New project, regarding the wiring design of the control system
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The design for the new project is about to begin. It’s a large project with a high number of points. As an instrumentation specialist, should we consider installing a wiring error cabinet? I have limited experience in design; please offer your advice!
It's necessary; it needs to facilitate maintenance and additions/deletions in the future.
Is it the junction box method? If direct pulling can be ignored. It is recommended to use card holders~~~terminal cabinets~~~wiring boxes~~~meters
If a safety barrier is installed, a safety barrier cabinet can be used in place of a terminal cabinet; this solves the problem of scattered cables, reduces the number of wiring points, and lessens the workload involved in troubleshooting.
Regardless of the form, the grounding of the cabinet must be in place and in accordance with standards; the grounding resistance of the instruments must also be within the specified limits.
Why is a junction box still needed? Not to mention the cost and space required, there are also more failure points!
A wiring error cabinet is generally necessary; the AI/AO terminal cabinets and DI/DO terminal cabinets also need to be installed separately. It is recommended that all signal points, except for surge protectors, pass through terminals before reaching the safety barrier/relay/isolator, and then be connected to the cards in the system cabinet via ELCO cables.
It seems our company is designed in the same way as well; it’s quite reasonable.
We’re not talking about grounding; we’re referring to whether an intermediate junction box should be installed.
Personally, I think the purpose of installing an intermediate junction box is mainly to facilitate the design of the main cable from the wiring box to the control cabinet. Connecting the main cable directly to the safety barrier cabinet doesn’t seem to solve the issues related to the design of the main cable
When there are a large number of points, the SIS/DCS system should be equipped with control cabinets, terminal cabinets, safety barrier cabinets, relay cabinets, power supply cabinets, and communication cabinets. In short, the principle is to separate different functions. Do not mix them.