arc welder duty cycle

[aidank]

father has a machine like this

http://cgi.ebay.co.uk/NEW-250-AMP-A...&otn=3&po=LVI&ps=63&clkid=7082714892729402787
for the last 20yrs, stickers are long gone off it I think it is an Arkitnay maybe the brand that was on it

anyway just wondering how do these machine compare to a modern inverter with regard to output power and duty cycle

 

[GrahamGKD]

Power output seems reasonable at 250A but 10% duty cycle is pretty dire assuming that 10% is at full power (they don't specify as far as I can see). Having said that, if the duty cycle is at full power and it was used mainly at 70 to 130A (where I mostly have my machine set) it might not be too bad. My Lorch inverter is rated at 40% on full power (220A) and 100% at 160A. Of course, ambient temperature has an effect on duty cycle.
Graham.

 

[PTvor]

Inverters vary a lot in their claimed duty cycles.

The cheapest, where they specify anything, may sometimes be not much better than 10% at max amps. The expensive ones can be nearer 100%. You've also got to consider the temperature the duty cycle is stated as being at. It's usually 40C, but it might be 25C or not given. The other dodge is to specify what the 100% duty cycle current is, e.g. 75A and not mention any other current.

A welder with say, a 50% duty cycle at 40C and max amps should have a much better duty cycle at lower temperatures, say 15C, because it's easier to get rid of the heat with cold air.

Inverters ought to have better duty cycles than roughly equivalent buzz boxes because they are more efficient, however, if you start to cut corners with the heat sinks, the fan, the purity of the copper and you generally compromise the design to make something for what's absolutely the lowest price, the advantage is whittled away.

 

[TechnicAl]

That set on the ebay link looks like one of those sets they sell in Aldi for £30 or £40.

 

[ab56452001]

Hi , i got one of those of e-b a week ago , paid 106$ plus 55$ delivery , i live 1400km away from there store in aus !. Anyhow arrived with defective fan , put in a replacement and the seller paid for it , since then have done a veriety of jobs with amps ranging from 70 to 160 amps , and rods 2.5 to 4 mm , no probs as yet , welds great . Weighs a ton wich is ok , not really a fan of alu coils and lightwieght inverter welders !....