In a control panel I want to know is it necessary to separate the network cable (Cat 5) and the signal cable (4-20 mA) and 24 Vdc cables?

I would be thankful If someone could refer me to a Standard to explain this issue.

 

It is not necessary to separate these 3 systems. I assume your 24 VDC is just for loop power. If you have 110 VAC wiring it's best to separate that.

Roy

 

Working within an organization having engineering and management experience outside of industrial instrumentation and automation (different from previous organizations I'd belonged to that either included or acknowledged that experience) I am facing challenges convincing others that 120 VAC power being run among 6 and 24 VDC wiring and alongside (within 1/2") of circuit boards including processors within a panel will lead to serious analog loop (combustion control, specifically among other processes) controlability issues.

I've produced numerous items relating wiring and EMI standards and best practices; but the request is that I "prove" there is a problem, rather than those designing this (anomalous) system prove that deviation from standard separation schemes will work. While I've explained the consequences of losing control of fuel and air measurement and control unpredictably, and that the problem is aggravated as current & associated magnetic fields increase (versus the relatively low currents present now during continuity checks) my concerns appear to be less important than the project schedule.

Suggestions? Thanks!

 

And the worst part is that it may well work, except when it doesn't. It's very hard sometimes to win these if you don't have the credibility to simply say it needs to be done right. When you get towards commissioning, throw a DSO on your critical signals and record the noise levels and show them. Even done right the noise levels on a lot of automation gear are scary. You can rent a DSO for $100 a month or less. Run the traces past the electronics supplier chances are they will support you. I'm not sure which is better career wise, winning or losing. I won all of them and am enjoying unemployment.

Regards
cww