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Forum Index : Electronics : Where to find large Toroid in USA?
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LadyN Guru  Joined: 26/01/2019 Location: United StatesPosts: 408 |
Yes, appreciate it Jason! A $500 core would have atleast $100 shipping plus insurance costs of atleast $50 etc. Then there are wires. With Ben's estimate of $200, wow. Does not make financial sense. Power Jack might sell us their toroid cores. I am sure they get returns - what do they do with all of those? Plus now that they are offering newer units, what happens to the older ones they have already? I heard that they have a warehouse in California, so if anyone's interested and can reach out to them to see if we can buy cores from them, I can have my dad or brother pick them up from their warehouse (if it's within driving distance) and we can then ship them by freight or truck out to you all here in the U.S. instead of by air Another option might be to contact a well reputed seller on Ali and ask for quotes. Given this information, I will seriously start thinking and learning about building transformerless step square inverters. |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
No Power Jacket going to sell you a core Not for a price you're going to like anyway The guy I know that works for Power Jack Parts out a machine if the Transformer goes bad his cost is well over 300 bucks for what they call a 8000 watt be warned i am good parrot but Dumber than a box of rocks |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
When I go to build my warpspeed inverter I will be using Square Transformers By all means do check on them other power jack Warehouse may be different from the guy I know Caution this may be very dangerous and you might burn your house down On my little inverter that poida the great help me with I used regular household electrical wire to wrap the secondary the High side It is 10/2 I cut the outside sheath and separated the wires I thought I read somewhere that there's only like one to 3% difference between toroidal Transformer and square Transformer be warned i am good parrot but Dumber than a box of rocks |
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| kentfielddude Regular Member  Joined: 09/05/2019 Location: United StatesPosts: 89 |
What size do you suggest I get a quote for for a 3kwh inverter? |
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| tinyt Guru Joined: 12/11/2017 Location: United StatesPosts: 438 |
This looks easy: DIY toroid core if we can get the electrical steel strip, looks like the surfaces have insulating coating. I think that is what differentiates it from ordinary steel sheet. I wonder how loud it hums. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
1/ Yes the biggie. 2/ Each transformer was first tested for idling power measured with a 50Hz sine wave, because its the only practical way to test a bare transformer. Largest transformer 20 watts. Second transformer 19 watts. Third transformer 8 watts Fourth was never measured for idling power, but its probably about two or three watts. Very happy with the largest transformer, but I stuffed up the second one by designing it for a slightly higher operating frequency, which was a mistake. Should have designed all four transformers for 50Hz and one Tesla flux density, which is what I am advising people to do. None of these transformers actually run with 50Hz sine waves in the inverter. All run with square waves, and the smaller transformers switch at a much higher frequency than 50Hz. The result is that the actual running flux density will be far lower than the design figure at 50Hz, but that compensates for increased core losses. If we design all four for 50Hz sine waves, it gives a nice final result and makes the design process a whole lot simpler. Final idling power with everything running is 35 watts. Five of those watts are just all the bare electronics with no transformers fitted. And thirty watts for all four transformers under real operating conditions. Cheers, Tony. |
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| LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408 |
I am very open to that idea. For some reason I thought that Ben did that exactly and already (make toroids from scratch from strips) but it could be that he was just taking one apart to see how cores are made and I misunderstood his pictures to mean he was making one |
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| LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408 |
Thank you Tony. Would it be accurate to say this Warpverter has an overhead of 1kWh a day? |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
Warpspeed I Unwound all the wire off of several small Transformers after this was done I Unwound the Silicon Steel I used a sewer PVC pipe 4 the center forum to rewind all the Silicon Steel You can make a toroid as tall and wide as you want this way Now this one I don't know if it'll work or not but I read you could use soft steel like bailing wire and make a toroid core Before I tried anything like this or would have anybody else to I would run it past warpspeed and see what he says 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 |
Its probably a bit less than that maybe 900 watt hours. Idling power is very important in the great scheme of things, and we can reduce that by designing all of our transformers to have a very low flux density. There is not much difference between a Warpverter and PWM for idling power losses. Its mostly all in the transformer design. Just eyeballing my average daily total power consumption over the last seven years its typically 4Kwh to 5Kwh per day total load, and that has not really changed. So maybe 20% of power down the drain through idling power loss here. But the inverter is running way below what it is capable of power wise. Cheers, Tony. |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
To me it looks clumsy the way that guy went about the job. I would start with making a better former with cheeks on both sides that are big enough to accommodate the final OD. Then, the hand held rag friction tension idea would never do, it should be easy to make an adjustable soft jaw clamp to keep the tension on the strip as it is wound on. Lastly, holding the end with sticky tape is not going to hold it there while annealing in a 800 deg F oven  .I would apply super glue under the last layer *before* cutting the strip, it being still held taut in the clamp. Then the core needs to be clamped securely around the OD, preferably with that steel packing tape to keep it taut in the oven. That way its not going to hum later. I wonder why the annealing process, when I was working, making very large transformer cores (a very long time ago) they used grain oriented sheet steel, 3 sheets per mm thickness. It had an oxide type surface which did the insulating trick. That was never annealed. Baking the core at very high temperatures as in that Utube would ruin any insulation on the strip unless its high temperature paint. That idea might be doable with some paint brush arrangement as the strip is being wound. Ben's idea of using fencing wire is not a solution for that application. Steel wire does not have the combined area of sheet for a given core size - too many air spaces between the wires. Klaus |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1138 |
The last bare core I had made by TWS here in NZ for a 10KW inverter cost near $500, they also recommended the annealing process, didnt cost any more to have it done, thing weights 60kg, yet to put any wire on it... Cheers Mike |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
That works out to about $8.30 per Kg. E and I laminations made from identical material cost me about $18.50 per Kg, about the same cost as for the copper wire per Kg. A toroid is definitely cheaper, but more difficult to wind. Cheers, Tony. |
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| noneyabussiness Guru Joined: 31/07/2017 Location: AustraliaPosts: 513 |
So if i was to rewind say 4-5 smaller cores into 1 big one, how would you attach each new laminate strap to each other while winding ?? I think it works !! |
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Clockmanfr Guru Joined: 23/10/2015 Location: FrancePosts: 429 |
How is your spot welding. Watch there promo vid where the guy on the old lathe starts winding. https://www.wiltan.co.uk/ oooowwwwwwhh all those cores, Its very sexy! hehe Everything is possible, just give me time. 3 HughP's 3.7m Wind T's (14 years). 5kW PV on 3 Trackers, (10 yrs). 21kW PV AC coupled SH GTI's. OzInverter created Grid. 1300ah 48v. |
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| kentfielddude Regular Member Joined: 09/05/2019 Location: United StatesPosts: 89 |
I've been talking with the guy who is selling this toroid. He says it weighs 180 pounds. If I can get it cheaper do you think it is a good idea. How much watts do you think the idle current will be? |
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| Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Has anybody asked you ever how long is a piece of string? Your answer would have been similar to that you get here for asking about that idle current by looking at a picture  .Klaus |
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| kentfielddude Regular Member Joined: 09/05/2019 Location: United StatesPosts: 89 |
Yes in math class |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
You're not going to know the idle current till you get it all built But if you read Around on this form you will find that the world's greatest Minds has came together in one place So you have a really good chance of making something with the lowest idle current as possible but you got to be willing to listen to these guys If you need a lot of power and you can afford that big Transformer I'd say get it if I could afford it I'd buy it Keep in mind what I told you though I know absolutely nothing I depend on these guys on here and I make a lot of mistakes if I don't directly get my information off them Bigger means bigger wire bigger wire means more wattage so big Transformer equals awesome inverter None of us know exactly what the metal in that Transformer is made out of and exactly how it was put together so anytime you buy a used Transformer you're taking a little bit of a risk or at least I think so 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 reality is, unless you purchase a core brand new from a manufacturer, its not possible to obtain suitable loss curves for the material from which to work. The percentage of silicon in the iron alloy, the heat treatment, and final thickness of the steel layers can have a large influence on the final magnetic characteristics. Anyhow, assuming you buy brand new, and you can locate the appropriate loss curve for your specific material at the frequency you plan to run it (50/60Hz etc). Its a log/log curve with loss in watts per Lb (or Kg) plotted against flux density in Gauss (or Teslas). You can fairly easily find the supposed loss at the operating flux density you decide to use. Now these curves look as though there is only a slight bend, but in reality this is a log/log curve and the core loss increases with flux density at a highly exponential rate, seeming to rise to infinity at ever increasing rate up to full magnetic saturation. Depending exactly where you are on the curve, lowering the flux density by 10% might reduce core loss by 30% for example. So for an inverter, there is a great incentive to run at a quite low flux density to reduce idling power as much as possible. The problem is, we don't know where we are on the curve of an unknown Chinese steel material, and the results are VERY sensitive to working flux density. So trying to work it all out for a totally unknown mystery toroidal core theoretically is not really possible. As Klaus says, its the proverbial piece of string problem. But you can fairly easily measure the idling current at different applied voltages from a variable voltage transformer (variac) and draw your own idling loss curve, and decide from that a suitable operating flux density for your new transformer design. Watts are watts, and if you energise an unknown core with 10 volts and 10 turns and see 1 amp of idling current, the idling loss will be 10Va. If you fitted 100 turns, and applied 100 volts you might measure 100mA, with the same 10vA idling loss. The volts per turn are the same, the flux swing in the core will be the same, and so will the losses in the core be the same. So grab a variac, know your test turns, and plot a curve of idling power versus volts per turn and that will tell you all you need to know. Its a case of actual testing being far more reliable than theory, when there are significant unknowns. Cheers, Tony. |
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