I've seen
these advertised at a semi local energy fair and was wondering what exactly it did. For owners who are billed a KVA demand charge according to the power factor of their equipment, power factor correction may be useful. For residential users, the only advantage in terms of energy consumption would be via line losses.
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As the demand for power runs through your home, there is non-productive current (heat) that strains your home appliances and wiring. This heat is wasted energy that you are paying for. The KEC optimizes the power that comes into your home, allowing your appliances and equipment motors to operate more efficiently. This reduces heat (wasted electricity), which in turn lowers your electric bill
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These line losses are proportional to the the current draw of a device (squared), it's power correction factor, and the resistance of the home's wiring. For example, an electric air conditioner motor rated at 1000W would only use ~600W according to a killawatt or similar and has a PFC of about .6. The penalty of the additional power draw of ~400W measured in VA is excess line losses, which are the current squared times the resistance. In this case, 400W over 120V AC would result in 6.6bar amps of current, and assuming we had roughly a quarter of a km of 14 AWG wire at 8ohms/km, lines losses would account for around 23-23W, or 25W for the sake of simplicity. This is roughly 2.5% of the power draw, and assuming the device was on constantly for eight hours a day six months out of the year, would result in an extra 36kWh saved.
Given an entire household full of items with PFCs of .6, something like this could save upwards of 150kWh/year. Which at the average rate in the U.S. is around $15/year. The only problem with this is the
price of the unit... Assuming the owner installs the device themselves, it would only take a mere 25 years to recoup it's initial cost, and on the other side of the spectrum, for those of us who aren't electricians, want to keep the warranty, and don't have many devices w/ a low PFC, well... a payback period of more than a century may be possible. This is a bit puzzling considering that the site states the device has an...
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Investment return (36 months or less)
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But I suppose the company could be assuming household electricity consumption of seven or eight times the national average.
In short, given the high cost and low potential savings, even for a residential home with nothing but low PFC items, these cannot amortize their costs anywhere near the claimed time interval. That being said, it looks that a circuit for passive power factor correction can be put together on the cheap, so even if the mentioned product isn't the best this isn't an idea w/o merit.