Interlocking issue?
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What does it mean that the level gauge and the pump are connected by dotted lines? What do the symbols inside the framed circles following I and M, marked with red lines in the diagram, mean?
What different line types represent is something that most instrument designers should understand; if not, they can look up the relevant standards. You can find out what the letters mean by looking at the image on the homepage; if not, check the specifications. By just showing a screenshot like this, it’s impossible for anyone to explain exactly what is meant. It’s better to go ask the person who will edit the image; they can explain clearly what needs to be conveyed.
What was said upstairs is correct; it depends specifically on the design illustration legends. Simply put: the dashed line represents a DCS internal signal, as it does not exist on the actual circuit. I: Interlock – the pump stops when the liquid level is too low. Since M refers to the motor: MOTOR, II107/ZS107/XS107 should represent the operating status of pump P107. II107 is the current indication, while ZS107/XS107 are presumed to be signals indicating the pump’s operating status or remote/local indication signals. (Because there are two pumps, AB, shown in the diagram, it indicates that interlock for mutual backup is required.)
S: The position switch XS refers to vibration or displacement interlock actions; the function of X depends on the design specifications, but it is generally related to displacement or vibration (XS P107 likely refers to the displacement of pump shaft 107). II: Current indication. PG: On-site pressure gauge. ZS P107, XS P107, and II P107 all appear to be position switches, displacement sensors, and current indicators for pump 107. The dashed line indicates a connection between them; the level value of LISA107 determines whether pump 107 starts or stops operating
The interlock for stopping the pump when the liquid level is low, as well as the pump’s operating status and current
Sweet skewers – I like them too.
High and low level alarm signals of the level gauge are interlocked with the pump motor