What is the basis for the delay values set in DCS and PLC?
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Hello, everyone! What is the basis for the delay values set in SIS, ESD, DCS, and PLC? Is there a standard requirement for setting the delay value, or is it based on experience? Thank you!
Delays are often incorporated into the interlocks of large rotating equipment, especially as equipment manufacturers frequently request this to prevent frequent shutdowns due to interlocks during operation. This value is generally proposed by the manufacturer based on experience during the first trial run, and after the actual operation begins, the production department decides whether to retain it and what value to use. In the case of interlocks on process units (which is relatively rare), they are usually proposed by the process package manufacturer, after which the owner decides on the appropriate value once operation begins.
That’s the experience value. **The department doesn’t seem to agree with this claim.
Our units no longer have a delayed interlock shutdown feature; in the original domestic production project, since the units were being operated for the first time after being developed domestically, a delay mechanism was used, but it was removed after regular operation began. Additionally, all the detection components are high-end products imported originally, and with a three-out-of-two or two-out-of-two configuration, downtime caused by detection failures is significantly reduced; therefore, it is also entirely feasible to eliminate such downtime. Also, our local work safety supervision agency does not conduct such detailed inspections.
This should be provided by the design institute
This is determined by the manufacturing processes and equipment; empirical values are generally not used
It’s set based on the instrument’s fault response time, I think that’s the case. If there’s anything wrong, please let me know