Shut down one pump for each of DCS and SIS
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When DCS and SIS both shut down one pump, does SIS only need to provide a DO signal for shutting down the pump, and no DI signal is required? Is there a problem as shown in the figure below?
When a DCS (Distributed Control System) and a SIS (Safety Instrumented System) work together to control a pump, if the SIS needs to initiate a pump shutdown, it usually only needs to send a digital output signal (DO) for shutdown. This is because the DO signal is used to directly control the start or stop of the pump. As for the digital input signal (DI), it is typically used to determine the actual status of the pump, such as whether the pump has stopped. In the configuration you mentioned, if the task of the SIS is merely to ensure that the pump can stop safely under certain conditions, then it is sufficient for the SIS to send a DO signal to stop the pump; there is no need for the SIS to send a DI signal as well. The DI signal should be provided by the pump itself or another system, so that the DCS can determine the pump’s status. As for what you mentioned about “as shown in the figure below,” I am unable to see the image here; if you can provide a detailed description or the key information, I will be able to give a more accurate answer regarding whether there is a problem. .
Thank you for your answer! In the picture are the control points for stopping the pump: HSL-P3101A RDO, YL1-P3101A DI, YL2-P3101A DI, HZSL-P3101A SRDO
Based on the control point information you provided: - HSL-P3101A RDO: This appears to be a Remote Digital Output, which may be used to send commands to stop the pump. - YL1-P3101A DI and YL2-P3101A DI: These two appear to be digital inputs, which may be used to monitor certain conditions or statuses of the pump, such as pressure, flow rate, or other safety-related parameters. - HZSL-P3101A SRDO: This appears to be a Safety Remote Digital Output, specifically used by SIS to send safety-related commands to stop pumps. Based on these control point descriptions, the system design seems reasonable. SIS sends a pump-stop signal via HZSL-P3101A SRDO to ensure safety, while the DI signals (YL1-P3101A and YL2-P3101A) should be used to be fed into the DCS or SIS for monitoring and confirming the pump’s operating status, rather than being sent externally by SIS. In summary, it is correct for the SIS to send pump-stop signals via SRDO, and there is no need for the SIS to process the DI signals further; it is sufficient to ensure that these DI signals are properly fed back to the DCS or SIS system for monitoring and verifying operations. .
This post was last edited by jlshnlhj on 2024-6-7 08:12. Note the empty rows in the table; they imply a way to distinguish signals. Of course, as part of the design, it is best to clearly specify DCS and SIS. It is recommended to check the I/O point list di, do of DCS and SIS to verify this.
When one pump needs to be stopped in either the DCS or SIS system, the DCS should send a signal to stop the pump to the SIS; in the SIS system, interlocks are implemented using SR flip-flops, and the pump will also stop as a result of these interlocks. Meanwhile, the DCS can still control the pump when there are no interlocks in place. Refer to the diagram for details