The CP 302 is a three phase powered welder industrial welder. Cannot be run on single phase with out a phase converter. It is a very good Mig welder power supply.
Voltage is adjusted by a hand crank on the front. so no remote voltage control. The crank moves a set of three brushes across the face of a variable transformer.
So remove the right side panel and inspect the faces. make sure they are not pitted and burnt up. use a mirror and look at the brushes check and see if they are broken. Brushes are still available. small pits in the face are ok. when we get these in the shop we clean the faces and apply cool amp silver plating to them.
Makes them work like new. we change the feeder and meter control relays because the wires inside have started breaking. easy fixes for a shop.
So it works best with any of the low tech miller feeders. any 24vac miller feeder with the14 pin plug will work. the hi-tec feeders may need modification to work.
should be able to run 115 volt feeders also. look at the feeder receptacle. find the locating pin. A and B and G will have sockets, these are used by 24vac feeders.
if I and J and G/k have sockets then weld can use 115 volt feeder. like the R115 or the S52.S54 feeders. The lincoln LF742 & LN7 &LN8 can be adapted to run on this welder.
So if you have 3 phase power .$300 is a great price even if you have spend up to $1000 for a used feeder. 3 phase industrial equipment doesn't sell well on the used market.

 

They can be converted to successfully run on single phase.
https://practicalmachinist.com/foru...m/threads/haas-kamp-conversion-for-miller-cp-300-and-cp-302-200-230-460.356007/

 

Is this a "first" welder idea? Its an ok thing for some people but a hard way to start out. You can start a new career as electrical engineer first with this though.

 

You would be surprised at the size of Rotary phase converter to run these bigger transformers.The short arc draw is quite something, but it will work in the spray-arc zone much easier. I am guessing a 30 hp RPC to be able to get it working in the short-arc well.