Green Home Ideas: Power Factor and Saving Electricity

Understanding electricity and how it works in your home is important for almost everybody. At least you need to have some little understanding how it works. If you want to refer further to any engineers or an electrical engineering company, it will be much easier for you.

One of the ways to save electricity is to understand the relationship between power factor and how electricity behaves in your home’s wiring. Low power factor is too expensive for you and inefficient. You have to pay electric bill for nothing or for something that you don’t use.

Low power factor also creates problems to your electric provider and for that reason they regularly charge additional fee. This article describes power factor and how you can reduce your electric bills.

Improve Power Factor Means Less Electric Bills

 Power Factor = (Real Power)/(Apparent Power)


The perfect value for Power Factor is 1 or Power Factor = 1. The benefits when you improve the  power factor are as follows:

Your electric bill will be smaller than before. Lower power factor requires more electric utility generation and electric transmission capacity. This is because of the reactive power that exists in the system. Electric provider usually charge a penalty fee to clients with low power factor.

Low power factor also will cause power losses in your electrical distribution. When power losses increase, you can experience voltage drops. This can cause overheating and failure of electrical motors, machines as well as inductive equipment.

power factor animationWhat is Power Factor?

The easiest way to explain how power factor relates to your home electrical circuit is by visualizing how a horse pulling a mechanical work such as a boat or a car in a straight line. You can imagine as the horse is puling a car at an angle α to the direction of travel. In the diagram, the horse is pulling the car with a rope with an angle α to the direction of travel.

Working power or the Real Power is the actual power that moves the car to the direction of travel when the horse pull the car. However the effort of the horse is the total power or the apparent power.

Since the position of the horse when pulling the car is at an angle α, thus not all of the horse’s effort can be used to move the car to the direction of travel. Just part of the horse effort is used. You can use this equation to calculate the working power (or real power) in relationship with the apparent power.

Real Power = cos α (Apparent Power)

Apparent Power=(Real Power)/cos⁡α

power factor angleVariation of Angle α

If you have a calculator, you can manipulate values of α and calculate what is happening when the angle α is changing. For example, the table below shows you what happen when the angle α becomes less and less from angle of 60° to 10°. As you an see the value of cos α is increased to near 1.

ΑCos α
ΑCos α

When the angle α is reduced, the Apparent Power is also reduced to be near to Real Power. In this case the horse can work with higher efficiency when the wasted effort or non working power (or Reactive Power) is reduced approaching zero.

Even without those equations above you can imagine that the horse work less if the car is being pulled to near to the center rather than sideways. Power factor is defined as the following equation.

Power Factor=(Real Power)/(Apparent Power)

The perfect value of power factor is 1. This can happen when the Apparent Power is reduced to be the same as the Real Power.

Apparent Power usually more than the value of Real Power where the value Power Factor is always less than 1. In real world Power Factor of 1 is impossible to achieve. You can maximize the value of power factor to near 1 to increase efficiency of your home electrical wring and pay less electric bill.

Examples of Power Factor

Given the values of Real Power= 100kW and the Apparent Power = 142 kVA

Power Factor = 100kW/142kVA

= 0.70 or 70%

We can use those values to calculate the value of Reactive Power with Pytaghoras triangle.

Reactive Power= √((Apparent Power)2 – (Real Power)2)

= 100 kVAR

How to Avoid Low Power Factor

Electromagnetic components or inductive loads are the main cause of low power factor. Electric and electronic equipment such as electric motors, high-intensity discharge lighting and air conditioners are some of the equipment that produce electromagnetic field in their circuitry.

Inductive loads require current to create a magnetic field then the magnetic field shall produces work accordingly. Resistive loads are totally different than the inductive loads. Resistive loads consume power in kW and produce heats in their circuitry.

In inductive loads, the apparent power is the total power that is being used in the circuitry.

Apparent Power= √(〖Reactive Power〗2 +〖Real Power〗2)

Electric power is wasted through unuse or non working power which is called Reactive Power measured in kVAR. Reactive Power is caused by the magnetizing current that exists in any electromagnetic circuitry to run a device.

One of the techniques to increase the value of power factor is called power factor correction. Electrical engineers and electrical engineering company can do the correction for your property if you face this problem. We will discussed in other article the basic theory how electrical engineers do power factor correction and solve your problem.

Once power factor correction has been done, you can see your electric bills reduce immediately. Thanks for reading.

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