Is it okay if the DCS control room is located too far away from the equipment?
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Current safety regulations require that the DCS control rooms for Class A and B production facilities be located outside the facilities; otherwise, explosion-proof design is necessary. This results in the control rooms being situated at a distance from the facilities. The automation specialists argue that such long cable distances affect the control efficiency, and they require that the distance be within 200 meters. Is that so?
The low-voltage room and the control room are two separate things; fiber optics are used for communication between them, so there’s no such situation as you mentioned. However, considering costs, the low-voltage room is generally located near the equipment.
It’s getting farther and farther now. It’s about the transmission scheme.
Thank you! What is a low-voltage room? Is it the on-site cabinet room?
Who proposed the requirement for 200m? The specifications clearly specify this distance. However, if it is located near the equipment, for Category A and Category B applications, it is necessary to calculate the shock resistance level in order to create an explosion-proof control room. 35m fire separation distance for Class A, 30m for Class B (as specified in SHT3160-2009). Additionally, due to the long distance, fiber optic communication can be used; it is best to use cables to connect the cabinets. The cabinet room can be built together with the control room or separately.
The factor of blast resistance distance is certainly taken into account, but the main decisive factor is the calculation regarding the explosion of the device; it is only through such calculations that it can be determined whether blast resistance is needed. It’s not as simple as saying that since it’s outside the device area, blast resistance isn’t required – who says that? As for the distance affecting signal transmission, that is certainly a factor, but there is a limit; longer cables result in greater voltage drops, which prevent the instrument from functioning properly ； I have calculated that for normal instruments powered by 24V, transmission over a distance of 500 meters is not a problem; the maximum recommended distance is around 400 meters. So everything must be supported by data; you can’t just arbitrarily claim a value of 200 meters without any basis.
The cabinet room is located on-site, and fiber optic communication is possible between it and the operation room/main control room.
Thank you all for your advice! The automation technicians in our unit are worried that the long distances and lengthy cables will result in high voltage drops, which might not be sufficient to power the instruments. It seems no calculations were done beforehand; the requirement that the distance should not exceed 300 meters, ideally 200 meters, was only raised after the overall design was completed, which left everyone very frustrated!
The nearest on-site cabinet room is connected to the central control room via fiber optics. If you have the money, use Emerson’s electronic wiring technology: lol
The cabinet room seems to also need to be kept away from explosion-proof areas; generally, a distance of 400 meters is sufficient. If that’s not possible, use thicker cables, such as those with a cross-sectional area of 2.5 square millimeters