1. WHAT IS POWER FACTOR?
Power factor is an index used to compute the efficiency level of electrical usage. The index is measured from 0 to 1. A higher index shows efficient usage of electricity and vice versa.
Certain appliances have a power factor of 100%, meaning that they are 100% efficient. However, in some appliances whereby additional power is needed, Low power factor not only shortens the lifespan of electrical appliances but also constitutes a loss to both the consumer as well as TNB.
To understand Power Factor, we will start with the definition of some basic terms:
|KW||Working Power (also called Actual Power, Active Power or Real Power). It is the power that powers equipment and performs useful work.|
|KVAR||Reactive Power. It is the power which magnetic equipment such as transformers, motors and relays need to produce the magnetizing flux.|
Power Factor is the ratio of Working Power to Apparent Power [Power Factor = KW / KVA].
Let’s look at a simple analogy in order to better understand these terms.
Let’s say you are at a park and it is a hot day, you order a glass of a carbonated drink. The thirst-quenching portion of the drink is represented by KW. Unfortunately, along with your drink comes a little bit of foam. The foam does not quench your thirst. This foam is represented by KVAR.
The total content of your glass, KVA, is this summation of KW (the carbonated drink) and KVAR (the foam).
Thus, for a given KVA:
– The more foam you have, the lower your power factor.
– The less foam you have, the higher your power factor.
For efficient usage of electricity, power factor must approach 1.0. Power factor that is less than 0.85 shows an inefficient use of electricity.
2. CAUSES OF LOW POWER FACTOR
In our carbonated drink analogy, low power factor resulted when the foam is large. Low power factor is caused by inductive loads, which are sources of reactive power.
Examples of inductive loads are:-
• Induction Motors
• High Intensity Discharge (HID) Lighting
Inductive loads constitute a major portion of power consumed by commercial and industrial sectors.
WOW, DOES LOW POWER COST YOU MONEY? YES, AND THAT’S WHY YOU NEED POWER FACTOR CORRECTION.
When your average monthly power factor falls below 85%, a surcharge is added to your electricity7 bill. The lower your power factor, the higher the surcharge. The rates fixed by TNB are as follow:
|A||Below 0.85~0.75||1.5% per unit|
|B||Below 0.75||3.0% per unit|
The percentage total of (A) and (B) will be levied on your electricity consumption for the month.
3. BENEFITS OF POWER FACTOR CORRECTION
Reducing KW (Working Power) billing demand.
Low Power Factor or requires high reactive power (KVAR) and apparent power (KVA), which is the power that TNB supplies. Therefore, a facility’s low power factor forces TNB to increase its generation and transmission capacity in order to handle this extra demand.
By increasing power factor, customers use less KVAR. This results in less KW, which equates to RM savings for TNB.
Eliminating power factor surcharge
Utility comprises all around the world charge customers an additional surcharge when their power factor is less than 0.95. In fact, some utilities are not obliged to deliver electricity to their customers at any time the customer’s power factor falls below 0.85.
Thus, customer can avoid this additional surcharge by increasing power factor. In Malaysia, TNB is allowed through the Malaysian Grid Code and the Malaysian Electricity Distribution Code, to impose a surcharge to the customer if the power factor is <0.85 for customers receiving less than 132kV.
Increased system capacity and reduced system losses in your electrical system
Low power factor casuses power system losses in the customer’s electricity system. By improving power factor, these losses can be reduced. With the current rise in the cost of energy, increased facility efficiency is important. Moreover, with lower system losses, customers are able to add additional load in their electrical system.
Increased voltage level in your electrical system, resulting in more efficient motors
As mentioned before, low power factor causes power system losses in customer’s electrical system. As power losses increase, customers may experience a voltage drop. Excessive voltage drops can cause overheating and premature failure of motors and other inductive equipment.
Therefore, by raising the power factor, customers can minimize these voltage drops along feeder cables and avoid related problems. Motors will run more efficiently, with a slight increase in capacity and starting torque.