Home Page
   Articles
       links
About Us    
Traders        
Recipes            
Latest Articles
Those rooftop wind turbines again
Page Previous  1, 2
 
Post new topic   Reply to topic    Downsizer Forum Index -> Energy Efficiency and Construction/Major Projects
Author 
 Message
dougal



Joined: 15 Jan 2005
Posts: 7184
Location: South Kent
PostPosted: Mon Jun 27, 05 11:58 am    Post subject: Reply with quote
    

woody wrote:
we are looking for an effective wind turbine for our project can anyone help


Woody, did you spot this?
https://forum.downsizer.net/viewtopic.php?p=66541#66541

Do register, and tell us about your project!

fonant



Joined: 01 Feb 2005
Posts: 24
Location: West Sussex
PostPosted: Sun Jul 03, 05 10:57 pm    Post subject: Reply with quote
    

dougal wrote:
Generators simply cannot "plug in" because they'd have unsafe exposed live plug 'pins' if ever unplugged... (and yes, Windsave's publicity does talk about "plugging in" )


Yes, they can. Any grid-connected power generation system _must_ switch itself off if the grid fails. This is so that anyone working on the disconnected part of the grid is safe.

I've seen solar PV inverters that are like a large wall-socket power supply - you do just plug it in. For example https://www.mastervolt.com/sunmaster/soladin.asp. Very cool and very portable for when you move house

I love electronics - these things work so fast it makes the 50Hz mains frequency look slow!

dougal



Joined: 15 Jan 2005
Posts: 7184
Location: South Kent
PostPosted: Mon Jul 04, 05 3:42 pm    Post subject: Reply with quote
    

fonant wrote:
dougal wrote:
Generators simply cannot "plug in" because they'd have unsafe exposed live plug 'pins' if ever unplugged... (and yes, Windsave's publicity does talk about "plugging in" )

Yes, they can. Any grid-connected power generation system _must_ switch itself off if the grid fails. This is so that anyone working on the disconnected part of the grid is safe.

I already stand corrected on this!
nathanbriggs wrote:
{22 June 2005}... there is nothing in BS7671 which precludes the use of a 13Amp plug as a source of power as long as it safe to touch... Removal of the plug and touching the pins has to be safe, the energy must be below 50V within 2 cycles and less capacity than will stop a human heart, btw its still possible to get a little tingle if you are quick.
The windsave device is fitted with a plug, having said that most people will get it installed by a competent electrician who will promptly hard wire it.
Lastly the plug is standard but the socket requires a metal cover plate


One point that hasn't been brought out is the necessary implication that such systems therefore *cannot* provide independence of the mains. During a powercut, your own generator *must* shut down too.
I'm not saying its physically impossible, just that it is the inevitable consequence of a "plug-in" system's mode of operation. (But would a power outlet on the generator side of the isolater be possible..?)

However there are a couple of points that might be taken in mitigation of my error.
1/ Isolating from the mains to protect maintenance/repair workers, does not require an *instant* disconnect. Personal safety on accidental unplugging demands a much more rapid response.
2/ While you can safely *just* isolate a solar pv panel, my understanding is that a wind turbine generator can't just be left to freewheel 'off-load' in the same fashion as one might isolate the pv panel. My understanding is that such freewheeling could destroy the turbine and/or the generator - please correct me if I've got that wrong! A mechanical brake can substitute for the braking effect of the electrical load, but I don't think such things are part of the design of these small domestic turbines. (Note that this is independent of the "self-furling" self-protection from increasing windspeed.) And dumping a kilowatt from the braking load is not exactly inconsiderable.
3/ And, Milud, I was mislead!
nathanbriggs wrote:
{23 March 2005}...this means you can directly connect the Windsave power into the mains (although not by just plugging it in it must be hardwired).
{My emphasis - Dougal}


fonant wrote:
I've seen solar PV inverters that are like a large wall-socket power supply - you do just plug it in. For example https://www.mastervolt.com/sunmaster/soladin.asp. Very cool and very portable for when you move house
As above, I think solar pv isolation can be just switching off, but that its more involved with turbines. And I note that those units are handling just 1/10th of the claimed maximum output of a Windsave.

fonant wrote:
I love electronics - these things work so fast it makes the 50Hz mains frequency look slow!
I remember learning Assember programming on a 1Mhz 6502 Microprocessor system, 25 years ago. The response and stability of stepper motor control is an experience that lives with me! Shortly thereafter I was faced with the problem of measuring the quiescent current of CMOS custom chips (nanoamps) in a rather noisy RF environment. Having rather fancy test equipment, I didn't bother with shielding at all. I simply made 1k measurements (!) and averaged them by adding and shifting the "decimal" point (1k rather than 1000 so it was simply a matter of a "binary shift"). The results were brilliantly reproduceable for particular chips - it worked!
I suspect that the programming problem for the solar inverter isolater would have been in reliably and quickly recognising the difference between noise and a powercut.
I am well aware just how quickly microelectronics can respond, and how difficult this can make interfacing to the real, slow, physical world..!

Post new topic   Reply to topic    Downsizer Forum Index -> Energy Efficiency and Construction/Major Projects All times are GMT
Page Previous  1, 2
Page 2 of 2
View Latest Posts View Latest Posts

 

Archive
Powered by php-BB © 2001, 2005 php-BB Group
Style by marsjupiter.com, released under GNU (GNU/GPL) license.
Copyright © 2004 marsjupiter.com