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Forum Index : Electronics : Bryan's Inverter build
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KeepIS Guru  Joined: 13/10/2014 Location: AustraliaPosts: 1379 |
That is good to know, the ones I tested were really bad, they were not the big units shown in the pictures. It will be interesting to see how these big Welder units go. BTW if you happen to remember where the transformers you used came from I would like to know, as they my be handy for a beefy backup Inverter, at the moment I'm having trouble getting the toriods I want to use. . Edited 2023-10-12 08:41 by KeepIS It's all too hard. Mike. |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 380 |
HI Aaron, I would be interested in knowing what transformers you used on the E core inverter too. If E cores can be made to have such low idle currents It would be fantastic to know which ones, no more looking around for torroids. Seems all the best commercial ones I have seen have torroids, as I said the Powerstar W7 is horridly wasteful on power. I have a 48 volt Powerstar in the shed too, but as I only use 24 volts I have not used it (it was given to me) if those transformers were easy to alter to give low current draw that would be good Cheers Pet |
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Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 961 |
Mike, Pet. The transformers I used were from old Telecom battery chargers, They were well made, bolted together, or clamped not welded cores, how much difference that make we will have to find out. Most of these chargers were multiple taps for different input voltages and sometimes out put voltage as well, they were often left switched on ready to charge when the demand was needed. I have heard a few stories about the W7's and the likes, might be worth powering one with a variac. lower the voltage and see if the idle current drops much, just for curiosity anyway, not sure how hard it would be to put on a few more turns. The EI type can be used as a back up inverter I guess, so you have power while the main inverter is under repair, I thing think its best use is for powering a shed or workshop during the day and solar will help supply the loads taking up the inverters inefficiencies, keep the Toroids for running the house overnight. At the moment I'm running 3 HF inverters continuous with a total of 150w Idle consumption, will change them out soon after the next inverter is built. What quality these welder cores are I don't know, The single phase welder I fixed up the other day was around 60w orso when the trigger was pulled and power setting 8 I should have tested the power consumption at lower power settings (check Transformer voltage in and out) also I should have disconnected the fan, and power supply circuit that runs the wire feeder, power consumption would have been lower then. Easy for someone to check on this if they want to experiment, spare time job. Cheers Aaron Off The Grid |
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| Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 961 |
Failing all that You could try, https://www.aemcores.com.au/technology/unicore/duocore/ I did get a price off them for a duo core, didn't seem that cheap, BUT when you consider the rest of the inverter you built cheaper than a bought one its really not bad if you have the appropriate copper wire and wind the transformer yourself, then spot weld it together.  Cheers Aaron Off The Grid |
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Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1211 |
That e-core I have came out of a 48 volt forklift battery charger and I'm now on the hunt for some wood to make the former so I can wind the secondary in my lathe. i'll just setup both wire spools in line on a supported shaft and put an old touch counter on so each jaw on the chuck will index it. So 4 counts a revolution and as each side of wire is layed I'll give it a tap with a leather hammer to get the wire nice and straight as the secondary will need to be wound pretty tight to allow the primary to fit in the slot. I do have enough 16mm cable left so that will be used for the primary and it will be an easy task to swap the toriod out for the E-core one. I do need to learn what measurements to take so when the transformer is swapped over the results can be compared. Now with that huge E-core in that 300 amp mig welder being a figure 8 configuration I'm wondering if all 3 sides can have their own windings so 3 sets to join which in theory give a heap more power. Cheers Bryan |
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Murphy's friend Guru Joined: 04/10/2019 Location: AustraliaPosts: 586 |
Bryan, a tip about winding on wooden formers on a lathe. My experience was no good with that idea, had the coil ruined when trying to knock out the former into which corners the wire had bitten. You can try to wind a thick layer of stiff paper on your wooden core first and wind on top of that. After my above experience all lathe winding formers were made from aluminium, have quite a few to fit different choke cores. |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 380 |
We used a lot of wooden formers when I was an apprentice, but as Murphy suggested they had a layer of insulation taped to them to allow the coil to slide off. We used slot insulation that had a layer of mylar on the outside. Mylar side to the coil and they came off fairly well. Other than that if the wooden former is cut on a diagonal so it is made up of two wedges then the former can be removed fairly easily. But use insualtion on them to make them slide without damaging the windings Pete |
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| Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1211 |
Thanks Murphy thats a great tip that would of saved me a lot of heartache  Now the former I need to make is 82x58 and 170mm for the coil width. I do have some heavyduty insulation that came from stripped transformers so that will be used to wrap around the former. The idea is snug to loose fit in the E-core so once that heavy insulation is wrapped with my yellow tape I can do a trial fit in the E-core to make sure of the fit.Now as this will only be doing 2-3Kw do you think going 2 inhand 1.6mm wire is overkill and a single wire is enough as this will drop the thickness by a 1/2 which would allow me to use a heavier gauge wire for the primary. Cheers Bryan |
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phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 1799 |
1.6mm dia. = 2 sq. mm 3kW @ 230V = 13A So current density = 6.5A / sq. mm For intermittent use at 3kW its probably ok. |
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| Murphy's friend Guru Joined: 04/10/2019 Location: AustraliaPosts: 586 |
Another trick, which I use on my aluminium formers, is to make one end 0.5mm bigger than required. This makes the thing ever so slightly conical and, if you mark the smaller end and knock it out from this end, it'll just pop out after a few mm of knocking. |
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wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 1001 |
Aluminium former ? That sounds like a giant shorted turn in my mind, so how do you avoid that ? Does the chokes run hotter than expected ? If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 380 |
Wiseguy, the former is just something to wind the coil on, so that it is the right size to slip over the transformer core. You wind the coil, have some tape under it and up the ends and tie the coil with the tape, then remove the former. Generally then you tape the coil and fit it to the core with some insulation between it and the core. Pete |
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| wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 1001 |
Thanks for the explanation Pete, I have been winding formers/bobbins for over 40 years but I always leave the winding on the former assembly and insert it all in the cores. Of course I don't have a lathe and have never tried to make a very tight high current winding for a steel core, but I'm always learning lol. I suspected there would be an explanation for it... If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 380 |
Hi Mike, we often made formers from fibreglass sheet, but if you tried to wind a heavy winding on them they would collapse, so the wood went in the middle and then the fibreglass former and winding would be slid off the wood. I didn't do too much transformer winding as such, lots of little coils, and plenty of electric motors. The workshop where I did my aprentiship was soley involved in motor rewinding. From clock sized things up to a few megawatt alternators. Pete |
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| Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1211 |
G'Day Guy's, Well found some scrap 4mm ali plate at work so got on the guilo and cut some pieces 83mm wide 2 off and 50mm wide 2 off. I'm going to cut some 75x50mm RHS and use some countersunk M4 screws hold the ali down. On the 50 mm side I'll use some 0.5mm steel packing to get the 1mm clearance. This will give me 1mm clearance and I will put a slight taper on to get the secondary off the former easy. As I do have 2 spools of that 1.6mm may aswell go 2 inhand as the room is there in the E-core for 6 layers and the old saying the more the wire the better. Cheers Bryan |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 380 |
Hi Bryan, you could just use a couple of bits of sticky tape to take the aluminium to the RHS. Then just put some insulation over the aluminium so the wire doesn't get scratched when it is wound on. If there is not much tape on the aluminium it would make it easier to get the coil off the former. Just wondering if you know of a reasonably priced supplier of the enamelled wire. I have been looking and it seems that it is around $100 / kilo, and mostly coming from India. I am hoping to find about 3 kg of 1.8mm diameter closer to home than India. Pete |
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| Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1211 |
Sorry Pete I've had this wire now for over 13 years mate and I got it from work off memory the company was called O'Brien Aim and I'm not sure if they are still trading as the yanks bought out the group back in 2010. The deal they offered was that bad I told them where to jump and 6 months later that million dollar + gearbox repair shop was closed and all the bench's etc I made sold for scrap as they couldn't find anyone to replace me. down the track I will have a hunt and I'll ask my mate at work tomorrow who does the ordering if he knows of any suppliers. Cheers Bryan |
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| Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1211 |
Eh Pete I did ask my mate about buying wire and he did say down the road is motor re-winder who would have a heap of wire on the shelf, so my tip would be for you to check out motor re-winders in your area and you may just get luckily Got some scrap 75x50 RHS home today so this weekend I'll make up the former so I can get this huge E-core up for testing and if it does work out buying another board from ali will work out cheaper than the parts I need to finish the mad inverter. Now with me getting a CMM2 this old battery checking project can get going as my intention is to hook an inverter so the shed is on it's own array so the missus can get her hobby out to the shed and out of the house. If this old battery does work out and it is an old sonnenshein 2 volt 600AH bank i'm going to take the caps off and make a diluted solution of sulphuric acid and top them up with the hope of riving this original batteries that powered the farm. Now please note when these batteries went down I put a 600AH 24 volt forklift battery in that is still going today aswell as the Selectronic inverter that has been going 24/7 since '03. So this is all part of my 20 year upgrade and a huge thanks to this forum is on the cards. Cheers Bryan |
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| Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1211 |
Well went and had a look at those old 600AH sonnenshein AGM batteries today and put 2 litres of rainwater in each cell so the glass mats in each cell can become moist again. Now on measuring open voltage I did find each cell on around 2.7-8 volts each and the total pack voltage was 32 volts. So these may be a lost cause but nothing ventured nothing gained is the old saying. So for ease I pulled out the original 24 volt mod sinewave inverter that came with the farm connected that up and found my sander did work at first then not after that. Tried my vacuum and no go so used an old 100 watt light globe which did work and I'll leave going all night then check the voltage in the morning. I do think a few deep discharge/recharge cycle will prove good for them and my old Kipoint inverter will come down from the shed to be used. The main goal of these old batteries is to supply lighting for the shed so if it does workout it will be less load on the house inverter a Selectronic SA32 that has been going since '04. Cheers Bryan |
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| Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1211 |
Well guy's my Kipoint inverter has finally died  Since the first week of this year it has been powering my shed fridge and working nicely and when I went into the shed when I got home as soon as I turned on the lights it went into fault mode and stays there. I do need to get some round tie points so I can wire in the shed wiring in that inverter I made and thats tomorrows job. As I'm working fulltime nightshift I'm staying down in town and coming home Friday which is the start of my weekend then I go back on Sunday night to startup the plant ready for Monday morning.As I did work last night today is my main free day so very soon it will be beer'O'clock  and it does make sure I get a goodnights sleep and most of the morning too.Anyway now it does look like I have a wound toriod to use for my Mad inverter board and got 99% of the parts now so thats one job to get onto. I do want to use my lathe and mill this weekend so I'm sure that new inverter should handle it OK. Cheers Bryan |
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