Flowserve 3400MD Digital Positioner - Manual (Page 23)

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Logix 3400MD Digital Positioner FCD LGENIM3404-08-AQ – 5/15
flowserve.com
Example: Stroke length is set to four inches. If the valve is moved
from 0 percent to 100 percent, four inches will be added to the travel
accumulator. The travel accumulator units will be inches. If Stroke
length is 90 degrees for a rotary, the travel accumulator will now have
units of degree. A 0 percent to 100 percent stroke will add 90 to the
travel accumulator.
Table 11: Transducer Block Characterization Parameters
Parameter Description Value - Meaning Comments
MODE_BLK
The operating mode of the transducer
block
Auto - Auto (target mode) The transducer block must be out of service
before characterization can be edited or
changed.
OOS - Out of Service
CURVE_ SELECT
Selects the characterization curve type
when the DIP switch is set to ‘Other’.
This parameter is inactive when the DIP
switch is selected to ‘Linear’.
0 - Equal Percent
Sets the characterization to equal percent
mode.
1 - Quick Open Sets the characterization to quick open mode.
2 - Custom
Sets the characterization to use the curve fit
parameters CURVEX and CURVEY.
USER_ INTERFACE_ ACTIVE
Software version of the physical DIP
switches. The parameters can be
changed either in the parameter or at
the device via the DIP switches.
1 - Air Action
Select 1=ATO or 0=ATC
Select 1=Linear or 0=Other
Three bits of the parameter reflect the value
selected on the Rotary Actuator Gan switch
as follows:
A=111, B=011, C=101, D=001
E=110, F=010, G=100, H=000
2 - Characterization Linear
3 - Rotary Actuator Gain
CURVEX
Numeric X value array for custom point.
(1 x 21 array points)
X-axis value for custom stroke
characterization point.
Range –10 to 110
Pair each X-value with corresponding Y-value
to define the desired point. Values must be in
ascending (or equal) order.
CURVEY
Numeric Y value array for custom point.
(1 x 21 array points)
Y-axis value for custom stroke
characterization point.
Range –10 to 110
7.15 Characterization Retention
Once a custom curve has been loaded into the Logix 3400MD digital
positioner’s memory it is retained in the EPROM until it is either edited
or replaced. Turning Custom Characterization Active on or off now
selects between a linear response (off), or the new custom curve (on).
If either of the other two factory curves is selected it will overwrite
the custom curve in RAM only. The custom user-defined curve will
automatically be activated again when the factory curve is deselected.
7.15.1 Initiating a Valve Signature
A feature of the Logix 3400MD positioner is the ability to capture and
store a valve diagnostic signature. A signature is the collected data
response of the valve to a predefined set of operating conditions.
This stored data can later be uploaded to the host system for analysis
of potential problems. By comparing a baseline signature, when
the valve is new, to subsequent signatures at later times, a rate of
change can be tracked which can help predict possible faults in the
valve before they happen. This is called ‘predictive maintenance’. It is
important to note
NOTE: Stroke length is for information only and is not used during
calibration.
that the purpose of the positioner is to act as the data acquisition
device for the signature. Analysis of the data is not done on the
device, but in the supervisory system.
NOTE: Signature data is lost if the positioner is reset or if the power
is cycled.
7.15.2 System Preparation
c DANGER: By definition, the collection of the signature requires
the unmanaged operation of the positioner. Therefore, the process
must be in a safe operating mode where unexpected movement of
the valve will not cause a hazardous condition.
Before a valve signature can be run, the Transducer Block must
Out-of-Service (OOS).