Electricity North West says plans to lower its volta ge could cut emissions by 10% and save customers £60 a year

FWIW 10% lower V means 10% lower I and 20% lower P for a heating device. It therefore takes longer to get upto temp, losing more heat & using more energy.

NT

Not sure where your numbers come from, the project reports are a bit hard to piece together, but the wrap-up reports state possible savings in the region of £44M in the NW, and £519 across GB (not clear on timescales) . They also talk about average customer bills reducing by £70 a year, which seems a lot compared to those other figures. The savings seem partly financial in that investment could be deferred, but savings none the less.

This trial and projections look more complex than the simple extrapolation people are making from a one-bar electric fire, based on elementary physics and Ohm's law. It's likely that for the network as a whole, V = IR with R a constant doesn't apply; major users like the railways and Google's server farms as well as domestic appliances may well mean that efficiency varies with supply voltage.

On the domestic front a major unknown is the take-up of electric vehicles, with the need for many chargers.

The capacitors they installed *raised* the voltage by 5 or 6 volts.

First of all the colour temperature of an incandescent lamp is determined by the boiling point of tungsten.

The hotter the filament, the more visible light it gives off. Incandescent lamps give off very little UV, to the point that UV detectors can be still be used to detect flames in the presence of such lamps.

Nonsense. I can assure you the increase is monotonic with temperature.

On Mon, 28 Oct 2019 22:07:23 +0000, Steve Walker snipped-for-privacy@walker-family.me.uk> wrote: [snip]

Thanks for the heads-up. I'll make sure I avoid them and go for a different supplier :-)

Could it actually isolate itself from the rest of the UK grid, in order to do that?

I *think* that "go for a different supplier" was a joke, I hope it was anyway! :-)

The companies we pay for our electricity have very little, if anything, to do with the actual supply of electricity to our homes. They certainly can't change the voltage.

I didn't think you were being serious, but was just curious as to the possibility.

Ta! You've confirmed what I thought.

We've had this discussion before

quote During ?Smart Street? trials over four years, engineers for Electricity North West found they could carefully lower the grid?s voltage by enough to save on energy without noticeably slowing household appliances or causing light bulbs to flicker.

?Nobody noticed the changes until they were given their bill and suddenly found out they?d been using less electricity,? said Steve Cox, the company?s engineering director. /quote

That is simply not possible, as all the grid is connected together. In any case if you lower the voltage within the permitted amount all that will happen is wattage taken will increase. The only devices I can imagine that would be using less would be heaters with no thermostats and filament lighting.

I think we had this discussion before. As an aside, I once had a psu for a computer, a Lynx, which was made for the French Market, when I used it it almost melted. Likewise a psu for a so called international portable TV. If the French do use a lower voltage, how come we can share the power through an undersea cable?

OK I know the answer its because of the voltage used for distribution over a long distance is very high and standard, but its transferred down by a transformer at the local sub stations. So maybe they are pinning their hopes in less lossy transformers. If you really want transformer efficiency you need power at over 400hz though. Not a good prospect. Brian

But the ENW project wasn't (as people [myself included] initially thought) about turning down the volts on the street-side of the transformers, it included turning down the HV lines into the substation, and adding PF capacitors in the street to raise the street voltage, so it was about overall efficiency.

There used to be a whole library of documents from multiple years of the study at

but they're gone now ...

and it isn't as if these are new. The substations within BBC TV Centre had automatic tap changers in 1962!

And we got it wrong then too ...

When they say "grid" they did actually lower the 11kV supply into substations

and fitted power factor correction capacitors in the street, so that the

The overall annual figure of £70 saving per customer comprised £7 loss to the DNO, £7 loss to the TNO, £39 loss to the ESO and £15 loss of tax to the government ...

No need to isolate from anywhere, they just use a different outgoing tap on their local transformers. A 5 minute job, turn off the high voltage supply, unbolt the cable or bar connecting the low voltage, replace the low voltage cable onto another part of the transformer. Turn back on.

Things with SMPSU's and these days that includes nearly all "wall warts" will draw whatever power (wattage) then need. The current drawn goes up as the supply voltage goes down.

Other mainly resistive devices the current drawn goes down with the voltage so the power taken is lower. That will be heaters, filament bulbs, motors, etc.

'cause there isn't a galvanic, contigious bit of wire, between the two grids. There are AC<>DC convertors and transformers in the way.

Which all have variable tappings to get the "standard" distribution voltages(s) right and that goes right down to the 230 v consumer level. Most of these tappings are selected on installation but some are under automatic control to compensate for varying line losses as the load varies, "regulators".

There were full reports of the trail on their web pages

they are still available - now at

As you say, they tell a very different story from many posters seem to have, err, got - with the project covering also how to manage a network with a lot embedded generation and a lot more heavy loads (heating and EV).

Thanks, bookmark updated.

There are tap-changers that are fully automated. These go in voltage steps, and are not continuously variable as a variac might be. The step size here might be 3V or so.

The tap-changer feeding my neighborhood, is programmed to go up a tap, at 8AM.

But the tap-changer is also used to "center" the voltage setting for our neighborhood.

The tap changer is accessible from the operators desk, because I was on the phone one day while he made an adjustment. Two linesmen were outside my house, and had verified my report that the value was not correct, and I got to talk to the operator while he changed it. (This gives you some idea what a small power company this is. The power company only provides distribution in our city.)

I was taught in class, that "make before break" is what makes it work. Ref here.

There's a fun animation here.