Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
I've read a lot of posts regarding stator configurations and the pros and cons
of different peoples experiences(It's good reading weather in SE Queensland )''
I'm tending to think a star/delta configuration would be best but am a little unsure about how to go about it on a dual stator F & P.
What configurations have others found successful ?
Is it best to have all your delta connections on one stator and star the other ?
What about the number of poles/coils on your delta winding/s ?
Just an aside...... what about star/delta motor starters, why are these internal currents not a problem in a 3 phase motor or is it just that manufacturers precisely
position the poles in the stator and squirrel cage rotor ?
Mick
Edited by WindyMick 2010-12-28Manly to win !
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 05:58am 27 Dec 2010
Copy link to clipboard
Print this post
Mick, for an answer to your last question consider this:
A squirrel cage motor starts in star and once up at speed switches to delta - and stays there.
A wind generator speeds up and down all the time, meaning the star/delta contactor works overtime and quickly gives up the ghost. You cannot compare the running conditions of a fixed speed motor to a highly variable speed wind generator.
Hope that explains it, for the rest of your questions you'll find answers in the forum, happy hunting Klaus
In relation to the motor starter, I was thinking more about the currents people talk about in delta that eddy around and create problems rather than the actual starting
sequence.Once the motor starter is in delta it's basically a delta winding connected to the mains.You could compare that instantaneous situation with an instantaneous point on your alternator curve or perhaps if you had it in a lathe at a certain speed, albeit you'd be comparing a generator with a motor.On most induction motors you'll usually find an efficiency rating which is often around 85% or so, I'm wondering how much of the 15% is lost in the stator eddy currents and comparing that to the good old F & P.
I'd still like to know what delta arrangements people run.I found the staggered stators section in TheBackShed very informative but when I came to the real life example(1x6,1x5,2x4,3x3, I wondered how to best incorporate the delta winding.Initially I thought it best in the 3x3 configuration as that's dealing with the higher end anyway,but not real sure.I'll keep going through the archives but so far have not seen anything really definitive. Edited by WindyMick 2010-12-28Manly to win !
Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301
Posted: 08:53am 30 Dec 2010
Copy link to clipboard
Print this post
Hi WindyMick,
Just a suggestion, detail the voltage you are planning to run along
with the location/site statistics and the forum might provide you with options to
consider. There are a lot of smart guys out there!
cheers Rastussee Rastus graduate advise generously
I'm slowly piecing together what I'm going to do although it certainly seems an
inexact science (half the fun)
I'll probably run a dual F & P,probably an 80S and a 100S but my initial design point is the load.I'm going to start at the load and work backwards.At first I was going to go straight into a GTI via Latronics Turbine controller but the "voltage window" it looks for is too narrow meaning lost power at low speed(courtesy Downwind's post).
I might add here that a battery bank probably looses about 10% in efficiency as well.
Seeing as I've decided to buy some sort of new GTI instead of risking overloading my Latronics PVE1200 (1.44KW arrays), I'll opt for a 24V battery bank as long as I can find a decent GTI that will accept 24Vdc.I liked the sound of the Ginlong inverter but that starts at 30Vdc.A lot of the cheaper Chinese inverters seem to except lower voltages but is it worth the risk ? Bit of a bugger if you fried a linesman !! 24Vdc gives a lot more options down the track regarding experimenting with stator combinations and also I could add a few PVs onto the battery bank to keep the GTI powering/hooked up during the day, as we try to use as little house power as possible between 9am and 3pm, for max exporting. In QLD export power is 44c per KWH although I heard NSW has knocked theirs on the head so import price = export price. Correct me if I'm wrong.Looks like the Maroons win again.Who would want to be Christina Keneally ?
Also I'd like to experiment down the track with electrical gear changing with a star to delta switch or solid state changeover but that stuffs down the track,too much nuts and bolts stuff to worry about yet.
Not many on the forum seem to mention too much about the economics of home wind power but once we get a carbon tax I expect you'll see a few turbines around the place. A bloke could make a living out of wind power in a few years I dare say.
So.......my main sticking point seems to be what inverter at the moment.I'd prefer not to have to go to 48Vdc but I'll wait and see.
Mick
Manly to win !
Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333
Posted: 01:24pm 30 Dec 2010
Copy link to clipboard
Print this post
Hi Mick,
You talk of GTI..........one question is what sort of power meter do you have???
The reason i ask is because of something i become aware of recently.
If you have the old style meter with the spinning disc than all is fine.
If you have the newer digital meter than BEWARE.
The newer meters work off a single current transformer, that records current regardless of which way it flows.....meaning you will be charged for what you use, and also charged for what you put into the grid, so you pay both ways and receive no credit.
It can actually cost you by feeding into the grid.
Pete.Sometimes it just works
brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548
Posted: 09:14pm 30 Dec 2010
Copy link to clipboard
Print this post
Hello Pete,, Could you explain that bit again ,,about the new meters, I have one .
Be really pied off if we are paying for exporting ,hey??
Wish You and your Family a Happy New Year..
BruceBushboy
Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333
Posted: 11:31pm 30 Dec 2010
Copy link to clipboard
Print this post
With the new meters and if you have not had it changed to suit a solar system that is grid feeding then you will pay for imported power and exported power.
So in the case of Joe Blog down the road, decides to buy a GTI off fleabay and wire it into his house with some solar panels and a mill feeding the GTI, than he will be charged for all the power he puts into the grid.
Unless the meter has been upgraded to suit a GTI system the internals in the meter reads current passing through it regardless which way it is flowing and logs the current as power USED.
The old spinning disc style meters will run backwards the new ones wont.
For the more technical minds i understand the new meters have a single CT so are unable to know which way the power is flowing.
It is also fair to point out that the base load of your house might use all the power a small inverter makes and it never flows back to the grid, but if the base load is less than the GTI output than you will be charged for the difference (not credited)
Hope that helps.
Pete.Sometimes it just works
brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548
Posted: 12:04am 31 Dec 2010
Copy link to clipboard
Print this post
OK thanks Pete,, Mine was put in a couple weeks after the solar by energex linies ... I have it registered and I do get some sort of credit on my bill ,not as much as I thought..But ,who cares,at a consumption of roughly $2 per day ,there are better things to worry about ..
Just had a look at my bill and on the back it's got Queensland Solar credits Scheme then the number of KWHs and the price your bill has been credited. I dont think you'll have a problem if you get a reputable company to do your PV install. I remember filling out some paperwork for Ergon when I bought mine.
Talking of Ergon, I was talking to one of their supervisers a while ago and they are a long long way behind in infrastructure building partly I think because of the parlous position the QLD state government is in(Broke after a mining boom), and uncertainty in
what type and when we will get a future carbon tax.So when we get the carbon tax there will be a double whammy. At this point in time your average Jo Blow will be chasing every milli Watt he can get his hands on.My guess is 2013/14 for the tax.
Mick Manly to win !
Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333
Posted: 11:10am 31 Dec 2010
Copy link to clipboard
Print this post
Mick,
You are right as you have had your meter reconfigured to read both ways, the warning was to all who have added a system on the quite, and expecting to receive a benifit from the addition.
Sorry if i cause alarm to those who have a system that is in appliance with the requirements, my commets was directed to the few who have added a system outside of requirements, thinking they would benifit from their additions.
I too almost fell into the trap and is why i am making a point of view of it.
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
Print this post
'
