ABB AV3 Instruction Manual page 44

CALIBRATION
TROUBLESHOOTING CALIBRATION ADJUSTMENTS
4 - 12
2. Connect a customer supplied 0 to 207 kPa (0 to 30 psig)
instrument gage to the I port. The gage allows you to monitor the
pneumatic signal output.
3. Make supply air connections (172 to 1,034 kPa (25 to 150
psig)) to the S port. The minimum supply pressure should be 34
kPa (5 psig) above the operating requirements of the actuator.
4. Turn on the supply air to the positioner.
5. Check the zero and span of the servo assembly as follows:
a. Connect a current source to terminals TB1-4 (+) and
TB1-5 (-) on the terminal block (Fig. 3-1).
b. Apply 4 mA and observe the pressure at the I port. The
pressure value should be 20.7, ±1.7 kPa (3.00, ±0.25 psig). If
the pressure equals this value, go to Step 5c. If the pressure
does not equal this value, go to Step 6.
c. Apply 20 mA and observe the pressure at the I port. The
pressure value should be 103.0, ±1.7 kPa (15.00, ±0.25 psig).
If the pressure equals this value, proceed to Step 7. If the
pressure does not equal this value, proceed to Step 6.
6. Adjust the zero and span of the servo as follows:
a. a. Disconnect the servo motor wires from the EMI/elec-
tronics housing (Fig. 4-8).
b. Set the input current to 4 mA and record the setpoint volt-
age across P2 and P3 (Fig. 4-8).
c. Set the input current to 20 mA and record the setpoint volt-
age across P2 and P3.
d. Apply a reference pressure to the transducer of the EMI/
electronics housing (Fig. 4-8). Do not exceed 138 kPa (20
psig). Adjust the reference pressure to 20.3, ±1.7 kPa (3.00,
±0.25 psig). Connect the digital voltmeter across P1 and P3
(feedback voltage) and turn the ZERO potentiometer (Fig. 4-8)
until you match within 8 mV of the setpoint voltage recorded
across P2 and P3 in Step 6b.
e. Adjust the reference pressure to 103, ±1.7 kPa (15, ±0.25
psig). Connect the digital voltmeter across P1 and P3 and turn
the SPAN potentiometer until you match within 8 mV of the
setpoint voltage value recorded across P2 and P3 in Step 6c.
f. Repeat Steps d and e until the comparisons are stable.