Power-Save 1200

[Ivan Seeking]

How do you achieve savings?

When motors in your home start, they ask the utilities transformer for power (voltage and amperage) to run. This demand for power runs through the house wiring, thru the panel box, thru the meter and down the lines to the transformer. This demand for power heats up and strains the motors and wiring in the home, this heat (I2R losses) is watts.

The POWER-SAVE 1200 UNIT once installed stores and releases to the homes motors what they need to function properly, thus reducing heat on the wires and the motors. Lowering this heat will reduce your electric bill, reduce the chance of fires and increase the life of the motors. Note: The POWER-SAVE 1200 UNIT is compatible with installation on all breaker panel boxes.
http://www.savepoweramerica.com/store/1562424/product/PS-1200

I linked the site above because the manufacturer's site was having problems and the activity seemed suspicious - lots of data transfer but no screen update - but here is their claim.
The Power-Save 1200™ is a small gray box that fits neatly next to your breaker panel, saves you money year after year and protects the entire home.

The Power-Save 1200™ was designed with the homeowner in mind, providing lower energy bills, increased motor and appliance life, as well as surge and lightning protection for all of the equipment inside of your house.

Residential customers throughout North America could see a realized savings of 8% - 10% typically and as much as 25% on their electrical usage (and thus power bills). The Power-Save 1200™ is UL Tested and CSA certified.

Money isn't all that you are saving when you use Power-Save Energy Corp. products. It's an energy-wise purchasing decision with many positive environmental implications. Power Suppliers also benefit by being able to supply power to more customers without the generation or acquisition of additional power.
http://www.power-save1200.com/1200?gclid=CNDo_I2qiJMCFQY_agodenhEgg

[russ_watters]

The first quote is obviously completely bogus. The second is less bold, but still bogus. Typically these types of devices act to reduce power factor, but homeowners (in the US, anyway) don't pay for bad power factor anyway. Here's what it says in the FAQ: The Power-Save reduces the amount of power drawn from the utility by storing (in its capacitors) otherwise lost electricity (watts) caused by the inductive motors in your home. (Some examples of inductive motors are Air Conditioning units, refrigerators, freezers, washers, dryers, dishwashers, pool pumps, vacuum cleaners, furnace blower motors, fans etc.) The technology applied by the Power-Save 1200™ Unit supplies that stored electricity back to your inductive loads, thus causing you to decrease your demand from the utility. If you decrease your demand from the utility, your meter slows down, and you use less electricity. The thought is, you’ve already paid for that electricity, why pay for it and waste it when you can pay for it, store it, and reuse it again. This whole process is called power factor optimization.

What is Power Factor?
Power factor is the percentage of electricity that’s delivered to your house and used effectively, compared to what is wasted. For example, a 1.0 power factor means that all the electricity that’s being delivered to your home is being used effectively for its purpose. However, most homes in America today have a .77 power factor or less. This means that 77% of the electricity that is coming thru your meter at your home or business is being used effectively, the other 23% is being wasted by your inductive load. With a low power factor, the utility has to deliver more electricity to do the same work. However, the Power-Save unit increases that power factor in most cases to .97 or .98, thus increasing the effective use of your electricity and lowering your usage. Bad power factor increases your reactive power and thus your apparent power, but your power meter measures you true power, thus the above claim is a straightforward lie. Here's a description of the power factor concept: http://www.allaboutcircuits.com/vol_2/chpt_11/2.html

Businesses, however, benefit greatly from power factor correction. The utility has a separate device attached to the meter to measure it (the meter itself still measures only "true power"). But I wouldn't buy one of these devices, I'd buy one from a reputable manufacturer. Ie: Square-D (http://www.squared.com/us/products/power_management.nsf/unid/706F643B9C1799B585256C7D006CCB2C/$file/pfclvFrameset.htm)

[WCWally]

The big simple answer is NO. Although power factor is an issue in large commercial and industrial applications, there is no U.S. utility I know of that asses a penalty on residential customers for low power factor. The utility meters measure watt hours not KVA hours, so if the power factor is low, the meter doesn't see it. Correcting power factor in a residential application will save exactly zero dollars.

[Ivan Seeking]

Well, there may be a slight gain by eliminating I2R losses in the wiring that result from the increased currents, but that probably amounts to something in the order of 10 watts [assuming 0.00118 ohms per foot of wiring at an average of 50 feet, and an average of 10 amps reactive, which is generous], which would suggest something around 7 KWHrs, or about 70 cents per month in savings. So at $300, we might expect the unit to pay back in about 30 or 40 years.

[WCWally]

The problem with these devices is that the makers spin around with the I2R losses, distinct from the KWHr, as if they matter. They are real enough but the big point is that the residential utility meter will not see them nor will the utility bill directly for them. Corrections to power factor will help the utility, which is not a bad thing, but it is important to know that your 400 bucks are going to a noble global cooling cause and not coming directly back to your wallet.

[LowlyPion]

FWIW I came across a diagram for an electrical meter that might be found in a residential location.

http://www.themeterguy.com/Theory/watthour_meter.htm#The%20Meter%20Diagram

Such meters do read true power I see.

Anecdotally I use a table saw that when it switches on causes a noticeable surge in the circuit. I have thought that balancing that might be useful, but the few times a month I may use it, I couldn't imagine much of a savings. After stumbling across this thread and I now see the way the power is measured I'm just as glad that it was one of those things I never bothered with even looking further into.

I haven't seen the Power Save 1200 itself, so I was wondering if the device was just a simple array of passive capacitors or whether there are any active elements to it that might switch in response to inductive loading?

The real test of whether it could ever be a cost benefit is that if the device gets warm at all in normal continuous operation. If so then whatever heat the device itself generates surely would result in added cost to the bill and not any savings, even if the meter in the box wasn't measuring true power.

A little knowledge can be a dangerous thing in the hands of an infomercial sales guy. (Are you following this camera guy?)

[kokain]

Maybe if I tell my motor to say please when it “asks” the power company for more power.

Current is current. When your motor has a 20A inrush, it uses 20A. If you run it through a cap first, you still use 20A.

There is no way to damage wire in a house built to code. A breaker’s sole purpose is to protect the wire. Wire rated for 20A on a 20A breaker is safe even if you inrush 50A. The breaker trips and protects the wire. A short is theoretically infinite current and the wire is still safe thanks to the breaker. Fear makes people dumb. The desire to saving energy makes people dumb.

[Ivan Seeking]

The problem with these devices is that the makers spin around with the I2R losses, distinct from the KWHr, as if they matter. They are real enough but the big point is that the residential utility meter will not see them nor will the utility bill directly for them. Corrections to power factor will help the utility, which is not a bad thing, but it is important to know that your 400 bucks are going to a noble global cooling cause and not coming directly back to your wallet.

There are real reactive currents flowing through the wiring, and the resulting I2R losses are real and would be measured by the meter, but they are insignificant.

[WCWally]

Yes, the losses are real, no they would not be measured by the watt-hour meter. The reason utilities penalize large users for low power factor is that they would otherwise not get paid for it. In the case of residential users with low power factor they don't directly charge for it. It's only relatively recently that the utilities have had real time pf measurement on large users. They used to come out and test once in a while and assess a penalty based on the test until the next test. Large users that installed correction capacitors, or in some cases, synchronous motors, had to be re-tested to get rid of the penalties. The overall point is that these power factor correcting device claims of savings for residential users are basically fradulent. They play on something true but completely mis-applied.

[Ivan Seeking]

Yes, the losses are real, no they would not be measured by the watt-hour meter. The reason utilities penalize large users for low power factor is that they would otherwise not get paid for it. In the case of residential users with low power factor they don't directly charge for it. It's only relatively recently that the utilities have had real time pf measurement on large users. They used to come out and test once in a while and assess a penalty based on the test until the next test. Large users that installed correction capacitors, or in some cases, synchronous motors, had to be re-tested to get rid of the penalties. The overall point is that these power factor correcting device claims of savings for residential users are basically fradulent. They play on something true but completely mis-applied.

There is a difference between charging for the power factor, which determines how much extra current must be carried by the transmission lines, and metering losses resulting from wiring in the house. The power meter would measure these losses just as it would the energy used by a heater. If work is done, the meter will measure it. The power company has nothing to do with it.

They don't charge industry for I2R losses resulting from VAR because those losses are measured by their meter. They are charging for the added load on the xmission lines.

[WCWally]

The utilities attempt to charge the cost of delivering whatever they deliver plus whatever profit the markets and the public utility commissions will stand for. I2R losses are a component of KWHr as well. Standard watt hour meters do not pick up the difference between KWHr and KVAHr and there is no residential tariff in the US (that I am aware of) that contains a provision for power factor adjustments for residential service. The utility eats it case by case and just tries to adjust the overall rates to compensate in general. Here, for example, are excerpts from the current PECO tariff.

"power factor - As used herein, power factor is, in a single-phase circuit, the ratio of the watts to the voltamperes, and in a polyphase circuit, is the ratio of the total watts to the vector sum of the voltamperes in the several phases."

"billing demand - The calculated or measured demand after correction, if any, for power factor; except that the billing demand may be limited to a minimum figure."

They correct what their meter sees for the power factor, which it doesn't see.

http://www.exeloncorp.com/NR/rdonlyres/DF4E94D2-14F6-4495-98D7-7AB2FCE4CA2A/4375/s77_complete_011009.pdf

[LowlyPion]

Here is a picture of the product

http://www.city-data.com/profiles/photo/3913f

Apparently it requires a separate 20A dedicated circuit. (Another cost sink.)

It is apparently only a bank of capacitors. (I do see a pilot light. I wonder if that constant energy cost eats up any possible marginal savings.)

I see prices between $250 to $315. (There goes the economic stimulus check.)

[russ_watters]

Wally, what Ivan is basically saying is that the IR^2 losses lower the efficiency of the motor: the motor generates more heat without power factor correction than with power factor correction.

[Ivan Seeking]

Wally, what Ivan is basically saying is that the IR^2 losses lower the efficiency of the motor: the motor generates more heat without power factor correction than with power factor correction.

I was also thinking of the wiring in the house. We get slightly greater losses in the house wiring because of the reactive currents from motors and other inductive loads supplied by those wires. But now that I think about, if this device is mounted at the panel and not near the appliance, the losses would still occur as the charge cycles through the wires between the capacitors and the inductive loads.

[WCWally]

It's true whether I agree or not, but I completely agree that with a low power factor there will be more heat generated by any resistance that the additional current passes through. My point is that the electric meter doesn't see it, so the residential customer isn't charged for it, so eliminating it will not save any money. This illustrates my basic complaint about the marketing. The discussion of power factor and I2R losses is perfectly legitimate. There is a slick video showing a motor drawing significantly less amperage with the device (capacitors) connected. All true, all worthless to the residential power consumer. It's the money savings angle that is that is mis-stated. Truth is, you buy this thing, install it, improve the power factor by some amount (they don't state the KVAR value of the device) and save exactly no dollars. Not 5%, not 10%, not "up to 25%!!" .. no dollars. That's my whole point. Find me a utility in the US that charges residential customers for low power factor and I'll be right on board for customers of that utility.

[Ivan Seeking]

It's true whether I agree or not, but I completely agree that with a low power factor there will be more heat generated by any resistance that the additional current passes through. My point is that the electric meter doesn't see it, so the residential customer isn't charged for it, so eliminating it will not save any money.

VARs do not do any work on the inductor, but they do work on the intervening wiring. If it does work, it is measured by the meter.

The reason VARS do not do work on the inductor is that the energy stored in magnetic fields is returned to the supply. And a perfect inductor returns all of the stored energy. But, if there is work done on any intervening resistance, then the meter will see it. It will see it because not quite all of the energy is returned to the supply, and we see a slight voltage drop relative to what we would see in perfect wires.

If we had perfect inductors and perfect wires [ie no resistance], then the VARs would not do work, and the meter would never see it.

However, if this device is mounted at the panel, it will not reduce I2R losses because the stored energy oscillates through the house wires between the inductors and capacitors. As this happens, current flows, and losses occur.

[Averagesupernova]

There is one place that this little gizmo could actually do something useful that I don't believe is mentioned. Ivan, you are 100% correct in stating that it will NOT reduce current between the Power-Save 1200 and the motor. That wiring is part of a tank circuit and will pass circulating currents as you stated. However, imagine you have a hobby type workshop in an unattached garage that is fed by a sub-panel from your house. Suppose it's an older garage with a not-very-large service. What could happen if the Power-Save 1200 is installed at the service in the garage is that current would be lowered between the house and the garage. So without the gizmo the current used in the garage could approach the limits of the service in this hypothetical case. Add the 1200 and it will be reduced as it claims to. Might not save you money on power useage but it could certainly improve voltage drop on the run between the house and garage.
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However, this could then also allow any inductive load in the house to cause circulating current on the wires between the house and the garage. Power factor correcting devices should always be installed at the load in my opinion. Technically your neighbor could have large inductive loads and the gizmo you have installed in your house would be helping correct them.