SMB/SB Installation and Maintenance Manual 140-11000 • July 2003 4-16
Flow Control Division
Limitorque Actuation Systems
To set the the R/I signal converter:
NOTE: The pinion has been disengaged to prevent damaging the potentiometer prior to setting the valve.
1. Set the potentiometer by turning the pinion until the desired reading is obtained.
2. Loosen the hex nut on the back of the potentiometer and slide the potentiometer in the direction of the idler pinion until
the pinions are engaged.
3. Do not force the engagement of the pinions.
4. Retighten the hex nut on the back of the potentiometer.
5. Do not engage the pinion until the actuator and valve positions have been set.
To calibrate the R/I signal converter:
1. Position the valve at 50% of full travel.
2. Read the ohms from the wiper to either end of the potentiometer.
3. To set the potentiometer to the proper value, loosen the set screw on the potentiometer shaft pinion and rotate the potentiometer
shaft to a reading of 500 ohms.
4. Tighten the set screw.
5. Run the actuator to the fully CLOSED position.
6. Adjust the ZERO control to an output of 4 mA.
7. Run the actuator to the fully OPEN position.
8. Adjust the SPAN control to an output of 20 mA.
9. Repeat steps 5 through 8 to fine-tune as necessary.
Figure 4.6 – Typical Connection for a 50-ohm Potentiometer
Figure 4.7 – Typical Connection for a 1000-ohm Potentiometer
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