Power Savings Device Questions

They are ALL scams, designed solely for the purpose of separating you from your money. Correcting power factor does reduce the current on loads with poor power factor, such as electric motors, but it does NOT reduce the kW that is consumed from the utility. Power utilities only bill you for the kW consumed, NOT the current alone and unless you are penalized by the utility for having poor power factor, you will NOT save money either. I don't know of any utilities that charge ower factorpenalties to residential users, andmost small commercial users. f you are an industrial user, the devices shown in these website are grossly inadequateto do anything meaningful and in fact can be dangerous to your equipment because they are not part of a roperly engineered system.

There are many many threads in this site that duscuss these type of devices.

Bottom line, don't be fooled.

Nothing magic here, it's just simple "power factor correction" (also commonly called PFC for short).

http://en.wikipedia.org/wiki/Power_factor

The claims are actually possible where very low power factor loads (such as highly inductive loads such as motors and induction furnaces, etc) are concerned, but mostly this is just marketing smoke-and-mirrors. PFC is very, VERY well known and understood and most modern products have it built in or are designed to have a better power factor.

Of course this device won't work on a resistive load (such as a heater), where the power factor is already as good as it can get (PF=unity=1), or in less common "capacitive leading power factor loads".

The effect of the product entirely depends on the load you connect to it. Don't expect a 10-25% saving by buying it and connecting it up to your stove or fridge.

Further information can be obtained with a google search of "PFC basics" or "power factor correction basics".

There are two well researched articles in Silicon Chip Magazine which thoroughly debunk these scams.

In short power factor has no bearing on electricity charges in the domestic situation, you are not penalised for low power factor. Ordinary lamps and stoves etc run at PF of 1 anyway.

Large industrial complexes are penalised for low PF and therefore pay to correct it when the sums add up. They are not saving energy merely avoiding levies for low power factor which costs the supply authority if it gets too below 0.8

Actually, you can save money by using PFC capacitors, even if the power company does not charge extra for a low PF. I have studied this in great detail and even have a demo system that shows this effect. If you can put a PFC capacitor at the load, not at the main breaker box, then the high reactive currents will be isolated to the inductive load and the capacitor. That will reduce the currents in the wires from the power meter to the inductive load. The effective PF will go up (from the power company's POV), but the big saving is from a reduction in the I^2R loss in the wires between the power meter and the inductive load. In other words, if the reactive current is allowed to flow back and forth on those lines, the I^2R loss will be REAL and the meter will account for the loss. The big thing here that I see many people make the mistake on is the distance of the wires from the meter to the load. If the wires are short, then you will not get much benefit from adding caps. If the wires are long, (hundreds of feet) then you will get a benefit, esp. from the big HVAC motors, elevator motors, etc. You may not see much benefit in a house since the wires are shorter and the currents are typically smaller than a big buildiing.

Yes improving the PF (usually) saves energy but it might not be enough to pay for the device. For very large loads it is likely viable but not for small loads. Here is an example.

Your fridge might have a 500W motor. The losses in the house wiring are basically the only losses you will recuperate by improving the power factor since the utility company does not look at household PF. The wiring losses are usually less than 1% of the load. Improving the power factor from 80% to 100% will reduce the current by about 20% (not exactly but this is a quick evaluation).

20% x 1% of 500W is 1W. Assuming 50% on time, you save 12h x 1W = 12Wh per day. At $0.1 per KWh (high price) for electricity, you save 12/1000x0.1= $0.0012 per day or $0.43 per year.

How many year will it take to pay back the gizmos? Note that it does save 20% of your wiring losses. If you paid $10 you will need much more than 20 years.

So even if they don't lie, it might not be worth your trouble.

"...but the big saving is from a reduction in the I^2R loss in the wires between the power meter and the inductive load."

Define "big" in the above sentence please. If you have a common household circuit with properly sized conductors, the I²R losses are so insignificant that they barely warrant being measured. Take for instance the biggest load commonly found in a residence, the Air Conditioner. A typical 4kW AC unit at 230VAC will pull, at most, 22A on 2 conductors. Here in the US, an AC circuit is required to use at least a 30A circuit, so 10ga conductors. Lets say, for the sake of argument then, that the AC unit has a generous conductor run of 500 lineal feet from the meter. The resistance of the 10ga wire is .00118 ohms per foot. So at 500 ft., the total resistance in that wire run is .59 ohms. So take 22A, squared is 484, x .59 = 286W of losses in the wires. If you improve the power factor from .8 to .95 by adding capacitors at the load, that 22A becomes roughly 18A through the wires; the power loss then becomes 18² x .59 = 198W. So the total power savings by adding the capacitors is 88W for the "on-time" of the AC compressor. Considering an AC that runs maybe a generous 6 hours of compressor motor "on-time" per day, that is roughly .5kWH per day. If you live in Arizona where the AC might run 365 days per year, that comes to 183kWH per year, which at a generaous $0.15 per kWH, amounts to $27.45 per year, per conductor, making it $54.90 per year for the AC unit. So if that PFC capacitor at the AC unit cost you $350 to install, it would pay for itself in roughly 6 years of service, assuming it lasted that long without any added service costs. Factor inflation into that $350 capital expenditure and no accountant in his right mind would justify making that move. And remember, this is based on relative extremes, such as a large AC unit in a big house in a desert environment running 365 days per year. Make that an 500W refrigerator with a motor on-time of maybe 10 hours per day that is 25 feet from the meter and using 14ga wire; the numbers just don't amount to anything significant ($3.83 per year) compared to the cost of adding the capacitor system.

You guys with 10-15 cents/kwh electric power consider yourselves lucky. In northern CA PG&E country our incremental power cost is 35 cents/KWH once you get above the baselines that are hardly enough to run basic household appliances and a few light bulbs.

Still I agree that savings through addition of power factor correcting hardware wouldn't payback enough to make it worth the effort.

Ed Weldon

If the user can see a dollar value worth saving from the heat in his wires, HE NEEDS TO GET OUT OF HIS HOUSE QUICKLY and call the fire dept.

This crap logic has separated lots of fools from their money. A properly installed electrical system has wiring sized as to accommodate the currents with very negligible I²R losses. So-called demonstrations of the 'savings' that show a meter slowing down when the capacitance is applied are actually seeing the effect of a terrible LEADING power factor (same effect as a lagging one) affecting the ability of the energy to transfer from the source to the load. Ask them to have an amp meter in that circuit and a thermometer on the load and you will see they are full of it, especially by the logic in the post I am responding to.

If you have studied this in great detail as you claim, then you are here to cheat folks out of their hard earned money. Sorry pal, you have joined the wrong forum to peddle bad science.

I wasn't going to confuse things by going into Industrial situations. Briefly for industrial and commercial circuits such as fluorescent lighting circuits there is a requirement under AS3000 to correct the PF at source. This is cheap to do and does not involve BS gizmos or marketting spin. A lot of leckies chop PF caps out of fluoros when they fail rather than replace them (not all leckies are smart) after a period of time lots of caps are gone and the breaker trips. Ol' not smart runs around the place with a megger and can't find any worthwhile earth faults. The PF caps provide the VARS to the ballasts at point of use and the running current increases, the inrush also increases and in a really degrades circuit the inrush really pops the breaker hard and seems like a short. Remember this is for large lighting loads in Industrial and commercial only.

Now since the topic of at point of load PF correction is mentioned there are good uses for it in even the domestic situation (especially rural domestic). The specific situation is long cable runs with motor loads at the end such as bore pumps and compressors. Most important where only low voltage eg 110v, is available (luckily 110 is not one of my problems) or when a pump has been upgraded. The purpose is not to save money in energy costs but to reduce voltage drop due to I squared R. Voltage drop is a motor killer. Also compliance is an issue as under AS3000 no more than 5% voltage drop is allowed within the installation. Other juristictions will have similar rules. But even with 240v 5% only leaves 12v to play with.

There is another one around in the UK called PowerPerfector, this is simply a step down transformer that drops the mains supply into the building to 360 to 390 volts. This does reduce the energy used and filament lamps lost longer although they will be dimmer. It works for offices with no motor loads or other loads requiring the correct voltage

If you want to reduce your power consumption then elilminate the phantom power loads in your home. You will probably save more than this device promises.

Here are a couple existing threads:

Incredible-Power-Saver-Actually-Saves-Power

New technology cuts appliance power consumption...

There is one power-saving device in common use that has been proven to work effectively through a century or so of experience, and far more cost-effective than any other device currently offered, since it usually already comes with the product. It also does not require any sophisticated engineering to properly size it to the load. It is called an "on/off" switch. Of course, a lot of modern devices stay on even though you think you have turned them off. In this case, unplug them when they are not in use. As to a refrigerator, keep it full (if you can't afford or don't use a lot of food, use containers of water). The additional thermal mass will significantly reduce the cycling time...

"use containers of water). The additional thermal mass will significantly reduce the cycling time..."

I've found that a large quantity of beer works even better.

Taste Like Chicken