navitron
 
Renewable Energy and Sustainability Forum
Welcome, Guest. Please login or register.

Login with username, password and session length
News: Anyone wishing to register as a new member on the forum is strongly recommended to use a "proper" email address - following recent spam/hack attempts on the forum, all security is set to "high", and "disposable" email addresses like Gmail, Yahoo and Hotmail tend to be viewed with suspicion, and the application rejected if there is any doubt whatsoever
 
Recent Articles: Navitron Partners With Solax to Help Create A More Sustainable Future | Navitron Calls for Increased Carbon Footprint Reduction In Light of Earth Overshoot Day | A plea from The David School - Issue 18
   Home   Help Search Login Register  
Pages: 1 2 [3]   Go Down
  Print  
Author Topic: An off-grid expeience  (Read 6424 times)
biff
Global Moderator
Hero Member
*****
Offline Offline

Posts: 11874


An unpaid Navitron volunteer who lives off-grid.


« Reply #30 on: April 22, 2014, 03:58:55 PM »

I did wonder about the dc coming down from the lump,
                                      I would not fancy that either.You can do a lot lot more with the 3 phase when it is down on the ground.It travels better and it is more forgiving. It is rather strange that a turbine that size would be rectified in the head but they must have had their reasons other than the extra slip ring because sticking the rectifiers in the head like the cheapies,(aulous 300) means you do not get a chance to short it out on the ground if the rectifiers in the head pack up,so I would say there were a few of these that never survived because of that design.
                                                                                                    Biff
Logged

An unpaid Navitron volunteer,who has been living off-grid,powered by wind and solar,each year better than the last one.
Eccentric Anomaly
Sr. Member
****
Offline Offline

Posts: 404


WWW
« Reply #31 on: April 22, 2014, 06:56:51 PM »

Yes, I too don't like the idea of the rectifiers in the head. As Biff says, if the rectifiers fail open circuit you can't brake the thing. With AC and the switch upstream of the rectifiers you don't run the risk that the short-circuit current will break the rectifier rather than brake the turbine. Also with AC (three phase, presumably) you can use much cheaper switches or relays for shorting; DC high current switches can be much more expensive and difficult to get.

I think all the variants of the Futurenergy 1 kW turbine have the rectifiers in the head which is the only thing that puts me off them, really.
Logged

He who refuses to do arithmetic is doomed to talk nonsense - John McCarthy.
heatherhopper
Sr. Member
****
Offline Offline

Posts: 347


« Reply #32 on: May 22, 2014, 12:24:28 PM »

Just another bit about frequency shift diversion loads:

There is a slight problem with generator operation under our system. With the Sunny Island the grid frequency is generator led during generator operation and varies. During warm up (while the Sunny Island is synchronising) this can be as high as 51 hz and during operation it varies according to load although not so high (maybe 50.5 hz). Obviously this variation will trigger the dump loads and in the warm up period they can all be activated causing the Sunny Island to drop the main contactor (on over-current) until the generator comes on line. None of which would be good for batteries, SI health or diesel consumption. Not an insurmountable problem. In time I think the loads will need to be deactivated by the generator start signal or using the spare Sunny Island relay (making them SOC dependent) but since I invariably start the generator manually (on rare occasions it is required) it is a simple routine to switch off the diversion loads for the duration.
Open to any other suggestions.
Logged

Off grid AC coupled, 6kW Proven, 2.8kW PV, SMA SI/SB/WB Inverters, 4x576ah Rolls batteries @ 24v, 25kW Biomass Boiler, Wood Stoves, Spring/Well water. Sorry planet - I did try.
camillitech
Hero Member
*****
Offline Offline

Posts: 5402



WWW
« Reply #33 on: May 22, 2014, 09:00:42 PM »

I have a relay fitted that disables my AC dump loads during generator operation. It just seems barmy to me to have your generator 'fighting' against them. Then there is also the hysteresis that instantly shaves a few volts off the batteries as the generator stops it's EQ. The only minor snag with my setup is that on wet, windy, sunny days the inverter is working quite hard to cope with all the dumps and consumer loads. This can lead to a 'load assist' start which then disables the very loads you need. I've learned to live with this though by disabling the generator during periods of stormy weather.

Cheers, Paul
Logged

http://lifeattheendoftheroad.wordpress.com/

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SI6.OH, 800ah Rolls, 4.75kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
Pages: 1 2 [3]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.20 | SMF © 2013, Simple Machines
SMFAds for Free Forums
Simple Audio Video Embedder
Valid XHTML 1.0! Valid CSS!