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samuk
Starting Member
14 Posts |
 Posted - 15/03/2008 : 17:43:38
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Further to Keith's post about the unusual turbines I spotted this on the motorwavegroup site:
Steel case containing a kWh meter, a 12 VDC/230V AC 0.8 kW inverter, a bi pole 230V AC relay contactor, a low & high level battery sensor, a general control switch and a green light indicating when the system is powered by MotorWind.
Function: When the battery level is high, the inverter powers the electrical appliance. When the battery level becomes too low, the system switches automatically back to the grid avoiding any interruption.
The inverter will only start if the battery voltage reaches approx. 13.5 volts and keep working until the battery level goes down to approx. 11 volts, then the inverter will shut down and will only restart when the battery is recharged.
http://store.motorwavegroup.com/changeover-electrical-box.html
Does this seem safe? would it need a CE mark to be re-sold in Europe?
I like the idea, I could try and power my Tv, computer and DVD player from a renewable source, with the addition of a small UPS my viewing would be uninterrupted..
Thanks
Sam
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daveb
New Member
United Kingdom
52 Posts |
Posted - 16/03/2008 : 17:44:30
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Hi samuk its not really clear on the picture but it looks like the unit wires into the bottom of the meter and there is your first problem,to gain access you would have to break the company seal which is illegal.So you would have to ask who ever own'ed the meters permision and in these days of swapping companies its not an easy task secondly they wouldn't let you do it on the grounds of health and safety and would want to charge you a small fortune to carry out the work if they permitted you at all.When it comes to loosing money you'd soon see how green they where.And as you say if it hasn't got a CE mark it would be an automatic knock back,On the surface it looks good including the price but if i where you i would e-mail the company first to find out if it does carry a CE mark and contact my electricity supplier and make enquiries about fitting one,Since last year the regulations have changed concerning doing your own electrics i have qualifications for electrical instilation but am not allowed to carry out work on my own home?
Daveb |
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ghurd
Junior Member
USA
304 Posts |
Posted - 16/03/2008 : 19:28:29
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The kWh meter confuses me. What does it measure and why, kWh from the battery?
Not clear on the inverter, 50HZ because 230V, or 60HZ because priced in $.
The 11V to 13.5V seems 'sloppy'. I sure don't want my batteries below 12.2V if I can help it, let alone every cycle. Waiting until they reach 13.5V can be a long wait if the input amps are low compared to the battery AH.
Seems like a LVD circuit, a DPDT or 3PDT relay, and an inverter with GFCI suited to the areas devices would be just as good (or better) and cheaper.
G-
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dc2000
Starting Member
16 Posts |
Posted - 17/03/2008 : 12:11:36
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safe? legal??
If you wanted to conect direct to the grid it would need g83 type approval I suppose you could provide mains in via a socket outlet the Kwh meter has no point as you could just as easily work out amps taken from battery over time. the inverter would probably have CE approval ( but if modified by taking cover off??) I also assume here that it is pure sine wave
All in all its something that could be put together using off the shelf parts for relativly low cost
The way I intend to make use of my renewable energy is to have a second consummer unit installed to feed lights TV fridge etc, all low wattage, this unit would be able to take a feed from inverted current or in times of low sun and no wind be switched back to the grid |
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ghurd
Junior Member
USA
304 Posts |
Posted - 17/03/2008 : 15:01:46
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No Way it's pure sine wave. 800W pure sine wave inverter is over $300.
G- |
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dc2000
Starting Member
16 Posts |
Posted - 17/03/2008 : 17:34:31
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| if its not then its as much use as a chocolate fireguard |
Edited by - dc2000 on 17/03/2008 17:35:37 |
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ghurd
Junior Member
USA
304 Posts |
Posted - 17/03/2008 : 18:46:04
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It's useful, just not worth $300.
It looks like a LVD controlling the relay. If the batteries are high enough, the relay puts power to the inverter, and another set of contacts puts the inverter output to the household device wires.
If the batteries are not full enough, the relay drops out, and the contacts disconnect the inverter, and the grid power feeds the household device wires.
So an inverter, LVD and relay. Plus the meter.
G- |
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Sundowner
New Member
Ireland
55 Posts |
Posted - 18/03/2008 : 11:31:13
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I think this gadget, like many items on the internet is a perfect reason why people should do their research before they buy.
I've seen turbines priced at crazy money, and I feel sorry for anybody that buys one, thinking that they are going to free themselves from the electricity companies stranglehold.
The only solution to deceptions like this is the three "R's"........Research, Research, Research, isn't that what brought most of us here to this forum.
Sundowner....huh.........thats what they call us.......Sundowners |
Edited by - Sundowner on 18/03/2008 11:31:56 |
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samuk
Starting Member
14 Posts |
Posted - 21/03/2008 : 18:40:01
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Hi all
"it looks like the unit wires into the bottom of the meter and there is your first problem,to gain access you would have to break the company seal which is illegal." Well if that is the case it looks useless. I assumed that you could plug it in.. (note that they seem to have built a additional (pointless?) meter into the unit.)
"I suppose you could provide mains in via a socket outlet"
Yes this seemed to be the appeal of the device to me. A way of easily switching between batteries/mains without getting a electrician in.
Seems like a LVD circuit, a DPDT or 3PDT relay, and an inverter with GFCI suited to the areas devices would be just as good (or better) and cheaper.
Could people recommend supplier(s) for the above bit's of kit?
Thanks
Sam
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Tim L
New Member
United Kingdom
70 Posts |
Posted - 21/03/2008 : 21:43:38
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Forgive me if I'm being particularly dumb here, but what about synchro? There would seem to be 2 choices, either this sort of box goes into the system somewhere between the company meter and your appliance and makes very, very sure there is a definite break from mains before make to inverter (and I am unsure of the legality of doing that in UK, even on "your" side of the system), or if you're planning to push the inverter output back into the house wiring through a normal socket as a sort of "assist" device to reduce the power pulled from the Grid, it absolutely must be the type that senses mains phase and synchroes with it, the sort specifically sold as "Grid Tie". Otherwise your little inverter will fight the National Grid and the results will be extremely pyrotechnic.
Also, using relay contactors you're looking at some really spectacular arcing on make and break, not to mention the instantaneous drain that the inverter itself will suddenly see, even with purely resistive loads, never mind trying to drive reactive loads up in a couple of milliseconds. Most inverter instructions I've seen require the inverter to be powered up first and only then have the loads connected, and likewise when powering down the loads must be disconnected before the inverter itsef is switched off - so it sounds like inverters normally hate waking up / going to sleep with connected loads. Perhaps it's a special inverter? Or have I misunderstood the intended application of this thing?
PS: I'd be wary of driving expensive electronic kit from a modified square wave, too. Wouldn't mind betting the insurance company would laugh its socks off. |
Edited by - Tim L on 21/03/2008 22:22:47 |
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samuk
Starting Member
14 Posts |
Posted - 22/03/2008 : 15:02:08
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either this sort of box goes into the system somewhere between the company meter and your appliance and makes very, very sure there is a definite break from mains before make to inverter (and I am unsure of the legality of doing that in UK, even on "your" side of the system),
I think it must be legal as more 'high end' inverters offer this:
http://www.powermastersystems.com/combisl.htm
or if you're planning to push the inverter output back into the house wiring through a normal socket as a sort of "assist" device to reduce the power pulled from the Grid, it absolutely must be the type that senses mains phase and synchroes with it, the sort specifically sold as "Grid Tie". Otherwise your little inverter will fight the National Grid and the results will be extremely pyrotechnic.
Sure :) I did not imagine that you could push current through your house..
Also, using relay contactors you're looking at some really spectacular arcing on make and break,
this does not sound so good!
not to mention the instantaneous drain that the inverter itself will suddenly see, even with purely resistive loads, never mind trying to drive reactive loads up in a couple of milliseconds. Most inverter instructions I've seen require the inverter to be powered up first and only then have the loads connected, and likewise when powering down the loads must be disconnected before the inverter itsef is switched off - so it sounds like inverters normally hate waking up / going to sleep with connected loads. Perhaps it's a special inverter? Or have I misunderstood the intended application of this thing?
Could you not just plug one of these cheap UPS in? http://www.ebuyer.com/product/126404
PS: I'd be wary of driving expensive electronic kit from a modified square wave, too. Wouldn't mind betting the insurance company would laugh its socks off.
Would the UPS not create a nice smooth output? |
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Tim L
New Member
United Kingdom
70 Posts |
Posted - 22/03/2008 : 16:12:09
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Good point you make there about the principle - it must be legal because high-end inverters do it all the time.
I would be surprised if the Belkin unit is a continuous type UPS where the unit is always running off the battery, but battery is also being continuously charged by the mains. However, as you point out, the standby type is designed to wake up with a connected load so maybe that end of things wouldn't be a problem.
What I thought I read though was that you would be powering the UPS fron this relay-controlled inverter box? In which case the first inverter in the box should really be designed the same way as one of these high-end ones so that it's expecting to be instantaneously hit by the load. The load from the UPS would not only be from your connected equipment but also from the UPS itself looking to recharge its own batteries. Still it's a small unit so there might not be too much of a thump.
Presumably you'd be looking to disable the ups beeping at you all the time its on.
Regarding electromechanical relays, something like 70% of all failures are the result of arcing. Modern arc-suppression is quite good, but I understand it has to be well matched to the load. Simple arc-suppression (I used a 0.47UF X2-type capacitor in series with a 100R resistor across the contacts in my own controller switching 50A at 24V DC) is good enough with low voltages but more complex circuitry is usually used for additional RF suppression in higher voltage units. I don't like electromechanicals myself, will be replacing my own in due course with MOSFETs.
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Edited by - Tim L on 22/03/2008 16:25:14 |
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daveb
New Member
United Kingdom
52 Posts |
Posted - 23/03/2008 : 16:59:41
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Hi samuk which ever way you decide to go to connect to your homes electricity supply ether this unit a socket out let secondry consumer unit or isolation switches[ Ive thought about them all ] under the new legislation there's no way round it you can not do it yourself all installation work now has to be certificated if its not and god forbid it should happen if you had a fire for what ever reason[ may not be electrical]your home insurance would be invalidated.Its so frustrating Ive been doing stuff like this for over 40 years and i would have to pay someone to do something i can do myself ive just fitted one of those round waterproof caravan type fitting to my outside wall and ran a wire through to a double surge protected[screwfix UK]socket then ran an extension from my inverter with the corresponding caravan round plug to it[screwfix]not very pretty but at least it gets power into the house.But i don't know if even that falls foul of the new legislation if its classed as a new circuet.Perhaps if there's any posters from Australia or newzealand they could let us know how it works there they've had this legislation there for years.
Daveb |
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samuk
Starting Member
14 Posts |
Posted - 23/03/2008 : 17:36:30
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under the new legislation there's no way round it you can not do it yourself all installation work now has to be certificated
Does this mean that all these products are now illegal?
http://www.onboardenergy.com/acatalog/Transfer_Switches.html
It is exactly the same principle, plugging a inverter and mains supply into a switching unit. It seems there are some grey areas.
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ghurd
Junior Member
USA
304 Posts |
Posted - 24/03/2008 : 02:44:41
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The original item is certainly not a grid tie inverter.
The automatic change over switch is close to the original item.
MSW is fine for 99.9% of items. Most people don't even have a true sine inverter.
Using an UPS would almost certainly waste more power than the RE systems seen here make.
G- |
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daveb
New Member
United Kingdom
52 Posts |
Posted - 24/03/2008 : 11:06:06
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No samuk all these items are not illegal it just that the legislation says it has to be fitted by a suitably qualified person and a certificate issued to prove it.There have been a few tragic incidents over the last few years where electrical fires have started by instillation's by people who really don't have a clue.I can see some of the reasoning behind this legislation how do you determine who is capable of doing this type of instillation and who isn't? or is just jobs for the boy's pressure from the unions or is it just another example of our goverments over reaction to a few isolated incidents?Which ever of the later it is its a simple fact that once something is lost in the UK its gone for ever.As far as installing it yourself and then having it checked and certificated goes as you say is a grey area Ive looked on the youguv site for information but as usual its just political and legal gobbledygook.
Daveb |
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Topic |
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legal/safe? Change-over electrical Box
