4-20 ma signals shielding for DeltaV

[bigbb]

Hi all, need your advice. I am dealing now with upgrading of Bailey Infi to Deltav, (small heating/power plant). All field instruments should be disconnected from the Bailey cabinets, moved to the auxiliary JBoxes and using multipair cable connected to DeltaV cabinet. Somehow happened that this multipair cable has only one shield for all pairs.
Question is: replace the cable (time and money) or somehow to handle it. How bad it could be. Most of the equipment - auxiliary systems probably not so critical for the operation.
All opinions are welcome
Thanks

BB

 

[itsmoked]

It may be no problem if the surrounding equipment isn't noisy. A power plant is relatively quiet electrically speaking. If it's a hydro plant, probably even quieter.

Also if no power cables closely parallel this instrument cable then that helps a lot.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[roydm]

If you comnnect all the sheilds to the common sheild in the J Box and connect the common to Delta V it should be OK.
Take an Ohmeter and make sure no sheilds are connected in the field while you have them disconnected. If any are leave them off until you get a chance to fix.
Roy