GE Masoneilan SVI II ESD Installation And Maintenance Manual page 204

Characteristic
Closed
Compliance Voltage
Conformity
Compliance, HART
Condition Monitoring
CONFIGure
Custom
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Positioner input setpoint command can be selectively modified to
provide a desired relationship between setpoint and valve position. In
the valve, the relationship between stroke and Cv is also named
valve inherent characteristic. It is often adjusted by design, to equal
percentage, for example. Positioner characteristic is applied to mod-
ify setpoint to travel relationship of the actuator. The characteristic of
positioner must be chosen to compliment the valve. If the valve is
equal percentage, the positioner should be set to linear. If a linear
valve is installed the positioner can be set to an equal percentage
characteristic to improve flow control. SVI II ESD offers an eleven
point custom characteristic option that can be created and edited in
ValVue ESD. Local display can be used to select custom characteris-
tic, but cannot adjust the points.
The valve position in which the flow is minimum or zero. See Tight
Shutoff.
The available voltage at the control system output in order to drive
the control current through the SVI II ESD and all the resistive devices
in series with it.
The closeness to which position approaches the theoretical position
curve, for example equal percentage or quick opening. It is indepen-
dent of effects due to valve or actuator rigidity at mechanical limits
of travel. See Accuracy.
®
Manufactured and tested in accordance with the HART
cations Foundation standards.
A technology for measuring the performance of process equipment
and valves over a period of time to predict the need for maintenance.
The technology evolved to meet NRC requirements GL 89-10, and
has proven valuable to other process industries. SVI II ESD and Val-
Vue ESD offer a suite of diagnostic tools to implement condition
monitoring.
A positioner mode of operation where you have access to changing
permanent parameters required for position control or communica-
tions.
The custom characteristic in SVI II ESD has ten points to define (See
Characteristic) the relationship between setpoint and valve position.
The pushbuttons allow selection of the custom characteristic that
are downloaded as pairs of data using HART
®
a HART master. ValVue ESD offers a graphical drag-and-drop
method to define the characteristic. It includes a method to correct
for geometric non-linearity of positioner feedback linkage.
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