Baker Hughes Masoneilan SVIII AP, Installation And Maintenance Manual, Page: 129 / 204

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Masoneilan SVI II AP Installation and Maintenance Manual =
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9. Operation and Maintenance
Principle of Operation
The SVI II AP Electro Pneumatic Digital Valve Positioner receives an electrical position setpoint
signal from a controller or other device and compares the position setpoint input signal to the
valve position. The difference between the position setpoint and position feedback is interpreted
by the position control algorithm. This is used to compute a new output pressure. This output
pressure is amplified by a pneumatic relay that drives the actuator. When the valve position
agrees with the value called for by the position setpoint input signal the system stabilizes with no
further movement of the actuator.
Figure 50 Block Diagram with I/P Converter and Pressure Sensor
Input Current
4 to 20 mA