How is the correctness of the logic interlock diagram ensured in new projects these days?
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The instrument logic interlock diagrams are created by instrumentation professionals based on the process interlock descriptions provided by the process engineering team. These process interlock descriptions are in textual form and are presented in a clear and easy-to-understand manner, allowing them to be readily reviewed by others. However, instrument logic interlock diagrams, especially those with complex logic structures (such as those related to startup and shutdown processes), are often only understandable to the person who created them. Even when shown to other instrumentation professionals, it takes a lot of time to understand them. Given the urgency with which projects are carried out these days, one person is usually responsible for creating the interlock diagrams from start to finish. Even if process engineers take a look, they generally only check whether the inputs and outputs meet their requirements, without delving into the complex logic involved. Once the interlock diagram is completed, it is handed over to the system manufacturer for configuration. They simply configure things based on that diagram, without referring to the original process interlock specifications. So how can we ensure the accuracy of the process from the interlock specifications to the actual interlock diagram? Interlocks are extremely important; if there are mistakes, the consequences of starting up the system could be severe.
Use simulation software. Give input, see output.
Before driving, there is a loop interlocking check, which includes the verification of interlocks.
What’s the point of managing? Even if a chain makes mistakes, what’s the use of coordination then?
Hello, I would like to learn about interlock logic diagrams systematically, but I’m not sure where to start. Do you have any book recommendations? Thank you so much
1. Familiarize yourself with the process control instructions. 2. Refer to those instructions while examining the interlock logic diagram (if something is unclear, consult the legend). 3. If there are still aspects that are not understood, ask the process engineer to explain the process control instructions to you before reviewing the interlock logic diagram again. 4. Review it several times and work through the interlock scenarios multiple times – this will help you understand it better
It’s mainly about looking at more logic diagrams. If possible, get in touch with those at the lower level, try to configure things, and then compile to see if it’s accurate. By drawing analogies, one can understand that other similar operating conditions are largely the same.
During driving tests, the interlock process still needs to be carried out once again; it involves everything from writing the logic according to process requirements to the configuration by the manufacturer, with automatic control systems possibly playing a role in this process as well. The interlock debugging before driving is a task that focuses on the process aspects, with instrumentation and electrical systems playing a supporting role, and it requires the cooperation of the construction team; finally, it must be signed off on – control measures are indeed in place.