My name is Thales Camargo,
Many thanks for your valuable feedback regarding this matter:
There is a control valve with Actuator Fisher 657 ( power fail:Open ) and a DVC 6010 Hart and an Electronic Position Transmitter Fisher 4211.
The actual configuration on DVC is : Zero Power Condition : Valve Closed
The control system uses the Feedback from the 4211 Fisher ( Not from the DVC ).
My recommendation was to Set the Zero power Condition to Valve Opened ( Actuator 657 ) BUT the whole team denied this technical advice.
What is the consequence of setting this parameter in the wrong way?
They are triying to match the command (current to the DVC) and the Stroke of the Actuator BUT They could not so far.
From their point of view, that parameter Zero Power Condition is not vital, important or relevant for their application.
Could you provide me some technical feedback on this point?
Many thanks for your valuable answer,
I look forward to receiving your comments on this issue.
How can I attached some pictures in order to ilustrates much better my case?
Nice to meet you.
The Zero Power Condition of a valve assembly (in terms of open/close) is a result of the type of control valve, actuator and the relay in the DVC6000 or DVC6200.
A Push-Down-to-Close (PDTC) valve with the Fisher 657 actuator (air pushes stem down) and DVC6010 with a single direct acting relay C will have a ZPC of open.
The sequence of events will go:
As I do not have information on the relay type of the DVC6010 on your site, it is difficult for me to say what will happen on your end.
You can email me at email@example.com if you wish to discuss this more at length.
Thales Carmago got in touch.
The valve on site is a EWD 6x4 valve, 657 size 45 actuator, DVC6010 with Relay C. (serial number: F000138958).
Summary of reply:
Suggested a reverse acting relay B if the ZPC needs to be changed to close.This will give full air output to the actuator at 4mA (or 0mA) and zero air output at 20mA.
This will give zero power failure (ZPC) of close and pneumatic failure of open to the current valve assembly.
In reply to Alex Quah:
In reply to Thales:
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