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Forum Index : Electronics : What can I expect from this transformer ?
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| hary Regular Member  Joined: 15/04/2019 Location: FrancePosts: 89 |
Hi. I found a small toroid 230V/12.6V 300VA transformer that weight 2.6kg with copper wiring (if that information is of any use). As I'm planning to make a small DC24V/AC230V inverter, I think the secondary and primary are very close to what is needed for my need. What do youthink and what power inverter can I expect from this transformer ?  |
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| BenandAmber Guru  Joined: 16/02/2019 Location: United StatesPosts: 961 |
I had a little under 20 them just about the same size as yours I gave a few of them to friends And a few of the other ones I unwrapped and made a bigger toroid I've been told by some of the greats on here that wire size has the largest part in how many watts you can get out of a transformer With that being said most Transformers ratings in watts are a little under the VA if I had to guess and by the way there's a lot better people on here to guess I'm guessing 250 watts I've had people on here tell me all about my Transformer with just a picture no info And it would be very very close If you can get your hands on a few more of these you can unwind them and make you a big Transformer with a big hole in the center for big wire be warned i am good parrot but Dumber than a box of rocks |
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| hary Regular Member Joined: 15/04/2019 Location: FrancePosts: 89 |
Hi BenandAmber. Unfortunately? I've only 1. But for my first project attempting to make an inverter (little chinese EGS002/powerboard just ordered), I think it is the right candidate. What about the winding ? I think 12.6V/230V is ok for a DC24V/AC230V inverter. Maybe I don't even need to touch anything at the winding part. If the inverter is a success, it would be perfect for my little 120W fridge ! I need to find some bigger ones, but have no source and no idea where to get them from at the moment. |
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poida Guru Joined: 02/02/2017 Location: AustraliaPosts: 1419 |
Just thinking out in public (should be a law against it), I think the 24V DC supply will mean 24 x 0.707 = 17V AC RMS maximum will come out of the inverter board. This transformer has a 12.6V winding and the 12.6V is read by me as 12.6 V AC RMS. This transformer will work perfectly fine, with the EGS002 controlled inverter board. At 230V AC output, I expect the PWM modulation duty percent to be about 12.9/17 or 75% from the 24V DC supply. I aim for 80% at normal operating conditions. 300VA is not big, but good enough to test things and learn. The transformer is ideal. wronger than a phone book full of wrong phone numbers |
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wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 1156 |
Poida is quite correct I have been using a 230V - 12.6V (actually 2 x 6,3V) toroid for my recent 250W inverter playing and it works fine. I found a 1U 250VAC capacitor was the best choice for the secondary. With no load I get around 0.2 - 0.3A idling current. Ideally a toroid secondary of 7.5V for me or 15V for you would probably have been better but only marginally. If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Just one thing I learned from oztules long ago, when dealing with inverters connected to a battery *always* design for the minimum battery voltage than be expected. So, 23 Volts perhaps? Klaus |
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LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408 |
A 120W fridge could probably draw 3x that much to start up - I am not sure but if you look it up and post here I would really appreciate it. Ben gifted me 3x of his toroids and they are bigger than yours, so I think the 300VA rating is a bit on the high end for that core. If you can post the OD, ID and H of the core, that could make estimations easier. If you want to make a little 300VA inverter I will be your biggest fan and wish you much luck. If your objective is to get a fridge up and running quickly, I would look for a pure DC solution. A lot of what we use at the home runs very well on DC except of course, motors that need AC like the fridge. IT'S VERY LIKELY your blender, vacuum, power tools will run very well on DC (a modification will need to be made to switch contacts to handle DC) But you can replace the AC compressor with a DC compressor or even buy a ready made "solar fridge" that's just a DC compressor instead of an AC compressor but marked up in price because all the cool kids are going solar now. I look forward to you listing your power needs and your final decision. |
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| hary Regular Member Joined: 15/04/2019 Location: FrancePosts: 89 |
LadyN, about the toroid, it is still winded at that moment, so, not sure if OD, ID and H would be of any use measuring it with all wires on it. I think the fridge is like 7-9x the 120W nominal at start. About the inverter planned from that 300VA toroid, wouldn't it be able to start the fridge ? That's what we're on here ! LF inverter because they have tremendous ability to start inductive loads. Concerning running power tools (universal motor) from DC, I thought about it, but it still needs a boost converter. Plus you always have an induction motor power tool like the bench grinder or concrete mixer that would need proper AC sine 230V. It would need different circuit for powering each different tool, AC and DC. At the end, imagine I make the mistake of plugging the concrete mixer (induction motor) on DC ! We already have so many pipes and valves for the watering ! My main problem is my power tools with high inrush current. Otherwise, I woudl be happy with 2.5kVA. The extra power needed is only because of inrush current indeed. Well, at least if I have good power, I would be able to do stick weld if needed. |
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| LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408 |
I currently lack practical experience winding toroids, but if you know the wire size of the secondary and assuming the size of the primary (which is probably the innermost), experts here can arrive at a pretty close estimate. Oh! Updated my notes. Thank you. In that case, if the inrush needs are 7-9x the 120W nominal it's unlikely this toroid, atleast without additional cooling, will be able to start the fridge. Now, if you were to design a Warpverter, I see a reason why you could start it but then you will need atleast 4x these cores, which is where I am stuck. At 24V, yes. OK, 2.5kVA is a completely different beast than the 300VA you're planning. In the end, it's up to you. If 2.5kVA is your target, I recommend following the Warpverter build thread. Otherwise, a 300VA ozVerter would be an interesting thread to see! |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1138 |
You would be surprised, last time I checked our medium sized fridge surge current with a scope it drew 840 watts on startup. Motors cause huge startup surges, I'm currently building a small Low frequency portable inverter for use as a portable AC generator, running off 8 x 200ah lifepo4 cells = 24 volts. I need to run power tools in remote locations, the drop saw needs > 4KW or so surge capability on startup, will use a small 1.5kw toroidal core with some big mosfets. Cheers Mike |
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| hary Regular Member Joined: 15/04/2019 Location: FrancePosts: 89 |
But, starting the fridge, even if the inrush power is 7-9x120W will last only ms, maybe max 1 to 2 second. The transformer won't have time to heat up or melt (I don't think). And After this hard starting time, it should power it with ease. That's what I've understood from my readings on this forum. It would be some kind of over rated 200-250VA chinese PowerJack inverter ! A that moment, I must admit I'm a little lost with all the version of inverter going on this forum. I've been advised to go with a nano control board, and I think, a mad power Board. As I'm quite comfortable with Arduinos, I'll probably follow the nano route for the control board. For the power board, as a novice, I'll follow this forum's specialist advices..... By now, I've followed Amber first go and ordered a Chinese 1000W EGS002 based powerboard for first try ! |
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| hary Regular Member Joined: 15/04/2019 Location: FrancePosts: 89 |
Yes compressor fridge and air conditioning are terrible at start up ! Sometimes up to 10 or 11x Other power tools too. I've noticed 3-4x |
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| LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408 |
hary, I would be interested in your build. BTW, there are two Arduino implementations for the Warpverter already. One of them do complete grid sync as well. Plus, the original discrete Warpverter is extremely easy to understand and rock solid compared to an Arduino While the ozVerter uses sPWM, the Warpverter uses DDS that simplifies the output stage significantly. While in both cases you would have an AC bias on your batteries given how you intend to use the inverter, the Warpverter simply gives you more hardware to spread the stresses over. For example, the Warpverter tries to trade the battery life with trading off high quality, high ripple low ESR capacitors. The ozVerter will give you less margin - how much? We will find out. But yes, both are miles better than the PJ options you see, so either is a step in the right direction. Everything I told you is theoretical, I lack practical experience and I have seen practise beat theory all the time so I have a lot to learn from you! Good luck! Thank you Mike. Before I add this to my notes, can you tell me the running (after start) draw of the fridge? Wow, that's 4.8kW from those lifepo4 cells. What kind of motor is the drop saw? Induction? |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
I'm curious to what kind of inverter board he ordered I've been using the heck out of this little four mosfet inverter I have thanks poida I ran a small air conditioner about 2 hour couple days ago that's along with a chop saw occasionally circlesaw occasionally Sawzall occasionally I put two big caps in mine How long it'll last before it goes pop I don't know but I am surely impressed with it so far He's already been schooled by the experts But they are very careful what they say with good reason of course I think it's got a good chance of starting that fridge take in mind who's saying it though Please inform us what kind of board you ordered be warned i am good parrot but Dumber than a box of rocks |
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| hary Regular Member Joined: 15/04/2019 Location: FrancePosts: 89 |
Hi BenandAmber and others; I've ordered this one But it's already with caps ! Should I get bigger ones ? I'm now seeking 15V TVS diode to make Poida's modification. As things takes time to arrive, tell me if I need anything to make the thing working. I've the board I've the toroid I've shown you. I'm now trying to figure out the right TVS diode I need. Any thing else ? |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
  I have a post called Little China inverter board got to go read Poida tells how to make it Bulletproof I put Hy 4008 mosfets in mine along with everything poida told me to do It has for Transformer cores about the size of yours stacked up made into one That's pretty good idle current also I think be warned i am good parrot but Dumber than a box of rocks |
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| hary Regular Member Joined: 15/04/2019 Location: FrancePosts: 89 |
I don't know his lifepo4 brand but from WINTSON datasheet 200Ah cell he can safely draw 2000A for 5s or 600A for 15 minutes, so I would say he's on the safe side, as @24V, he could at most get 48000W (48kW) for 5s or 14000W for 15 minutes. I've got mine of 160Ah and plan to be using them for 5/6kW surge, 2/3kW nominal @24V. |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
I wonder how much postage would be to France from USA West Virginia I bought extra diodes and mosfets I'm not the best person to be asking advice from cuz I don't know anyting but I have built one with the help of other people on here I love it it's awesome can't believe how good of a inverter it is it'll start anything I've hooked up to it so far If you don't care to see how much shipping is if it ain't very much I'll ship you the diodes and the mosfets be warned i am good parrot but Dumber than a box of rocks |
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| hary Regular Member Joined: 15/04/2019 Location: FrancePosts: 89 |
Really nice from you but I think postage from USA to EUROPE is quite expensive. I'd better get electronic component from China often with free shipping ! At the moment I'm wondering if I absolutely need unidirectional 15V TVS diode or if I could put bidirectional instead as they are easier to find ? I was not thinking replacing the EGS002's mosfets china power board with HY4008 by now. Should I order some ? I remember from some reading from your post about the small china board it was not on the "must do" list. I remember more about TVS diode to protect mosfets' gate driver and disabling all the overcurrent protection to avoid fast damageable STOP/START behavior. My main problem is toroid availability for now. I've only a small one and don't know where to source some more and/or bigger ones. |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
Poida is the man what he says is the gospel Make buddies with him and he'll tell you anything you need to know If it was me I would definitely go with h y 4008 or bigger You'd have to ask poida but I think you're going to be surprised at what you can start with that if you have big enough caps From my little bit of almost no experience I would put the biggest wire I could on that little toroid that's if I couldn't find another one The power jack units you here people talking about a lot of times have big capacitors and a small toroid they start some pretty big loads they just get hot pretty quick a lot of the times you won't be needing to run a big load very long just mainly to get a big load started So big wire and big capacitors and big mosfets if you can't get big toroid Just remember before you do anything or spend any money you better ask somebody else because I am literally just a hilljack hillbilly with no experience be warned i am good parrot but Dumber than a box of rocks |
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