Re: [foxboro] IOBAD

Thanks for all the great replies.  We knew about the OSV, but the =
problem we had with that was, where is the right setting?  I guess using =
a rule-of-thumb value of 10% will be OK for most transmitters, but we're =
still leery of a transmitter failing at say, 3% or 5% below or above =
range, and the system not registering that as bad and the controller =
being happy with a bad measurement.  Every transmitter, or at least =
every transmitter type, is different at the mA value where it actually =
fails, and it's going to take some effort to keep after that OSV =
parameter for each individual transmitter through routine maintenance =
and turnarounds.

The CEOPT parameter in the PIDA looks like the answer.  I had never done =
any research on this one before.  It sort of showed up in version 4.x or =
5.x and I never really paid much attention to it.  We tested it out this =
morning, and it looks like setting it to 2 will do what we need.  I =
think combining setting the CEOPT to 2 with raising the OSV slightly or =
maybe researching where at least the most critical transmitters actually =
fail is the best solution.

Thanks again for all the help.

Tim Lowell
Control Systems Engineer
ConocoPhillips, Trainer Refinery
Phone:  610-364-8362
Fax:    610-364-8211
Tim.C.Lowell@xxxxxxxxxxxxxxxxxx
 
 
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