With the current rise in the cost of energy, increased facility efficiency is very desirable. By implementing Power Factor correction into the power distribution circuit, the Power Factor is improved thus minimising wasted energy, improving the efficiency of your plant/building, liberating more kW from the available supply and saving you money!
The purchase cost of the installation is usually recouped between one and two years of electricity savings.
Please note that Harmonics are not discussed in this document in the interest of simplicity. Power Factor
What is Power Factor ?
Simply put, it is a measure of efficiency!
3 What causes low Power Factor
So, now that we understand some basic terms, we are ready to learn about power factor: Power Factor (P.F.) is the ratio of Working Power to Apparent Power.
Looking at our beer mug analogy above, power factor would be the ratio of beer (KW) to beer plus foam (KVA).
Thus, for a given KVA the more foam you have (the higher the percentage of KVAR), the lower your ratio of KW (beer) to KVA (beer plus foam). This means that you will have more reactive power and a lower power factor. The less foam you have (the lower the percentage of KVAR), the higher your ratio of KW (beer) to KVA (beer plus foam). In fact, as your foam (or KVAR) approaches zero, your power factor approaches 1.0 which is the theoretical perfect power factor.
Our beer mug analogy is a bit simplistic. In reality, when we calculate KVA, we must determine the "vectorial summation" of KVAR and KW.
Therefore, we must go one step further and look at the angle between these vectors.
2.3 The barge Analogy
How power is wasted can be shown graphically since in 3 phase power supplies "power" can be represented and measured as a triangle. Active Power is the base line and is the "real" usable power measured and paid for in kW. Reactive power is the vertical or that part of the supply which causes the inductive load. The reactive power in is measured in kVAR (kilo volt-amperes reactive). Apparent Power is the hypotenuse. This is the component the electricity generator must supply and it is the resultant of the other two components, measured in kVA.
Mathematically the power can be calculated by pythagoras or trigonometry whereby Power Factor is expressed as COS phi Ø (The angle between Apparent Power and Active power)
Since the horse cannot walk on water its pulling effort is reduced by the "angle" of the tow rope.
If the horse could walk on water then the angle Phi Ø would be zero and COSINE Ø=1. Meaning all the horse's power is being used to pull the load.
However the relative position of the horse influences the power. As the horse gets closer to the barge, angle Ø1 increases and power is wasted, but, as the horse is positioned further away, then angle Ø2 gets closer to zero and less power is wasted
So, by improving Power Factor (reducing the angle), the reactive power component is reduced
The "Power Triangle" illustrates this relationship between KW, KVA, KVAR, and Power Factor:
So, inductive loads (with large KVAR) result in low power factor.
4 Why is Power Factor Important
5 How do I Correct / Improve My Power Factor
6 Investment Return on Investment