Is this a single phase welder ?

[JD6400]

Hopefully the picture's have uploaded otherwise this thread will be a bit pointless !

I got called to this old oil set last week as it keeps blowing its 32 fuses , it was a replacement for an old oxford 2 phase one that had given up the ghost .
Being a farmer install it had been wired like for like , but I have a feeling this one is only capable of single phase connection .
Although I have not come across any other oil sets that have not been capable of being connected in either single or twin phase it has come from a rocket reasearch facility , and I seem to remember being told that the old oil welders in shipyards had to be single phase for some reason , so this might be the case here ?
Can anyone else make out what the connection should be from the uploaded face plate pictures .
Many thanks Dave

 

[Marvo]

Yep, looks like it. Wire it up as it says for 240v so connect T1-T10 and T4-T7 and use T1 and T4 for power. I'm not sure I'd trust this thing if you don't know it's history, maybe supply via a 30ma RCD and if it trips, especially if it's before an arc is struck, I'd investigate its safety.

 

[Richard Burns]

This part of the plate seems to indicate single phase?

 

[JD6400]

Thanks for the replies , that is how I read the face plate but it is the first oil set that I have come across that is only 240v .
The other thing that threw me a bit is the isolator on the side seems to be rated at 20 A which is a bit low for a single phase set I would have said ?

 

[Deleted member 26818]

Not if the load is less than 20A.

 

[JD6400]

Good point Spin , but I was looking at it as more than a hobby craft set all be it a large one at 20A .

I normally see these on a 2 phase 32a supply , so 20a single phase just seems a bit low to me ?

 

[Marvo]

It might not be an on-load isolator so as long as the primary leakage current is less than 20A (which it may or may not be looking at the photos) it should be fine


**edit**

You've got 3 wiring options, 240v L+N, 400V L+L from a 3-phase supply or 460V L+L from a split phase supply. You just need to configure accordingly as per the chart in the picture.

 

[Deleted member 26818]

I have a Clarke 180 single phase welder, which was at the time I bought it, was the bottom of their industrial range.
That should be on a 20A plug, but I used a normal 3 pin plug which has served me well for about 20 years.
The plug fuse has been changed only a few times during that time.

 

[Lucien Nunes]

Yes, it's single phase, but the wide range of tappings allows use between the lines, when it will take only sqrt(3) of the current compared to running L-N. As I was saying in my very first post on this forum, it remains a single-phase load when operating on two phases of a three phase supply.

The plate seems to state 320A continuous MMA output and a max intermittent input of 28kVA. If they are doing heavy work on it I am not surprised it's eating 32A fuses! If the work is light it might be OK, but in any case if a 3-phase supply is available take advantage of it. Connect tappings to suit the line voltage e.g. with 400V connect T5 to T8 and feed T3 from L1 and T7 from L2.