Finally, the Matlab version:
Setup:
* E36313A (1.1.1 FW) in series mode. Current set to 1A. Voltage sweep from 0V to 3.5V.
* One DMM (3446XA) in DC current mode, fixed 3A range, directly plugged to the output of the PSU, as documented for the series mode (left terminal of Ch2 and right terminal of Ch3).
* One DMM (3446XA) in DC voltage mode, fixed 1V range, plugged to the same terminals.
What we see:
* 0-0.4V: CV mode. Readout voltage similar on PSU and DMM and ~= Set Voltage on PSU. Readout current similar on PSU and DMM and proportional to Set Voltage. All good.
* 0.4-1.3V: CC mode. Readout voltage constant and similar on PSU and DMM. Readout current similar on PSU and DMM and ~= 1A. All good.
* 1.3-1.6V:
mode. Readout voltages agree but resume climbing. PSU readout current showing stable ~= 1A while actual current on DMM goes up.
* 1.6+V:
CC mode. Everybody is constant again. Voltages agree but currents don't. PSU current claims ~= 1A while DMM ~= 1.1A. Voltages agree with DMM current, definitely not with PSU readout current.
I tried at 2A and it's pretty much the same with an inflection zone ~2.4-2.8V and at 0.5A, the zone is ~0.7-1.1V.
The inflection zone also changes with the burden voltage. With Set Current to 1A and comparing the 10A input of the 3446XA vs. the 3A input in 3A range, the burden voltage is ~0.058V vs 0.425V and the inflection zone is 0.59-0.85V vs. 1.32-1.66V.
I have an email out to Keysight. I'll keep everybody posted on this. I'd still be interested to see if somebody can reproduce it or if this is just my unit.