Power Factor Optimization.  Put simply, some buyers of electricity buy 100% of the electricity they buy, but only use (as much as) 85% of that that they buy.  Reactive power charges can be made significantly smaller by the introduction of Power Factor Correction Capacitors which is a widely recognized method of reducing an electrical load and minimizing wasted energy, improving the efficiency of a plant and reducing the electricity bill. It is not always necessary to reach a power factor of 1. A cost effective solution can be achieved by increasing your power factor to greater than 0.95.  A full site survey is required to determine what type and size of system is required to meet your current and future needs.

 

What is Power Factor?

 

Power Factor is a measure of how efficiently electrical power is consumed. In the ideal world Power Factor would be unity (or 1). Unfortunately in the real world Power Factor is reduced by highly inductive loads to 0.7 or less. This induction is caused by equipment such as lightly loaded electric motors, luminaire transformers and fluorescent lighting ballasts and welding sets, etc.

 

What does it do to my electricity bill?

In a 3 phase supply, kW consumed is (VOLTS x AMPS x 1.73 x Power Factor) / 1000. The Electricity Company supply you VOLTS x AMPS and they have to supply extra to make up for the loss caused by poor Power Factor. When the power factor falls below a set figure, the electricity supply companies charge a premium on the kW being consumed, or, charge for the whole supply as kVA.  Often this premium charge can be thousands of dollars a year depending on the loads and uses. 

What causes Power Factor to change?

Inductive loads cause the AMPS to lag behind the VOLTS. The sine wave forms of VOLTS and AMPS are then "out of phase" with each other. The more out of phase they become then the lower the Power Factor. Power Factor is usually expressed as Cos Phi. (Ø)

In 3 phase power supplies the "power" can be measured as a triangle.  ACTIVE Power is the base line and is the real usable power measured in kW (kilowatts).  REACTIVE power is the vertical or that part of the supply which causes the inductive load. The reactive power is measured in kVAr (kilo volt-amperes reactive) and the APPARENT Power is the hypotenuse. This is the result of the other two components and is measured in kVA (kilo volt-amperes). 

What's a good example of these differences?

Consider a box car being pulled by a horse. If the horse could walk on the tracks in front of the box car easily, then the angle of the pull would be zero (Phi) Ø and the COSINE Ø=1.  This means that all the power of the horse would be pulling straight ahead with no tow angle.  Since the horse can't easily walk on the tracks, it would need to be off to the right or left at an angle.  As this angle increases, the horse has to work harder to pull the same box car.  When its easiest for the horse to walk, its also hardest for the horse to pull.  This is the best, simple explanation of power needed and power used. 

Why do I need Power factor correction?

Capacitive Power Factor correction (CPFC) is applied to electric circuits as a means of minimizing the inductive component of the current and thereby reducing the losses in the supply.  The introduction of Power Factor Correction capacitors is a widely recognized method of reducing an electrical load, thus minimizing wasted energy and improving the efficiency of a plant or machine and reducing the overall electricity bill.  It is not usually necessary to reach unity, i.e. Power Factor 1, since most supply companies are happy with a PF of 0.95 to 0.98.

Traditionally, we isolate the machine on a circuit and test that specific circuit using highly calibrated power factor tools for both before and after readings.  Before changes are made, the problems can be identified and solutions can be designed.  Then, after the changes are made, a second read is taken to ensure the changes or improvements have actually been realized. 

How does it work?

By introducing suitably sized switched capacitors into the circuit in front of the machine, current and voltage are stabilized and less out of phase with each other.  As the Power Factor is improved, the value of the difference becomes nearer to 1 thus minimizing wasted energy and improving the efficiency of an overall circuit or machine. 

How do I get started on this?

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• Document your current electrical load and usage
• Capture usage statistics after isolating the chosen circuits
• Analyze the data to describe the problem
• Recommend the improvements 
• Implement the improvements