Eric,
It seems I am making the things more complicated than they really are.
Instead of protecting the 4-20mA input with an overcurrent limiter circuit, I will use a simple fast acting of of 50mA and a rated 250 resistor (1W or 1/2W), as it was said by SPDCHK. Also, I will implemente my own supply to the 4-20mA loop so I can implement overcurrent and shortcircuit protection on it.
What could be a good short-circuit protection for the source?
Here is my circuit for overcurrent protection:
Thank you,
Rodrigo