27-02-2013, 02:02 PM
Power Factor Correction
Power Factor.pptx (Size: 827.04 KB / Downloads: 47)
What is "Power Factor?
"Power factor is a measure of how efficiently, or inefficiently, that electrical power is used by a customer.
For industrial customers, a low power factor is generally caused by inductive loads such as transformers, electric motors and high-intensity discharge lighting.
Customers that do not use electrical power efficiently are being charged additional fees for the inefficient use of power by their electric utility company.
Power Factor Fundamentals
Most plant loads are Inductive and require a magnetic field to operate:
Motors
Transformers
Florescent lighting
The magnetic field is necessary, but produces no useful work
The utility must supply the power to produce the magnetic field and the power to produce the useful work: You pay for all of it!
These two types of current are the ACTIVE and REACTIVE components
Why do we care about Power Factor?
In Industrial Facilities, Mostly Induction Motor loads
Energy Efficient Motors not optimized for PF
Low power factor is caused by oversized or lightly loaded induction motors
Low power factor results in:
Poor electrical efficiency!
Higher utility bills *
Lower system capacity
On the Supply Side, Generation Capacity & Line Losses
Power Factor Correction Capacitors (PFCC) provide an economical means for improving Energy utilization
CAUSES OF LOW POWER FACTOR
A poor power factor can be the result of either a significant phase difference between the voltage and current at the load terminals or it can be due to a high harmonic content or distorted/discontinuous current waveform.
Poor load current phase angle is generally the result of Poor load current phase angle is generally the result of an inductive load such as an induction motor power transformer, lighting ballasts, welder or induction furnace, Induction generators Wind mill generators and high intensity discharge lightings.
A distorted current waveform can be the result of a rectifier variable speed drive, switched mode power supply, discharge lighting or other electronic load.
POWER FACTOR CORRECTION
Power factor decreases with the installation of non resistive loads such as induction motors, Transformers.
Lighting ballasts and electronic equipments. Power factors can be corrected by using capacitors.
These are rated in electrical units called VAR or KVAR.One VAR is equivalent to one volt of reactive power. VAR then are units of measurement for indicating just how much reactive power the capacitor will supply.
As reactive power is usually measured in thousands the letter K is used for thousand. the capacitor KVAR rating then shows how much reactive power the capacitor will supply. Each unit of the capacitor's KVAR will decrease the inductive reactive power demand.
CONCLUSION
By observing all aspects of the power factor it is clear that power factor is the most significant part for the utility Company as well as for the consumer. Utility company rid of from the power losses while the consumer free from low power factor penalty charges.
By installing suitably sized power capacitors into the circuit the Power Factor is improved and the value becomes nearer to 1 thus minimising line losses and improving the efficiency of a plant.