46
NDX VALVE CONTROLLER
default), Fast, Aggressive, Max Stability FO, Stable
FO, Optimum FO, Fast FO, Aggressive FO.
þ
Max Stability: Slowest response to signal changes
and no overshoot. Trying to keep the valve
position as stable as possible.
Stable: Fairly slow response to signal changes and
no overshoot.
Optimum (factory default): Optimum performance
controlling the valve regarding response time
and valve speed when signal changes. There is
typically no overshoot.
Fast: Fast response to signal changes but may also
have small overshoot.
Aggressive: Fastest possible response to signal
changes and typically some overshoot.
þ
FO = Fast Open; The reaction time to setpoint
change will be faster when recovering from the
cutoff position.
þ
Max Stability FO, Stable FO, Optimum FO, Fast FO,
Aggressive FO: Similar behavior than in above
mentioned performance levels respectively, but
always faster recovering from cutoff than above
because of fast open (FO) function.
þ
Once Performance level is selected, press enter to
edit the parameter. Change value with arrow keys
and confirm that with enter.
•
Cut off closed
þ
Cut off closed is used with valves that require great
torque to be closed. It is used to ensure that the
valve is fully closed at a 4mA input signal.
þ
When this value is exceeded, the valve is forced to a
0 % position. This is called the tight cutoff feature.
If, for example, the value is 2 %, tight shutoff starts
when the input signal goes below 2 %, then valve is
closed with full actuator force.
þ
Once Cutoff closed is selected, press enter to edit
the parameter. Change value with arrow keys and
confirm that with enter.
•
Signal direction
þ
This parameter defines opening and closing
direction of the valve with rising current loop
signal. The value Rising signifies the increasing
mA signal to open the valve and Falling means the
decreasing mA signal to open the valve.
þ
Once signal direction is selected, press enter to
edit the parameter. Select or change value with
arrow keys and confirm that with enter
.
•
Instrumentation
þ
NOTE: This parameter is not available in NDX Ex d
enclosure (NDX_512_) version at the moment
þ
This parameter defines additional instrumentation
for the fast valve opening and/ or closing.
12 LOCAL USER INTERFACE (LUI)
