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Zero power condition cofiguration on DVC 6010 Hart

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?


3 Replies

  • Hi Thales,

    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.

    For example:

    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:

    1. No power (0mA) to DVC6010, relay C is designed to give zero pneumatic output to the actuator. 
    2. Zero pressure to Fisher 657 will retract the stem upwards.
    3. This will pull the plug to an open position on a PDTC valve.

    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 alex.quah@emerson.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:

    • The ZPC of this EWD valve assembly (based on the info provided) is open. It is written on the actuator nameplate (Power Fail: OPEN).
    • Mentioned that the configuration on the 475 handheld is not an option, it is for the user to let the DVC6000 know how the valve and actuator has been set up.
    • Putting the ZPC as close in the DVC6000, when it is actually open does not change the actual ZPC, it will likely cause the travel feedback to be inverted.
    • In the event of a loss of power to the DVC6010, the valve will be open and allow flow through. 
    • Screenshots show that the users are aware of the inverted feedback. The words "INVERTED" and "100% fully closed" are noted in the description of the tag.

    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:

    Many thanks In advance Alex for your valuable answer.The DVC has a relay type C.
    I verified the configuration and it was set the Zero Power condition as Valve Close (default value). However the actuator is 657 Fisher (Open).
    I tried to persuade the team without sucess. They are trying to match stroke and command to the DVC But there is no positive results.
    I am sending some information to your personal mail.
    Again, thanks a lot for sharing your knowlegde and expertise.Thales
  • In reply to Thales:

    Thanks Alex for your response. Thales, do you think that requirement is AIR FAIL CLOSE Valve action (air to open) and you are trying to convert existing FAIL OPEN valve to FAIL CLOSE by reversing the signal? As Alex have explained to you that you can certainly reverse the air action but on air fail, due to actuator construction valve will go to FAIL OPEN condition. best way will be to have 667 actuator to achieve the set up. if this is not an option than you may employ Reverse B Relay in DVC6010, which will provide you Air to Open and AIR FAIL CLOSE. However, this will be ETT (Energize to Trip) configuration for DCS HOST system.
    if you can provide us your exact geographical location and contact email or phone, we can have one of our local engineer contact you and guide you accordingly.