cjosey
Member
- Location
- Fremont, CA, USA
My company designs capital equipment mostly for the semiconductor industry. For our control systems in the past, we have typically wired the PLCs in a ?homerun? configuration (where all cabling goes back to the PLC in the main electrical enclosure).
We are currently moving to a fieldbus configuration with low-voltage distributed IO nodes located throughout the tool. Most control manufacturers sell both the IP20 DIN-rail mounted versions of IO (with ?slices?) and the IP67 wash-down rated versions that require M8 or M12 connectors.
We are having an internal debate about which version of IO to use. All of the nodes will be mounted on the tool framing and located behind removable (but not locked) panels. There is also no risk of wash-down for our tools. Our goal is to select one version for all tools and be able to pass any third party/SEMI/CE safety inspection.
I believe that we can use the IP67 versions without comment by any safety inspector, but they are typically more expensive, larger and less flexible than the IP20 slice IO. The concern about the IP20 IO is that NFPA 79-2012, paragraph 11.2.2.2 states: ?Pipelines, tubing, or devices (e.g., solenoid valves) for handling air, gases, or liquids shall not be located in enclosures or compartments containing electrical control equipment.?
So, is the area behind the removable panels considered an enclosure/compartment or not? Are there any other issues I am not addressing? What do you think?
We are currently moving to a fieldbus configuration with low-voltage distributed IO nodes located throughout the tool. Most control manufacturers sell both the IP20 DIN-rail mounted versions of IO (with ?slices?) and the IP67 wash-down rated versions that require M8 or M12 connectors.
We are having an internal debate about which version of IO to use. All of the nodes will be mounted on the tool framing and located behind removable (but not locked) panels. There is also no risk of wash-down for our tools. Our goal is to select one version for all tools and be able to pass any third party/SEMI/CE safety inspection.
I believe that we can use the IP67 versions without comment by any safety inspector, but they are typically more expensive, larger and less flexible than the IP20 slice IO. The concern about the IP20 IO is that NFPA 79-2012, paragraph 11.2.2.2 states: ?Pipelines, tubing, or devices (e.g., solenoid valves) for handling air, gases, or liquids shall not be located in enclosures or compartments containing electrical control equipment.?
So, is the area behind the removable panels considered an enclosure/compartment or not? Are there any other issues I am not addressing? What do you think?