NU-Tool NW255P Mig Welder

[Richard B]

I have this MIG and there are two earth clamp sockets. One is at the end of the Transformer and the other comes out 1/2 way through the transformer, shown on the right in the picture. Is one for 1/2 power or something else?

This welder is about 25 years old and I have no manual. Says "Thunderbolt" on a sticker inside.

 

[GrahamGKD]

There is a thread which may be related here.

 

[willie.macleod]

That's so you can swap the torch polarity for running gasless wire. If you are planning on running it with gas you can safely ignore the other socket.

 

[Richard B]

Thanks for that Graham. The polarity reverse uses the socket on the left and either of the two sockets on the right for earth. From you link it looks like one of those earth terminals is for using lower power.
I never have used gasless with it.

 

[waddycall]

2 inductance settings?

 

[Robert Mullins]

Most definitely dual inductance sockets; the return lead needs to exchange places with the power lead going into the torch to reverse the polarity;
We've had dual inductance sockets for years, yet no-one (on the shop floor) knows what they're for, or supposed to do: inductance (from memory) is something to do with the decay/collapse of electro magnetic field: now, I'm no expert, so maybe we need a welding engineer, or electronic expert to explain

 

[a111r]

For your car bodywork / thin stuff, best with the low inductance setting I think. Just another variable.
This page explains it and there's a short video too:
https://www.weldingtipsandtricks.com/mig-welding-inductance.html