Fisher FIELDVUE DVC6200 Instruction Manual page 47

pressure control until Travel Pressure Select is
changed to Travel or Travel with Pressure
Fallback/Auto recovery. It is not necessary to
enable the Travel Sensor Alert for Pressure
Fallback to occur.
Tvl/Press Cutoffs (1-2-2-2-2)
D Tvl/Press Cut Hi—Travel Cutoff High defines
the high cutoff point for the travel in percent (%) of
ranged input current. Above this cutoff, the travel
target is set to 123.0% of the ranged input current.
When a Travel Cutoff High is set, the Travel Limit
High is deactivated, since only one of these
parameters can be active. Travel Cutoff Hi is
deactivated by setting it to 125.0%.
Pressure Cutoff Hi defines the high cutoff point for
the pressure in percent (%) of pre-characterized
setpoint. Above this cutoff, the pressure target is
set to 123.0%. A Pressure Cutoff Hi of 99.5% is
recommended to ensure valve goes fully open.
Pressure Cutoff Hi is deactivated by setting it to
125%.
D Tvl/Press Cut Lo—Travel Cutoff Low defines
the low cutoff point for the travel set point. Travel
Cutoff Low can be used to ensure proper seat load
is applied to the valve. When below the travel
cutoff low, the output is set to zero or to full supply
pressure, depending upon the zero power
condition. A Travel Cutoff Low of 0.5% is
recommended to help ensure maximum shutoff
seat loading. When a Travel Cutoff Low is set, the
Travel Limit Low is deactivated, since only one of
these parameters can be active. Travel Cutoff Low
is deactivated by setting it to −25%.
Pressure Cutoff Lo defines the low cutoff point for
the pressure in percent (%) of pre-characterized
setpoint. Below this cutoff, the pressure target is
set to −23%. A Pressure Cutoff Lo of 0.5% is
recommended to help ensure maximum shutoff
seat loading. Pressure Cutoff Lo is deactivated by
setting it to −25.0%
Travel Limits (1-2-2-2-3)
D Tvl Limit Hi—Travel Limit High defines the
high limit for the travel in percent (%) of ranged
travel. If is the maximum allowable travel (in
percent of ranged travel) for the valve. During
operation, the travel target will not exceed this limit.
When a Travel Limit High is set, the Travel Cutoff
High is deactivated, since only one of these
parameters can be active. Travel Limit High is
deactivated by setting it to 125.0%
D Tvl Limit Lo—Travel Limit Low defines the low
limit for the travel in percent (%) of ranged travel. It
is the minimum allowable travel (in percent of
September 2010
Detailed Setup
ranged travel) for the valve. During operation, the
travel target will not exceed this limit. When a
Travel Limit Low is set, the Travel Cutoff Low is
deactivated, since only one of these parameters
can be active. Travel Limit Low is deactivated by
setting it to −25.0%.
Pressure Control (1-2-2-2-4)
D Press Range Hi—Pressure Range Hi is the
high end of output pressure range. Enter the
pressure that corresponds with 100% valve travel
when Zero Power Condition is closed, or 0% valve
travel when Zero Power Condition is open. This
pressure must be greater than the Pressure Range
Lo.
D Press Range Lo—Pressure Range Low is the
low end of the output pressure range. Enter the
pressure that corresponds to 0% valve travel when
Zero Power Condition is closed, or 100% valve
travel when Zero Power Condition is open. This
pressure must be less than the Pressure Range Hi.
End Pt Press Control (1-2-2-2-5)
(Instrument Level ODV)
Note
End Point Pressure Control is
available for instrument level ODV.
D End Pt Control Enab— Select Yes or No. End
Point Pressure Control allows the digital valve
controller to pull back from saturation of the
pneumatic output after reaching the travel extreme.
Rather than having the instrument provide full
supply pressure (saturation) continuously at the
travel extreme, the digital valve controller switches
to an End Point Pressure Control where the output
pressure (pressure controller set point) to the
actuator is maintained at a certain value. This value
is configured through the Upper Operating
Pressure feature. Because the digital valve
controller is constantly in control and not allowed to
reach a dormant or saturated state, it is constantly
testing its own pneumatic system. If there is an
output pressure deviation, for example, the
instrument will issue an alert. To ensure there is an
alert when an output pressure deviation occurs,
setup the alert as described under Pressure
Deviation Alert.
D PST Start Pt—Defines the travel stop the
valve needs to be at before a partial stroke test can
be initiated. Also defines the travel stop for end
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