Voltage Optimisation for the Home

[Ashley Cawley]

A question I feel Justin might be qualified to answer!... I recently stumbled upon this thing called VPhase, which does 'voltage optimisation'? Regulates an incoming voltage of around 245V to a steady 220V by the looks of things and saves you money.

Any good? Anyone experience of them? - http://www.vphase.co.uk/




http://www.youtube.com/watch?v=QqgK29XRfhc

[Martin]

We looked at this at work. Looks like a good idea on paper but depends on what your incoming voltage is. The further you are from the supply, the lower your base voltage is.

I also have a problem with the claims that are made as my limited knowledge tells me that if you lower the voltage but keep the current the same you must therefore reduce the power that the appliance operates at. It's a simple (O level) law of physics.

The simple fact is, you don't get nothing for nothing. If it was really that good then everyone would be doing it, wouldn't they?

Martin

[Ichneumon]

I quote from their web page:


The VPhase unit reduces and stabilises the voltage at the property to a level within statutory limits but below the voltage that is usually supplied by power companies, in the UK the VPhase output is typically 220V. This elimiates 'over voltage', which is a costly and unnecessary waste of energy and ensures many electrical appliances use less electricity and cost less to run, as well as cutting carbon emissions.

This is conveniently vague as I does not specifically say the it will stabilize the voltage to 220. The rest of their page is equally vague and their technical pages talk a lot of semi-nonsensical techno-babble. Hidden in the small print it strongly infers that it will drop the voltage by a fixed amount rather than stabilise it at 220v

Based on this I strongly suspect that it is acting like a step-down transformer (I can see from the pictures that it is not a simple step-down transformer). This is fine and will certain drop the voltage but the output voltage relies on a consistant over-voltage input. Typically they would use an approx 8% reduction which will bring 240v down to about 220v (give or take).

All electrical products sold in the EU marked with the CE logo are designed to work at the EU nominal voltage of 230v +/- a tolerance. The bureaucrats set these tolerances such that the UK and other EU countries could continue supplying at their old individual voltages - in the case of the UK 240v and 220v for most of the continent. In other words: In the UK we generally do have a consistant over-voltage for these appliances.

If this is working in the way I suspect, disaster stikes when the supply voltage drops. If the supply voltage drops to, say, the nominal 230v that it should be this device will reduce it to 211v which is below the CE minimum of 216v.

Some devices would definately benefit from a lower voltage - old incandescent light bulbs are a good one. But as Martin has pointed out - you don't get aught for naught (and much for sixpence)! Watts(Power) = volts x amps: So, at the lower voltage, your electrical kettle will just take longer to boil the water (less for longer = the same). Other devices, ones with power supplies in them, like this computer, will consume more current to compensate for the drop in voltage and may actually run hotter because they have to work harder.

Is this likely to save money and the planet? If used selectively with the right appliances it would probably save a bob or three - IMO. Will it pay for itelf? Dunno, I couldn't find a price for one. Would I buy one, even if they are cheap?...........Nah! :)

[jus_young]

Some interesting points so far, how about the science bit first… :D

We are generally used to everything having a power rating which is made up from voltage x current. The assumption is that if you reduce the voltage then the current has to increase to compensate so therefore you would not save anything, but we need to take a step back first.

Using Ohms Law - Voltage = Current x Resistance. If the internal resistance of the appliances does not change then a reduction in the voltage will also have the affect of reducing the current to some degree. Once you have used this equation to gain the voltage value it is then that you apply P=IxV. So in theory you should then find that savings can be made through reducing the voltage to your appliances.

Now the other bits…

The VPhase cannot be used on circuits with elements so your shower, cooker, immersion, electric heating circuits, high powered tools… This is obviously going to impact on the savings that can be made and the reason for these limitations is that the unit cannot sustain a load of over 20Amps for any real period of time. :confused: So when you start looking at the costs involved for one of these units (£250 + VAT + fitting) then you are looking at a long term investment. Various figures are being thrown around with regards to the money that can be saved but VPhases figures of £56 per annum average savings means that an eco friendly home is still going to be looking at 5 or 6 years payback period. But, to be fair, these units have been installed in Housing Authority stock as a means of monitoring the benefits and it was shown that savings could be made.

My concerns are however that although there is energy being used from many electronic appliances that could be saved, there are plenty of homes out there that use motors within the installations either through appliances or water treatment/sewage treatment plants. It is a well known issue when it comes to motors that voltage loss is bad!! It has the effect of shortening the normal lifespan of the motors and appliances and leads to some costly repair costs, a situation I come across all the time due to incorrectly sized cables feeding motors that have burnt out due to excessive volt drop.
I think its still early days yet on this one and the benefits still need to be proven. Personally I think that a well thought out energy saving plan, energy efficient appliances and maybe the use of some ingenuity could save you a lot more money than paying out for one of these.

Hope this helps, pleasure as always.

Head hurts now...

[Ichneumon]

Sounds like we are singing from the same hymn-sheet Justin. There is nothing in your general arguement and conclusion that I disagree with - in fact we concurr.

However I question the science part. This is what you said:


Using Ohms Law - Voltage = Current x Resistance. If the internal resistance of the appliances does not change then a reduction in the voltage will also have the affect of reducing the current to some degree. Once you have used this equation to gain the voltage value it is then that you apply P=IxV.

I submit that you are using Ohm's Law in the wrong format. The voltage is the voltage, either with or without VPhase - it is what it is. The resistance is also fixed (thermal and other variable effects ignored). So the formula should be used in the format I = V/R. As the voltage and resistance are fixed it must be the current that changes. To achieve the same amount of power - using the formula P=IxV - the current must increase.

This really only works with resistive loads - as we have both pointed out. The VPhase would not help for such devices. So, to some extent, all this is academic.

I used to work on micro-hydro electic systems. Small hydro power plants supplying enough AC power to supply a house, farm or even small village in the Third World. We consistantly set the voltage a tiny bit low. Not because it saved money - the power was free - but because it prolonged the life of appliances. Too low and, as you say, things start to go belly up.

Just out of curiosity: Have you any idea what they're talking about when it says in their technical spec that - VPhase only converts and transforms the 'anti-phase' component of the voltage? I understand all the words but not what they mean. Ideas? See here:- http://www.vphase.co.uk/getattachment/Trade-Zone/Info---Downloads/074---VPhase-Technical-FAQ.pdf

So, to sum up, we agree! We just got there by different routes. :)

ATB

Paul

P.S. If anybody is interested in small scale hydro power please direct questions to me. If I don't know the answer, I know somebody who does. :)

[jus_young]

Admit the format is wrong - I was watching Bear Grylls and Jonothan Ross at the time so didn't transpose the formula. I was only going for the nitty gritty as opposed to going too heavy, as we know it takes years to become a sparky :rolleyes:

Thats an interesting document you have linked to. They state in their literature that the unit can only sustain 16 Amps for a short duration. With regards to the 'anti-phase' element, I assume they mean the negative side of the waveform. I have heard of the term used this way before but its not common terminology down this way at least!

Nice to know we have a hydro boff on the forum. This is one tech that I have had little to do with to date. Other techs not such a problem so may pick your brains at some point.

[Ashley Cawley]

Thanks guys! Some really useful points there - sorry we got your head hurting Justin! I almost felt the same reading your calculations! :p

Not that it offers any great technical detail but it looks like Dick Strawbridge had one installed and were selling them via their eco website, although I can't seem to see it on his website now...



http://www.youtube.com/watch?v=WrjIaNjJ-_k



I'm not particularly interested in buying one of these units, I just thought I'd better check I wasn't missing out on a good trick though! Thanks for everyones input.