There’s a problem with the locator; could you help figure out what’s going on?
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An intelligent locator – a signal below 70% from the DCS is sufficient; the valve can operate normally； When the DCS sends a signal of over 70%, the valve fails to operate, and the DCS issues an alarm; the alarm message is the same as that indicated by a disconnected locator. Please help analyze what’s going on.
If it is intelligent, a maximum opening of 70% may have been set.
Enter the valve positioner, set the maximum opening to 100%, and disable the alarm; this should be available in the basic settings.
The maximum opening should be reset to 100%.
A locator with DCS alarm output? The poster, please explain this part in detail
This is not a matter related to the locator, but rather to the DCS configuration. For reasons of production safety, certain control loops have limits set on the opening degree of the control valves; in other words, the control valves in these loops cannot open beyond a certain degree. Once this opening degree value is specified in the configuration settings, the output of the regulator will not exceed the current value corresponding to that degree, and as a result, the control valve will not move. An alarm will then be generated on the regulator or the DCS operation interface. It’s a problem with the DCS system settings, not with the on-site control valves. In industrial plants, it is common to set a lower output limit as a means of controlling variable-frequency pumps. To prevent these pumps from running idle without delivering any flow, they have a minimum output frequency; the corresponding control current signal is set on the DCS, so that there is no situation where the output is 4 milliamps.
The circuit current can be measured first, and then it can be determined whose fault it is.
Check whether the valve requires a limited opening degree. If the design requires a maximum valve opening of 70%. A setting requirement was added in DCS.
There is no setpoint limit in the DCS, nor in the locator; we had thought of this long ago. I suspect it’s a load issue with the locator, but I can’t find solid evidence.
When the DCS sends a signal of over 70%, the valve fails to operate, and the DCS issues an alarm; this alarm indicates that the corresponding AO channel of the DCS is open-circuited.
Intelligent locator: It can resolve at least 60% of problems through self-checking and automatic stroke adjustment