Is there a bypass soft button set for DCS interlocks?
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As the title suggests, whether a bypass soft button should be provided for the DCS interlock – are there any relevant specifications regarding this, or can it be installed depending on the process requirements?
According to the “HGT 20511-2014 Design Code for Signal Alarming and Interlocking Systems”, there is no strict requirement for this; generally, it is handled in accordance with the design specifications. By bypass, you mean soft switches or hard switches – for example, setting up soft test switches or maintenance switches. Since all circuits involving interlocks need to be tested regularly to check whether the measuring components are functioning properly and whether the actuating components are in good condition, these operations require the interlock switches to be disabled/enabled in order to carry out.
. There is no requirement saying it cannot be added. However, installing chain bypass switches increases the likelihood of accidental or improper operations, thereby reducing the system’s security score. Therefore, a bypass switch is not installed unless it is absolutely necessary. .
Personally, I believe one more can be added. After all, there are situations involving system debugging and maintenance; having an extra one would be more convenient.
There is no need to set up a dedicated bypass soft button; the faceplates of current DCS modules come equipped with a bypass option for all interlock conditions. Of course, to bypass a particular interlock condition, it is necessary to fill out the relevant forms and obtain approval from the supervising manager in advance. For safety reasons, the permission to bypass interlocks is generally granted at least at the engineer level.
In practical use, the interlocks of DCS systems are usually equipped with a switching switch, namely a bypass maintenance switch, which is used for room debugging, equipment maintenance, and similar purposes.