This is a reply to the power issue from a friend of mine:
Yes, it's true.
Heavy industry uses this technique to reduce their electrical utility costs.
Steel production is an example.
Some utility companies require that customers with large inductive loads use
and pay for capacitor banks to correct the plant's power factor.
The issue arises when large inductive loads are connected to the electrical
grid.
For example, a large horsepower electric motor presents two loads to the grid.
One load is the energy consumed or dissipated in work.
The other load is inductive. The inductive load stores electrical energy, does
not dissipate it, and it is returned to the grid.
It can't be helped. It is built into the design of electric motors. This is
understandable. We understand that practical electric motor armatures are
turned by a strong magnetic field. That magnetic field is produced by large
inductors.
As an electrical circuit, you can visualize the motor as a resistor in series
with an inductor driven by a sine wave 60 Hz alternating voltage source ("AC").
On the positive half cycle voltage swing (0-180 degrees), electrical energy is
dissipated in the load, the resistor. In the resistor the energy is dissipated
in heat. In a motor, the energy is dissipated in work done.
The inductor stores electrical energy on the positive half cycle then returns
the energy to the grid on the negative half cycle (180-360 degrees). The
resistor again draws and dissipates energy on the negative half cycle.
In the electrical circuit analogy, if the inductor was zero Henrys and the
Resistor was non zero Ohms, the Power Factor (PF) is defined as 1.0, or
unity. This is a purely dissipative load.
If the inductor was non zero Henrys and the Resistor was zero Ohms, the PF is
defined as 0.0. This is a purely inductive load.
In a practical circuit with some inductance, L, and some resistance, R, PF
therefore varies between 0.0 and 1.0.
For given values of L and R, PF can be measured or computed.
The utility company sells the energy dissipated in a load. If PF = 1.0, the
utility company sells all the energy it supplies.
As PF decreases due to inductance, the load increasingly stores and returns
larger amounts of energy to the utility company.
The utility has to generate the additional power needed to charge the connected
inductive loads, even if the energy is returned to the grid. The utility needs
significantly more capacity and therefore greater investment and operating
capital.
Worse yet, the increased current flow causes more dissipative energy loss in
the line resistance. This inefficiency is a measurable loss of money to the
utility.
Adding capacitance across and close to the load helps a lot.
Briefly and simply, it works like this.
The utility initially charges the capacitor. Then, when the inductive load
draws current, the capacitor supplies it. When the inductor dumps its stored
energy, the capacitor takes it and recharges. AC cycle after cycle the
capacitor and inductor exchange stored energy. The utility company does not
have to generate the additional energy. The load continues to dissipate energy
on each half cycle, no change there.
This is called Power Factor Correction. With PF correction, the utility
supplies mostly dissipative energy and sees a PF approximately = 1.0.
With the capacitance located close to the load, excessive line energy loss is
eliminated too.
You might have seen these capacitor banks on a utility pole outside a factory.
Entrepreneurs have applied this industrial technology to the home.
You can buy a franchise and sell PF correction as a retail consumer product.
The franchise provides all the equipment and marketing materials.
I have seen a franchise website with convincing evidence of a decrease in a
utility bill.
The utility company has to supply the electrical energy a home draws, whether
the homeowner uses it all or not.
The idea is that PF correction can reduce the load to nearly pure dissipation,
reducing a homeowners utility bill.
So, the technology works. Is is cost effective? It is for a large industrial
load.
Home installation requires labor of a licensed electrician, a capacitor bank,
and wiring.
This sounds expensive. Maybe it will pay off over a long period.
It depends on how inductive a load your home presents.
To me, there is a larger picture. We are in an era of energy conservation. PF
correction for the home sounds to me like a stimulus for increased electrical
energy consumption. PF correction controls your cost of increased consumption.
A homeowner might install a bigger air conditioner, put an additional
refrigerator in the basement or garage. Motors and transformers are inductive
loads, presumably having some impact on PF.
California has asked people to unplug the extra refrigerators in garages to
conserve energy.
Now the "Energy Police" are after us about "Vampire Power" - all those small
transformers plugged in 24 x 7 to supply our gadgets. (There is a Vampire
Power website.)
So, it seems to me, a modern life style places a branch in the road for us. If
we want to continue as was proper and fitting in the past, viz. the more energy
we use, the better the lifestyle, then PF correction is an economic
consideration.
If we want to live better using less energy and try to minimize a carbon
footprint and climate damage, then PF correction looks like an obsolete old
technology, important to an earlier era of innovation.
We can save some energy with PF correction. I speculate that we can save lots
and lots more by just turning off appliances we don't need, and applying energy
conservation to home renovation and our lifestyle in general.
After all, when we turn something off we save both the inductive AND
dissipative electrical energy needed. Turning something off saves more than PF
correction alone.
That's my take on it!!
--Bill
KA9MXW
