# POWER SAVER N/T



## Madman (Jan 5, 2008)

I'm sure most of you have seen articles about these power savers. They are supposed to reduce electrical consumption by storing power in capacitors. That's where my understanding of them stops. How do they actually work?


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## Greg Elmassian (Jan 3, 2008)

Do you have a link or example? 

Greg


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## Madman (Jan 5, 2008)

That would have required too much thought







, thanks Greg. These things include a surge protector.


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## DKRickman (Mar 25, 2008)

So... adding extra components (which according to the laws of physics must be LESS than 100% efficient) is supposed to INCREASE overall efficiency? Or have they managed to figure out how to store alternating current in a capacitor? 

I can only see two realistic ways in which a capacitor could do anything useful IN THEORY. One would be that they are somehow supposed to smooth out the demand. The only trouble with that is that it doesn't matter, since your meter should be doing the same thing. The other would be to store energy during off-peak hours for use during peak hours. Trouble with that it, it would take a MUCH larger capacitor or battery bank than shown in that picture. Oh, and both of the above would require a rectifier and inverter large enough to handle ALL of the power that you will ever use in your house. To meet code, that means a full 200A (2.4 kW) rating, and those are expensive. The device pictured is rated at only 220V/7A - 1.44 kW 

Of course, it could be a device intended to somehow trick your meter into running more slowly. In that case, it doesn't actually change your power consumption, it merely defrauds the power company. I doubt such a device would be legal, and even if it were, it wouldn't take the power company long to fix the problem. 

I'm no expert, but that device just doesn't fit my basic understanding of anything rational. It sounds like a great way to make money, though - just like all those wonderful fuel economy boosters that add hydrogen, or make the air swirl, or tap into so extra-terrestrial power, or some other similar garbage. A fool and his money...


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## kormsen (Oct 27, 2009)

i could see one use for it. 
if the powercompany is as bad as ours here, at changing from one source to the other, everything "blinks out" for a moment. 
that could be bridged. 
so the energy consuming restart of tubes etc. could be evaded.


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## Semper Vaporo (Jan 2, 2008)

Posted By DKRickman on 25 Jan 2011 06:49 AM 
So... adding extra components (which according to the laws of physics must be LESS than 100% efficient) is supposed to INCREASE overall efficiency? Or have they managed to figure out how to store alternating current in a capacitor? 

I can only see two realistic ways in which a capacitor could do anything useful IN THEORY. One would be that they are somehow supposed to smooth out the demand. The only trouble with that is that it doesn't matter, since your meter should be doing the same thing. The other would be to store energy during off-peak hours for use during peak hours. Trouble with that it, it would take a MUCH larger capacitor or battery bank than shown in that picture. Oh, and both of the above would require a rectifier and inverter large enough to handle ALL of the power that you will ever use in your house. To meet code, that means a full 200A (2.4 kW) rating, and those are expensive. The device pictured is rated at only 220V/7A - 1.44 kW 

Of course, it could be a device intended to somehow trick your meter into running more slowly. In that case, it doesn't actually change your power consumption, it merely defrauds the power company. I doubt such a device would be legal, and even if it were, it wouldn't take the power company long to fix the problem. 

I'm no expert, but that device just doesn't fit my basic understanding of anything rational. It sounds like a great way to make money, though - just like all those wonderful fuel economy boosters that add hydrogen, or make the air swirl, or tap into so extra-terrestrial power, or some other similar garbage. A fool and his money... 

I agree. "Snake Oil" is another name for it!

As a kid I knew a couple of fellows that worked for the electric company. Their job was for one of them to find a way to bilk the electric company of power and then the other one had to find a way to discover how it was done so as to stop it. One method of doing it is to resonate the house by adding large capacitors across the incoming power line. Get the house perfectly resonated at the power line frequency and the meter can be stopped while power is still being consumed. The electric company frowns upon doing such things and will disconnect (and sue for fraud) any customer that they discover doing it... and it won't take them long to discover it.

The most common methods used are to put jumpers across the meter or tap into the power lines on the incoming side of the meter. They can discover those pretty quick, too.


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## Semper Vaporo (Jan 2, 2008)

Posted By kormsen on 25 Jan 2011 08:31 AM 
i could see one use for it. 
if the powercompany is as bad as ours here, at changing from one source to the other, everything "blinks out" for a moment. 
that could be bridged. 
so the energy consuming restart of tubes etc. could be evaded. 

Capacitors alone won't do for that. Capacitors store Direct Current (DC), and the power lines are Alternating Current. Capacitors are kind of like a battery, or a rechargable battery, it is just that they cannot store all that much energy so as to release it slowly over time the way a battey does. AC power is changing direction 60 times every second (in North America, anyway), so a capacitor across the line would be charging in one direction and then discharging only to charge in the opposite polarity at the same rate. There would be times (120 times each second) where the capacitor would have no energy stored in it at all! Power line glitches that occur when the power company changes sources can take more than 1/60th of a second to occur, so even if the capacitor were at full charge at the instant the switch-over started, it would lose all of its charge long before the gap in supply were to be terminated by the re-application of power at the end of the switch-over. You'd still see the lights blink. Besides, most of the time the capacitor would not be at "full charge".

Now, if there were a power converter to change the incoming power from AC to DC and that used to charge the capacitors (or better yet, rechargable batteries) and that power then used to supply a DC to AC power inverter to convert the power back to AC then there is some merit to that.

In fact, you can get a device that does just that, and it is known as a "Non-Interuptable Power Supply" or "Un-Interuptable Power Supply". Many people buy these devices to run their computer from. They contain, not a capacitor, but a rechargable battery and will often supply power for a computer long enough for the user to perform an orderly shutdown and thus save any work being done at the moment of a power failure. They also smooth-out the little power line glitches that WILL occur right between the time you have entered some really important piece of data in to memory and the time when you go to store the data on the computer's long term storage (hard drive).


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## kormsen (Oct 27, 2009)

thanks. and yes, i know and use the UPS things.


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## DKRickman (Mar 25, 2008)

On resonance with a capacitor:

A capacitor coupled to an inductor will resonate at some frequency, depending on both the capacitance and inductance. Since a house's wiring will have some natural inductance (as well as capacitance, no matter how small) and any device with a coil (transformer, motor, etc.) will have inductance, theory says that a capacitor across the terminals should cause the system to resonate at some frequency.

Now, that's theory. Whether it works in practice is another matter. It would depend on being able to determine the EXACT inductance and capacitance of the house, which would vary depending on what was plugged in, and what motors were running. I suspect that it reality it would be all but impossible, and possibly even counter-productive. If you were able to make the house resonate, and thus store a very small amount of AC, it could potentially shock somebody working on the house wiring, even when the main breaker is off.

Also, just for fun, how about a little math? The picture apparently shows two 40F capacitors in the system - totaling 80F. A capacitor will charge by one volt per farad per amp second - meaning that an 80 farad capacitor will charge from 0 to 220 volts at 7 amps (the stated rating on the device) in 31.43 seconds. It will also discharge that quickly. Your house is probably on a 200 amp circuit, and you're probably using 20 to 50 amps at any given time. At that rate, those same capacitors will fully discharge in about 10 to 20 seconds. Of course, that's a full discharge, which is useless for your purposes. A capacitor's discharge is not linear, but falls quickly, followed by a long taper to 0. Voltage is allowed to vary slightly - by a few percent - but even assuming that you could have a 20% drop in voltage without noticing, those capacitors only store enough power for a couple seconds of normal use.


In other words, they're useless as a UPS, even if they did have some sort of resonating circuit or inverter to generate usable AC. Since they can't store useful amounts of power, and they can't modify the current in the line in any useful way, I really don't see how they do anything other than enriching the people selling them.


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## Greg Elmassian (Jan 3, 2008)

There is actually something to this. The technique is correcting the power factor. 

Basically this is when the current and voltage get out of phase. Normal resistive loads do not affect the power factor, but inductive loads, basically motors, do. 

Capacitors are often used to "correct" the power factor (lag between voltage and current phases). 

_Done correctly_, it can reduce overall power consumption. (basically what your electric meter sees).

Also, there are things called "motor savers" you have seen in the stores, that by correcting the power factor, allow the motor to run on lower current. 


So, it's real... I suggest googling "correcting power factor" and you will get all the technical details. 

Here's a relatively straightforward explanation: *http://www.energyideas.o...trong>**

Regards, Greg*


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## DKRickman (Mar 25, 2008)

Posted By Greg Elmassian on 25 Jan 2011 10:25 AM 
Normal resistive loads do not affect the power factor, but inductive loads, basically motors, do. 

Capacitors are often used to "correct" the power factor (lag between voltage and current phases). 

_Done correctly_, it can reduce overall power consumption. (basically what your electric meter sees).


True, but I submit that the vast majority of an average home owner's electricity usage is not going into a motor. As such, while correcting the power factor is definitely of use to an industrial user, I doubt it would do much for a residential user. I wonder if it would really make enough of a difference to pay for itself in any reasonable time?


Also, mea culpa. I completely screwed up my math above. Let me try again, before somebody else corrects me.  

An 80 ohm capacitor will charge one volt in one second with 80 amps of current. 7 amps will take 11.43 seconds to increase the charge by one volt, thus it would take 2514.29 seconds (just under 42 minutes) to charge completely to 220 volts. Discharging 11 volts (5%) would take approximately 44 seconds at 20 amps, or 17.6 seconds at 50 amps.


Thus, there would indeed be enough capacity there to smooth out power surges - assuming that it had an inverter capable of converting the very pure DC in the capacitor to the AC needed by everything you plug in.


Now, looking at the photo, it indicates that it is designed to work at 50 or 60 Hz. The only way that makes sense to me is if Greg's assumption is correct, and this is designed to correct the power factor rather than smooth out surges and momentary losses. SO it may not be as much snake oil as I had originally assumed, but I still question whether or not it is really worthwhile for a residential load.

*
*


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## Madman (Jan 5, 2008)

Greg, If I understand you correctly, then what you are saying is that this thing might be of some value. At $120.00 to the door, it is not that expensive. I checked with an electrician friend, and they are going for $500.00 installed professionally. He installs quite a few of them each week he claims. 

Ken, in my case I have a well pump, boiler circulators, washer dryer, garbage disposal, pond pump, numerous stationary power tools in the shop, and other miscellaneous stuff that uses a motor. I agree that the average person probably has nowhere near the number of motored items that some of us do. 

So what you are saying is that these things may smooth out the waves, so to speak, in the usage of electricity?


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## Greg Elmassian (Jan 3, 2008)

I would refrain from trying to characterize it differently... I'd either use the technical description, which is accurate, or just say, the effect saves electricity. 

There's no smoothing going on, as a filter capacitor in a DC circuit does. 

Capacitors have different effects depending on AC, DC, the "size" of the capacitor and the circuit. The misconceptions in this thread assume mostly electrolytic capacitors in DC circuits. 

These are non-polarized capacitors in an AC circuit. 

Regards, Greg


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## SteveC (Jan 2, 2008)

Greg

Isn't this basically the same thing that had to be addressed in commercial/industrial settings with the advent of the rapid increase in the number of micro-computers in the work place. Which caused problems with utility power transformers over heating because of the collective harmonic distortion caused by the non-linear characteristics of switched-mode power supplies?


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## Greg Elmassian (Jan 3, 2008)

I don't think so, because degradation in the power factor, i.e. the shift in phase between current and voltage, normally comes from inductive loads. This is normally motors, especially during startup. 

Microprocessors are always driven by a regulated supply, normally a switcher, and present a constant (average) load to the supply side, thus no inductive component. Basically you are running an oscillator. 

I have to profess that the term harmonic distortion, which I am familiar with, as applied to AC power does not seem to apply to any line side load presented by switched mode power supplies. Harmonic distortion caused by the load on the AC lines would normally, again, be presented by inductive loads. I'm really at a loss as to what non-linear characteristics of a switched mode power supply you are referring to, as applied to the INPUT of the power supply, which is the "side" that would have to affect the supply (line) side. 

Again, the goal here is to reduce the power used at the "meter" so as to save money. 

Can you fill an explanation of your last sentence? 

Regards, Greg


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## SteveC (Jan 2, 2008)

Greg

Not exactly what I was looking for but it should give you an idea.

Overheated Transformers & Neutrals[/b]


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## Greg Elmassian (Jan 3, 2008)

Wow, interesting. So in a three phase distribution system, the common neutral was carrying a lot of current, because, as you stated, of the harmonic distortion caused by the PC power supplies. 

In a single phase system, I believe you don't care, this problem was the unequal potentials between the 3 different distributions systems and the common neutral between them. 

But, I would agree, the harmonic distortion does do some strange things to current, so the real question is what is this effect on your house meter, and what, if any, inefficiency is caused to your appliances. 

I had no idea that the switching power supplies were using power in a way that the current drawn caused harmonic distortion of the power source. 

Learn something every day. 

Would be interested in real world tests on reading your electric meter, that's really the bottom line to us, but it's true that messing up the supply voltage can cause extra charges for commercial customers, certain power companies measure the power factor and charge for having a "poor" one. Have not heard this regarding residential. 

Thanks Steve! 

Regards, Greg


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## SteveC (Jan 2, 2008)

Greg

I'm not trying to say that this would necessarily be a problem in the residential arena, but one thing to remember is that there are very few if any residential structures that aren't wired as "split phase" (i.e. 220v service / two phases and a neutral). Which for example is the reason that most all electrical distribution boxes/panels are designed for balanced loading of the service drop (i.e. every other breaker on a given side is wired to the opposite phase, and I believe the other breaker bank (if one exists) is also wired so that breakers across from each other are on opposite phases).


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## Greg Elmassian (Jan 3, 2008)

Yep, I agree completely, of course that's "your" neutral that could be carrying extra load. 

The big question is does this harmonic distortion cause extra power consumption, and consumption that is measured by your meter? 

I read several discussions that the power factor problem (voltage out of phase with current), which the "Power Saver" box addresses is not detected by a typical residential meter. 

That's the bottom line in terms of if one of these will help. 

Very interesting subject. 

You're a scary guy Steve! (meant as a compliment) 

Greg


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## SteveC (Jan 2, 2008)

Greg

I realize it's a simplistic view, but as I see it if you've got heating (e.g. neutral and/or transformer) then power has to be being consumed.







As to whether the meter reacts to this in any way good or bad I don't know, yet, but then I'm still looking around. The one thing I'm quite sure of is the information won't be found on any power utility web site.


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## Greg Elmassian (Jan 3, 2008)

Absolutely, the simple law of conservation of energy makes that clear. Of course, you need a lot of heat to notice a significant power loss... 

I think in our homes, we don't have this problem, otherwise your main panel would be hot! Watts is watts. 

It's the question of significant power loss/heat... 

I have seen "motor savers" show a lower current drain, but they run the motor at a reduced power, so it's not black magic. 

The theory there is that as long as you have enough current to start the motor, the motor will continue to run and operate the appliance at a reduced power (both horsepower output and current consumption). 

But I digress, I don't believe this is the aim of the product that this thread was started with, I believe this product attempts to correct the power factor. 

Regards, Greg


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## John J (Dec 29, 2007)

I remember there was a company running around phoenix putting power savers on air conditioners. It had a demo box that showed a Fan motor ran smoother on their power saver then on strait power.

I think but not sure they used the peak portion of the sign wave by controlling SCRs or something.

I think it shortened the life of the motor.

One of my customers printed the brosure for the device. He did a lot in Spanish. I think the sold a lot of these in Mexico 

I am not comfortable with this device


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## Greg Elmassian (Jan 3, 2008)

You know JJ, there's another law of "practical" physics, "you never get something for nothing".... the "breakthrough" 300 mpg carburetors, the magnets on the fuel lines, all that stuff, if it worked, the major manufacturers would have already embraced it. 

There's also ways to "fool" a measuring device... 

So, it's wise to be suspicious of "miracles"... measuring the facts is best. 

Regards, Greg


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