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[roseway]

British Gas and Southern Electric have teamed up with a company called VPhase to trial a unit which is said to save energy usage by controlling the mains voltage at the reduced level of 220V. The company claims that many electrical devices are optimised for working at this voltage. They refer to things like fridges, freezers, central heating pumps and (of course) lighting.

I find it hard to believe their claims. Pumps used in fridges, etc., will run more slowly at the reduced voltage, and will therefore have to run for longer to do their job, so where's the saving? Tungsten bulbs will certainly last longer at reduced voltage, but will produce less light; energy saving bulbs will produce less light. Electronic equipment using switch-mode power supplies (i.e. nearly all such equipment) will simply adjust its operation to take slightly more current at the lower voltage, for the same power output.

Am I missing something?

[oldfogy]

Unfortunately there is no date on the link supplied.
But this was discussed a "log time ago" (years ago) and was dismissed by industry as not being a viable option.

However, from the link above I see it is now being marketed mainly to the domestic sector at a price of £299 "plus installation"

As with energy saving devices "which are not money saving devices" I expect this will get the same response.

[roseway]

There's a link on the site to a recent BBC programme which was effectively an advert for the device (thanks, BBC! )  I found out about it from a promotional insert in the paper a few days ago. So it seems that they're pushing it hard now, and no doubt many people will be 'persuaded'.

[orainsear]

Am I missing something?

No I think I'd agree with you.  Although there are many different devices in the house, and some will react differently to others, energy usage will remain pretty much the same irrespective of the voltage.  In fact you may end up losing a bit of energy due to the transformer losses.

[sevenlayermuddle]

It sounds a bit dubious to me.

As far as I know, the normal UK mains voltage is 230V (used to be 240V).  But it's allowed a defined tolerance (+10% and -6% according to a quick google).  So to begin with it looks like this was originally designed for use elsewhere in the world, another quick google suggests that lot's of places, such as Canada, Hong Kong, use 220v Mains.  UK stuff has to work at 220V as our own mains may occasionally drop to that level, but 230V remains the standard, so I would assume that apparatus sold for the UK would be optimally efficient at 230V

If the device is acting as a switch-mode regulator that regenerates the mains AC at the exactly correct national voltage then I suppose it might in some circumstances it might allow things like fridge motors to run at their optimum voltage, and hence optimum efficiency, but only if they made a UK version for 230V.

More likely, I suspect it's just a step-down.  That would have all the drawbacks already described by Eric and Orainseer, and it would also cause big problems for folks like myself.  We live out in the sticks and every year, when cooking Christmas dinner, my oven seems to under-perform with embarrassing results.   It's OK the other 364 days a year so I suspect the cumulative load of Christmas dinners all over the county brings the voltage down to the legal minimum, which is to low for my oven.  A step-down transformer would make that much worse.

[roseway]

It's not just a step-down, it's an electronic device, some sort of switch-mode PSU.

[oldfogy]

It's not just a step-down, it's an electronic device, some sort of switch-mode PSU.

No, it simply smooths the voltage, which is also nothing to do with PSU (Power Supply Units)
As for the UK standard voltage, that still does not exist, our voltage is still rated as between 220v - 250v.

My current voltage is being shown as 243v on my AVO meter. (Which is accurate)

[sevenlayermuddle]

It's not just a step-down, it's an electronic device, some sort of switch-mode PSU.

Yes, the installation instructions give more detail.  It's not just a step-down, and moreover it is designed for UK as the input voltage is 230V.  So why do they think that appliance manufacturers would optimise for 220V?

There's a good wiki page about mains voltages, including the UKs, at

 http://en.wikipedia.org/wiki/Mains_power_around_the_world

Mine's reading 234V at the moment.

[waltergmw]

Sorry if this is slightly off-topic.

Electricity distributors are aware of voltage drops at higher loads and that's why most 33 kV to 11 kV transformers have auto tap changers, but they do have limits on the number of taps. I remember one transformer where the changer got stuck and the new tap was not inserted before the old one pulled out. The result was an exploded oil-filled tap change compartment and a fire which caused the oil in the main transformer compartment to boil.

Those who can remember back to the bad old days will recall that 3% and 6% voltage drops were used to reduce the generation load before load shedding commenced. If the forecasters are correct in saying we're going to run out of power stations by 2020 it's time the younger generation woke up and bought large UPS systems and / or generators. We all also ought to consider how our life styles have changed since the miners strikes. How many of you have seen a standby generator beside a mobile mast? I wonder how many of Virgin's level three cabinets have had  battery tests recently and when all the batteries were last replaced? (A couple of years ago I discovered my phone went dead after about 20 minutes of a power cut. I reported that fact and Virgin replied later that they had discovered a faulty cell in their UPS.)

Kind regards,
Walter

[Weaver]

Am I missing something?

No. :-)

Of course, unless they've found a hole in the laws of physics, their device will itself require energy to operate or at least will involve joule heating within some of its own bits. So you'll end up consuming more energy. Its just a complete nonsense. Of course we could all save energy by running our one bar electric fires on 20V rather than 240V, but then we would just be feeling colder. This kind of nonsense is inevitable in the growing climate of moral panic about energy consumption with its accompanying tidal wave of ignorance and misinformation.

[sevenlayermuddle]

This kind of nonsense is inevitable in the growing climate of moral panic about energy consumption with its accompanying tidal wave of ignorance and misinformation.

One of the best (by which I mean 'worst') examples I've heard of  is described here:

http://www.guardian.co.uk/environment/2009/jun/15/sainsburys-kinetic-plates-speed-bumps

Surely the reality is that they are generating their electricity via a very inefficient chain of mechanical linkages that's ultimately energised by their customers' vehicles' fuel-burning engines, which is a disastrously inefficient means of generating electricity.   It would be infinitely better for the environment if they just plugged their tills into the mains.

Or, to quote Eric, am I missing something?

[Weaver]

Stunning. Thanks for that.

> Or, to quote Eric, am I missing something?

Of course, the fact that the vehicles have to drive over these requires the vehicles to consume more fuel. They may either lose speed by encountering increased rolling resistance, then wasting even more energy afterwards as they have to accelerate away. Or even worse, it could be that they have to first waste energy by braking to slow down for the bump. Truly unbelieveable.

So in fact the supermarket is simply stealing energy from its customers!

The article not only propagates myths but also contradicts itself in several places. It first uses words like "create" in "create 30kWh in an hour" (ie 30kW [!!], illiterate journalist) and "produce". It then goes on to tell us that the system "does not affect the car or fuel efficiency" which is directly implies that the system does nothing and so does not work, or else attempts to claim something that is impossible. At the end of the article they finally come clean and admit that their earlier claims are nonsense, "not totally free".

If these cynical or stupid people wanted to do the right thing then they could just place a very, very long, straight ascending ramp at the entrance to the car park. Then cars could compress the ramp as they ascended travelling along it. If it was placed somewhere where the cars would naturally be needing to slow down to enter the car park anyway, then the ramp would assist in the process of slowing down, and so would reduce the need for wasteful braking. This would then steal some energy "ethically", in a sense.

[sevenlayermuddle]

Stunning. Thanks for that.

Glad you liked it, I actually heard it in Radio 4 a few weeks earlier.

What bugs me the most is that devices such as these are quite high tech and, in order to create the illusion of being effective, would need to have been designed by competent Engineers who will be very well educated in the laws of physics and thermodynamics.  That suggests to me that it's not just ignorance or misguided environmentalism, but rather a deliberate and cynical ploy to cash-in on the 'moral panic' to which Weaver refers, whilst actually having a deliberately negligible, or maybe even detrimental, effect on overall environmental pollution.

[orainsear]

cash-in on

The crux: ££££££