A
I recently faced a problem with a control valve installed in the Natural Gas line. The output to the valve was varied between 0-100 from DCS (honeywell C200) but it did not opened physically hence no feedback. When i diagnosed i found out in its AO channel showing a message "loop current fixed". when i stroked the valve from field using the loop calibrator it moved perfectly fine.
What does this mean and why does it occur? i tried refreshing the connections but the error still remained. i then reloaded its control module in the control builder and the error went away but i could not understand the reason for its occurrence. Is this related to the min voltage required for the positioner? please someone explain this to me and what is its proper solution?
Following are the specs for the Metso ND9100H positioner installed on it:
Supply power: 4-20mA
Minimum signal: 3.6mA
Current Max: 120mA
Load Voltage: up to 9.5vDC/20mA Corresponding to 475ohm resistance
Voltage: 30vDC max
What does this mean and why does it occur? i tried refreshing the connections but the error still remained. i then reloaded its control module in the control builder and the error went away but i could not understand the reason for its occurrence. Is this related to the min voltage required for the positioner? please someone explain this to me and what is its proper solution?
Following are the specs for the Metso ND9100H positioner installed on it:
Supply power: 4-20mA
Minimum signal: 3.6mA
Current Max: 120mA
Load Voltage: up to 9.5vDC/20mA Corresponding to 475ohm resistance
Voltage: 30vDC max
