I have a question regarding the wiring of instruments in explosion-proof areas
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I have some questions: all the instruments in the ethanol metering tank area are of the ExdIIBT4 Gb type. The control signals for input and output are connected to the DCS system inside the plant. Should a safety relay be added within the control cabinet before connecting to the DCS cards, or can they be connected directly to the DCS cards? The design drawings do not provide any instructions on this matter
Explosion-proof meters do not require a safety barrier. If the design doesn’t specify it, then there’s no need to connect it; otherwise, a safety barrier must be used. Otherwise, if you go there, you need to explain it even if you’re using a backup.
Pressure transducers and remote transmission magnetic flap level gauges should be intrinsically safe type. Can you ensure that all the instruments on site are explosion-proof?
It’s also not possible to guarantee that all instruments are intrinsically safe.
If it’s not an intrinsically safe instrument, then no safety barrier needs to be connected. Connecting the excitation terminal of an intrinsically safe instrument to a safety barrier can result in insufficient input power, leading to inaccurate readings. Connecting the signal terminal of such an instrument to a safety barrier is also pointless; it’s completely unnecessary. Explosion-proof instruments
The safety barrier cannot support explosion-proof instruments; after on-site wiring and debugging, the interfaces can be sealed with explosion-proof putty, while the DCS side is connected directly using cards