Answer / carl_ellis

Answer:
A Cold Loop check is cold because it is done without
powering the loop.

A cold check consists of checking wire continuity from the
field instrument through junction boxes and through DCS/PLC
marshalling panel terminals to the control panel. Once
continuity has been confirmed, then a Hot Loop Check is
performed on the Loop's I/O.

A Hot loop check is 'hot' because it is done with the loop
powered up.
A Hot loop check consists of
- simulating a process input at the field instrument and
then checking the instrument's output and the response to
the process signal input at DCS/PLC.
- simulating outputs at the control end and checking for
correct response at the field end.

Carl Ellis
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