Control valve with fisher DVC6020F positioner cannot move occasionally
Control valve with fisher DVC6020F positioner cannot move occasionally
(OP)
In our plant we use delV control system, some control valve with fisher DVC6020F can move by DCS, but occasionally these valve cannot move by DCS, after re-wiring(only disconnect then connect wire in valve terminal box) then it can move by DCS again, i want to know the root cause, anybody can tell me? Thanks a lot!





RE: Control valve with fisher DVC6020F positioner cannot move occasionally
Is this just one particular valve or more than one?
Are these small change commands or any change?
How far is this valve from the generated control signal?
What kind of facility is this, equipment density, electrical noise wise?
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Control valve with fisher DVC6020F positioner cannot move occasionally
for your question i answer here one by one
1.there are about 5-10 valves fault with this phenomenon.
2.Valve could not move regardless control signal change.
3.The distance is about 100 feets, but the valves which is far than 300 feets distance has no this phenomenon
4.The valves in the same enviroment has no this phenomenon.
i don't know my answer is clear or not, any more questions pls let me know. Thanks again!
RE: Control valve with fisher DVC6020F positioner cannot move occasionally
Exactly what is the control signal, 4-20mA or HART?
RE: Control valve with fisher DVC6020F positioner cannot move occasionally
Start by investigating the control modules. Any block that has a question mark on it has something wrong with it.
Also, DeltaV has a diagnostics tool that will help determin what the actual output is. This may help.
Also, if it is HART, Profibus or Foundation Fieldbus, you may be able to check it our with AMS, if you have it. If you don't have AMS (an Emerson product very handy with DeltaV), use a handheld communicator for HART or Fieldbus.
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RE: Control valve with fisher DVC6020F positioner cannot move occasionally
when fault occured, we have diagnose them with delV and AMS, We could not see any alarm but deviation alarm (between controller output and valve travel sensor feedback), this is what i wonder.
RE: Control valve with fisher DVC6020F positioner cannot move occasionally
You could maybe duplicate this error by disconnecting the linkage momentarily.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Control valve with fisher DVC6020F positioner cannot move occasionally
Are these positioners all of the same make and model and firmware version?
Are the 'problem' positioners all on the same FF communications link?
Further, several positioners periodically, but at the same time, fail to respond to a DCS position command. Correct?
Further, by disconnecting a positioner control wire in a field junction box and then reconnecting the wire, a valve positioner can be forced back into proper operation. Does disconnecting/reconnecting the wire solve the problem for more than one positioner at once? Like all the positioners on the comm link?
Would you agree with these restatements of your situation?
What brand and model positioners?
Dan
RE: Control valve with fisher DVC6020F positioner cannot move occasionally
RE: Control valve with fisher DVC6020F positioner cannot move occasionally
RE: Control valve with fisher DVC6020F positioner cannot move occasionally
RE: Control valve with fisher DVC6020F positioner cannot move occasionally
RE: Control valve with fisher DVC6020F positioner cannot move occasionally
We found that the linkage attached to the stem of the valve was rubbing against the positioner cover. It ended up being a physical/mechanical issue, and not an issue with the DVC or communication. We found that there were different positioner covers also, and we were sent the wrong ones!
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RE: Control valve with fisher DVC6020F positioner cannot move occasionally
Here i want to explain that:
first this thing only happen random and on specific valves which are hook on different segments. we have checked all hardware installation no problem.some valve are simple loop contrller output, some are a little complex but often use.I think it's no relationship about how complex the loop is since valve only execute the controller output.
Welcome your advice.
Thanks again.
RE: Control valve with fisher DVC6020F positioner cannot move occasionally
Have you investigated the milliamp on each segment. I think they limit is 80mA or 120mA. If you are drawing to many mA, it will affect the overall signal quality.
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RE: Control valve with fisher DVC6020F positioner cannot move occasionally
Also, if these DVCs are add ons, perhaps the wrong mounting kits were used. Many look the same.