Emerson Fisher FIELDVUE DVC6000 Instruction Manual page 137

AUXILIARY
TERMINALS
DRIVE
SIGNAL
I/P
CONVERTER
E0408 / IL
and the output B pressure decreases. The output A
pressure is used for double-acting and single-acting
direct applications. The output B pressure is used for
double-acting and single-acting reverse applications.
As shown in figure A-3 the increased output A
pressure causes the actuator stem to move
downward. Stem position is sensed through the
feedback linkage by the travel sensor which is
electrically connected to the printed wiring board
assembly submodule. The stem continues to move
downward until the correct stem position is attained. At
this point the printed wiring board assembly stabilizes
September 2013
4−20 mA
+
HART
TERMINAL BOX
PRINTED
WIRING BOARD
PNEUMATIC
RELAY
Figure A-3. FIELDVUE DVC6000 Digital Valve Controller Block Diagram
Principle of Operation
INPUT SIGNAL
VALVE TRAVEL
FEEDBACK
OUTPUT A
SUPPLY
PRESSURE
OUTPUT B
VALVE AND ACTUATOR
the I/P drive signal. This positions the flapper to
prevent any further increase in nozzle pressure.
As the input signal decreases, the drive signal to the
I/P converter submodule decreases, decreasing the
I/P output pressure. The pneumatic relay decreases
the output A pressure and increases the output B
pressure. The stem moves upward until the correct
position is attained. At this point the printed wiring
board assembly stabilizes the I/P drive signal. This
positions the flapper to prevent any further decrease in
nozzle pressure.
A
A-3