Performance Tuning; Input Characterization - Fisher FIELDVUE DVC6200p Instruction Manual

Instruction Manual
D103563X012
Tuner
WARNING
During tuning the valve may move, causing process fluid or pressure to be released. To avoid personal injury and property
damage caused by the release of process fluid or pressure, isolate the valve from the process and equalize pressure on both
sides of the valve or bleed off the process fluid.
Tuner is used to determine digital valve controller tuning. It will move the valve slightly and monitor the effects of
small tuning changes until an optimum control response is achieved. Because the tuner can detect internal instabilities
before they become apparent in the travel response, it can generally optimize tuning more effectively than manual
tuning.

Input Characterization

Input Characterization defines the relationship between the travel target and the setpoint received from the output
block. Travel target is the output from the characterization function.
Linearization Table
You can select from the three fixed input characteristics shown in figure 3‐3 or you can select a custom characteristic.
Figure 3‐3 shows the relationship between the travel target and travel set point for the fixed input characteristics.
You can specify 21 points on a custom characteristic curve. Each point defines a travel target, in % of ranged travel, for
a corresponding set point, in % of ranged set point. Set point values range from -25.0% to 125%. Before modification,
the custom characteristic is linear. You cannot modify the custom points if the Input Characterization is set to custom.
Linearization Type
Select the linearization type:
No linearization (default is linear)
Linearization table
Equal percentage— a valve flow characteristic where equal increments of valve stem travel produce equal percentage
changes in existing flow, or
Quick opening— a valve flow characteristic where most of the change in flow rate takes place for small amounts of
stem travel from the closed position. The flow characteristic curve is basically linear through the first 40 percent of
stem travel.
Configuration
June 2017
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