Physical And Operational Description; Electronics Module - GE Baker Hughes Masoneilan SVI FF Installation And Operation Manual

Digital positioner

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Physical and Operational Description

The SVI FF is housed in an industrial, tough, weatherproof, corrosion resistant aluminum

housing that has been designed for operation in hazardous areas as listed in Appendix B.

Electrical connections are made through two 1/2" NPT conduit entries. Pneumatic connections

are made through two or three ¼" NPT ports.

The Electronics module consists of an electronic circuit encapsulated in a housing. The

electronics include a multiplexer, A/D, D/A, temperature sensor, Hall-Effect magnetic position

sensor, pressure sensors, a micro controller, and a power management/distribution circuit.

The programs controlling the SVI FF digital valve positioner are stored in a flash memory that

allows for the downloading of upgraded firmware.

A separate non-volatile memory stores configuration information, and continuous diagnostic

results. Expansion capabilities include connectors for the addition of the optional local display

with pushbuttons. Using the internal programmed positioner algorithm, the CPU computes

the required output based on information received from the measurement sensors. The base

module has no user repairable components.

Magnetic Position Sensor

A non-contact sensor uses a magnetic field to transfer the position through the wall of the

housing, without penetration, to sense the valve position. A Hall effect device, sealed within

the electronics housing, senses the rotation of a magnetic assembly mounted on the end of a

rotary valve shaft or on a driven linkage mounted on a reciprocating valve.

The output of the Hall sensor provides the position feedback signal to the position control

algorithm. The magnetic assembly is environmentally sealed and is entirely external to the

electronics housing (See Figure 26 on page 57). The Hall effect sensor has a maximum travel

range of up to 140° rotation.

Position Display

The position sensor also provides, through the electronics module, a readout of valve position

on the optional display and communication of valve position via FF protocol.

Pressure Sensor

The pressure sensor located in the Electronics Module measures the output of the single

acting relay. The pressure measurement is displayed on the local display or read by an FF

communication device.

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BHGE

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