Regarding the issue of shared instruments between SIS and DCS systems
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I need time off to deal with an SIS issue. The specifications state that for SIL2 levels, it is not advisable to share detection instruments. If sharing is necessary, how should the wiring be arranged? Can it be connected directly from one system cabinet to another? Should the signal go to the SIS first or to the DCS first?
We often use alarm setters to divide the signal into two parts, which are then connected to the SIS and DCS systems respectively. I’m not sure if it’s feasible.
Is it better to use a one-to-two isolation distributor, or to use the SIS power supply as the power source for the isolation distributor?
China’s standards are generally not followed. Hahaha
Meeting the SIS specifications is sufficient, after all, SIS has high requirements
It is possible to go into SIS first, and then establish communication with DCS. Alternatively, the field instrument signal wires are fed into a split safety barrier, which then supplies signals to both the DCS and SIS.
Our approach here is to use a two-part safety barrier: one output goes to the DCS, and the other goes to the SIS. The safety barrier is located on the SIS side, with a jumper wire connecting it to the DCS.
Configure a one-input two-output safety barrier: the instrument signals go into the safety barrier, while the output signals are sent one way to the SIS and another way to the DCS.
Configure a safety barrier with one input and two outputs, with one connection to the SIS and another to the DCS. If a safety barrier is not installed, it is advisable to first go to the SIS and then communicate with the DCS. From what I’ve seen, on-site there is definitely one measurement point with two instruments; both are displayed on the DCS, and one of them serves as a communication point.
Shouldn’t utility meters have certain prerequisites first? For example, in a 3-out-of-2 scenario, they can be shared, but it’s likely not possible in cases that aren’t 3-out-of-2, no matter how you configure them