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Forum Index : Electronics : Sourcing Toroids and enamel wire for inverter
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Haxby Guru  Joined: 07/07/2008 Location: AustraliaPosts: 418 |
Hi all, Over a decade ago, I was playing with F&P motors with the help of this forum, but then life and kids and work became a priority. With being stuck at home now, I have resurrected the urge to get back into tinkering. I have bought a 48V 10KW pure sine wave PCB from ebay: 48V pure sine wave board After googling for a large transformer to suit this board, I came across the Ozinverter and now will be going down the path of winding my own transformer... After googling some more on where to buy toroids, I have only seen the brand name Aero-Sharp being mentioned. Are there any other brands to look for? Specifically I am in Melbourne South East suburbs of Australia. Also, I'm interested in a good-and-cheap supplier for the 1.8mm enamel wire. Please let me know if you have any leads! With the aerosharp toroids, what is the stock configuration on them? If they are close to 1:2 ratio then they might also be good for another project of mine! |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Aerosharp is not a brand of toroid, but a type of grid tie inverter. Many of these grid tie inverters get junked for various reasons, and sold for scrap metal value, there are other types of scrapped or blown up inverters that occasionally come up on e-bay or gum-tree for sometimes less than a hundred dollars. These can be a great source of major parts, such as the toroidal transformer, large heat sink, and the metal enclosure. These recycled major parts can then make a great basis for building your own home brew inverter at minimal cost. The Aerosharps are especially sought after because they come in the 3Kw size, and two of the 3Kw toroids when stacked together make the basis of potentially a low cost 6Kw inverter transformer. There are not as many of these Aerosharp inverters around now as there were a few years ago, but they still sometimes surface if you are patient and quick to react. The usual routine is to completely strip the wire of the original toroid, which is often 1.6mm or 1.8mm, and rewind it using one or two toroidal cores stacked together. These original grid tie inverters usually have a high voltage primary and a 230 volt secondary which unfortunately, is often the top winding. That is why both windings need to come off. The original wire can then go back on to create a suitable 230v winding, and a low voltage primary then put over the top of that. This has been done many times by Forum members, and you will get plenty of help and advice from members here. Cheers, Tony. |
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| Haxby Guru Joined: 07/07/2008 Location: AustraliaPosts: 418 |
Thanks Warp speed. Any other brands of solar inverters to look out for? Would most of them use high frequency inverters nowadays with smaller magnetics or would I be likely to find large toroids in most brands? I guess I could pay a visit to our local recycling centre (tip)? Also I'm a bit reluctant to re use the copper wire. I fear I will damage it on recovery. Any suppliers in Melbourne that have reasonable prices for 1.8mm enameled? |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
For safety reasons the supply authorities in Australia demand that any grid tie inverter isolates the mains from the solar dc side. So all Aussie grid tie inverters will have a large steel cored toroidal transformer inside, to provide that isolation. Pretty much any grid tie inverter you can get your hands on will have a suitable toroid and heat sink that can be reused. just be guided by the advertised power rating, some of these grid tie inverters can be rather small, and so will the transformer. If you have the opportunity to buy two or three identical inverters together of smaller size, if the transformers inside are the exact same, its then possible to stack the cores together into something much larger. Just search e-bay and gum-tree for "grid tie inverter", many will be working units, but a blown up one will go very cheap, as they are usually not worth repairing. I just had a look, and nothing available right now, but they do turn up from time to time. In many cases the company that made these inverters went out of business years ago, or older grid tie inverters no longer comply with current supply regulations and can no longer be legally fitted into a new installation. That makes them pretty worthless to most people, but a great opportunity for us. No matter how much any internal damage, the transformer core and heat sink should be perfectly reusable. Cheers, Tony. |
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Murphy's friend Guru Joined: 04/10/2019 Location: AustraliaPosts: 580 |
I got my torodial transformers from a solar installer. You need to contact the person in charge of returned/ replaced inverters. Very few of returned inverters get repaired nowadays so they get sent away for scrap value. If you offer to pay a little more than they get from the scrap merchant they might sell it to you, especially for cash. Now, a lot of the newer grid tie inverters have those small, high frequency winding, toroids inside. Quite useless for home built inverters. What you need is to personally lift the offered inverter, if it is very heavy take it. For example, the 3KW Aerosharp weighs at least 30kg in its box. I'd be suspect of anything under 15kg in the box unless its just 1KW or less. Other brands I sourced toroids from are Sunny Boy, this had a yellowish plastic case and Latronics inverters. The Latronics had a useless internal heat sink though. Again, check the weight and read the label as to its power handling to give you an idea what the toroid can do when re wound. BTW, if the toroid is not fully varnished outside its relatively easy to re use the copper winding. There are plenty of posts here how to do that without damaging the wire. Also, how to straighten the wire and then re wind it. Buying enameled wire new is expensive unless you have a personal friend in a winding shop. That wire comes in 20kg reels, you certainly can buy it in that quantity  . |
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| Haxby Guru Joined: 07/07/2008 Location: AustraliaPosts: 418 |
Ok I'm off to the recycling centre then. Wish me luck! The next question is about the choke before the transformer. I think it's 4.7uH?? Am I likely to find a suitable one in a solar inverter? |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
I have that same inverter board in my bus My son has been hanging out down there at bus with his friends using it every day almost I turned it on when I installed it over a year ago I modified the egs002 like poida explained to me I think they make good inverters I am now building a farm inverter the board is not the same but similar I am adding alot larger caps These boards make building a inverter possible for anyone Have a blessed day be warned i am good parrot but Dumber than a box of rocks |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
The deceased grid tie inverter(s) you rescue, will also have a steel cored choke as well as the toroid. That choke, when rewound will also make an excellent choke for your inverter. If you decide to stack a couple of toroids for higher power, stack the choke cores as well. The relative sizes of the toroid and choke were right for the original grid tie inverter, and should work just as well in your new inverter after a rewind. Cheers, Tony. |
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| nickskethisniks Guru Joined: 17/10/2017 Location: BelgiumPosts: 409 |
About a year ago in my quest to search for transformer cores I decided to look for old/broken solar inverters, well it wasn’t easy, there are not many here in Europe. And it’s sometimes ridiculous how much they ask for broken or used appliances. My best chance was Ebay Germany, so I had searched for types with a toroid in them and I had a few brands/ types in mind. After a few months of active searching I found someone that was selling broken inverters, he was selling broken Diehl Platinum inverters. Downside, I had to buy a whole pallet. So 16 inverters for 570€, and inverters were between 2100S - 4601S series. Then there was another 345€ for transport, they were really heavy! So around 57€ a piece, for transformers between 1400 and 2600VA. That time I thought the price was ok, it was the only source with a reasonable price, china was to expensive so as the EU based company’s. Now I know a source in UK recommended by Clockmanfr for 80€ excl transport(200OD, 100ID, 120H). Although the 2100S type suggest 2100VA there was only a 1400VA ( rated for 1750W AC nomnial) transformer in it, with the 4601S there was only a 2600VA (rated for 3800W AC nominal) transformer in it. So a little bit disappointed, another disappointment was that the transformers were incapsulated with epoxy… But a few weeks ago I succeeded to remove the epoxy with a chisel quit easily (still about an hour of work). The outside winding is lost, but the primary stays intact. They have an enormous heatsink as well and a pair of big igbt’s, various capacitors, filterstage, dc disconect switch,... The remarkable thing about those inverters is the fact that they are all basically the same, except for the inductor, transformer and firmware… all the rest is the same! The inverters were in fact all broken, and because they were all the same, 90% of the breakdown fault was also the same, a faulty power supply, the flyback circuit went BANG, ic’s and some zeners. I have repaired 3 of the most easy to fix, and they are now in service at my father’s place. I think there was an overvoltage or lighting strike. I'm using one enclosure for my solar controller, and I will make a second one as spare. Another one will be used for a spare 48VDC-240VAC inverter. I will find projects to fit in.  A few pics of the inside:    Edited 2020-07-24 19:27 by nickskethisniks |
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