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Power Factor Correction and System Design |
There has been and will continue to be a variety of measures developed to increase the efficiency of electrical systems and reduce electrical cost. Very few, by themselves, address the demand cost and power quality as effectively as our GE/Ultravar Power Factor Correction and Harmonic Suppression System. Our system employs the principals of low voltage power factor correction to dramatically reduce an electric bill while actually increasing the electrical system capacity. This will allow commercial and industrial users of electricity to save appreciably on their power cost and to add new equipment without a costly electrical system upgrade.
What
Is Power Factor?
The power used by commercial
consumers has two components: Apparent Power which is the combination of kW and
reactive power (kVAr) which is measured in kVA.
Reactive power is needed to
generate the magnetic fields required for the operation of an inductive piece of
equipment, sometimes called wattless power. The load does not consume this
component of electricity. A good analogy of this is purchasing a beverage
that is packaged in a recyclable container. We need the container to consume the
product but we do not consume the container. The inductive component is
relative to the container and a power factor capacitor literally recycles this
non-consumed element of electricity and supplies it back to the load. Inductive electrical
equipment, such as motors and transformers, therefore must take from the
electrical distribution system more current than is necessary to perform the
work involved. The ratio of kW to kVA apparent is called Power Factor.
How
the System Saves Money
The power factor correction system lowers the
electrical costs in three ways:
1. In many areas of the country, electric
rates include a charge for low power factor. This is done via the demand
charge portion of the bill. The monthly demand is typically measured in
both kW and in kVA. The power company takes the highest 15 to 30 minute
demand measurement (peak demand). The billing demand is typically arrived
at by taking a percentage of the peak kVA demand, (90% to 100%) and comparing it
to the peak KW demand. The higher of the two figures becomes your billing
demand.
Our power factor correction
system, connected within your electrical distribution system, supplies the
wattless power to the inductive loads making it unnecessary for the power
company to supply it. This dramatically reduces the peak kVA demand
figure. Savings are realized in reduced kVA demand charges.
2. The second savings possible through the use of
our power factor correction system is in the form of increased capacity of the
electrical distribution system. Installation of our equipment to furnish
the non-productive current requirements of the facility makes it possible to
increase the plant's connected load as much as 20% without a corresponding
increase in the size of transformers, conductors and protective devices
servicing the load.
3.
The third area of savings is improved voltage and
power loss reduction. Electrical system losses are also reduced by the
reduction of total current and power that is delivered. This would result
in less KWH consumption.
How
Does The Power Factor Affect My Electric Bill?
A typical industrial/commercial electric rate
calculates a demand charge by taking 90% of the kVA demand figure and
multiplying it by the demand rate. Let’s assume the demand charge is
$10.00. If the monthly kW demand was 500 and the Power Factor was .70, the
kVA would be 714. 90% of 714 equal 643, and 643 becomes the "billing
demand". To calculate the "demand cost" you multiply the
billing demand by the demand charge (in this case $10.00) or 643 X $10.00 =
$6,430.00.
Now let’s assume the same
demand rate of $10.00 and a kW demand 500. If the power factor were .90,
the kVA demand would be 556. 90% of 556=500 and 500 becomes the billing
demand. The demand cost is calculated the same way as above 500 X $10.00 =
$5,000.00. So for the same 500 KW (working power) it would cost the
customer $1,430.00 less at a power factor of .90 than at a .70 power factor.
A
Word About
Harmonics
Most power factor correction equipment employ the
use of special power factor correction capacitors. Power factor capacitors
have low impedance at the commonly generated harmonics levels of 5th, 7th and
11th. Installing a PF capacitor in an adverse harmonic environment could
damage the capacitor and/or the load generating the harmonic, such as a VFD
drive. It is important to consider the harmonic levels. Please see
Harmonic Testing for more information on this service.
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