engineering, the concept of power factor is only discussed in AC circuits. Whereas there are no power factor concepts in case of DC circuit due to its Zero frequency. Its value becomes 1 (unity) for DC Circuit. But in the case of AC circuit, the absolute value of Power Factor always lies between the ranges 0 to 1 (0 < Cosθ < 1).
Generally a high and leading PF is good and preferred in the Electrical system. Ideally the minimum and maximum value for PF becomes 0 and 1 respectively. But in Practically, it is difficult to achieve unity (1) power factor.
A low power factor is generally the result of inductive loads such as Induction motors, Power transformers, ballast in the luminaire, a welding set and an induction furnace.
Power factor value near to 0.9 is considered as satisfactory. It is calculated with the help of Power Triangle.
Power Factor Definition
- Power factor is defined as the ratio of Active Power (kW) to Apparent Power (kVA).
P.F = Active Power(kW) / Apparent Power (kVA)
- Also Power factor is the cosine of the phase angle difference between voltage and current pharos.
P.F = CosθWhere θ is the angle between V and I.
- One more way of defining the Power Factor is, It is the ratio between resistance (R) and Total Impedance (Z) of AC circuit.
PF = Resistance/Impedance = R/Z
Why Power Factor is Important?
It means that only 80% of the incoming current does useful work in the circuit and 20% is used by reactive elements in the circuit.
In other words, we can say that 80% of the power is useful power which is also known as real or True Power, and the rest 20% of power is Reactive Power used by reactive element in the circuit.
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Due to poor PF, the consumer pays fewer amounts to Power company. It will be considered a loss for power company as well as no benefit for the consumer.
So power company penalizes the consumer for maintaining the poor PF. So higher PF is beneficial for both power utilities as well as consumers.
Problem with Low Power Factor
It means the power distribution system is operating less efficiently because not all the current is performing useful work in the circuit. For example, a 50 kW load with a power factor of unity (Reactive power = 0 kVAR) could be supplied by a transformer rated for 50 kVA.
However, if the power factor is reduced to 0.7 (70 %), then the transformer must also supply additional power for the reactive load.
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Nice article
ReplyDeleteHow to improve power factor
ReplyDeleteHi Freewish4u..
ReplyDeleteThanks for your queries..
Here is very good article about the improvement of power factor..
Please go through it..
https://www.electrical-technology.com/2019/05/power-factor-correction.html
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ReplyDeleteWhat happens, when power factor will be zero
ReplyDelete