Interlock value, alarm value, linkage value
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The alarm value serves as a reminder to operators that the process parameters are abnormal and have deviated from the normal values; it is a set value that indicates a potential risk. It requires the personnel on duty to take corrective actions and to monitor the situation continuously in order to prevent the situation from worsening. Interlock values are typically set as protective limits to ensure safety and prevent various types of accidents. Once these limits are exceeded, it indicates that adverse consequences will occur, including impacts on product quality and safety threats to production equipment and personnel. In such cases, the control system takes automatic protective measures based on predefined logic, without the need for human intervention. This is commonly referred to as safety interlocking, and a Safety Instrumented System can be established based on factors such as the operating conditions and SIL level. The interlock values are typically set based on production requirements and process control; the activation of these interlocks is generally achieved through DCS/PLC, and they fall within the scope of basic process control in BPCS. BPCS is for routine daily operations, whereas alarms and interlocks fall under the category of safety instruments; risk analysis and assessments of the safety function integrity level must be carried out in strict accordance with the regulations related to safety instruments and functional safety, so as to configure alarms and interlocks properly and ensure safety.
You are absolutely correct. These three terms are very important concepts in control systems. The alarm value refers to the point at which a parameter of a device or system exceeds the normal range, triggering an alarm mechanism to alert the operator that certain adjustments or actions are necessary in order to prevent potential problems or accidents. Interlock values represent a safety redundancy mechanism; when system parameters reach dangerous levels or even exceed them, the system automatically carries out predetermined actions to protect the safety of equipment or personnel. For example, if the temperature is too high, the heating device may shut down automatically. The linkage value represents the logical relationships in a control system. For example, the lighting system in a factory building may be linked to the doors of that building; when the doors open, the lighting system turns on automatically. These three values are extremely important in practical operations, serving as key means to ensure product quality as well as the safety of equipment and personnel. Therefore, when setting these values, it is necessary to fully consider factors such as the equipment’s performance, process requirements, and potential risks. At the same time, these values need to be regularly evaluated and adjusted to adapt to changes in production conditions. .