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Say 180 turns on the example core to give a 240v output.
Do I have all that mathematics correct?
If it looks OK, then I can document this for next time, and armed with this, I can build toroids of different power depending on what I need.
Using the same example above, if the core was wider at 250mm but thinner at 50mm deep and same 100mm centre hole size, the resultant number of turns would still work out at 179.23 turns for the same 240v winding due to the slight change in size of the core, correct?Smoke makes things work. When the smoke gets out, it stops!
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 02:08am 19 Jun 2016
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Same on my calculator Grogster. There are only 10 types of people in the world: those who understand binary, and those who don't.
Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9308
Posted: 02:14am 19 Jun 2016
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Goody. Thanks for your post.
Where did the magic 2800 figure come from?
EDIT: More to the point, where did OZ get the magic 2800 figure from?
I assume this is correct if you are designing for a 48v system, or does the number of turns on THIS side of the transformer not care one jot about the low-voltage primary, simply cos you can easily change the LV primary turns to suit?Edited by Grogster 2016-06-20Smoke makes things work. When the smoke gets out, it stops!
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 02:58am 19 Jun 2016
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You will have to ask Oz, but I think he said he just worked it out through trial and error.
To answer your other questions I suggest you go here http://www.anotherpower.com/board/index.php/topic,1044.0.html and have a good read it is all in there.Edited by Madness 2016-06-20There are only 10 types of people in the world: those who understand binary, and those who don't.
oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 01:02pm 19 Jun 2016
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Grogster,
The 2800 was derived from simple measurement
Mad has a transformer, if he were to wind say 10 turn onto one of them when he pulled it from the inverter before he unwinds it, put 240v through the windings labelled as such ( it has 230 and 260... either one will do really)
Measure the voltage in the 10 turns.... strip transformer, get cross section do the math, and presto we get around the 2800mmsq for a volt turn @ 50 hz.
This won't change for primary or secondary... in his case it would be around the 1.2-1.3 volts/turn...( pure guess... he may or may not have done this to see) so we can say that it will have around 1.2x2800 or 3360 mmsq or somewhere in that region.
Alternative is to unwind the original, and see how many turns for the 260v or 230v winding... and divide to get the turns/volt, then measure the core and do the ,math again... that will get very close to that cores characteristics
This is not scientific, it is rule of thumb, but seems to work just fine where ever I have needed to use it on core I have not measured first, or am extrapolating for a wind of some kind on core mix ups.... like mads will be.
.........oztulesVillage idiot...or... just another hack out of his depth
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 04:30pm 19 Jun 2016
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Hi OZ,
I am just working on blind faith that your figures stack up.
Reality will give the final answer, but I have no reason to doubt your wisdom.
GaryThere are only 10 types of people in the world: those who understand binary, and those who don't.
oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 08:09pm 19 Jun 2016
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2800 is conservative, so all should be good.
........oztulesVillage idiot...or... just another hack out of his depth
yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166
Posted: 09:12pm 19 Jun 2016
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so using those figures
the primary is 22.4 turns
Are we still using (48 volt DC X 0.7071) minus switching losses and resistance = 30volt AC for the primary winding? Assuming lead acid battery bank.
what about voltage margin for saturation etc?
22 turns primary 180 turns secondary would give 30volt:245volt
23 turns primary 188 turns secondary would give 30volt:245volt
I take it 23:188 will have lower idle losses and the first one will be more aggressive at the top end?
I remember there was some tweaking for something from the original powerjack wind with the new inverter eg8010 chip but I dont remember what it was. I'm confused, no wait... maybe I'm not...
oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 10:08pm 19 Jun 2016
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Yahoo... aiming for 26v for the 48v system.
The dynamics of the 8010 are not as high as the PJ card for some reason.
If you wind for 30v there is a fair chance you will lack voltage under low SOC conditions.
This seems not to be problematic, even though instantaneous currents must be higher, there is still prolific power available to play with.
There are some chinese sites selling the egs002 in a transformer mode board, and they too recommend 26v... which I was happy to see...
So about 9:1 instead of 8:1 that we used for the pj
...........oztules
Village idiot...or... just another hack out of his depth
yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166
Posted: 01:43am 20 Jun 2016
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thanks Oz, so it looks like 19 or 20 passes through the core with the primary winding if grogster & madness winder-upperers inc are close to the estimate. I'm confused, no wait... maybe I'm not...
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 02:11am 20 Jun 2016
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My calculations for a core 198 OD, 100 ID 140 high (2 cores together)
Primary 11 turns
Secondary 98 turnsThere are only 10 types of people in the world: those who understand binary, and those who don't.
Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9308
Posted: 02:46am 20 Jun 2016
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If I get a pre-wound core of 200 OD x 110 ID x 75 depth, with 200 turns on it - based on the calculations above for a 240v winding, do you think I am going to have any issues getting enough turns of the primary on there?
I designed for a 110mm ID to allow more room to get those big primary turns in there....
I can get a professionally wound toroid with 200 turns of 1.6mm for NZ$430 + GST. This is the toroid core rolled to my specs, insulated, and wound on the toriod winding machine.
2mm single(one-in-hand) for NZ$510 + GST, 2mm dual(two-in-hand) for NZ$581 + GST.
In my case, I am looking to build an inverter for a tiny-house, so I don't expect to ever need to suck 30-amps from it, so I am purposely scaling down the toroid a little to save LOTS on the cost of the toroid, but stil have plenty of grunt for what I am wanting. 1.6mm should be good for 10-amps of 240v, and I doubt I will be running that much either. The other prices are just for reference, and allowing options to make the toroid more grunty for more output current.
These prices might frighten some of you, but for ME, $430 + GST is a good price for a professionally rolled core with the winding done by the toroid winding machine. I will put on the Mylar top-wrapping, once we have confirmed the turns is right etc, as I may need to remove a turn or two etc, to get the secondary winding right.
.....unless Oz thinks that I can just seal it up at the factory as 200 turns, and adjust the output voltage by changing the primary windings......Edited by Grogster 2016-06-21Smoke makes things work. When the smoke gets out, it stops!
oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 06:55am 20 Jun 2016
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The 200 turns is fine, the hole is good, but if you are using only a 1.6mm winding, it is pretty puny and you could go for a smaller hole, as you could use 16mmsq wire for the primary for that.... not a deal I would consider as good.
The $581 is the one I would do.... but way to expensive.... and that is pretty much a standard 3kw aerosharp transformer... which are obtainable.
The inspires are very similar too.
Check out Frackers on anotherpower, he has found torroid material over there, or find some other way out.
Freight from aus to nz is pretty reasonable, at about 110 dollars..for 20kg or so.
There must be better options for you than that you have found so far.
..........oztules
PM me if you can't get anywhere with this.
Edited by oztules 2016-06-21Village idiot...or... just another hack out of his depth
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 11:40am 20 Jun 2016
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Grogster I should be able to get another Aero Sharp Inverter in the next few weeks. They are $65 AUD each plus $120 for post and a bit for packing. So for about $200 AUD you get a tranny. Maybe Oz has a better solution but this is way cheaper than getting one wound, might cost you a couple beers if I ever visit NZ too.
Jeez OZ you where up late.Edited by Madness 2016-06-21There are only 10 types of people in the world: those who understand binary, and those who don't.
oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 12:10pm 20 Jun 2016
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.. no he gets a much better tranny than he was proposing.... for about 1/3 the cost.
I was hoping you would chime in Mad.
Grog, a standard one will just need the outer( primary 260v) winding removed to have the same thing as you were getting for $600.... then add your own primary of around 22-23 turns.
For the duty you talk about, 25mmsq will probably do fine, so fits very easily, and will still so 2-3kw cont, and 10kw excursions to start things up, or cover for electric jug or toaster etc for small duty cycles of less then 10 mins at a time on top of the house usage.
This will cover more than most off gridders dream of.
It was blowing and raining hard and heavy all night. so I got up and played a bit.
...........oztules
Edited by oztules 2016-06-21Village idiot...or... just another hack out of his depth
Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9308
Posted: 03:42pm 20 Jun 2016
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Thank you very much guys, for your posts and offers of help.
I would like to take Madness up on his offer - that makes a-lot of sense IF and ONLY IF he is prepared to do this for me......
That is certainly the way to do it - I have had no response at all from the PM contact Madness sent me, so they obviously are not interested in sending to me themselves - and that's fair enough.
Madness - if you are getting another one soon, could you get me a couple, and send me two transformers? Naturally, I would reimburse you for this BEFORE you went and got anything, so you would be covered, then I would just need to be told the total for freight and I can sort you out for that then. It may well work out cheaper to send them separately rather then together due to the total weight of two vs separately.
Perhaps PM me your thoughts on that, Madness, and we can go from there.Smoke makes things work. When the smoke gets out, it stops!
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 03:55pm 20 Jun 2016
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Yes can do will PM you.There are only 10 types of people in the world: those who understand binary, and those who don't.
yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166
Posted: 06:11pm 20 Jun 2016
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I know Toll do an international parcel and courier service to NZ (parcels up to 300kg) they do an express and economy version.
if they do a competitive price it could be better to send the inverters complete. I think the weight is calculated from the dimensions of the parcels for their pricing.
most of my freight is delivered by Toll or Toll IPEC. I'm confused, no wait... maybe I'm not...
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 09:23pm 20 Jun 2016
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Ready when you are Grogster if you still want them.
There are only 10 types of people in the world: those who understand binary, and those who don't.
BrianD Newbie Joined: 06/05/2014 Location: New ZealandPosts: 7
Posted: 11:53pm 20 Jun 2016
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I would also be interested in getting a couple of toroids sent to NZ as well if Madness or any other forum member is able to help. I have had an inverter build in progress for a while and have it working with a small transformer but have also been unable to find a source of reasonably priced toroids locally
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.
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