Technical Specifications

ValVue Digital Communications Software Ver. 2.80
572
GE Oil & Gas
Language The SVI can display its menu in English or French. The AMS Snap-on
program is not affected. Separate language versions of AMS
Snap-on are available.
Pressure Units The pressure reported by the SVI can be in psi, bar, or kpa units. If the
pressure units are changed after the unit has been fully set up, the
SVI automatically converts all of its internal parameters to the
appropriate units. Diagnostic and memory dump data saved to a file
is not converted.
Position Fault Limits You can configure how position errors are handled. A position error
occurs when the valve position differs from the requested position
(from the input signal in Normal operating mode or the Manual set-
point in manual mode) by more than the Position Error Band for more
than the Position Error Time 1. When this occurs, a status flag is set is
reported during the next HART message (Only that a flag is set is
reported. You must send a Read Status message to find out the
cause of the status flag). If the error persists for Position Error Time 2,
the valve is put in failsafe position. This Iater action may be disabled
by unchecking the Enable box next to the Time 2 entry.
For practical considerations, Time 2 (if enabled) must be larger than
Time 1 by at least two seconds. Time 1 must be at least as long as
the time required to open the valve fully or unnecessary position
errors are reported. The maximum time is 327 seconds.
Characterization Control valves are often characterized to give a specific relationship
between flow capacity (Cv) and percent opening of the valve. The
valve can be characterized with special purpose trim or with the SVI
positioner Several characterizations are available:
 Linear: Causes the valve to open proportionally with the input
signal. This option should be selected if non-linear trim is used
in the valve.
 Equal Percentage (50) and Equal Percentage (30): Two equal
percentage characterizations are available, one with R=50
and the other with R=30.
 Quick Opening: The quick opening characterization is the
inverse to the Equal Percentage (50) characterization curve.
 Custom Configuration: Selecting this option displays an
additional dialog where to enter or draw a custom
characterization curve. The curve can have up to nine points
and points in between are linearly interpolated.
Air-to-Open I Air-to-Close You must select whether the valve is an air to open valve or an air to
close valve. This selection determines whether an increasing signal
opens or closes the valve.