SMB/SB Installation and Maintenance Manual 140-11000 • July 20034-15
Flow Control Division
Limitorque Actuation Systems
4.6 Position Indication
4.6.1 Local Position Indicator
NOTE: The local dial position indicator displays valve position. The position indicator can only be adjusted when the actuator is
mounted on the valve. See Figures 7.1-7.3 (SMB-000), 7.4-7.8 (SMB-00), 7.9-7.12 (SMB-0 through 4), 7.13-7.16 (SMB-5).
To set the position indicator:
1. Disconnect all incoming power and open or remove the Limit Switch Compartment Cover.
2. Place the valve in the fully “close” position.
3. Loosen the round head machine screw that holds the pointer in place, move the pointer to the “C” position, and retighten
the screw.
The indicator is now set.
4.6.2 Remote Position Indicator (50 ohm or 1000 ohm Potentiometer)
The SMB or SB actuator with a potentiometer installed, transmits a 0-10 VDC output signal to a remote position indicator (meter).
The potentiometer is powered by 120 VAC. For additional information, see Bulletin 410-10000, Limitorque Position Transmitters
and Indicators.
To set the potentiometer:
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 potentiometer:
1. Position the valve at 50% of full travel.
2. Read the resistance 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 for the 1000-ohm potentiometer, or ~25 ohms for the 50-ohm potentiometer.
4. Tighten the set screw.
5. Run the actuator to the fully CLOSED position.
6. Adjust the CLOSED position setting to a value at or above 0 ohms.
7. Run the actuator to the fully OPEN position.
8. Adjust the OPEN position setting to a value at or below 1000 ohms for the 1000-ohm potentiometer; at or below 50 ohms for the
50-ohm potentiometer.
9. Repeat steps 5 through 8 and fine-tune as necessary.
4.6.3 Remote Position Indicator (Resistance-to-Current Signal Converter)
The SMB or SB actuator with a signal converter installed transmits a 4-20 mA output signal to a remote position indicator (meter).
The signal converter responds to the input of a 1000-ohm potentiometer and can be powered by 24 VDC or 120 VAC
for the older version R/I converter; or 18 VDC, 24 VDC, or 120 VDC for the PT20SD style R/I converter.
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