Voltage Optimisation

[DavH]

What are peoples thoughts on the glut of companies jumping on the CRC bandwagon and offering voltage optimisation equipment. I have been approached by one of these companies, and reading there glossy literature (and between the lines) it seems that voltage reduction and addressing power quality issues (Power factor & harmonics) would have the same effect.

What are everyone's thoughts in the benefits (or not)?

 

[rbulsara]

May be you should join them to write their literature! I cannot make out head and tail of your post.

What do they do and what benefits do the claim? What is a CRC bandwagon or even voltage optimization?.

Rafiq Bulsara

http://www.srengineersct.com

 

[DavH]

Rafiq - Sorry re-reading I was not very clear.

Follow link as prime example-

http://www.powerperfector.com/Downloads/general/Rebranded pP brochure 10 09.pdf

In UK all large energy consumers have had to sign up to CRC (Carbon Reduction Commitment), there are a number of companies offering similar products to the attached which promise big reductions in energy usage.

 

[rbulsara]

Ahh...A quick browse tells me it is not worth reading.. but it's just me.

If you think it has some merit, find about 8 to 10 full sentences in there that makes technical sense or even a paragraph that says what their "technology" involves, put it on one page and re-post.

It says voltage optimization is not voltage reduction. Then what is it? It appears to indicate "benefits" that any resistive loads would see upon voltage reduction. Even for that there is no need for a new "technology".

Rafiq Bulsara

http://www.srengineersct.com

 

[waross]

The powerPerfector's main feature is its ability to optimise and improve the incoming voltage for a whole site and therefore cut energy costs. This reduces energy bills and also improves the efficiency of electrical equipment.

Gee, dropping the voltage to save energy.
Yes it may reduce costs. Reduced voltage heating may spread to load over a greater time period and lower the demand charges.
Some devices react to lower voltage by drawing more current, negating most of the benefits.
Interestingly, I once installed a set of auto transformers on a lighting panel to drop the voltage to the incandescent recessed ceiling lights in a department store. There was some energy saving, but the big saving was in the greatly reduced re-lamping labor costs resulting from the greatly extended lifetime of the lamps.
It may be cheaper to set the taps lower on your transformers. You may do this in small steps and monitor the savings. If issues develop you may go back to the last known good setting.

Bill
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"Why not the best?"
Jimmy Carter

 

[Skogsgurra]

A clear case of a company using customer's lack of knowledge to make good profit. If voltage is harmonized the way it should be, then PP isn't needed. Incandescent lamps are manufactured to have a decent life and good light/Wh efficiency.

Reducing voltage certainly prolonges life, but also reduces light output - which means lower efficiency.

For induction motors running below rated power, the power factor is improved when voltage is reduced. But the slip will increase (slip increase is proportional to voltage drop squared) so motors will have lower efficiency. Not exactly a CO2-correct way of doing it. VFDs are the correct choice.

Computer loads and other electronic loads (which we are getting more and more of) do not reduce current - current increases because the power drawn from the internal DC supply is constant and therefore I=P/U applies and a 10% decrease in voltage will cause an 11% increase in current. Wrong, there too.

If utilities do their job, the voltage level will be correct and nothing needs to be done about it. I would say that the PP operation and advertisment is dangerously near scam.



Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[ScottyUK]

Wow. They have discovered the transformer!

They claim their box of tricks modifies the reactances of certain loads. I'm still wondering about the validity of this claim - the rotor reactance as seen from the stator does change as slip changes, and slip in turn will vary with voltage. I would expect that any savings achieveable by a simple reduction in voltage could equally be had by choosing the right size motor in the first place.

I'm wondering why I might want to be running at a voltage around 218V, instead of a nominal 230V, as they claim I should be. Perhaps I want dull yellow lamps which last forever, motors which run hotter than necessary, and heating elements which take longer to reach setpoint. But really, I don't.

Possibly the harmonic and some of the power factor improvement is an incidental result of phase angle controllers running at a smaller delay angle (longer conduction angle) to compensate for the lower voltage?

I also wonder if they have considered that there is a huge installed base of 415/240V equipment within our aging industrial base, and much of that could already running 4.2% below nominal voltage if it is fed from the LV public utility supply, thus obtaining some of the pseudo-benefits of voltage reduction. A lot of hazardous area certification for motors in invalidated by operation outside of [±]5% of nameplate voltage - something else to think about!

With all that said, my domestic supply actually rides high, sitting at about 244V this evening. Maybe I need one of these things!


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If we learn from our mistakes I'm getting a great education!

 

[Marmite]

I think there are one or two misconceptions out there regarding the voltage of the low voltage distribution system in the UK. Harmonisation of supply voltage across Europe was a paperwork exercise. We were never going to nationally alter the supply voltage to suit Europe overnight, just like we won't be harmonising driving on the right hand side of the road. The real system voltage has never changed. There are thousands of existing transformers on the network giving out 250V at the substation, and the low voltage network is tapered so that you get around 6% drop at the end of a main. This means that the majority of customers receive far higher voltage than the harmonised nominal 230V. There is some merit in customers controlling the voltage, whether it be tapping the transformer or some other device. I know of several of the large supermarket chains here that have generated substantial savings by tapping transformers down where they are fed direct from a substation on the premises. My own Company is involved in trials of a device made by VPhase which is designed for domestic application and it has so far shown some promising results.
Regards
Marmite

 

[Skogsgurra]

It wasn't supposed to happen overnight. But two - three decades shouldn't be too difficult. Or is it?

As far as I know, it has been done in rest of the EU. And, if it is so good to have lower voltage - why can't you at least have nominal voltage instead of too high a voltage?

Comparing an adjustment of LV voltage to changing to right hand driving is really not a valid argument.

Scam it is. Tapping down transformers is the standard way of adjusting voltage and that is what most utilities and MV customers do. This company seems to be utilizing the slow voltage adjustment process as an aid to sell snake oil.


Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[ScottyUK]

Hi skogs,

Marmite is right - there's a massive amount of equipment on the UK network dating from the 1960s when the last big network reinforcement took place with assets being added at all levels from central generation right through transmission and down to the distribution system. Those assets were well-specified by the CEGB and old regional boards and for that reason many are in remarkably good condition. I doubt we'll see much equipment from this era lasting so well. The loss of load due to de-industrialisation has left many parts of the network ridiculously oversized for the load they presently serve, so they run cool and unstressed. It's difficult to justify replacement of transformers which have perhaps another 30 years of life.

As an example from the perspective of a private network operator, the site I'm working on at present has a 66kV intake from the DNO. Our 66/11kV transformers are nearly on bottom tap because our load is a fraction of what it once was here, and if we retire another processing train then we probably will be on bottom tap. We do have the option to drop to the -5% tap from nominal on the 3.3/0.415V transformers but that introduces an element of risk in operating a tapchanger which hasn't moved in nearly 40 years. I'd prefer to see the site voltage riding slightly higher than nominal rather than slightly below nominal because it eases starting with our large number of motor loads. We also would be in trouble with our hazardous area equipment at the lower voltage; it's easier to buy 415V equipment intended for the Middle East and other British-influenced places than re-equip the whole site.


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If we learn from our mistakes I'm getting a great education!

 

[waross]

A clarification;
The reduced voltage lamps in the department store were not general lighting, they were intended to highlight displays. The customer was happy with the color shift. Because these fixtures were installed in a high ceiling and the displays were then constructed below them, re-lamping was extremely labor intensive.
The cost analysis was based on the cost of re-lamping and the expected savings. The labor cost to change one lamp was so great that the customer didn't bother to calculate the energy savings. (This was back in the day of cheap Hydro-electric energy.)

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Skogsgurra]

Scotty and Marmite

I still cannot see why the UK should be so special. Or is it the usual 'conservative' thinking?

In the eighties, I visited a plant in Derby and went to a pub in the evenings. There, I talked to guys from the local papers printing press. We discussed technical problems in printing presesses and paper machinery when they said that 'the new press is running quite well now'. I asked when the 'new press' was installed. No one was sure, but they should find out. Next evening, I got the answer. It had been installed in 1934.

Last time I did work in the UK (last year), part of the equipment (motors and switchgear) was from 1954. So I can understand that there are some older installations. But, from what I have seen, it is not a good idea to cling to that kind of equipment just because it still works.

Anyhow, the Power Perfector is very near a scam. Can we agree there?

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[ScottyUK]

Oh yes, we agree there!


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If we learn from our mistakes I'm getting a great education!

 

[DavH]

Thanks for the replies. Confirmed my thoughts, might as well target specific energy issues rather than a dubious fix all. Tap settings and harmonics filters are the way we will go. Thanks again.

 

[stevenal]

Is VO really a scam? Here it is being promoted by a US government run utility:

http://www.bpa.gov/Energy/N/Utiliti...eness/pdf/ESUE_Rural_Feeders_Presentation.pdf

 

[Skogsgurra]

Voltage optimization is not a scam per se. But the way the Power Perfector is being marketed is.

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[jraef]

There have been many many posts on this subject in here and in other forums, the term "Voltage Optimization" is just a new euphemism for the 40+ year old technology that is the Nola Energy Saver. If you do a Keyword Search on "Nola" you should be able to find most of them.

While not a total scam, it has the high likelihood of being used as such by slick marketeers (rhymes with Privateers, another name for Pirates). The possible energy savings on the vast majority of applications are minuscule and yet, they cite a few of the very specialized applications that have demonstrable savings, exaggerate them by twisting the numbers and using terminology that most people don't recognize, then suck in both customers and investors. The latter are the main goal; most of these snake-oil purveyors do everything they can to grab investors and "distributors" but when the rubber hits the road, end users are very disappointed.


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