SMAR HART FY500, Installation Operation & Maintenance

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Section 2
2.1
OPERATION
Principle of Operation
Figure 2.1 – FY500 Digital Valve Positioner (Exploded View)
The FY500 receives a setpoint signal from a controller or other device through a twisted pair of
wires. It compares this input signal to the actual valve position, which is measured with a position
sensor, in this case, Hall Effect sensor. The difference between the setpoint and the actual position
is processed by internal PID, and a corrective current signal is sent to the I/P converter module.
The supply pressure to the FY500 passes through an internal pressure regulator that regulates it to
approximately 22 psi. The air then goes through an orifice that restricts the flow and air
consumption. The I/P module converts the current signal to a pneumatic signal, which is sent to the
diaphragm module and the spool valve. The spool valve directs air supply to the actuator to move
the valve until the Hall Effect Sensor reading agrees with the setpoint.