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Alternative to AE - P.F. Correction

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ignisuti

New Member
Does anyone have experience with any of the Power Factor Correction devices on the market?

I've been interested in adding an array of solar panels to my house and connecting them to a Grid Tie Inverter for the purpose of reducing my energy bill by 30%. However, I recently came across a much less expensive device that claims to reduce my energy bill by the same amount.(YouTube - XPower Lowers your Electric Bill up to 25%).

There are tons of these on eBay for less than $30. If these actually work, then I'll get just as much savings out of a $30 device as I would out of a solar array setup that costs thousands. That alone is making the little alarm in my head go off saying this sounds too good to be true.

However, the theory sounds plausible. They're simply correcting the power factor therefore improving the efficiency of inductive loads in your home like: Air Conditioner, ceiling fans, freezer, florescent bulbs, etc...
The other great thing IF these devices work is that they should prolong the life of many the electronics in the home.

Anyone have good or bad experiences with them?
 

tcmtech

Banned
Most Helpful Member
Yep I have one. Its another totally worthless 'Green energy' scam device. :(

Your house electrical power is measured by true power used not apparent power. The microscopic level of savings would take most of your life time to offset its purchase cost even at $30. :(

Now the solar panel and GTI system will at least give you a real avoided utility grid purchase number that can be measured from month to month.
However given the market value of factory built solar and GTI systems It will likely die of wind, hail, out of warranty failures or other damage long before its avoided cost pay back breaks even also.

Not always but more often that not the break even point on the purchase is about identical to its avoided cost payback time period assuming the system doesn't break down or need any maintenance by then which is very unlikely. :(
 

mneary

New Member
The YouTube video could be misleading - he does not say what he's measuring. From 60 down to 30 whats? Milliamperes? Methane? Watts? Volts? Power factor? Wires go everywhere without explanation.

Everything I've bought in the past 10 years has had a power factor of 95% or better. My TV has a 99% power factor. It's impossible to improve that.

I put a "power factor correction" device on my old Frigidaire refrigerator and it screwed up. The ice maker made a horrible noise; fortunately no permanent damage. My new Samsung fridge has a 96% power factor when the motor is running. In the US and EU, power factor of new electrics/electronics is strictly regulated.

And you cannot save a penny. Your residence is not metered for power factor. Residential power factor correction is more economically accomplished by the power company on a system wide basis.
 
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tytower

Banned
Yep I have one. Its another totally worthless 'Green energy' scam device. :(
Your house electrical power is measured by true power used not apparent power. The microscopic level of savings would take most of your life time to offset its purchase cost even at $30. :(
Now the solar panel and GTI system will at least give you a real avoided utility grid purchase number that can be measured from month to month.
However given the market value of factory built solar and GTI systems It will likely die of wind, hail, out of warranty failures or other damage long before its avoided cost pay back breaks even also.
Not always but more often that not the break even point on the purchase is about identical to its avoided cost payback time period assuming the system doesn't break down or need any maintenance by then which is very unlikely. :(

So I'm intrigued , what do the following statements mean exactly or what do you intend them to mean
"real avoided utility grid purchase number " and
"avoided cost pay back ".
Similarly "avoided cost payback time period"


"Cost" is a term familiar to all and is what you shell out
"Time " is another easy one
"Depreciation" is writing off cost over time
 

Papabravo

Well-Known Member
Seems fairly clear to me.
"real avoided utility grid purchase number" -- how much cost can you avoid paying the electric utility by installing device x?
"avoided cost payback" how much electric utility cost do you have to avoid to pay for energy saving device x?
"avoided cost payback time period" how long will it take for the avoided cost savings to equal the initial investment in device x.

Don't forget that taking the time value of money into account the answer to the last question may in fact be -- NEVER! It is the basis of all scams.
 
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tytower

Banned
So we are not talking about cost, rather about a saving
So The cost is for the device ?
And the saving is being compared to the device cost and how long it takes for one to equal the other ?

Well why not say " this device costs X and at a saving rate of Y dollars per month it would take z months to recoup your cost "

And I suppose the "time value of money is ..." , crikey! I give up , tell me.
 

tcmtech

Banned
Most Helpful Member
You bought an energy saving device for $100. Its saves you a $1 a month off of what you would normally spend in a month on electricity. It would take 100 months (8 years 4 months) before what it saves per month equals what you spent buying it. Thats the break even point on cost avoidance savings.

You have it hooked up and working but its warranty expires in 5 years. (60 months) In year six (72 months) it burns out. you just lost the remaining $28 you had spent on it. :(
Not only did it not save you anything over 6 years it cost you $28 more than had you done nothing for the 100 months (8 year 4 months) time it would have taken to break even. :(

You spend $56 to have it repaired since thats still cheaper than buying a new one. Now your new cost avoidance break even point is 156 months (13 years) from when you first bought it assuming it doesn't break again in that time. Which for anything but commercial and industrial electronics thats not a realistic operating life expectancy when used in a continuous duty application. :(

Thats how most solar and small wind systems for private use are set up unfortunately. Their avoided cost will pay for itself in about the same time period they are rated to survive for in near ideal conditions. :(
Realistically they break down and maintenance costs push the point of break even so far out that realistically no one will have actually saved anything but rather will have spent more than had they done nothing at all.
A commercial grade system may cost you 3 times more but may put out twice the power in the same size and have a far greater chance of living longer than its cost avoidance point takes.
 

audioguru

Well-Known Member
Most Helpful Member
You are ripped off if you pay $30.00 for a little capacitor that is not the correct value to improve your power factor. Businesses are billed extra for a poor power factor, not homes. The capacitors at a business match the power factor of the load.
 

ignisuti

New Member
I'm getting some mixed messages here. I can understand if you want to attack the cheapo units out there. If all their doing is attaching a random capacitor to the line, then that's pretty dumb.

But, what do you fellas think about the theory: That the correct amount of capacitance applied at the right time can significantly reduce (say at least 10%) your electric bill? I'm not yet convinced that such an endeavor wouldn't work. A motor can be modeled as a giant inductor. So when the motor is running, it pulls power from the grid, but inefficiently. It pulls more Real Power (what you're paying the electric company for) than it would if it had a power factor of 100%. So, if you give it a higher power factor, then you'd spend less money. Is this logic correct?

I can understand the argument that most appliances sold today already have a power factor near unity. I personally don't have enough experience to agree or disagree with this, but if you want to argue that point, I'll go along with it.
 

audioguru

Well-Known Member
Most Helpful Member
The electric consumption meters for homes ignore the power factor. The electrical utility pays for the inefficiency, not the home-owner.
Industrial factories are billed extra for a poor power factor so they properly calculate the size of capacitors to correct it.

People are selling useless very expensive ordinary capacitors to gullable people and they have ways to trick their demo meters.
 

ignisuti

New Member
Before I can agree with you, I need to understand if this logic correct or not.

A motor can be modeled as a giant inductor. So when the motor is running, it pulls power from the grid, but inefficiently. It pulls more Real Power (what you're paying the electric company for) than it would if it had a power factor of 100%. So, if you give it a higher power factor, then you'd spend less money. Is this logic correct?

A better power factor should allow your motors at home to pull less Real Power through the Power Meter and still get the same amount of Work done. Right?
 

audioguru

Well-Known Member
Most Helpful Member
A poor power factor increases the apparent current, not the real current.
Your home meter does not read apparent current.
Read about Power Factor in Google.
 

ignisuti

New Member
A poor power factor increases the apparent current, not the real current.

I disagree. A poor power factor means that you need more Real Current than you would otherwise if you had a good power factor.

Your home meter does not read apparent current.

Technically correct, but I must state again that a poor power factor makes you use more Real Power to run the same load of laundry. The Real Power is read by your home meter. Therefore, you end up paying more on your electric bill because of the poor power factor.


Read about Power Factor in Google.
It's been awhile since I learned about Power Factor in school. So, I took your advice and Google'd it to make sure I wasn't making stuff up. I found several sites that supported my understanding of Power Factor.

POWER FACTOR CORRECTION - I like the horse diagram as it really simplifies the issue.

**broken link removed**
Here is a direct quote: "End users should be concerned about low power factor because it means that they are using a facility's electrical system capacity inefficiently.....Most importantly, low power factor can increase an electric bill with higher total demand charges and cost per kWh."


So, I think power factor correction is a good thing if you're running at less than 95%. That part is debatable because many devices today may already have a high power factor. Another debatable part is whether or not, you run the inductive loads in your house (A/C, Refrigerator, Washer/Dryer, Fans, etc...) enough to even justify the cost of power factor correction. Lastly, I'd like to better understand tcmtech's claim saying that the one he bought was worthless. Was it worthless because it was just a random capacitor inside that wasn't matched to his house's needs? If so, I don't think it'd take a ton of ingenuity to monitor the AC line in your house and build a circuit that switched in the correct combination of capacitors based on the current need for power factor correction.
 

smanches

New Member
How would poor power facter affect real power?
 

ignisuti

New Member
Why all the fuss, you're not charged for PF in a home.

By what means to you suggest these sources are unreliable!? It's been several years since I was in school, but these sources are consistent with my education as an electrical engineer.

Why all the fuss, you're not charged for PF in a home.
Please read my last post more closely. You're indirectly charged more because you use more Real Power to get the same tasks done in your home if you suffer from a poor power factor.

I'm trying to state my sources and be as factual as possible. Are you guys suggesting that my statements are my opinion? I believe they are facts (laws of physics which can't be disputed). I'm open to the idea of being told that I'm wrong or ignorant, but please respond with constructive information I can learn from if that be the case.
 

blueroomelectronics

Well-Known Member
Ahh I've never seen a Reactive Power Charge on my Hydro bill. Guess it's a local thing.

Here's my prediction, lets say you fix all your reactive power inefficiencies in your home and lets say the whole neighborhood. I'd be willing to bet the charge won't disappear of your bill.

PS I'd stick with putting up solar panels and a GTI.
 
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ignisuti

New Member
Ahh I've never seen a Reactive Power Charge on my Hydro bill. Guess it's a local thing.

Here's my prediction, lets say you fix all your reactive power inefficiencies in your home and lets say the whole neighborhood. I'd be willing to bet the charge won't disappear of your bill.

PS I'd stick with putting up solar panels and a GTI.

It seems like everyone is against me. So, I must conclude that I'm not doing a good job of explaining myself. Let me try again...

There is NO Power Factor or Reactive Power charge on my electric bill. I'm charged for Real Power like all of you. However, if you have a washing machine with a poor power factor, you end up using more Real Power to run one cycle than you would if you use the correct amount of capacitance to improve the power factor. I don't think this is disputable. I believe it is a fact and there are many websites that confirm this.
 
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