Issues related to cable laying
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Chemical industry standards specify that instrument power cables, instrument signal cables – including intrinsically safe and non-intrinsically safe types – should be laid separately; this can be achieved by using different cable trays or metal partitions to separate them. Communication cables should also be laid separately. I would like to ask whether the power cable for 220VAC electric valves counts as an instrument power cable, and whether it too needs to be laid separately from the status feedback cables. Does the communication cable necessarily require its own dedicated cable tray? Metal partitions are required to be grounded. Since these partitions are welded to the cable tray and the cable tray is already grounded, is it still necessary to ground the metal partitions as well?
Regarding cable laying, it is indeed necessary to pay special attention to the regulatory requirements. The power cable for 220VAC electric valves is generally not considered an instrument power cable; it falls under the category of power cables. It is recommended to lay it separately from signal cables. If the metal partition has been reliably welded to the grounded tray, it usually does not require separate grounding, but it is advisable to use a multimeter to verify the conductivity. Whether communication cables must be in their own tray depends on the specific regulatory requirements; in some cases, it is allowed to share a tray with non-intrinsic safety signal cables, but a certain distance must be maintained. For practical implementation, it is recommended to refer to the latest standards such as GB/T 50892-2013, or consult the design agency for confirmation.
The purpose of this regulation is to require that cables of different voltage levels be separated from each other in order to avoid signal interference. Cables at 220V and 24V should be laid separately. Since intrinsically safe and non-intrinsically safe cables have different parameters, they also need to be separated to prevent any impact on the capacitive and inductive properties of the intrinsically safe cables. If the partition has good contact with the cable tray, there is no need for separate grounding.