Manual Mode in Closed Position

K

Thread Starter

Kaushik

I am working with a Cause & Effect Diagram. There I find that for certain process interlocks, the control valve is closed via "Manual Mode in Closed Position". I have a little difficulty in understanding this.

Whatever I have understood is as follows - "During an MMC, the controller output is set to Zero. So the valve goes to its FAIL POSITION. And the controller changes into Manual mode. When the trip condition is removed, the operator have to set the controller to automatic again."

However, I would appreciate if someone can put some more light in it.

Regards.
 
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