V Phase

Reducing voltage will reduce the current that resistive loads (e.g. immersion or storage heaters) take, but if the appliance is controlled by a thermostat it will run for longer to reach the required temperature.

For equipment with switched mode power supplies, lowering the peak of the A/C waveform will just tempt the PSU to draw power for a greater fraction of each 50Hz cycle.

In short not likely to save much ...

Oh yes ... will also dim incandescent bulbs (by a greater factor than the cost saving) but probably not affect CFL or halogens on electronic transformers.

There was a VPhase rep in my local wholesalers last week.

He claimed that the VPhase will give GU10 lamps an extended life due to the lower voltage when they are switched on.

Sounds feasible, though I'd think the lower voltage while running would also be a factor rather than just the switch on surge

It will indeed. And of course reduce efficiency. So less light from the electricity they use.

In general, the cost of the lamp itself is a fraction of the cost of the electricity it uses in its lifetime. So better to fit a smaller lamp. In practice, most 50w GU10 types can be replaced with 35w without anyone noticing - unless they are side by side. Low voltage 50w with 20w.

If you have an awkward to change one and the light output isn't too important stick a diode in series. That will extend the life greatly.

I used to do that with mains xmas tree series chains, diode in the 13A plug. I have at least one set still going that is 25 or 30 years old. Two further advantages are the brightness is reduced to a more appropriate level (these things always seem to be designed to over-run) and I perceive a pleasing 25Hz flicker.

As has ben said before, there are ways to shave a few pennies off electricity use, but none suit all appliances, there's no single cure- all.

NT

here:

Presumably this is little more than a 15v high current transformer wired in anti-phase with the supply?

Bob

What does "wired in anti-phase with the supply" mean?

Wired such that the low voltage subtracts from the incoming supply. Actually the voltage would need to be more like 25v not 15v - my mistake

Bob

Forgive me being obtuse; I'm still not with you. How would you wire the transformer and the load such that "the low voltage subtracts from the incoming supply"?

Thanks.

I'd assume like this

I have drawn a diagram here

Hope this helps Bob

Many, many moons ago I bought a switched & indicated plug for my 15W soldering iron. Soldering a diode across the switch gave me a 2-heat iron. Just hot enough to melt 60/40 solder on "cool" and quick to heat up to full. The neon also dims to show when the iron is on "cool".

OK, so this is an ersatz form of autotransformer. I've not come across this technique before.

I say ersatz because there is no guarantee that the insulation on the secondary wiring (of any given transformer not designed for this purpose) is rated or proof tested for mains voltage operation.

The idea that confused me intially was the "anti-phase" bit. I suppose you would say that if you connected the secondary winding the other way round, it would be "in phase" and boost the 240V to 260V.

Cheers, DaveyOz

Google autotransformer..

If you use a standard modern plastic bobbin transformer, insulation wont be an issue.

NT

If you use an autotransformer, its less copper and it doesn' matter a damn because there is no secondary..

here:

Ever heard the expression `brown-out` thats what these create deliberately ,usually an autotransformer.

In large buildings if you wanted 220V you could get the power tapped down so with these substantial savings why aren`t they?

Mag ballasted lights will not like the lower voltage and will pull more current probably losing efficiency to heat, another myth bites it.

Motors, Ohms law means lower voltage will draw more current for same work done, meaning possibly higher heat losses, you canna change the laws of physics Cap`n...

Motors and ballasts are 2 things can think of that may have seoerate taps for 220 and 240V

It isn`t a new idea, and it still isn`t a good one.

Cheers Adam