There are things I don’t understand in the SIS system
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In the SIS system, there is an item called fan shutdown bypass. What does this mean? I don’t quite understand it. As shown in the diagram, those who know can please explain it
This bypass is required when the interlock factors that stop the fan need to be disabled/maintained. At this time, the interlock factors of the fan have no effect on it.
As the name implies, a bypass serves the same purpose as an instrument bypass: it allows the interlock to be disabled for maintenance or other reasons, enabling operation via the bypass path, at which point the interlock no longer functions
Maintenance override. Repair override. After maintenance and during testing, using a medium different from the original design, such as nitrogen, may result in an excessively high outlet temperature, triggering an interlock. To ensure smooth testing, this interlock is usually overridden.
There are two states: bypass and in use, similar to a on/off switch with a toggle. Bypass means it is not in use