Ammeters

[arceyered]

Not at all, jut buy a shunt that's adequately rated for the load intended, I've got boxes of them here going right up to 600 amps.

Why buy a shunt?
Just measure the voltage drop across a length of the welding power cable ie 10inches Ohms Law. Moving coil ammeter veriable resistor across the meter for calibrating the meter ,Clamp meter for calibration.
We are always on about the volt drop on cables when a current flows through a resistance ie "the welding cable" it will cause a voltage drop measure it .

 

[rtbcomp]

If you're measuring the voltage drop across a length of cable you need a voltmeter not a moving coil ammeter, and the calibrating resistor would be in series with it.

The meter itself would be calibrated in amps although it is actually measuring volts.

 

[Jim Davey]

Why buy a shunt?

If almost all welding plant manufacturers do it that way then there must be a good reason. It's robust, simple and therefore economical plus it's easy to install and accurate.

 

[arceyered]

If you're measuring the voltage drop across a length of cable you need a voltmeter not a moving coil ammeter, and the calibrating resistor would be in series with it.

The meter itself would be calibrated in amps although it is actually measuring volts.

Cheers its been such a long while since I used to work on them that the old grey is forgetting
Still the principle is there, we used to add meters for calibration to welding machines using that method 25 years ago when welders did not have the song and dance machines of today and robots were kids toys.