Power Correction 

Electrical Systems

Poly-phase electrical systems were primarily invented by Nikola Tesla, Galileo Ferraris, and Mikhail Osipovich Dolivo-Dobrovolsky.

Tesla designed electrical power systems for large motors and generators. The system could generate power hundreds of miles away from the users, and with another Tesla invention, the poly-phase transformer, deliver the electric power with only a modest power loss en route. As a side benefit, electric incandescent lamps (Edison bulbs) work perfectly with AC electrical systems.

The inventors of the electrical power system realized there was a missing component for the efficient operation of the system. There was a need to match the generators to the motors electrical use. This component is the “condenser” or capacitor. Electric motors had a “lag” in the current because it takes time to magnetize the iron core of the motor for each cycle the AC. The capacitor has exactly the opposite behavior as they easily absorb the leading current. Thus adding capacitors compensates for the motor lag current.

Measurement of the “lead” or “lag” current were designed, and capacitors were added to the electrical power system to balance the motors. Since capacitors are expensive and only needed to balance out the use of motors, metering was invented to charge industrial electric users for the “power factor” caused by industrial motors. In response, industrial electric users installed their own capacitor systems to balance the power factor and reduce the electric charges. These capacitor systems were expensive, but cost less than the electric charges they saved.

Over time, more electric motors were used by light commercial and residential electric users. The electrical power system added capacitors to generally balance the power factor. The metering required to measure power factor at every user was too expensive, so electric rates were increased to pay for the capacitors on the electric grid.

Now there are a wide selection of power factor correction systems. Most are quite expensive. The EnergyMizer is a low cost power factor corrector. It has at least one large capacitor. The manufacturer claims there is some automatic circuitry to adjust the capacitor, but I have not been able to verify that claim.

The EnergyMizer power factor correction will reduce the electric use of electric motors used on the same sub panel just as the industrial systems. The motor runs better because the current “lag” is compensated by the EnergyMizer capacitor “lead”. The current stays local to the sub panel instead of going through the power meter and grid wiring. The motor runs more efficiently, so it uses less power, which provides a second amount of electric savings. If the motors are indoors, like refrigerators, more power is saved because the motor runs cooler, which requires less air conditioning power.

For air conditioners there are more savings. In addition to the savings above, the air conditioning compressor is cooled by the freon, so more efficient motor operation means less heat into the freon, so the freon is colder. Colder freon drops the evaporator coil temperature which dehumidifies better. The colder air cools faster, so the air conditioner cycle is shorter.

References:
Please read this first reference article. It clearly explains what Power Factor is, and that customers can supply their own power factor correction equipment, with an example of an automatic power factor correction unit.