Measure TI/MIG Power Output

Does the customer seem to know what they are doing or does it seem like they are just going overboard with "contractors shall calibrate all equipment"?

The manufacturer of your welding equipment can probably provide some sort of an answer.

I worked as welding supply store service tech and to calibrate and certify a welder I ran them on a load bank that would pull a specific amp draw for the required testing time period.

In your example I would set the load bank for 150 amps load at what ever voltage that model is to be certified at and then internally recalibrate the welder power supplies controls and gauges to match what the load should be according to the load banks certified meter readings. It wasn't hard and it only took a short time usually.

To be honest getting a welder certified is about 10% physical work and 90% paper work cost wise. And both only took a short time to do. Basically its just bureaucracy hard at work !

Depending on the person and the application many times certifying a welder was completely pointless. I often did recalibration and certifying of pipe line welders rigs and had to mark where they had it set for how they 'thought it should feel' then adjust and calibrate the machines settings and readings to where the certification matched the paperwork requirements on everything.

Once I had filled out the paper work and put the certification stickers/tags on the machine and had given the certification paperwork to the owner would then readjust the machine back to where he had it before the certification work was was done. That way his settings had certification paperwork that said that the controls and gauges where accurate and properly calibrated. The machines controls and gauges said exactly what they should be when set for what ever range but in reality the actual machines outputs may have been far higher or lower than that.

The pencil pusher got his paperwork, the welder guy got his machine set for how he liked to weld, and the company I worked for got some easy money for basically nothing! Technically I had legally calibrated and certified that welder and what the operator did to it afterwards was non of my business.

You have posted another post on the same subject

Calibrating and Verifying TIG / MIG Outputs

In addition to ratings design features are required to say anything about calibration of welding machines.

Does these have any indications & adjustment controls for operator [welder] to pre-fix the power [VxI] with individual adjustments of current & voltage independently?

And what else user-friendly features?

Is it has taps on transformer for adjustments of voltage & current?