ABB 266 MODBUS User Manual page 70

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.
Repeat this process for each digit until the entire low value is selected. To change a digit's value after moving
ii.
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.
Repeat this process for each digit until the entire high value is selected. To change a digit's value after moving
ii.
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.
62 | 266 MODBUS® multivariable transmitter User manual 2105216 Rev. AB
5 Service and maintenance