Voltage harmoniser ????

Markee

fwor wrote: »

I've seen this "overvoltage" point made before, but to me it seems a bit of a red herring.

The fact that mains voltage could at times be 250V is nothing new. It's been part of the specification for UK mains power for many decades, and designers of electrical equipment should all know about it and design their equipment to cope with the possible variations in voltage.

It's most definitely not a red herring!

Yes, manufacturers have to make their equipment compatible with voltage fluctuations, but it doesn't mean that they run at their most efficient!

stevemcol

I can see why this technology is contraversial and would have people who actually undertsand more about power enerygy and electricity agruing with each other.
My take on it is that the technolgy is aimed at appliances whose efficiency is opimtised at a certain power and voltage level. ie losses start to increase above and below a certain rating. So appliances with heating elements are probably not that relevent. However, units with motors and elecronic devices with stabilised power supplies may well benefit from constant voltage supplied at, or close to their design value.


Not a prefect example but if you take a basic zener diode regulated power supply: for every volt above its design value current is pretty much dumped to earth and lost as heat. This isn't exactly the same principal but a way of visualising how voltage ompimisation may be benficial.

espresso

!!!!!! wrote: »

The way that I read that article is that the savings were achieved by removing imbalance in a 3 phase supply - that I can understand. How is anything like that saving achievable in a single phase supply?

I still fail to see how any appreciable saving can be made in a single phase home environment

It does not say that at all. It states that "if you supply a motor with a 5% imbalance in a three phase supply it will draw approximately 20% more power" that comment is not specific to the quoted example savings given.

It makes no difference if it is a single phase supply or a three phase supply because the voltage optimisation is done desperately on each supply phase.

It also states that "if you supply a 230V rated bulb with 240V it will only achieve 55% of it's expected life".

The National Grid is now over 40 years old but technology has moved on and priorities are different now.

The majority of appliances operate more efficiently at a lower voltage, although they need to be able to work the within the agreed statutory range for voltages across Europe 230V +/-10% (207V to 253V).

That article also states that "over 90% of sites in the UK continue to receive voltage at the historic average level of 242V and will continue to do so because of the design of the infrastructure". By supplying equipment at over 20V higher than it's optimum level, huge amounts of energy are wasted.

Just because inactive thinks that it's snake oil doesn't mean that it is - do your own research on the subject.

fwor

Markee wrote: »

It's most definitely not a red herring!

Yes, manufacturers have to make their equipment compatible with voltage fluctuations, but it doesn't mean that they run at their most efficient!

That's what I mean about it being a red herring. The saving is due to lack of efficiency, not because there is anything intrinsically bad about the supply being "overvoltage".

Your quote earlier makes it sound as though preventing "overvoltage" is an ~extra~ benefit of power optimisation, when it's not.

Hammyman

espresso wrote: »

I am amazed at your 'input' to this thread. You obviously don't understand the basic principle of voltage stabilisation!

Do you even know what you're blathering on about?

Hammyman

espresso wrote: »

It does not say that at all. It states that "if you supply a motor with a 5% imbalance in a three phase supply it will draw approximately 20% more power" that comment is not specific to the quoted example savings given.

It makes no difference if it is a single phase supply or a three phase supply because the voltage optimisation is done desperately on each supply phase.

Oh. My. God. Three Phase devices work nothing like a single phase, especially when it comes to effieciency. You have obviously never ever done any electronics theory whatsoever.

Fifer

espresso wrote: »

So are you stating that if the UK domestic mains is reduced from a typical 242V down to 220V that there will no reduction in metered kWh consumption?

Yes, but that reduction in kWh consumption will result in a corresponding reduction in useful heat or light output.

espresso wrote: »

There are a few naysayers spouting their opinion that it's snake oil etc. but no evidence has been provided proving that it does not work. I assume that you are familiar with ohms law?

Little evidence has been provided that it does work either. You are familiar with Watt's law?

Hammyman

espresso wrote: »

There are a few naysayers spouting their opinion that it's snake oil etc. but no evidence has been provided proving that it does not work. I assume that you are familiar with ohms law?

Very. Lets put this to you.

Heating:
We're going to heat a room with an electric fire which is basically a resistor. It takes a certain amount of energy to heat a room by 1°C, lets say 100BTU. You have an electric fire which produces 50BTU/hr @ 240V so it'll take 2hrs to raise the temperature the 1C. Now lets change the voltage to 200V. Remember the formula for resistor in AC circuit is P=I x Vrms. If you lower the voltage to the fire, it lowers the heat and energy generated so in this case, the fire will now only be producing 41.6 BTU/hr. So in order to provide the same rise in temperature you'll still need 100BTU but you need to run the fire for longer ( 2hrs 20 minutes in this example) hence there is no saving when raising the temperature of the room by 1C - it'll just take longer - 20 minutes longer in this case. So overall, you'll still use the same amount of energy to achieve the required end result.


OK, so lets move on from heaters. Lets take a device which needs to draw 1000 watts to provide enough power run the circuit at the required voltage for the load on the secondary side of the transformer, lets say something like a very power hungry telly.

P=I x V. Looking at the formula we can instantly deduce that in order for P to remain the same then if V lowers, I would need to increase. So going on 240Vrms supply, 1000 W would draw 4.16 amps. Going on a 200Vrms supply, 1000 W would draw 5 amps. Even though we've dropped the voltage by 1/6th, it would still use 1000W but would just draw more current if the voltage was lowered but at the end of the day as consumption is measured in kW and not voltage, it would still cost you exactly the same amount of money to run it for an hour.

And thats why on single phase they are snake oil for the most part. Sure they'll cut the cost in lighting but only if you don't change the bulb for a higher rated one because the level of illumination has dropped.

However in the example of the telly, you now have an additional problem. 5 amps is a standard fuse rating. As you know, to be safe you should use the lowest rated fuse possible so for a TV drawing roughly 4 amps, a 5 amp fuse could be used. Only problem is now that you've dropped the voltage, the current has increased to 5 amps so therefore its likely the fuse will blow. So going on the fact that most people don't know jack about electrics, they're likely to think its gone bang and will either call out a repair man or needlessly go buy another. I know its a bit pie in the sky but it does illustrate some of the shortfalls.

espresso wrote:

By supplying equipment at over 20V higher than it's optimum level, huge amounts of energy are wasted.

What was that you were saying about understanding ohms law? The only thing that comment is valid for is incandescent light bulbs. It isn't remotely valid for either of the examples I've posted above because Watts law is.

Fifer

stevemcol wrote: »

My take on it is that the technolgy is aimed at appliances whose efficiency is opimtised at a certain power and voltage level. ie losses start to increase above and below a certain rating.

But if that was the case, it would assume that all appliances are optimised at the same voltage, which seems unlikely.

Fifer

The other factor that appears to be missing from this discussion is the efficiency of the optimiser. I'm assuming these things are some form of autotransformer. 97% is a very good efficiency rating for a transformer, but even one that good suffers 3% loss.