Logix
®
520MD+ and 510+ Digital Positioners FCD LGENIM0105-15-AQ – 05/16
36
Figure 37: 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 pro-
vides 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 with Advanced or Pro
diagnostic levels.
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 de-
termine 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. While the calibration is in progress, the
LED lights will flash status codes indicating the calibration progress.
See section 19.3 Status Code Descriptions for an explanation of the
status code sequences.
The initial calibration of extremely large or very small actuators may
require several calibration attempts. The positioner adapts to the
actuator performance and begins each calibration where the last
attempt ended. On an initial installation it is recommended that after
the first successful calibration that one more calibration be completed
for optimum performance.
8.4.1 Quick Calibration Switch – Jog
Set the Quick Calibration Switch to Jog if the valve/actuator assembly
has no internal mechanical stop at the fully open position. In this
case, follow these instructions:
1. Press and hold the
.
ACCEPT/QUICK-CAL button for approximately
3 seconds.
This will initiate the jog stroke calibration. The positioner will
then close the valve and set the zero position. The zero position
is automatically always set at the valve seat. At this point the
LED‘s will flash in a sequence of G-R-R-R (green-red-red-red)
which indicates that the user must use the jog keys to manually
position the valve to approximately 100%.
2. Use the up and down keys to position the valve at approximately
100% open.
3. Press the
.
ACCEPT/QUICK-CAL button to proceed.
No more user actions are required while the calibration process is
completed. When the lights return to a sequence that starts with a
green light the calibration is complete.
The jog calibration process will only allow the user to set the span.
If an elevated zero is needed a handheld or ValveSight DTM are
required.
8.4.2 Tuning Options
Quick-Cal Custom Gains - This is typically the fastest way to achieve
ideal gains. Set the Auto Tune Configuration Switch to On and the
Selectable GAIN Switch to “E”. Then perform a Quick-Cal. During the
Quick-Cal, custom tuning parameters will be determined based on
measured response parameters. The gains can then be fine-tuned by
adjusting the Selectable GAIN Switch. Selecting “D” “C” or “B” will
More
Responsive
More
Stable
