Advice for measuring voltage from a welding machine.

[Dibbley]

Hi

A little back-history. I have a Picoscope 2205A MSO which I use in conjunction with a TA167 Current Probe to measure the current during the welding phase of our welding machines (weekly tests, 3 welds each test). The machines are powered by 400v 3 phase. I use Picolog Software to log the results, view them in excel, and if the results from the log, deviate by more than +/-10% of the setting on the machine then the machine goes back to the manufacturer for service and repair. I.e. if I set the machine to 1000 amps, and the log results are between 900 to 1100 amps for the duration of the weld (up to 2 seconds), it is operating within spec.

I now have some machines that are powered by domestic UK 240v power, and these machines are set by selecting a voltage rather than amps, from 3 to 200 volts (the machines use capacitors to weld rather than live current, up to 132uf for a maximum of 10ms per weld). Is there a simple 1-stop-shop probe I can use with my existing Picoscope and Picolog Software that will allow me to measure the voltage during the welding cycle and output it to Excel, again +/- 10% is acceptable within the spec.

Thanks.

[bennog]

I would go for a differential probe to measure the DC voltage like TA041 or TA057, and also use the TA167 for current at the same time the 2205A can do this.

But I am absolutely no expert on welding, this is only what my intuition would tell me.

Benno

[Dibbley]

Hi

I got the TA041, and tried it, however it isn't accurate when used in the welding circuit, as the circuit breaks during the welding process. The manufacturer of the machine has recommended using a calibrated multimeter on the busbars of the capacitor banks to get a static reading charged and discharged. Can the TA041 directly probe a capacitor bank (200v 66K-132K uf) like a multimeter, and then I can record and measure the full charge to discharge process, or will this end up blowing the probe do you think?

Thanks

[bennog]

you can do this with the TA041 it can handle up to 700V without problem.
Even so the TA041 and 2205A can do this far better than a mulimeter.

Should be interesting to see the discharge of the capacitor bank during the welding.

Benno