GE Baker Hughes Masoneilan SVI FF Installation And Operation Manual page 54

Rotary - 90°
For actuators with 60 to 120° rotation, follow the instructions in "Mounting the SVI FF on
Rotary Valves" on page 50, except mount the magnet at plus or minus 45° while the actuator
is de-energized as shown in Figure 22.
Magnet Orientation on Rotary Valve Shafts
The same mounting hardware is used for Models 35, 30 actuators. For each actuator type the
magnetic coupling must be properly oriented to the active sensing angle of the positioner's
Hall Effect sensor. The active range of the Hall Effect sensor is plus⁄minus 70° from the null
magnet axis.
If the total valve travel is less than 60°, allowing a margin for tolerances, the best accuracy is
achieved by mounting the magnet with the axis vertical in the valve-closed position. The axis
of the magnets is the line through the centers of both magnets.
If travel of the valve exceeds 60°, the magnet must be assembled to the rotary valve shaft so
that the magnet axis is vertical when the valve is at mid-scale.
Dismantling the SVI FF from Rotary Valves
WARNING
To remove the SVI FF digital valve positioner from a rotary valve perform the steps in
"Mounting the SVI FF on Rotary Valves" on page 50 in reverse.
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BHGE
Magnet
axis
Figure 22 Model 33 Actuator
Before carrying out any work on the device, power off the
instrument or make sure that the device's location conditions for
potentially explosive atmosphere permit the safe opening of the
cover.
Magnet axis
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