Instruction Manual

DVC6000 SIS
September 2013
5-4
approximately 10.0°, 1.0°, and 0.1°, respectively, to
the rotation of the feedback arm.
If another adjustment is required, repeat step 5.
Otherwise, select Done and go to step 6.
6. The remainder of the auto calibration procedure is
automatic.
During calibration, the instrument seeks the high and
low end points and the minor loop feedback (MLFB)
and output bias. By searching for the end points, the
instrument establishes the limits of physical travel, i.e.,
the actual travel 0 and 100% positions. This also
determines how far the relay beam swings to calibrate
the sensitivity of the beam position sensor.
Adjusting the minor loop feedback bias is done around
mid travel. The valve position is briefly moved back
and forth to determine the relay beam position at
quiescence. Essentially, it establishes the zero point
for the Minor Loop Feedback circuit. The back and
forth motion is performed to account for hysteresis.
Adjusting the output bias aligns the travel set point
with the actual travel by computing the drive signal
required to produce 0% error. This is done while the
valve is at 50% travel, making very small adjustments.
Calibration is complete when the “Auto Calibration has
completed” message appears.
7. Place the instrument In Service and verify that the
travel properly tracks the current source.
If the unit does not calibrate, refer to table 5-1 for error
messages and possible remedies.
Manual Calibration (1-3-1-2)
It is recommended that you adjust the relay before
manually calibrating travel. For additional information
refer to Relay Adjustment in this section.
Note
Relay Adjustment is only available for
the double-acting relay (Relay A).
Two procedures are available to manually calibrate
travel:
 Analog Adjust
 Digital Adjust
Table 5-1. Auto Calibrate Travel Error Messages
Error Message Possible Problem and Remedy
Input current must
exceed 3.8 mA for
calibration.
The analog input signal to the instrument
must be greater than 3.8 mA. Adjust the
current output from the control system or the
current source to provide at least 4.0 mA.
Place Out Of Service
and ensure Calibrate
Protection is disabled
before calib.
The Instrument Mode must be Out of Service
and the Protection must be None before the
instrument can be calibrated. For information
on changing instrument protection and mode,
see the beginning of this section.
Calibration Aborted.
An end point was not
reached.
The problem may be one or the other of the
following:
1. The tuning set selected is too low and the
valve does not reach an end point in the
allotted time. Press the Hot Key, select
Stabilize/Optimize then Increase Response
(selects next higher tuning set).
2. The tuning set selected is too high, valve
operation is unstable and does not stay at an
end point for the allotted time. Press the Hot
Key, select Stabilize/Optimize then Decrease
Response (selects next lower tuning set).
Invalid travel value.
Check travel sensor
and feedback arm
adjustments, and inst
supply press. Then,
repeat Auto Calib.
Prior to receiving this message, did the
instrument output go from zero to full supply?
If not, verify instrument supply pressure by
referring to the specifications in the
appropriate actuator instruction manual. If
supply pressure is correct, check instrument
pneumatic components (I/P converter and
relay).
If the instrument output did go from zero to
full supply prior to receiving this message,
then verify proper mounting by referring to the
appropriate mounting procedure in the
Installation section.
Verify travel sensor adjustment by performing
the appropriate Travel Sensor Adjust
procedure in the Calibration section.
Making the crossover adjustment with the
valve positioned at either end of its travel will
also cause this message to appear.
Analog Calibration Adjust
Note
Analog Calibration Adjust is only
available in 4-20 mA or 0-20 mA
systems (point-to-point operation).
From the Calibrate menu, select Manual Calibration
and Analog Adjust. Connect a variable current source
to the instrument LOOP + and LOOP − terminals. The
current source should be capable of generating 4-20
mA. Follow the prompts on the Field Communicator
display to calibrate the instrument’s travel in percent.
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