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Trying To Understand Pf Further


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#1 Daniel Martin

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Posted 06 July 2007 - 06:24 PM

My Name is Daniel Martin I am a senior Environmental Studies major at SSU in CA.

I recently started a company with 3 friends selling Power Factor correction devices. However I have a tremendous amount of integrity and when I started to dig deeper into this technology I just came back with more and more and more questions.

There are 198 Power Companies that I know of in the United States, from what i had read on this website it sounds like almost NO residential customers, will save money from PF correction because very few Power Companies fine residential customers for PF. Is that true? If so is it just random chance that has had some people come back to me saying there bill went down 20% ?

The product we are being supplied is UL and CSA certified, does that really mean nothing in terms of savings?

What about Over PF correction, to what extent is that possible, we have two major models of units both use GE self Heeling capacitors inside I was told, both are installed at the breaker box to a dedicated breaker.

What about Harmonic problems? i have heard that these devices can have issues with PF correction, how do I insure that they do not?


"·Adjustable speed drives, variable frequency drives

·Induction furnaces

·Uninterruptible power supplies

·Switch mode power supplies

·Programmable logic controllers

·Computers "


I have spent a good deal of time talking to the Dean of the Energy Dept at my university and it while she says, yes they will save power somewhere, it is very hard to predict how much. The company video shows PF correction of massive proportions on the main line of both a residence and of a gas station. Also very large AMP drops, which I found out do not mean anything, since those amps were out of phase to begin with, correct?


What are the realities of selling only three phase units that are not sized to the correct specifications, I was told they are GE self heeling stepping capacitors, does that make a difference?

Please tear this website apart and tell me what you think, everyone?
The product we sell can be found on the corp website, http://www.power-save.com/

As a start up company we already have hundreds of companies who want to buy these from us NOW, large chains like 400 hard wear stores, solar companies, electrical contractors, green websites,

Have we conned ourselves and them? Do they work? thoughts?

Thank you

Daniel Martin


#2 marke

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Posted 07 July 2007 - 06:52 AM

Hello Daniel

Generally, power is metered and charged in KW. In industrial installations, there is typically an additional charge for power factor or maximum demand current or maximum demand KVA.

Domestic metering is KWHrs only, so in order to achieve a reduction in the electricity bill, you need to reduce the KW consumed.

Power factor correction reduces the reactive current which results from the magnetizing current in motors and inductive balasts in lighting circuits (generally flourescent tubes).

The reduction in the reactive current, will reduce the total current flowing from the supply.

Current flowing down a length of cable will cause some losses in that cable due to the resistance of that cable. The losses are the current squared times the resistance of the cable. The length of cable in the domestic installation is pretty short and so the losses are very small. At worst case, the losses should be less than 5%.

If the power factor correction is fitted at the switchboard, it will only reduce the losses between where the capacitors are connected and the meter, usually in the same switchboard, so no reduction in the losses as seen by the meter. If the capacitors were fitted in the actual appliance, then the losses between the appliance and the supply meter would be reduced, but these would typically be so low that you would not register them. If these losses are significant, then the cable used is well undersized.

The major advantage of power factor correction, is that the current supplied over the network is reduced and so the losses in the network cables are reduced. - This is not metered on your domestic meter because it only measures the power on the downstream side of the meter.

So the answer is that power factor correction does not save energy that will be recorded on the domestic users meter.

Additionally, it is very important to fit the correct amount of capacitance to suit the reactive current in the load. If there is too much capacitance, then there will be a bad leading power factor. If the major motors are switching on and off, then the power factor capacitors must switch on an off also. Otherwise, the capacitors can actually increase the current.

For example, lets take a case where there is 10 amps of continuous load, and a motor with 10 amps reactive current and ten amps resistive current. The power factor of the motor is cos(45 degrees) = 0.707. The resultant current is the square root of (20 x 20 + 10 x 10) = 22.36 amps and the power factor is 0.89
If we now add 10 amps of capacitive current, the inductive current will be cancelled out and the current will drop to 20 amps, and the power factor will become 1.0.
If the motor is now switched off, and the capacitors remain connected, we will have ten amps of resistive current and 10 amps of capacitive current. This will result in a total of 14.14 amps and a leading power factor of 0.707. If we now remove the capacitors, the power factor changes to 1.0 and the current drops to 10 amps.

The demonstration video shows the current reducing when capacitance is applied to a motor. This does happen, but note the current into the motor remains the same. The KW drawn by the motor does not change. The video also shows the power factor improving, but nowhere does it show the KW being reduced.

If you have a power factor of 0.7 and a current of 14 amps, then adding the right amount of correction correction will reduce the current to 10 amps, and the power factor to 1.0, but the KW will not change.

KW = V x I x pf
KW1 = 230 x 14.14 x 0.7071 = 2.3KW
KW2 = 230 x 10 x 1.0 = 2.3KW No change.

Over correction is where the capacitive current is higher than the inductive current and will certainly occur if the capacitors are not controlled to match the load. The self healing capacitors are just capacitors that should not develop an internal short circuit.

To correctly apply power factor correction, you need to first of all ascertain if there is a power factor penalty being paid. This may be in the form of a power factor penalty or a maximum demand charge. If the bill is based on KW only, there is no advantage in adding pf equipment.

Next, you need to decide to either add the correction as static correction to each machine, or bulk correction at the point of supply. For more information, see http://www.LMPhotonics.com/pwrfact.htm

UL and CSA are standards covering the safety of the equipment and do not have any interest in the ability of the equipment to save energy.

Best regards,

#3 Daniel Martin

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Posted 07 July 2007 - 07:41 PM

Thank you so much for your detailed response.

It has most certainly helped everyone in our group to grasp the reality of this product.

My new question then is, what can be done? Why are these products sold so widely, why has no one placed a lawsuit against them for misrepresentation of their product.

What about the use of Stepping Capacitors? Are there any products on the market that do work that can be sold and installed relatively easily?

Thank you so much again

Daniel

#4 marke

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Posted 07 July 2007 - 09:11 PM

Hello Daniel

In this country, power factor correction is sold extensively and for the right reasons. I have not seen power factor products promoted for domestic situations.
There definitely is a market for power factor correction and there definitely are benefits from the use of power factor correction, but only where there is a penalty charge.
To work with the product correctly, there is a relatively high engineering input required. Each application needs to be analysed and engineered to suit.

Have a good day,

#5 kens

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Posted 08 July 2007 - 11:54 PM

Hi Daniel, as Marke has said, the domestic account is charged on kilo-watt-hours. The makers of this device and many others like it will always speak about current. In the literature on the website is the university study (http://www.power-sav...-Save_study.pdf)which is written in a favourable manner but must be read carefully.

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Note that the only claim that is made concerning energy savings is reducing the losses between the meter and the device, just as marke stated earlier.

The other thing which is fairly common is the claim that power bills have reduced. This can also be misleading as my March power bill will be different to my July power bill simply because the weather is different. The only way to show savings is to put this device on a specific installation and show the changes on a kW meter. If you reduce the kW load then you are saving power. This will translate into kWh savings and therefore $$$ savings at a domestic installation.

The device will save some losses on the distribution networks so in a way they are helping to save energy but at the household level I for one would not promote them with a clear conscience sad.gif

Cheers

Ken
An expert is one who knows more and more about less and less until he knows absolutely everything about nothing

#6 Daniel Martin

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Posted 09 July 2007 - 02:13 AM

What about there industrial units, those would not be worth selling from what I understand as well. Because they could do damage if they are not sized correctly is what I understood.

This company and many others unless I am mistaken are all liable for falsely representing their products promising 10 percent savings or more!

Thank you for the ongoing commentary.

Daniel

#7 marke

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Posted 09 July 2007 - 06:57 AM

Hello Daniel

Industrial units are worth selling, but they must be engineered to suit the application.
Used correctly, there is worthwhile savings and good paybacks, but you need to be electrically competent in order to understand and engineer the installations.
Oversizing with static correction can cause major problems and damage. Oversizing with bulk correction can result in a high capacitive current and no savings except where the bulk correction is automatic.

As I mentioned earlier, there is a basic description on my web page. Additionally, I have an electrical calculations software package that will help to size the capacitors provided you understand what you are doing and have sufficient information on the application.
The program can be downloaded from http://www.LMPhotoni...om/busbar32.zip

Best regards,

#8 jraef

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Posted 09 July 2007 - 06:50 PM

QUOTE
My new question then is, what can be done? Why are these products sold so widely, why has no one placed a lawsuit against them for misrepresentation of their product


The answer is, who is going to start the lawsuit? A residential consumer? If he bought one, it inherently means that he did NOT understand the entire concept. If so, then how is he to know that it did nothing for him? If I bought one, I would know in advance that it was not going to be of any benefit, so I would be doing it just to prove them wrong. Then to sue them for fraud, I could ask for maybe treble damages? So if I spent $100 for this magic box, sued them and won, I'd get $300.00, but would have paid $5000 to a lawyer for the fun of it all! I have better things t do with my time. As for the CPSC or some other organization suing them, that takes years to get pushed through. They will be long gone by then.

Essentially, these companies are experts at preying upon the misinformed and unsuspecting. They pay lawyers to craft their wording so as to be technically correct but effectively misleading. It's a shame to be sure but, hopefully, market economics will eventually take care of them. They can only survive by finding new customers because most people are never going to buy twice. Once they start to saturate the market for sucker end-users, they use their old end-user market data to lure unsuspecting distributors. A few are now making quite a nice living by sucking in "exclusive" distribution deals that entail large stocking requirements. The poor distributors have no idea that they must become charlatans to survive, and many, like yourself, simply choose to get out when they figure it out. Either way, the manufacturer made his sale doesn't he?!

The rise of quick and easy advertising via the internet has lead to a resurgence of these kind of companies, but that will hopefully also be their demise as more and more people using search engines find websites such as this that speak the truth.

By the way, as to the industrial uses, sure they offer benefits. That's why you will find large mega-industrial electrical suppliers such as GE, Eaton, ABB etc. all selling power factor correction capacitors. If you were to try to enter that market, you could possibly slice off a niche of under served small industrial customers, but the big boys are already well entrenched wherever there is big money to be made.


"He's not dead, he's just pinin' for the fjords!"




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