Electronic – Designing a transformer with low usage time but high power output for small interval of time

transformer

I want to design a transformer ideally for arc welding purposes. The thing is that I want it to be designed in a way that the windings allo overloading of the transformer itself.

For example I had a transformer from old radio, the area of core of the transformer was no more than that of a normal 100 watt transformer but when I shorted the secondary leads of transformer at around 40 volts the calculated power output was 650 watts! The varnish inside the transformer started boiling after a minute or so. But I used that transformer for two years, at least at 200 watt (not full time).

Now the thing is that this property of being able to be overloaded is related with number of turns per volt of the transformer. To be more specific, in normal transformers we divide 7.5 by core area in inches to get number of turns per volt. I know that to make "overloadable" transformer we have to do with this number (7.5) but I want to know figures to be in safe range without tripping my breaker at no load or frying the transformer before I even put any load on it since these transformers have high no load current, and have a working transformer at the end.

Thanks for reading my question.

Best Answer

There are design features that can be used for welding transformers. A fixed or adjustable magnetic shunt or a series reactor are two concepts that you should investigate. A magnetic shunt diverts magnetic flux to a path that reduces the magnetic coupling between the primary and secondary. That increases the stray reactance similarly to putting reactance in series with the transformer. That does nor really allow the transformer to be overloaded for a longer time, but it uses the transformer more efficiently by reducing the voltage once an arc has been struck. The same thin can be done electronically. How to design a welder is too broad a question to be answered here, but more detailed information can be found in resources that can be found on the internet.