Issues with fiber optic cables used to connect junction boxes
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There is a project in which there are only 60 control points on site, and these 60 points include those related to FGS, ESD, and PCS. Since the distance from the control points to the control room is quite large, I now want to have a junction box to gather them all and connect them to the control room using optical cables. Do any experts think this is possible? What needs to be added to the junction box in order to make it work? How do we separate them after reaching the control center?
Remote I/O racks can be used, with fiber-optic redundancy for communication to each respective control system; SIS signals do not allow direct communication!
There aren’t many points, so perhaps just one remote IO cabinet will suffice. But since each system requires redundancy, is it necessary to use 6 optical fibers? Is it a convention or a regulatory requirement that the SIS signal does not allow communication? Thank you
It’s already difficult to do this; use remote IO instead.
It is a requirement that SIS signals involved in interlocking signals must not allow communication; multi-core single-mode fiber can be used!
According to the current requirements, FGS, ESD, and PCS need to communicate separately, which means 6 optical fibers (for redundancy) are required. Since one control cabinet cannot accommodate everything, it is necessary to use three control cabinets for the remote I/O devices, and UPS power supply must also be provided.
How far is ‘very far’? The control points of these systems of yours don’t allow communication, right?
About 500 meters, I guess. “The control points of these systems of yours don’t allow communication, right? I don’t understand what that means; some of these control points are used for sending alarm signals
SIS has clear regulations stating that \"measurement instruments shall not use fieldbuses or other communication methods as input signals for safety instrument systems\"; the same should apply to FGS and ESD. Although there are no explicit regulations for FGS, in many cases it is treated in a similar manner to SIS. If we have to say, maybe PCS can be used for communication? But with interlocking critical points, I’m afraid using communication methods wouldn’t be safe; it’s still better to use hardwiring, as there aren’t many points involved. And even assuming that, for example, SIS uses optical cables, then all the devices on that circuit must have SIL certification, such as fiber optic transceivers and the like. Are there such devices available?
Special modular junction boxes are installed on-site, including IO modules, power supplies, optoelectronic converters, etc., which are connected back to the control room via remote IO.