- Thread starter sardine
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normspanners
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An autotransformer is still connected to the generator by one 'leg', but an isolatating transformer output is isolated from direct connection to the genny windings but still transforms what goes in, to the output. therefore a spike is still a spike, it may smooth it slightly, but you can use a large normal 12v transformer out of a battery charger etc to buck/boost (lower or raise) the voltage to your welder by 12v ie 240v in 228v out or 240v in 252v out. depending which way it is connected, in phase or out of phase, I use one to increase the voltage to my small mig when running long extension leads
mike 109444
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How are you wiring this up norm?
normspanners
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Hi if the incoming mains to the welder are connected in parrallel to the extra transformer primaries, then the secondry of the extra transformer are then connected in series with the mains and thus to the welder input, the extra voltage produced by the extra transformer is either added or subtracted to the incoming voltage, depending on which way round the primaries are connected as to whether it is in phase or out, there is a way to check this on some trannies with the dot marks on the legs. But because the voltage is easy to check just check whether it is boosting or bucking ( sorry bout the americanism )The tranny secondries have to be of sufficient size to cope with the load but many, out of decent 'starting or boost' battery chargers are. There are loads scrapped because the rec.'s have gone down.
You can put this inside your welder if room or box it and wire it as a 'plug in when needed jobby', as I have, then you can use it on other welders or gear that suffers at the end of LONG extensions.
You can put this inside your welder if room or box it and wire it as a 'plug in when needed jobby', as I have, then you can use it on other welders or gear that suffers at the end of LONG extensions.
mike 109444
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Ah when you said "battery charger" I had in my head the shoe box size so could not get my head round it! Yes I understand that the large (wheel along) booster/starter type do have large trans in them. Use to work on USA kit that had "buck and boost" trans in (very jaring term). On a similar subject keep meaning to try the large 240 to 110 (yellow box) tran on a welder to see what sort of drop/work it might do if at all (internal 240 to 30 wirefeed tran would req bypass) As there are many with welders that don't go low enough for car body work >50amp. Would only suite lower power settings, restriction being rating of yellow box. May try if I get 5 mins...
mike 109444
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I wonder if it is surges rarther than spikes that kill inverters?
normspanners
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The tranny does not need to be massive because the secondry winding core being only a few turns can be easilly capable of passing the current ,and the induced voltage is only 12v which is added or subtracted, the tranny I use is roughly 4" square out of a medium sized boost charger approx 30amp ish, that was going to the scrap (as I love trannies, hum! got to be very careful who you say that to!Ah when you said "battery charger" I had in my head the shoe box size so could not get my head round it! Yes I understand that the large (wheel along) booster/starter type do have large trans in them. Use to work on USA kit that had "buck and boost" trans in (very jaring term). On a similar subject keep meaning to try the large 240 to 110 (yellow box) tran on a welder to see what sort of drop/work it might do if at all (internal 240 to 30 wirefeed tran would req bypass) As there are many with welders that don't go low enough for car body work >50amp. Would only suite lower power settings, restriction being rating of yellow box. May try if I get 5 mins...
) I thought that'll come in, and it did !
I do not know it's va, but the secondries are 2.85mm dia and handle the current without hardly getting warm, thinking about it I could even incorperate a double pole double throw switch to either raise or lower the voltage to suit !the only problem there would be dropping the wire speed maybe to much But 12v is a very handy raise it just gives the welder its edge back and can make the difference between a reliable weld and a s**t one.
mike 109444
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dan.taylor.1
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surely a regulator with some big capacitors is what your after to stop voltage surges, a transformer is jst going to pick up the surge and pass it on at a different voltage!
Powering an inverter using an isolating transformer and, to a lesser extent, an autotransformer would both tend to reduce the size of large "sharp" voltage transients seen at the welder's mains input. Better still would be to use a decent mains filter, although a good welder should have one of those fitted already, either as a separate internal module or using discrete components on the printed circuit board receiving the mains.
normspanners
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mike 109444
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Cheers norm making sense now
