WTR Series
Installation Instructions
L120 Installation & Maintenance Manual 120-11000 A
To Calibrate Position Transmitter PT20SD
1. Position the actuator to mid-travel; valve at 50% position.
2. Disconnect the potentiometer wiring harness from the PT20SD board and measure the
resistance from each end connection to the center connection on the potentiometer.
3. Set the potentiometer to the correct resistance reading. Loosen the set screw that retains
the spur gear on the potentiometer shaft and rotate the shaft until a reading of 500 ohms
is achieved.
4. Tighten the set screw and re-connect the wiring harness to the PT20SD.
5. Run the actuator fully CLOSED.
6. Calibrate ZERO position by adjusting the zero potentiometer until a 4mA ouput signal is
read at terminal +VE and -VE.
7. Run the actuator fully OPEN.
8. Calibrate SPAN position by adjusting the span potentiometer until a 20mA output signal
is read at terminals +VE and -VE.
9. Repeat steps 5 to 8 and fine-tune as necessary.
Figure 5 – 1000 ohm Potentiometer
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