User Instructions - Logix® 520MD+ Series Digital Positioner
FCD LGENIM0105-00
© Flowserve Corporation 21 Field Trial Version – Printed October 28, 2011
Single - Select Single when only one side of the actuator is
pressurized.
8.3.3 Signal at Closed Switch
Normally this will be set to 4 mA for an Air-To-Open actuator
configuration, and 20 mA for Air-To-Close.
4 mA - Selecting 4 mA will make the valve close when the
signal is low (4 mA) and open when the signal is high (20
mA).
20 mA - Selecting 20 mA will make the valve close when the
signal is high (20 mA) and open when the signal is low (4
mA).
NOTE: When using an Analog Output (AO) function of
the Multi-Function Card, the AO signal corresponds with the
Signal At Closed selection. If the valve closes with a 4 mA
signal, the AO will show a 4 mA signal at closed. If the valve
closes with a 20 mA signal, the AO will show a 20 mA signal
at closed.
8.3.4 Characterization Switch
The Characterization Switch allows a better match between
the input command and the actual fluid flow through the
valve. This feature is typically used with valves that have
non-linear flow characteristics. The positioner makes a
correction by applying an adjustment to the input command
according to a characterization curve.
Linear - Select Linear if the actuator position should be
directly proportional to the command input signal. (For most
rotary valves, this setting gives an =% Cv characteristic due
to their inherent =% characteristics.)
Other - Select Other if one of the pre-set characterization
curves or a custom curve is desired. The default will be the
Custom curve which is populated with a standard 30:1 equal
percent rangeability curve which generally opens less than
the input command. To select one of the other curve options,
use the LCD menu, a Handheld or the ValveSight DTM. To
modify the Custom curve, use the DTM. See section 10.3.6
Configuration (Characterization
)
for more information.
8.3.5 Auto Tune Switch
This switch controls whether the positioner will automatically
tune itself during the stroke calibration (Quick-Cal), or use
preset tuning parameters.
On - Selecting On enables an auto tune feature that will
automatically determine the positioner gain settings. The
automatic tuning will be based on response parameters
measured during the latest Quick-Cal. The valve response is
a combination of these response parameters and the current
position of the Selectable GAIN Switch.
Off - Selecting Off forces the positioner to use one of the
factory preset tuning sets determined by the Selectable GAIN
Switch. Settings “B” through “J” are progressively higher
predefined tuning sets.
Selecting “A” on the Selectable Gain Switch during a Quick-
Cal allows the user to use and preserve manually adjusted
gains.
See section 8.4 Stroke Calibration for more details.
NOTE: The gain switch is live meaning that regardless of
the Auto Tune selection, the gain settings can be adjusted at
any time during operation by changing the selectable GAIN
switch position.
Figure 16: Selectable GAIN Switch
8.3.6 Quick Calibration Switch
This switch selects between Auto and Jog calibration modes.
Auto - Use the Auto setting if the fully opened position of the
valve has a mechanical stop. This is typical for most valves.
In Auto mode during a stroke calibration (Quick-Cal), the
positioner will fully close the valve and register the 0%
position, then fully open the valve to register the 100%
position.
Jog - Use the Jog setting if the fully opened position of the
valve has no hard stop, but needs to be set manually. In Jog
mode during a stroke calibration (Quick-Cal), the positioner
will fully close the valve and register the 0% position, then
wait for the user to move the valve to the 100% open position
using the ▲Up and ▼Down buttons. Press the
►ACCEPT/QUICK-CAL button to accept the 100% location.
See section 8.4 Stroke Calibration for more details.
8.3.7 Valve Stability Switch
This switch adjusts the position control algorithm of the
positioner for use with low-friction control valves or high-
friction automated valves.
Lo Friction - Placing the switch to Lo Friction optimizes the
response for low friction, high performance control valves.
This setting provides for optimum response times when used
with most low friction control valves.
Hi Friction - Placing the switch to the right optimizes the
response for valves and actuators with high friction levels.
This setting slightly slows the response and will normally stop
limit cycling that can occur on high friction valves. See
section 10.3.7 Configuration (Pressure Control
)
for more
details.
NOTE: This option is more effective on advanced units
with the optional pressure sensors installed.
8.3.8 Spare Switch
If special features have been purchased they may be
controlled by this switch. See associated documentation for
more details.
8.4 Stroke Calibration
The ►ACCEPT/QUICK-CAL button is used to initiate an
automatic stroke calibration. The stroke calibration
determines the closed (0%) and open (100%) positions of the
valve and gathers information about the response of the
valve (such as valve stroke time) in order to determine the
gains. The gains are then set automatically. After a stroke
calibration, the positioner is ready to control.
To perform a Quick-Cal, first ensure the Quick Calibration
Switch is set to Auto or Jog as appropriate. Press and hold
the ►ACCEPT/QUICK-CAL button for approximately 3
seconds. This will initiate the automatic stroke calibration.
More
Stable
More
Responsive
To Next Page
Loading...
Need help?
General
