DVC2000 Digital Valve Controller
July 2009
4-14
Note
If optional limit switches are being
used, power must be applied to the
switch circuits throughout the
calibration routine. Failure to power
the switches may result in incorrect
switch orientation.
Auto Calibrate Travel
Select Auto Calib Travel from the Calibrate menu,
then follow the prompts on the Field Communicator
display to automatically calibrate travel.
1. The auto calibration procedure is automatic. It is
completed when the Calibrate menu appears.
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.
2. Place the instrument In Service and verify that the
travel properly tracks the current source.
Manual Calibrate Travel
Two procedures are available to manually calibrate
travel:
Analog Adjust
Digital Adjust
Analog Calibration Adjust
From the Calibrate menu, select Man Calib Travel and
Analog Adjust. Connect a variable current source to
the instrument LOOP + and LOOP
−
terminals. The
current source should be capable of generating 4 to 20
mA. Follow the prompts on the Field Communicator
display to calibrate the instrument’s travel in percent.
Note
0% Travel = Valve Closed
100% Travel = Valve Open
1. Adjust the input current until the valve is near
mid-travel. Press OK.
Note
In steps 2 through 4, the accuracy of
the current source adjustment affects
the position accuracy.
2. Adjust the current source until the valve is at 0%
travel, then press OK.
3. Adjust the current source until the valve is at 100%
travel, then press OK.
4. Adjust the current source until the valve is at 50%
travel, then press OK.
5. Place the instrument In Service and verify that the
travel properly tracks the current source.
Digital Calibration Adjust
From the Calibrate menu, select Man Calib Travel and
Digital Adjust. Connect a variable current source to the
instrument LOOP + and LOOP
−
terminals. The
current source should be set between 4 and 20 mA.
Follow the prompts on the Field Communicator display
to calibrate the instrument’s travel in percent.
Note
0% Travel = Valve Closed
100% Travel = Valve Open
1. From the adjustment menu, select the direction and
size of change required to set the travel at 0%.
If another adjustment is required, repeat step 1.
Otherwise, select Done and go to step 2.
2. From the adjustment menu, select the direction and
size of change required to set the travel to 100%.
4
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Страница 71: ...Parts July 2009 7 1 7 7 Section 7 Parts Parts Ordering 7 2 Parts Kits 7 2 Parts List 7 2 7 ...
Страница 77: ...Principle of Operation July 2009 A 1 A A Appendix A Principle of Operation DVC2000 Operation A 2 A ...
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