Positioner alarm
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There is an alarm related to a valve positioner in our facility; it functions properly on the DCS. It is a gas-shut off valve, and when the valve is closed, the voltage measured is 4.47 V at 20 mA. Some colleagues say that this low voltage triggers an alarm, but I don’t understand why. Could someone please explain this to me? Thank you
The locator receives current signals; it has nothing to do with voltage.
There is no such thing as a voltage alarm; the electrical-pneumatic locator receives 4-20MA current signals as input, and outputs pneumatic pressure signals. Does the DCS alarm indicate a problem with the locator? An alarm on the DCS can be caused by the control system that involves this valve along with other parameters such as flow rate and pressure; when the emergency panel is activated, if certain conditions are not met, an alarm will be triggered for the valve. For example, an IOP alarm can also result in an alarm for the valve.