×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

PLC/DCS - I/O Cables.

PLC/DCS - I/O Cables.

PLC/DCS - I/O Cables.

(OP)
I would request the Forum Members to suggest the type of cables to be used for connecting following I/Os to DCS/PLC based on their experience.

1 Analog inputs 4-20mA (from transmitters & VFD feedbacks)
2 Analog inputs  Thermocouples
3 Analog inputs  RTDs
4 Analog outputs 4-20mA (to I/P converters & VFD reference)
5 Digital inputs - voltage 24v DC (from field swithches & aux. potetial free contacts in MCC/VFD)
6 Digital outputs voltage 240/110 v AC (commands for start/stop, open/close to MCC/Solenoid coils)

Normally these I/Os are grouped (typewise)in Field Junction/Marshalling boxes so that Multicore/pair cable can be run from field to PLC/DCS panel in the control room.

Can we use Multicore armoured (0.8sq.mm for AI/AOs, 1.5sq.mm for DI/DOs & 1.32sq.mm for thermocouples)?

Or we have to use multipair screened cables for the above applications.

R.Thiyagarajan.  

RE: PLC/DCS - I/O Cables.

4-20mA inputs: use individually screened twisted pairs, in an overall screened multicore if you wish.
Thermocouples: use thermocouple compensating cable which is invariably screened,in an overall screened multicore if you wish.
RTDs: use an individually screened 3-core (triad) cable for a typical industrial RTD, in an overall screened multicore if you wish.
4-20mA outputs: use individually screened twisted pairs, in an overall screened multicore if you wish.
Digital inputs: use standard multicore control cable.
Digital outptus: use standard multicore control cable.

Sizes look ok subject to volt-drop around the loops, except the thermocouples - comp cable is usually much thinner than that.
  

----------------------------------
  
If we learn from our mistakes I'm getting a great education!
 

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources