Svi Ii Esd Components; Electronics Module - GE Masoneilan SVI II ESD Installation And Maintenance Manual

SVI II ESD Components

This section describes SVI II ESD major components and provides a physical and operational
description for each one.

Electronics Module

Electronics module consists of an electronic circuit encapsulated in a housing. Electronics
include a multiplexer, A/D, D/A, temperature sensor, Hall-Effect magnetic position sensor,
pressure sensors, micro controller, and a power management/distribution circuit. The
programs controlling SVI II ESD positioner are stored in a flash memory allowing download of
upgraded firmware.
A separate non-volatile memory stores configuration information, and continuous diagnostic
results. Expansion capabilities include connectors for addition of optional local display with
pushbuttons. Using internal programmed positioner algorithm, the CPU computes required
output based upon information received from the measurement sensors. Base module has no
user repairable components.
Magnetic Position Sensor
A non-contact sensor using a magnetic field to transfer position through the wall of the
housing, without penetration, senses valve position. A Hall effect device, sealed within the
electronics housing, senses rotation of a magnetic assembly mounted on the end of rotary
valve shaft or on a driven linkage mounted on reciprocating valve.
The Hall sensor output provides the position feedback signal to the position control algorithm.
Magnetic assembly is environmentally sealed and is entirely outside electronics housing. (See
Figure 73 on page 124.) Hall effect sensor has a maximum travel range up to 140° rotation.
Position Retransmit
The position transmission option provides a 4 - 20 mA signal proportional to valve position
transmitted on a separate pair of leads. A pair of contacts can signal high and low position
limits.
The position sensor also provides, through the electronics module, a readout of valve position
on the optional display and communication of valve position via HART
The 4-20 retransmit is galvanically isolated from the 4-20 input on the main board.
Pressure Sensor
Pressure sensor located in the Electronics Module measures output from the single acting
relay. Pressure measurement is displayed on the local display or read by a HART
communication device.
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Masoneilan SVI II ESD Installation and Maintenance Manual
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