Metso NELES ND9000 INTELLIGENT VALVE CONTROLLER

TECHNICAL DESCRIPTION

The ND9000 is a 4–20 mA or fieldbus powered microcontroller based intelligent valve controller. The device contains a Local User Interface (LUI) enabling local configuration. A PC with Field Care software can be connected to the ND9000 itself or to the control loop. The powerful 32-bit microcontroller controls the valve position. The measurements include: □ Input signal □ Valve position with contactless sensor □ Actuator pressures, 2 independent measurements □ Supply pressure □ Spool valve position □ Device temperature Advanced self-diagnostics guarantees that all measurements operate correctly. After connections of electric signal and pneu matic supply, the micro controller (μC) reads the input signal, position sensor (α), pressure sensors (Ps, P1, P2) and spool posi tion sensor (SPS). A difference between input signal and position sensor (α) measurement is detected by control algorithm inside the μC. The μC calculates a new value for prestage (PR) coil cur rent based on the information from the input signal and from the sensors. The changed current to the PR changes the pilot pres sure to the spool valve. Reduced pilot pressure moves the spool and the actuator pressures change accordingly. The spool opens the flow to the driving side of the double diaphragm actuator and opens the flow out from the other side of the actuator. The increasing pressure will move the diaphragm piston. The actuator and feedback shaft rotate. The position sensor (α) measures the rotation for the μC. The μC using control algorithm modulates the PR-current from the steady state value until the new position of the actuator, according to the input signal, is reached