domestic voltage stabilisers ?

[Graham.]

You mean energy, not power.

[George Miles]

my friend geoff asks: Does anybody have a view on domestic voltage stabilisers. From an engineer?s perspective, I can?t see why they would reduce your power consumption:

1) Anything with thermostat control (eg cooker) - no effect. 2) Nearly all electronic stuff has AC to DC inverter these days - no effect 3) Motors, maybe. But this is basically your fridge and these too, being thermostatically controlled use nearly the same power, whatever the voltage. 4) Central heating pump probably would use less.

BUT if the stabiliser has losses (it will have losses) these are 24/7.

So I would expect stabilisers to be at best useless and possibly cause you to use more power than without it.

Any opinions?

[Tim+]

Yes.

As above. ;-) Plenty of reviews on YouTube of these snake oil devices. Try Big Clive and ?energy savers?.

[Martin Brown]

Pure snake oil with a layer of marketing hype.

[geoff.harvey]

Thanks; I meant average power, to be more precise

[John Rumm]

IMHO, fairly pointless, so you can expect someone to put them in the wiring regs

yup

yup

Universal motors will run a bit slower and draw less current. Induction motors will slip a bit more and compensate by drawing more current, running hotter, and suffering a slightly shorter life.

Induction motor - so not much change, and any waste heat is dissipated into the CH water anyway, so a very minimal reduction of costs shifting some power consumption from electricity to gas/oil.

They are normally based on auto transformers, which reduces them a bit, but yup.

If you were were a salesman you could probably concoct a loading scenario that makes them save money, but harder in the real world, especially now that many people have phased out incandescent lamps which is one area they could make some savings, so long as you did not compensate for the reduction in light output by turning on extra lamps or fitting higher power lamps.

[Fredxx]

Please explain what you mean by 'average power'.

I pay for the energy I consume.

[tabbypurr]

240v mains is already stable in almost every case. And yes, it's 240.

I assume you mean a voltage reducer. If so...

slower to heat, bit more heat loss, not much

fridges object to undervoltage, it tends to kill them as they stall repeatedly & overheat.

yes, while increasing boiler heat loss up the chimney. Not a gain. I guess a smart pump would not be affected.

Increasing voltage to lighting was useful back in the filament lamp days. Not now. It enabled me to replace 100w lamps with 60w boosted to something like 65/70w. Life fell from 1000hr to 300hr, so only for fittings with easily accessed bulbs. And not fluorescents.

NT

[The Natural Philosopher]

aka 'energy'

[Brian Gaff (Sofa)]

Yes you don't get ought for nought as my gran used to say, if you are doing something then it uses energy. That energy is over and above the energy used by your system. Obvious one is starting a motor with a big load. Often it is started very slowly then brought up to speed and this to some extent can stop the equipment putting a darned great dent in the mains voltage at start up, created due to the heating up of the cables. Starting it slowly however and speeding it up will still use the same or more energy, but over a longer time period, no peak in current, just gradual increases over time. Brian

[Cynic]

The mains voltage here has been pretty variable of late. Over the last few days, following some switching round a network fault I've had varying readings from 259 to 240. Anything over 253 is deemed dangerous by northern power grid so they turned out to measure for themselves then switched network connections around that evening. I phoned the following day at midday when the voltage got up to 257 and further switching took place which took daytime volts down to 248. Not had much sun since but NPG engineers reckon my village has a lot of solar generation.

[The Natural Philosopher]

yet another reason to ban solar power

[charles]

It's not so much dangerous as illegal. 253 is the maximum permitted voltage. (230 +10%/-6%)

[Michael Chare]

My oil boiler has an induction motor which drives the pump and the fan. The pump has a pressure regulator so likely the pressure would remain the same if there was a minor change in the motor speed. However the fan would likely deliver the wrong amount of air. To little air cause the boiler to run black as not all the oil is burnt properly. To much air, and the hot gas is blown up the chimney instead of heating the water in the boiler.

So in either case the boiler does not run as efficiently as it should, not that I have ever bothered to check the voltage in the past!

[Scott]

The management decided to fit one at my last office. I pointed out that the electricity consumption comprised computer equipment (with power supply units), fluorescent then LED lighting, two kettles and two fridges. I pointed out to our office manager that I did not think we would save any electricity. She thought I was probably right but the decision had been made at a more senior level. I think it got removed in the end but 'the management' is exercising its right of silence on the subject.

[Andrew]

On reading this, I fished out my old Tchaibo plug-in "wattmeter" and it showed 214 V.

Hmm. Multimeter said 240V, and after being plugged in for an hour the Wattmeter shows 228 volts. Clearly something inside it is drifting or changing value. Time to bin it I guess.

Does anyone else use these things ?. It was cheap anyway. Are there more reliable (expensive) models ?.

[John Rumm]

Boiler fans are induction motor powered, so unlikely to change speed by any significant amount on a higher voltage.

[Fredxx]

Where the speed will be a strong function of mains frequency and only weakly dependent on precise mains voltage.

An induction motor is one of the devices where a voltage stabiliser might reduce power consumption slightly.

[Vir Campestris]

You sure about that?

It's spinning at the same speed, driving the same load, so the output power will be the same.

Won't it just lag the phase slightly less if the voltage is higher, and draw slightly less current?

Andy (who is not an AC motor expert)

[Scott]

How do you know the multimeter is not faulty?