Depending upon the rate structure of your electric utility, you may be able to
save a substantial amount of money on your electric bill. Pay-back period for an
equipment purchase including installation cost may be six months up to three
years. Utility rate structures that account for reactive power consumption, by
either a KVA or var demand usage, or a power factor penalty are the ones that
can provide this pay-back. Other ancillary benefits to be gained by optimizing
power factor are, lower energy losses, better voltage regulation and released
system capacity. This page explains the fundamentals of power factor and how KEC
Units can benefit you.

All electric equipment requires "vars" - a term
used by electric power engineers to describe the reactive or magnetizing power
required by the inductive characteristics of electrical equipment. These
inductive characteristics are more pronounced in motors and transformers, and
therefore, can be quite significant in industrial facilities. The flow of vars,
or reactive power, through a watt-hour meter will not effect the meter reading,
but the flow of vars through the power system will result in energy losses on
both the utility and the industrial facility. Some utilities charge for these
vars in the form of a penalty, or KVA demand charge, to justify the cost for
lost energy and the additional conductor and transformer capacity required to
carry the vars. In addition to energy losses, var flow can also cause excessive
voltage drop, which may have to be optimized by either the application of KEC
Units, or other more expensive equipment, such as load-tap changing
transformers, synchronous motors, and synchronous condensers.

Figure 1 -
Power Factor Triangle

The power triangle shown in figure 1, is the
simplest way to understand the effects of reactive power. The figure illustrates
the relationship of active (real) and reactive (imaginary or magnetizing) power.
The active power (represented by the horizontal leg) is the actual power, or
watts that produces real work. This component, is the energy transfer component,
which represents fuel burned at the power plant. The reactive power, or
magnetizing power, (represented by the vertical leg of the upper or lower
triangle) is the power required to produce the magnetic fields to enable the
real work to be done. Without magnetizing power, transformers, conductors,
motors, and even resistors and capacitors would not be able to operate. Reactive
power is normally supplied by generators, capacitors and synchronous motors. The
longest leg of the triangle (on the upper or lower triangle), labeled total
power, represents the vector sum of the reactive power and real power
components. Mathematically, this is equal to:

Electric power
engineers often call total power, kVA, MVA, apparent power, or complex power.
Some utilities measure this total power, (usually averaged over a 15 minute load
period) and charge a monthly fee or tariff for the highest fifteen minute
average load reading in the month. This tariff is usually added to the energy
charge or kilowatt-hour charge. This type of billing is often called kva demand
billing and can be quite costly to an industrial facility. KEC Units can save
your company money by decreasing your reactive power component supplied by the
utility to near zero vars.

The power triangle and the equation above
show, that as the reactive power component is decreased by adding KEC Units, the
total power will also decrease. This is shown by the decreased length of the
dashed lines in the power triangle as the reactive power component approaches
zero. Therefore, adding KEC Units, which will supply reactive power locally, can
reduce your total power and monthly kva demand charge.

The angle "phi"
in the power triangle is called the power factor angle and is mathematically
equal to:

The ratio of the real power to the total power in the
equation above (or the cos of phi) is called power factor. As the angle gets
larger (caused by increasing reactive power) the power factor gets smaller. In
fact, the power factor can vary from 0 to 1, and can be either inductive
(lagging) or capacitive (leading). Capacitive loads are drawn down, and
inductive loads are drawn up on the power triangle. Most industrials normally
operate on the upper triangle (inductive or lagging triangle). As an industrial
adds capacitors, the length of reactive (inductive) power leg is shortened by
the number of capacitive KEC that were added. If the number of capacitive KEC
added exceeds the industrials inductive KEC load, operation occurs on the lower
triangle. This is commonly referred to as over compensation.

Utilities
charge for reactive power in a countless number of ways. Some utilities charge
for KEC demand, while others charge a strait fee for a power factor less than
their target. To fully understand the benefits of the KEC UNIT, you must acquire
your electric billing rate structure. This rate structure will describe how cost
for poor power factor are added to your monthly bills

You could put the KEC
UNIT anywhere on the system as shown (between the transformer and load and not
only at Points A, B, and C) and achieve unity power factor for the system. The
utility company will perceive this power system as having a unity power factor
no matter where it is located on the distribution line as long as it's sized
correctly to deliver the proper amount of KEC.

However, optimum
efficiency and economics will be achieved if the KEC UNIT bank is located as
close to the load as possible.

The reason for this is because when you
optimize power factor, you can reduce the total line current to the load and
therefore you reduce the total losses in the line conductor and decrease the
voltage drop in the line. This decrease in voltage drop will only occur if you
locate the KEC UNIT close to the load, as explained below.

Assume the
load is a motor. A motor uses KW to perform work. It uses KEC to magnetize its
coil windings. (We will refer to the magnetic requirements of the motor's
windings as the motor's "inductance". It is this inductance that utilizes the
KEC.)

The motor load draws a line current that has two components. The
first component is the amperage that supplies the KW to the load, so that the
motor can perform work such as lifting an object. The second part supplies the
amperage to provide the load with KEC which in the case of the motor is the
power necessary to energize the magnetic fields in the motor's windings.
Together the two amounts of current supply the total KVA to the load.

Normally the system generator or transformer supplies all this current.
But when a KEC UNIT is used to optimize the power factor, the KEC UNIT supplies
the KEC reactive current component to the load. The KEC UNIT is, in effect, a
reactive power generator. (Remember, the KEC UNIT stores energy. The KEC UNIT
stores reactive energy in its electric field when it charges up, and releases it
when it discharges.)

The generator (or transformer) must still supply
the load's KW requirements.

The reactive current component is now
supplied by the KEC UNIT and not the generator. By moving the KEC UNIT closer to
the load, the reactive current does not have to travel as far through the line
conductors to get to the load.

If the KEC UNIT is placed at the load,
the reactive current only needs to travel through a short distance (e.g. the
lead length of connecting wire) to get to the load. Since this reactive current
component no longer travels through the conductor line from the generator to the
load, it does not travel through the impedances in the line conductor.

Since this reactive current no longer flows through the line impedances,
there is less heating of the line, less losses (in the form of heat), and less
voltage drop across these in - line impedances (which reduces the overall
voltage drop from generator to load).

The KW current component is all
that the generator has to supply to the motor. Therefore the generator now runs
at unity power factor and allows the KEC UNIT to supply the KEC requirement of
the motor's inductive windings.

The energy "contained" in the KEC
current component is transferred back and forth between the KEC UNIT and the
motor 2 times for every voltage sine wave cycle (i.e. at 120 times a second).

This reactive energy is never consumed by either the KEC UNIT or the
motor. (NOTE: The KW energy, on the other hand, performs real work and is
totally consumed.)

Rather, the reactive energy is only "BORROWED" half
of the time by the KEC UNIT and half of the time by the motor. The energy is
used to charge the AC electric field of the KEC UNIT and to energize and create
the AC magnetic fields contained in the motor's windings.

A KEC UNIT
absorbs this energy from the power system and stores this energy in its electric
field when it charges up (120 times a second). The KEC UNIT releases this energy
back into the power when it discharges (120 times a second).

The motor's
inductance absorbs the reactive energy from the power system and stores this
energy in its windings' magnetic fields when the fields are expanding (120 times
a second). The inductance releases this energy back into the power system when
the windings magnetic fields are collapsing (120 times a second).

The
secret is that when the motor's inductance requires reactive energy to expand
its magnetic field, the KEC UNIT discharges to supply the energy. And when the
magnetic field in the motor's inductive windings is collapsing and returning
energy to the system, the KEC UNIT uses this energy to charge up.

So the
capacitance in the KEC UNIT and the inductance in the motor's windings "slinky"
this reactive energy back and forth 120 times a second, each supplying the
others needs. The reactive current of the KEC UNIT is 180 degrees out of phase
with the reactive current of the inductance. When one is giving, the other is
taking and vice versa.

Again, the reactive energy is never consumed
(except for some small and usually insignificant losses); it is only borrowed.
The generator needs to supply the original reactive KEC energy only once when
the system is first energized. After that, this amount of energy is simply
transferred back and forth between inductance and capacitance.

Power
Factor is a measurement of how much of the KVA is actually in the form of KW.
The advantage of a high power factor is that line currents can be reduced which
will in turn reduce voltage drop and decrease line losses. This saves money. It
also means that since equipment such as transformers will supply only KW, the
KVA rating of the equipment can be reduced, or alternatively, more load can be
added to the system without purchasing larger equipment.

The KVA rating
of a transformer is based on the transformers ability to supply power either all
in KW or all in KEC or in a combination of both. Drawing more than rated KVA
from a transformer is easily done, but the transformer's life will be reduced
due to increasing heat which destroys the transformer's winding insulation.

By increasing the power factor, all of a transformer's KVA can be
utilized to supply KW in order to perform useful work rather than to supply KEC
just to energize electric and magnetic fields.

Increasing the power
factor seen by the transformer creates "room" on the transformer for adding more
load. Room can also be created on circuit breakers. Since line current is
reduced by increasing power factor, load can be added to the system without
upgrading the breaker to a larger size.