Is this right?

[ncoups]

http://news.bbc.co.uk/1/hi/business/8172850.stm

Isn't it that appliences will draw less amperes due the slightly higher voltage? or will they draw the same and the edditional power in volts is wasted?

 

[electronicsuk]

http://news.bbc.co.uk/1/hi/business/8172850.stm

Isn't it that appliences will draw less amperes due the slightly higher voltage? or will they draw the same and the edditional power in volts is wasted?

Depends on the type of appliance. Loads with a fixed impedance (negating the effects of heating and start up current) such as lamps, showers and motors will draw less current if the supply voltage is reduced. That's fine for appliances designed to run at 220v, but it will lead to a loss in performance of appliances designed to run at 230/240v, such as electric showers, fan heaters and the like.

Other electronics, namely those with switch mode power supplies, will still draw roughly the same amount of power regardless of input voltage. The nature of how a SMPS functions means that it will constantly be adjusting itself to meet both load on the output side, and input voltage on the mains side. There are, of course, limits to how low the mains input voltage can drop, but most modern units are designed to work anywhere between 90-260v AC. A drop in supply voltage will simply result in increased current being drawn, as counter-intuitive as it seems.

The device you link to sounds interesting, but there must be some loss within the unit itself - whether or not it would prove a worthwhile investment would surely depend on what you plan to run from it. If anything, it should at least extend the life of european devices that weren't specifically designed to run on our supply voltage.

 

[holmslaw]

..

 

[bernardgreen]

http://www.vphase.co.uk/Files/brochures/vphase026v4 VX1 Technical Specification Overview.pdf

The exact duration of operation depends upon many factors including ambient conditions, previous load conditions and the level of power consumption. Typically the VX1 can regulate for many hours at 2.5kW but only for a few minutes at 4kW.

and

VX1 Output - Bypass Mode: Input directly connected to output.
VX1 maximum current: 80A bypass mode
20A short term active mode
8A continuous active mode (typical)

 

[electronicsuk]

http://www.vphase.co.uk/Files/brochures/vphase026v4%20VX1%20Technical%20Specification%20Overview.pdf

The exact duration of operation depends upon many factors including ambient conditions, previous load conditions and the level of power consumption. Typically the VX1 can regulate for many hours at 2.5kW but only for a few minutes at 4kW.

and

VX1 Output - Bypass Mode: Input directly connected to output.
VX1 maximum current: 80A bypass mode
20A short term active mode
8A continuous active mode (typical)

So, in fact, the majority of the appliances whose power consumption would be reduced by lowering the supply voltage, will in fact cause the unit to run in bypass mode due to being large resistive loads?

What's more, as the unit switches in and out of regulation mode, your supply voltage will be changing between 220v and anywhere up to 250v or so. Excellent!

 

[Adam_151]

And like Eric, I wonder what happens when the unit is presented with a fault... does it try and and drive the fault through the unit briefly (with added impedance), realise that the load is too much and pull in the bypass contactor?, extending the disconnection time in the process?

 

[flameport]

Snake oil strikes again.

While the device probably does reduce the voltage, this won't actually save loads of money.
Even at the savings quoted in the video of around 10%, that's only £50 per year at their 'average' house usage, and as the device apparently costs £250 plus installation, it's 5 to 10 years before any savings are made.

Most people could easily save 10% of their electricity by just switching things off when not in use and fitting low energy lamps. The kitchen in the video has at least 13 halogen downlighters - replacing those lamps would be far cheaper and more effective than installing the device.

Heating appliances - no saving since they will just take longer to heat up. Looks like the device can't be used with them anyway.
Electronics with switch mode power supplies - no savings there either, at a lower input voltage they will just draw a higher current to compensate.
Lighting - possibly a saving, but many types of lamps would be dimmer, resulting in people fitting more powerful lamps.
Motors - possibly some saving but all depends on what voltage the motor was designed for. Motors are hardly big power users in the average home either, most power is used for heating and lighting.

 

[Spark123]

How does it work? Is it just a fancy dimmer which clips the sin wave and uses a big inductor to smooth it out?
If it is triac device then past experience is that unless it is protected by a quick acting fuse then the triac can fail.

 

[electronicsuk]

How does it work? Is it just a fancy dimmer which clips the sin wave and uses a big inductor to smooth it out?
If it is triac device then past experience is that unless it is protected by a quick acting fuse then the triac can fail.

Hmm... I would guess it's not working in the same way as a dimmer, as that would be asking for trouble when you don't know what kind of loads the unit will be feeding. The video seems to show a fairly large toroid in there, but it's certainly doesn't look large enough to handle 4kW unless it's an autotransformer and uses adjustable tappings.

I suppose it could be rectifying the incoming supply and then modulating back into a sine wave again, this would certainly allow it to adjust the frequency and amplitude very precisely, but the losses in conversion using this method would surely offset any energy savings.

 

[flameport]

Probably just a transformer with a 240v primary and an 18V or 24v secondary, with the secondary connected in line with the supply to the loads (L in and L out) and the 240v part connected across the supply (L and N).
The transformer is bypassed using some control circuit when the load is too much, and it probably has a sensor to prevent overheating.

 

[electronicsuk]

The transformer is bypassed using some control circuit when the load is too much, and it probably has a sensor to prevent overheating.

For sure, you can see a bi-metallic switch mounted atop it in the video.