SIS controls DCS devices
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My SIS has an emergency stop function that can be activated with just one click across the entire process line. I want the SIS to send a stop signal to the DCS, and once the DCS receives this signal, it should shut down the auxiliary equipment, such as closing the steam inlet valves of the heat exchangers, but the design team does not allow this to be done. Is it reasonable to have to go to DCS for manual operations?
You should first ask the design institute which regulation prohibits doing this
His principle is that since these interlocks at the root level do not pose any safety issues, he doesn’t want to handle them. It’s fine if your operator detects a stop situation and carries out a manual stop – there will be no consequences. If you really want to do it, you can ask the DCS manufacturer to handle it; there’s no need to get entangled with the design agency. Just let the DCS manufacturer know when they are doing the programming – there’s no problem with that. But you must think carefully about your logic, and decide what prerequisites should be used to prevent accidental activation
Of course not, sis. The reason why an independent system is required is to ensure that security can be maintained independently. By doing this, you’re once again giving control to the DCS, so how can there be independence?
This post was last edited by wll1986 on 2018-8-28 08:39. The design institute replied in the same way, stating that if the auxiliary systems are not related to critical processes that require simultaneous shutdown, then their control valves and similar components must be integrated into the SIS system. But I think it would be safer if the key processes required to be carried out are executed by SIS, while less important equipment is only shut down via DCS linkage, right?
For example, in the case of a heat exchanger where the steam inlet valve is involved, it is entirely possible to design it such that the solenoid valve in the gas circuit is controlled by SIS, while the opening degree is regulated by the DCS