This may be more off-topic than "General Electronics; however, I need some help!
A client has a product that had a specially built tester designed for it some 15 years ago. Unfortunately, both the tester and all information regarding the tester were lost in the flooding due to Hurricane Harvey. The original designer/builder has passed away...
I have been asked to try to replicate a part of the tester, specifically a current limited, variable AC source.
The diagram below shows (pretty much) what I need:
The variable transformer is among the items saved from the flood. It will ramp from 0 to max voltage and has a maximum output current rating of 3.5A.
The target device includes a logging device for the input voltage and current.
In a test mode, the logging device records the input AC voltage and current at the point at which the target system first begins to operate.
The logging device continues to record AC voltage and current through the AC voltage ramp.
The target device must be protected from over-current as the variable transformer continues to ramp to its max voltage...
So, for any voltage from the variable transformer, I must pass the AC voltage, until limited to a maximum of 25mA(rms).
(Fuses and/or circuit breakers are not viable)
My googlefoo has not found anything that would work
I have also looked at programmable AC power supplies, but the current limit resolution seems to be limited to ±10mA...
If you know of a model with better resolution, I would be happy to recommend it to my client!