I have an application which needs to measure current in sweeps which use 10mA steps from 0A - 50A, with an accuracy of 0.1% or better. Up until now, I've been using 2 34461A's in parallel for up to 20A sweeps with success, but as these current measurements get larger, ballasting/current sharing becomes problematic, not to mention stacking 5 of these meters seems excessive.
I am running an entire bench of instrumentation sequenced using VISA and python, so whatever instrument I end up using needs to speak SCPI and have auto ranging. I cannot find anything from any of the common vendors like Keysight etc. that satisfies these requirements.
Considerations:
(1) I've already considered using a shunt, however, my application would require 2 or 3 shunts of different values, plus different current sense amps with different gains, plus automated switching between them; so, high current relays. I do not want to get into the business of designing an ammeter and the serial interfaces required...sounds like a long drawn out custom lab equipment project.
(2) Clamp ammeters are not accurate enough for what we are trying to do, plus, I can't find a clamp ammeter that speaks SCPI.
(3) Autoranging would be required because these sweeps are automated and unattended. I cannot run a sweep up to 10A, then pause it and change shunts, then unpause it and change shunts again.
(4) I understand banana cable interfaces are good to about 10A, maybe 15A. It would be OK to use bus bars with studs to interface these high current paths in my lab bench, that is to say, I would not be limited to standard banana jacks for any of this work.
Does anything like this equipment already exist out there?
If it doesn't, can anyone chime in to why it probably doesn't exist?
Any other helpful thoughts?
Thanks for reading everyone.