shanefaulkner
Member
Electrical simpleton here, so show me mercy.
Plant previously had a 4-20ma valve that was controlled via pneumatic controller with a P/I. Now they have a ControlLogix 1756-OF8 in 0-20ma mode. Valve will move, but not fully open, and above a certain ma output from the OF8 the channel status shows an open wire. They claim they have tried it with both a 250ohm resistor and 1/4 amp fuse in the circuit with no change. They claim that the valve used to fully travel from 0-100% open when it was controlled via the pneumatic controller.
We will try a different channel on the OF8 when time allows, but I'm wondering what else could be wrong electrically.
Plant previously had a 4-20ma valve that was controlled via pneumatic controller with a P/I. Now they have a ControlLogix 1756-OF8 in 0-20ma mode. Valve will move, but not fully open, and above a certain ma output from the OF8 the channel status shows an open wire. They claim they have tried it with both a 250ohm resistor and 1/4 amp fuse in the circuit with no change. They claim that the valve used to fully travel from 0-100% open when it was controlled via the pneumatic controller.
We will try a different channel on the OF8 when time allows, but I'm wondering what else could be wrong electrically.