ABB/FFB problems

[bb1fit]

Have an interesting problem, using ABB PLC interfacing with FFB. About every 2 weeks, one entire segment 'dissapears'. I am trying to convince the powers that be that it is most probably a noise issue, but they say they have been over the trunk line numerous times. (however asking if they ever put a scope on it resulted in a no). Being the new guy in plant, guess I have to pay my dues. My thoughts are a broken shield somewhere in the line, or somehow noise injection interfering with the signal resulting in a 'losing its mind'. I have recommended though costly in the future redundancy just for this type of problem to stay on line. This of course shuts down a huge area of the plant. Any thoughts from the experts?

 

[Joe_WaZoo]

Hello,

What is the type and brand of FF cable that you are using? And what is the power conditioner, there was some units that had noise problems.

Is there any significant event that happens when the segment goes down, like motor or drives turning on? Do you have your FF cable mounted in the same cable try as the power cables? This could also cause the problems. And is your shield grounded at only one location on the segment?

Just some questions I might send your way. Here are some examples of FF projects that I have worked on.

Deer Park

Resin Plant

Joe_WaZoo

 

[bb1fit]

Thanks for the response. I asked the 'obvious' questions when I first was informed of this problem, such as grounding scheme(one end only..it is grounded at the conditioner), and checked the routing of the cable...it is in a tray with just signal wire.

They are using Pepperl and Fuchs conditioners. KLD2 type. The cable is Turk.

Failure results simply in shutdown, all valves for instance in the correct fail position. (open or close)