V-phase

[Jabbajaws]

Hi Everyone,

I have recently read an article in Professional Electrician magazine, regarding a fixed unit that can be installed, called V-phase. From what l can see this unit is placed between the electric meter and the Consumer Unit.

It restricts the incoming supply voltage to 220V and is supposed to be more efficient, saving the owner of the installation up to £100 per year on electrical energy.

Has anyone come across this unit or installed one anywhere?

Is it worth it in the long run? And does it actually do what it states? or is it merely a gimmick? The average supply voltage in my area for domestic use tends to be around 240-245V.

Could lowering the supply voltage to 220V have any problematic effects?

 

[GrannySmiff]

I can't understand why it would make your electricity bills cheaper, if the voltage goes down, the current will go up.

so by watts law if you are using 500 W at 230 V the current will be 2.17 A, and if you go to 220 V the the current will rise to 2.27.

As you can see the current has increased, but its the wattage used is how the bill is calculated right?

Woould really like to understand what differnce this would make, not because I am intrested in buying one but out of uinderstanding electricity a little bit better.

Plus how would they make this work would it be some sort of capacitor/inductor can't work out which one would could limit the supply voltage?.

Hmmmm.

 

[Jabbajaws]

Im not exactly sure to be honest how it works. Ive seen it advertised in a my monthy edition of Professional Electrician and was curious.

And it seems to make sense, what you say with regards to watts.

Im sure that the unit advertised will itself have some form of advanced electronics, to be able to do what it says, in my opinion.

I'll do some research and report back when ive learned more...

 

[Graeme Harrold]

This the one then........... V-Phase

Looks like it works like a restrictor keeping supply voltage to an otimum level for connected equipment. Bit like a car running at 56mph where optimum fuel consumption is

 

[Jabbajaws]

Thank You Graeme,

that is indeed the exact same V-Phase l am talking about.

Have you any comment on what GrannySmiff pointed out? Regarding a higher current value being used, in relation to the watts value. To be quite honest l have wondered about this before and would like to find out the answer. Im sure that theres a mathematical explaination that im missing in all this.

Are you or anyone else able to explain this to me as im dumbfounded at the mo...

 

[Sintra]

What I know on the subject is that appliances are designed to run on an optimum voltage ie 220V.
Running them on a higher voltage reduces efficiency and life span.
Appliances running at optimum voltage can be 13 - 17 % more efficient.
The car at 56 mph is an excellent comparison.

 

[Phil]

I had a chat to the guys from v phase at the elex show last month. nice looking unit the same size as a consumer unit. easy to wire up too. i think i may be investing some time soon

 

[GrannySmiff]

I was thinking about it myself and I presume it must be some sort of step down transformer, but as voltage fluctuates keeping it a steady 220 would require some form of alternating transformer if one exists???.

Also on safety point on an old install you will be upping the current and could cause nuisance tripping or worse maybe?.

 

[saveloy]

I was quite interested in this unit. However one thing that puts me off a bit is the amount of circuits you CAN'T connect to it

Circuits that must NOT be connected to the VX1:
Electric shower circuit.
Immersion heater.
Dedicated electric cooker circuit.
Circuits feeding high power tools.
Circuits where individual loads exceeding
13A rating will be connected.

A lot of high current circuits where the most savings could be made. Still think its a good concept though.

 

[Doug]

I can't understand why it would make your electricity bills cheaper, if the voltage goes down, the current will go up.

so by watts law if you are using 500 W at 230 V the current will be 2.17 A, and if you go to 220 V the the current will rise to 2.27.

As you can see the current has increased, but its the wattage used is how the bill is calculated right?

Would really like to understand what difference this would make, not because I am interested in buying one but out of understanding electricity a little bit better.

Plus how would they make this work would it be some sort of capacitor/inductor can't work out which one would could limit the supply voltage?.

Hmmmm.

This is not the correct way of looking at it. It is not the power consumption (or wattage) that is fixed, but rather it is the resistance that is fixed.The power rating is merely the power that will be drawn at a particular voltage. If you reduce the voltage, then you also reduce the current drawn and hence reduce the power consumed.

The relevant equation is Ohm's Law, V = I x R . If R is fixed, then reducing V will also reduce I. You can then use P = I x V to calculate power consumption.

This is why electric showers often have two power ratings listed. They can have a lower power rating calculated at the correct nominal voltage of 230V and also a more impressive power consumption using 240V.

Think what would happen if you connected a shower to a 1.5 V battery. Using my theory of a fixed resistance, the battery would supply such a low current that nothing would happen. With GrannySmiff's theory of a fixed power consumption, an enormous current would flow, frying the wires.

Hope this makes sense.

Is it worth it in the long run? And does it actually do what it states? or is it merely a gimmick?

I can see that having a steady voltage could be a good thing. I'm sceptical though about the voltage reduction. If things are designed for 230 or 240 V, then why use 220V? Do people really want the lights a bit dimmer?

The regs teach that voltage drop is a bad thing. How can you sign off on an EIC that you have checked for voltage drop if you have built in a big drop at the origin?

What happens when the unit packs up and the house is in darkness for a few days until a service engineer can visit?

 

[AEC]

Sanity at last.

 

[GrannySmiff]

I wish it did make sense Doug, and its not that I am going against what you are saying I am just new to this.

SO what I don't understand is

The relevant equation is Ohm's Law, V = I x R . If R is fixed, then reducing V will also reduce I. You can then use P = I x V to calculate power consumption.

When you say the resistance is fixed what do you mean, that if we say my kettle uses 2200W which it says it does at the nominal voltage of 230 the current will be 9.56, and with 220V I will be 10A.

Now what part is the fixed resistance, can we say that the load is the fixed resistance? if so which measurement would we use for R?

Thanks if you can help me understand this as I like to have a fundamental understanding of why.

 

[Doug]

GrannySmiff, using your example a kettle is rated at 2200 W at 230 V
rearranging P=IxV gives I=P/V
I = 2200/230 = 9.57 Amps
so, at 230V, the kettle draws 9.57A

To find the resistance of the kettle, use R= V/I = 230/9.57 = 24.03 Ohms
If the voltage is reduced to 220V, I = V/R = 220/24.03 = 9.15 Amps
the power consumption at 220V is P = IxV = 9.15x220 = 2013 Watts

So, if the voltage is reduced then current is reduced and less power is consumed. The rating of 2.2kW only applies at 230V. At 220V, the kettle is rated at 2.01kW.

The calculations could be simplified by combining P=IxV and V=IR to give R=V(squared)/P

At 230V, R = 230x230/2200 = 24.05 Ohms

At 220V, P = 220x220/24.05 = 2012 Watts

At 200V, P = 200x200/24.05 = 1663 Watts

 

[Jabbajaws]

Cheerz Doug,

Thats the missing link im after...

 

[albi]

v-phase are holding a seminar and installers corse in durhan (castle edan) on the 5 & 6 of may so i will tell you all about the ins and outs of it later its always worth a look

 

[GrannySmiff]

Ah yes I see now Doug thanks for explaining, should have got that by myself as I know its in there somewhere.

 

[Jabbajaws]

I was thinking along the same lines as you Grannysmiff. Quite easily done, l must say...

 

[jimbo1986]

As far as I know from reading the info on the site there is a bypass, this will activate and the voltage will return to normal levels in certain circumstances, but if the whole unit malfunctions? Guess if your that interested to know ask the manufacturer.

 

[jimbo1986]

It seems to me by looking at the site the kettle would take longer to reach boiling point thus using the same amount of power in the long run, same with central heating. I think there would be no saving with this sort of appliance.

 

[WDMDL]

I'm not convinced on this sort of thing.
Different types of appliances will react differently to the reduction in voltage. But simply:

Resistive loads (eg convector heaters)
Their output will be reduced. The only time this will be of benefit is if the heater was oversize for the room anyway.
If thermostatically controlled, the exact same amount of power will be used, as the heater will need to be on longer (Duty cycle) to achieve the set temperature.

Lighting loads (filament and magnetic ballast discharge)
Light output will be reduced, colour temperature will shift.
Lamp life will increase in most cases.

Motor loads (Fridge, Freezer)
A small reduction in available torque...but the appliance should have been designed to work correctly within the whole voltage range... so a small efficiency gain is possible

Equipment with linear power supply (Hi-Fi Amplifier, portable audio, alarm panel, etc)
Small efficiency gains are possible with items containing linear regulators.
But the maximum output of the amplifier will be reduced as the power supply for that stage generally does not have any regulation.

Equipment with switching power supplies (PC, TV, Freeview/Sky, advanced microwaves, HF Lighting ballasts,...)
THIS IS THE KILLER.
Most switching power supply designs are wide-range (90-264V), to use on any electrical system in the world.
They do exhibit the constant power characteristic.
So, as you reduce the input voltage, you increase the input current.
In this case, there can be no benefit from reducing the voltage. The higher current will cause more voltage-drop losses.

My next door neighbours just moved to a new house and wanted a few little jobs doing. They asked me if something was wrong with the electrics at the new place as the kettle was taking longer to boil and the shower was pathetic (funnily enough exact same model and rating)
Old house: 243V. New house 226V.

Does anyone remember those magnets that you could stick onto your car's fuel line to increase mpg lol?

 

[john25]

Actually just seen this for the First time today on TV and it sounds similar to what some of the American Electrical firms are doing by Installing a Capacitor next to the meter to reduce the Electricity bill (I'll look for the Youtube vid of it)

 

[Spudnik]

Just had some experience of these.

Basically, it will only work on current up to 8A, and anything over it will switch into bypass mode, thus through putting standard incoming voltage.

Once the load is reduced, it will switch back in.

So, in other words, it will just about do the lighting.

Also, if the unit fails, it will also go into bypass, but if you install the unit remotely, then you wont know until you check the front indicator is lit.

 

[john25]

lol so your basically paying around 300 quid just to save on Lighting energy when everyone is more or less using Energy saving Light bulbs anyway.

This wasn't the Exact vid I was looking for but it's similar[video=youtube;_h30X6EEsn0]http://www.youtube.com/watch?v=_h30X6EEsn0&feature=related[/video]

 

[RecycleElectron]

I believe it might save you money on the low consumption devices that don't automatically compensate for a voltage reduction.(like computers do). Low power heating will just take longer. They claim bulbs will last longer which may well be true and this will save some money, but only if people don't put higher power ones to get the light back. Small motors will be more efficient as the extra volts over 220 just results in resistive heating. It cuts out when demand goes up although they are talking about making a more powerful one.

I doubt that I could sell one confidently to a good customer on the money saving argument though.........Needs to go with a CU change but will double the cost......

 

[bugsy]

Strange but true, these units do work and as previousley stated provides optimome voltage , with regards to voltage drop calcs ( unless im the only one ) should be at 230/ 400v ( DNO state 230v + 10% - 6% )
There are a number of manufacturers supplying units for commercial use ( Claude Lyons ) for 1.

 

[aptsys]

Strange but true, these units do work

Based on what? What household appliances would benefit from a reduced input voltage?

 

[Paul.M]

I've done a bit of research into v-phase on another thread with the same arguments. I'm still not convinced on the estimated money savings.

All appliances made from 1990 with a CE mark are designed to operate on 220v so that's where this comes from. But people will just increase the watts of their light bulbs (luminaries), going from let's say 243v 40w down to 220v, you would see a difference. I didn't know that they don't work above 8A? So It's all about lights, radials with <8A and I don't think this will be worth the cost. May be worth while on new & rewire properties to design each circuit to use less current on each but we will end up with 15 way c/u's. If these units were free and we can only charge for installation it would still cost £120-£180 and would people go for it in large numbers to save money? The jury is out on this one for a while.

 

[bugsy]

Based on what? What household appliances would benefit from a reduced input voltage?

Based on the same principle this www.claudelyons.co.uk/energy.htm

 

[aptsys]

So basically BS then. Any type of resistive heating will take longer at a reduced voltage, and due to heat loss will end up using more energy. The majority of electronic items around the home use SMPSU's to comply with EU efficiency regulations, therefore will draw the same power at 220/230/240V, and this is likely to be one of the main areas where most people would expect/want to save money.

Incandescent lamps have a very non-linear voltage to brightness relationship, so a reduced input voltage has a significant effect on the brightness - perhaps enough for people to turn on another light. The colour rendering and temperature will also be affected negatively.

 

[Zimmer]

GrannySmiff, using your example a kettle is rated at 2200 W at 230 V
rearranging P=IxV gives I=P/V
I = 2200/230 = 9.57 Amps
so, at 230V, the kettle draws 9.57A

To find the resistance of the kettle, use R= V/I = 230/9.57 = 24.03 Ohms
If the voltage is reduced to 220V, I = V/R = 220/24.03 = 9.15 Amps
the power consumption at 220V is P = IxV = 9.15x220 = 2013 Watts

So, if the voltage is reduced then current is reduced and less power is consumed.

But the kettle will take longer to boil.

 

[MrMagoo]

What do you think a switch mode PSU does if AC volts is reduced?

 

[RecycleElectron]

It will adjust automatically, but there will be little or no change to the energy used as the current drawn will increase to maintain the output at the correct voltage. This is covered by some of the earlier posts in this thread. It is unlikely that voltage regulation devices will give a saving with SMPSU's as far as I can see, as the power supply is already doing that job really. Switch mode is a common technique in a lot of stuff these days and must amount to a significant proportion of the target energy saving (or not) for the voltage control device I would guess......

 

[Engineer54]

Just another gimmick that sounds good, but when thought about with an electrical mind, falls down in many areas.

Another thought, .... 300+ smackaroos for a unit that can only handle 8A tops?? ...And worst of all, having to wait and wait for that cup of tea or coffee that your absolutly gasping for, ... NO WAY!!! Leave this bit of kit for the yuppies and Gizmo kids!!! ...lol!!!

 

[Kamikaze]

Just another gimmick that sounds good, but when thought about with an electrical mind, falls down in many areas.

Another thought, .... 300+ smackaroos for a unit that can only handle 8A tops?? ...And worst of all, having to wait and wait for that cup of tea or coffee that your absolutly gasping for, ... NO WAY!!! Leave this bit of kit for the yuppies and Gizmo kids!!! ...lol!!!

I was thinking that myself....lol