5 Service and maintenance
62 |
266 MODBUS® multivariable transmitter User manual 2105216 Rev. AB
Calibrating the differential pressure (DP) sensor
1.
Verify that the transmitter DP calibration unit is set to the same measurement unit as the calibration device.
2.
Attach the low pressure calibrator to the manifold high side vent/test port.
3.
Verify that the high and low equalizing manifold valves (Figure 47, items A, B, and C, page 58) are open and that the high
(H) and low (L) tap valves are closed.
4.
Set the DP low trim value.
a.
Press the right soft key to access the HMI menu.
b.
Use the key pad to locate and select
Calibrate
>
Diff. Press. Sensor
>
Low Trimming
.
c.
Verify that the transmitter is sensing the low value desired through the manipulation of the pressure calibrator. Select
Continue
when the value is stable.
d.
Enter the low value number next to the
New
field.
i.
To enter a value, use the up or down arrow to locate the value of the first digit. When selected, press the left soft
key for
Next
. This moves the cursor to the next digit.
ii.
Repeat this process for each digit until the entire low value is selected. To change a digit’s value after moving
past it, select the
Next
key until the cursor reaches the incorrect digit then change it.
e.
When the value is equal to the value of the pressure calibrator, then select
Continue
. The user should now see the
indication that the low trim calibration is complete.
5.
Set the DP high trim value.
a.
Close the high equalizer valve (item B)
b.
Use the key pad to locate and select
High Trimming
from the menu.
c.
Pressurize the calibrator to the desired high trim value (100% of the differential pressure URV). Affirm that the
transmitter is sensing the high value,
verified by the user’s calibration equipment. Select
Continue
when the value is
stable.
d.
Enter the high value number next to the
New
field.
i.
To enter a value, use the up or down arrow to locate the value of the first digit. When selected, press the left soft
key for
Next
. This moves the cursor to the next digit.
ii.
Repeat this process for each digit until the entire high
value is selected. To change a digit’s value after moving
past it, select the
Next
key until the cursor reaches the incorrect digit then change it.
e.
When the value is equal to the value of the pressure calibrator, then select
Continue
. The user should now see the
indication that the high trim calibration is complete.
6.
Select
Save to User
.
a.
Select
OK
.
b.
The bar graph will show the status of the save.
c.
Select
Back
to return to the main calibration screen.
The differential pressure sensor is now calibrated
.
Summary of Contents for 266 MODBUS
Page 163: ......
