Various causes of DCS alarm issues and their solutions
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Hey guys, what should I do if the DCS shows an overcurrent alarm at the moment the mixer in the reactor is turned on or off? What should be done in case the pressure of the cooling water pipeline and the flow rate of the process water show negative values as an alarm? Currently, it is required that there be no unresolved alarms on the DCS panel, but I’m not sure what the best way to handle this is
For the alarm of excessive current in the reactor DCS, it is necessary to modify the high limit and the very high limit values. As for the alarms related to negative pressure in the cooling water pipes and negative flow rates of the process water, it is first necessary to determine whether the issue lies in the process settings or in the instruments themselves, before deciding whether to have maintenance personnel handle it or instrument technicians.
Excluding issues with the process itself, excessive current during startup and shutdown can be addressed by adding an alarm delay； When driving the engine under normal conditions, the pressure and flow rates should not show negative values; if negative values appear, it should be handled by a professional in instrumentation.
There’s no issue with the process settings; since it’s an old process, if no water is flowing through the cooling water pipes, the flow meter either keeps flashing red (without triggering an alarm) or displays a negative value (in which case an alarm is triggered). The DCS system does not allow negative values to be set for low and very low alarms. So I’m wondering whether it’s possible to adjust the zero point again – that is, to set it at a negative value – so that negative numbers are not displayed
I’ve encountered the same issue – how should the low-level alarm for motor current be set?
If the stirring current is too high, it is sufficient to adjust the alarm values set by the DCS for high and extremely high levels. As for pipeline pressure and flow rate, if the instruments themselves are functioning properly, either recalibrate them or simply cut off the low-level signals
The current and voltage are definitely high at the moment the mixer is turned on. This is correct. If there’s an alarm, then it should be triggered. Why can’t we call the police? An alarm indicating a negative flow value is an air traffic control alarm; it represents normal pressure as well. If you don’t want it, set the flow meter not to trigger an empty pipe alarm.
If the instantaneous current is too high, a delay of generally three to five seconds can be set in the DCS interlock