Emerson Fisher FIELDVUE DVC2000 Instruction Manual page 79

D A sensor on the printed wiring board measures
the motion of the small valve inside the pneumatic
relay. This measurement is used for minor loop
feedback to the control algorithm resulting in stable,
robust tuning.
D The change in relay output pressure to the
actuator causes the valve to move.
D Valve position is sensed through the non-contact,
July 2009
Principle of Operation
linkage-less feedback sensor. There are no moving
linkages and the DVC2000 is physically separated
from the valve stem through the use of a magnetic
Hall effect sensor. A magnetic array is mounted to the
valve stem and the sensor is embedded in the
DVC2000 housing. The sensor is electrically
connected to the printed wiring board to provide a
travel feedback signal used in the control algorithm.
The valve continues to move until the correct position
is attained.
A
A-3