- Thread starter sardine
- Start date
rich r
Member
- Messages
- 645
We'll need some numbers to be able to suggest anything useful. What's the output capacity of the generator (peak and sustained)? What current will you be welding with from the inverter?
Simple maths will tell you what the input current at the inverter will need to be (assume the inverter is around 80% efficient - most are better than this, but it's best to leave some margin).
For example, for MMA at 100A, you'd expect the output voltage to be about 25V (arc present, not OCV), so that's 2500VA. Which will need an input of 3125VA (allowing for that 80% efficiency).
However - when the arc strikes, the current will briefly be much higher than that, maybe even double for a fraction of a second. Even with an inverter rather than a simple transformer type welder. And that is why you need a generator that can either deal with sudden changes in load, or is big enough to provide it without the voltage dropping or the engine struggling.
Simple maths will tell you what the input current at the inverter will need to be (assume the inverter is around 80% efficient - most are better than this, but it's best to leave some margin).
For example, for MMA at 100A, you'd expect the output voltage to be about 25V (arc present, not OCV), so that's 2500VA. Which will need an input of 3125VA (allowing for that 80% efficiency).
However - when the arc strikes, the current will briefly be much higher than that, maybe even double for a fraction of a second. Even with an inverter rather than a simple transformer type welder. And that is why you need a generator that can either deal with sudden changes in load, or is big enough to provide it without the voltage dropping or the engine struggling.
The manual for the RTech TIG200PDC welder specifies generators thus:
"Minimum Generator KVA ouput - 8kVA continuous.
Generator to be fitted with AVR (automatic voltage regulation).
DO NOT USE ON A GENERATOR WITHOUT AVR".
Anything less will invalidate your warranty.
"Minimum Generator KVA ouput - 8kVA continuous.
Generator to be fitted with AVR (automatic voltage regulation).
DO NOT USE ON A GENERATOR WITHOUT AVR".
Anything less will invalidate your warranty.
HughF
Member
- Messages
- 6,482
- Location
- Work: Dorchester, Workshop: Corfe Castle, Wife's place: Frome
I run my chinese 150amp inverter off my Kirsch/Sachs 5kw 2 stroke (non AVR) and also from my 6kw Lister (again, no AVR).
Sachs:
http://www.youtube.com/watch?v=KvFZWUuQmUM
The R-Tech AC/DC, I run from the Lister only.
Hugh
Sachs:
http://www.youtube.com/watch?v=KvFZWUuQmUM
The R-Tech AC/DC, I run from the Lister only.
Hugh
