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rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 793
Posted: 01:37pm 05 Aug 2021
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I mentioned this on another thread but thought I'd expand over here as it may interest others looking for toroids.
I went to order some sheet metal and have some bending done for my solar heater project and the guy was quite interested and asked lots of questions. Seems he lives off grid out in the scrub and has an interest in alternative technology.
Anyway, when I said what I did for a living (repair circuit boards), he pulled out his phone to show me a photo ... and said he'd been looking for someone to fix the board in his inverter, but because he couldn't find anyone, he had to buy a new inverter.
He just couldn't get his head around throwing the old one away ... and then asked if I wanted it. Anyway, of course I took it home ... and after having a look, discovered that it was a 12 y/o SMA built SMC6000A Sunny Mini Central ... even though it was dressed up in a nice green BP Solar case. Good for 6000 watts.
The photo he showed was of a couple smd components burnt on the main board ... but being alongside the main IGBT suggested that it was blown.
Half a dozen screws and the board was out and IGBT exposed and sure enough it had burst at the seams.
Then I realised that the front section of the unit was pretty shallow and started to wonder what was in the rear ... especially seeing it was so heavy ... 63 kg.
Rolled it over and took off the nice flat aluminium cover ... and exposed what looked like a black plastic shroud covering the works.
Took out the half dozen screws and went to lift the cover off .... and realised the cover had a toroid embedded in it from the other side ... and of course, unless I tipped it over again and disconnected the wires running to it, there was no way it was coming out.
There isn't really any finned heatsink at all ... just the huge mass of aluminium case ... and two fans that can blow air up either side of the toroid, past the IGBT mount position ... and out the sides near the top.
The cover also has a label showing that the tx has a 168v primary and 230v secondary at 6000va.
Of course, the other thing that struck me was the size. It must have a massive toroid glued in there.
Check out the pictures ... and imagine stripping a pair of these to sandwich together to rewind.
They're all 1000uF at 300v capacitors ... 20,000uF 300v
That's my size 10.5 hoof showing here
Cheers, Roger
wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 993
Posted: 02:08pm 05 Aug 2021
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Hi Roger, that was a good score !
What are your plans for the Toroid ?
If you intend to remove the outer winding I will be very interested to see what method you come up with, hopefully it might make the task a bit easier.
I am assuming it is one of the potted toroids inside the plastic housing ?
I just finished that exercise with a 3kW unit, the potting made it very difficult.
It took many days and made my hands bleed raw - use gloves if you go ahead with it.
Now I have a large heap of small lengths of copper wire all useless & adulterated with resin - did I mention how hard it is to separate the resin from the wire, sheesh?
I'm thinking make a fire (petrol?) to burn it all off - but its probably flame retardant too.....If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 04:47pm 05 Aug 2021
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Its a bit like winning the lottery.
I think I would first try to get it going before ripping it completely apart. From the primary voltage it looks like its for a 250v to 300v dc supply. A battery at that voltage would be quite a wondrous thing, but a suitable electric vehicle battery might be a solution to that.
On the other hand, that toroid with its existing secondary would be ideal for a big Warpverter.Cheers, Tony.
flyingfishfinger Senior Member Joined: 12/09/2020 Location: United StatesPosts: 102
Posted: 05:32pm 05 Aug 2021
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Wait, this is exactly what I was talking about in my thread - I harvested those big caps to make poida's MPPT from a busted one of these I also got for free. Looks identical.
I just tossed the big toroid, I have no use for it. But I can still take it out of the dumpster if anyone wants it stateside...
Are any of the other bits worth saving?
R
rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 793
Posted: 11:26pm 05 Aug 2021
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Hi Mike, yeah I was a bit surprised because I wasn't expecting to see a toroid in there, though the weight of the thing should have been a clue.
I think I was surprised because I haven't read anywhere on here from anyone else ... that there are toroids available from anything other than Aerosharp and Inspire (which I've never seen) ... and some small versions of SMA which were also potted. I have a 1.5kW version here.
I haven't had time to think just how I might use it, though I still have my Warpverter to finish. I've wound the secondaries on three of the toroids ... just need to do the fourth one ... the big one ... but of course have put that on hold so I can finish my solar air heater.
I didn't pull it any further apart to be 100% sure, but that's what I expect.
I do know when talking about the 1.5kW one I have that Klaus made a comment about having used one ... so he must have had a method ...
... and I reckon Nick (nickskethisniks) mentioned having used some as well. I vaguely recall him saying the outer layer is destroyed, but the inner sections were re-useable. Maybe he'll pop up and refresh my memory.
I bought a small bottle of conformal coating solvent a while ago ... maybe I could try that, though it wouldn't be practical with something that size.
For any encapsulated boards I fix, I use heat to soften the the epoxy and use a blunt screwdriver to chisel it away ... and it's much easier now with my hot air desoldering tool because you can be a bit more selective with the direction and area compared to the old method of a standard hot air gun.
For a while I used to put one particular board in an old convection/microwave ... and that did a wonderful job of softening the epoxy ... you could easily dig it away like crumbly old cheese ... but then I discovered the process was ruining a tiny little transformer that I then had to spend hours and hours reverse engineering to rewind some more. Little RM5 formers, I think you know them.
I haven't used that process since ... very painful experience.
I can quite relate to that, sounds painful.
Actually that is not as silly as it sounds ... though I'm thinking heat, not fire.
I would try a hot air gun on a section of the material and see what happens ... and if it softens it enough, I'd put the whole thing in an oven to get it hot all the way through ... then use the gun to keep the area you're working on hot enough to chisel away.
The process I use on the boards works well enough to make it practical to fix ones full of smd components ... and they are a lot more fragile than copper wire ... so it should be do-able.
Yes, very pleased to have it ... and also to know where to look for other similar ones. SMA also made an SMC4600A, an SMC5000A as well as the SMC6000A ... so more inverters to put on the watch list, especially if there is a possible use for the toroids without having to rewind them.
I don't know what the demand is like over there ... but it would be easy enough to put it up on ebay and see what the interest is. Pretty sure it would have to be pickup only ... but still worth some bucks. Ben and Amber mention ones for sale over there from time to time.
Some of the hardware is very nice too ... connectors and fittings etc ... but only if you do a lot of building I suppose.Cheers, Roger
InPhase Senior Member Joined: 15/12/2020 Location: United StatesPosts: 178
Posted: 12:06am 06 Aug 2021
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What would it take to get that toroid from you?
Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1577
Posted: 12:15am 06 Aug 2021
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Didn't I read on here that the potting can be dissolved with acetone? Paint thinners may also work but might also kill the wire coating. I think the trick would be to put it in a plastic crate or something that could be sealed and let the solvent whatever it was really soak in and break it down. Bit of agitation now and then wouldn't hurt either.
The other thing is that stuff must melt at some temp. Whether it's below the temp the lacquer on the wiring is damaged is another thing.
It might be worth repairing that Inverter if you can Roger for your own install.
I have 5 Kw SMA up the back I am going to strip. It seems overly heavy as well. Might get it and break it down and see. Want to get rid of it anyway.
flyingfishfinger Senior Member Joined: 12/09/2020 Location: United StatesPosts: 102
Posted: 12:17am 06 Aug 2021
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Where are you located?
R
rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 793
Posted: 01:44am 06 Aug 2021
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I'm not sure about that. I have tried acetone, but while it certainly disolves the plastic housing the boards sit in ... it really only hazes up the surface of the epoxy ... at least with the ones I've seen. Plus I've never been patient enough to see what happens long term.
I've certainly thought about that. The IGBT and the couple smd parts are quite likely all that are wrong. I couldn't find a replacement IGBT readily, but the part came up on the Newark site at around $70 ... though out of stock. Might have to keep looking.
The only trouble is it might be a bit too big, power wise, to run with the Warpverter once I finish it ... I understand I'm better off having another 1 or 2 small GTI's ... like 2 or 3kW power level.
What's the model number, can you see it easily? If it has a toroid, you'd probably be able to sell it easily enough, as long as it's someone close ... and no freight involved. Cheers, Roger
InPhase Senior Member Joined: 15/12/2020 Location: United StatesPosts: 178
Posted: 11:55pm 06 Aug 2021
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Huntsville, AL
nickskethisniks Guru Joined: 17/10/2017 Location: BelgiumPosts: 409
Posted: 04:39am 07 Aug 2021
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Yes, I used a chisel and hammer to remove the hard epoxy, didn't try something else. I destroyed the outer layers to gain speed, it would take a very patient man to keep it 100procent intact. There was no mylar used on mine, so the outer windings would have very slim chances to show up in good state after the procedure. The inner layers were completely fine afterwards and packed in mylar.
rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 793
Posted: 02:57pm 07 Aug 2021
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Thanks for your input Nick.
I keep thinking angle grinder ... but I wouldn't be able to do it. Your way does make sense ... just get that top layer or layers off ... then unwind the rest like normal.Cheers, Roger
Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1577
Posted: 03:29am 08 Aug 2021
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I just stripped the SMA inverter I have. No torroid but what I think are 4 large, potted chokes. Couldn't even find any decent Mosfets in this one. The SMA's are supposed to be the ducks Guts but looking at the way they are built I fail to see why.
I have those potted Chokes from other GTI's as well.
Are they any good for anything other than just throwing them in a Crucible and aiming a burner at them to melt down the copper windings?
johnmc Senior Member Joined: 21/01/2011 Location: AustraliaPosts: 282
Posted: 05:38am 08 Aug 2021
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rogerdw
Why not try punching out the centre with a press (say 50 mm pin) with a hole under the torriod so that there is a shearing action pushing the centre out.
This should at least give you a starting point as to the size of the centre.
You then may be able to increase the pin size.
This is how I start to dismantle the other torriods.
Cheers johnjohnmc
wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 993
Posted: 10:08am 09 Aug 2021
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Hi John, I tried a club hammer and large drift punch and beat the crap out of it. I broke 1 wire off and it just laughed at me not moving a mm.
Then I drilled a series of 5mm holes around the centre aluminium mounting mandrel as deep as I could and turned it over and did the same from the other side.
Then I beat the crap out of it again & it still laughed at me. I don't have a press but it may work - the resin they use is pure evil!
Then I got one of those drills with the gnarled sides for pseudo milling and slowly ate out the remaining material from both sides then it finally came out.
Like Nicks unit no mylar on the outer just resin straight over and throughout the winding
I hated every minute of every hour I slaved to finally get to the inner layer which is intact (minus the wire I broke off so a small repair to do sometime when I can bear to look at it again).
I tried every solvent in my arsenal to no avail the heat gun just made it stink and hot to handle - maybe you can make it work. the only think that softened it up a bit was brake fluid but I only used a small amount. maybe a couple of litres and let it soak overnight (or a few more) might pay better dividends.
Good luck Roger..... . Edited 2021-08-09 20:10 by wiseguyIf at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike
rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 793
Posted: 01:45pm 09 Aug 2021
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Thanks John, that's a great idea. I don't have press, though could get access to one if I had to.
I'm not sure if I will tackle it or not until I get back onto the Warpverter build. I had just about decided on a core for the big transformer and the other three are wound already.
It would be nice to know the dimensions of this core when it's bare ... but I don't want to wreck it and find out what I already have is more suitable. At the same time, this one is a 6kW toroid ... so it's gotta be pretty big. Surely bigger than a 3kW Aerosharp.
Before I started the Warpverter I agonised over whether it should be 48V or 100V or so, by using some Nissan Leaf batteries perhaps ... though I settled for 48V.
It will be interesting to do the numbers on this toroid to see if it could be used without modification for a high voltage Warpverter ... or at least without unwinding it all.
Thanks for your suggestions.
Ouch, it does sound onerous. Not sure I'm that desperate yet. Maybe mine needs to be left right alone.
So there's no way to save the top winding which is the primary I assume ... so I wonder about feeding it through a bandsaw.
Take off slices down through the outer layers so you can get to the windings and chisel it from there ... like taking the peel off an orange.
Now I've had some experience winding toroids, maybe it's just as well to hack it all off down to the bare core and start afresh with new wire.
So you're saying you need a bit of time to think about if you're prepared to strip mine for me ... or was that a definite no?
Thanks for that, it's always helpful to hear what's been tried and what definitely doesn't work ... and what might be worth a second look.
I wonder if there are any toroid anxiety therapists available for a session or five.Cheers, Roger
wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 993
Posted: 03:35pm 09 Aug 2021
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I've taken my tablet and now feel a bit better after my rant.
Quick story on why I tried brake fluid. Many years ago we owned a Mazda RX4 and it had an area of flaking paint on the bonnet. Being a bit lazy and knowing how well brake fluid strips paint I doused the bonnet in brake fluid (after taking it off the car) to save sanding it with wet and dry - seemed like a good idea at the time.... When I went to scrape off the paint I found that half of the curved profile lines of the bonnet vanished too as they had been full of epoxy filler which the brake fluid had turned to jelly. It took another 2 solid days and lots of filler, filling/sanding/profiling to get it back to the original shape.
I toyed with the idea of an angle grinder and If you were going to remove all windings I am sure it would be great. But I did not want to damage the under winding so tried to be more cautious, I've seen what impatience can do too many times. The band saw might work ok but I don't have access to one.
Im not actually sure there's enough time left in the universe to get to a yes answer for that one.....
In hind sight, yes I think use an angle grinder to remove everything and start afresh - it would probably be faster and gives you an added option to stack 2 cores and have a very generous overload capability and reduced turns to wind albeit with a heavier core. Edited 2021-08-10 01:46 by wiseguyIf at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 09:05pm 09 Aug 2021
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Before you do anything, try connecting up the 230v secondary to the grid, and measure the idling current. If its acceptably low, the original secondary winding might be well worth saving.Cheers, Tony.
rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 793
Posted: 12:49pm 10 Aug 2021
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Ahh ... so you're saying it's a maybe?
I use an angle grinder with a cutting disk all the time ... very useful for steel ... though don't know how good it would be for copper. I also have one of those cut-off saws that is effectively a bandsaw ... I reckon you could slice the sides off with it still.
It's a pity I hadn't known about these big beasts before I started planning my Warpverter ... but I will certainly keep an eye out for another until I'm ready to start again.
And wow, 2 x 6kW cores together is serious stuff ... and could afford to remove some inner turns to enlarge the hole a little.
What size inverter was your toroid from Mike?
Yeah, I'd definitely do that before taking to it with my saw. It would be a real struggle to wreck it ... I hate chopping up perfectly good stuff.Cheers, Roger
wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 993
Posted: 04:25pm 12 Aug 2021
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Sorry for the late reply. My toroid was from a 2.5kW inverter so my suggestion of stacking 2 cores was really referring to my situation & others that haven't had luck finding a decent core like your 6kw toroid. It seems that 1.6 - 3kW are much easier to find.
I like your optimism and positive approach, when Tinker told me that winding your own toroid was like "a walk in the park" I asked him if he could take a walk in the park for me - he didn't take me up on that either. Edited 2021-08-13 02:26 by wiseguyIf at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike
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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