GENER
AL
INFO
SPECS
MOUNTING
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T UP
OPER
ATION
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AINTENANCE
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ORDER
LOGISTICS
9
NDX VALVE CONTROLLER
Product reliability
•
Designed to operate in harsh environmental
conditions
•
Rugged modular design
•
Excellent temperature characteristics
•
Vibration and impact tolerant
•
IP66/NEMA4X enclosure
•
Protected against humidity
•
Resistant to dirty air
•
Wear resistant and sealed components
•
Fully contactless position measurement
•
Fully encapsulated electronics
Predictive maintenance
•
Easy access to collected data with any FDT/DTM
software and drivers
•
Intelligent diagnostics analysis to visualize control
valve health and performance
•
Patented online valve signature
•
Historical trend and histogram collection
•
Diagnostics collected continuously while the
process is running
•
Extensive set of offline tests with accurate key
figure calculations
•
Clear notifications with online alarms
•
Condition monitoring tools available
3.3
OPERATION PRINCIPLE
The NDX is a 4–20 mA powered microcontroller based
intelligent valve controller. The device contains a local user
interface enabling configuration and operation without
opening the device cover. Configuration and operation
can also be made remotely by PC with asset management
software connected to the control loop.
After connections of electric signal and pneumatic supply,
the micro controller (μC) continuously reads measurements:
•
Input signal
•
Valve position with contactless sensor (α),
•
Actuator pressure (I, II)
•
Supply pressure (S)
•
Device temperature
Advanced selfdiagnostics guarantee that all measurements
operate correctly.
Powerful microcontroller calculates a control signal for I/P
converter (prestage). I/P converter controls the operating
pressure to the pneumatic relay (output stage). Pneumatic
relay moves and actuator pressure changes accordingly. The
changing actuator pressure moves the control valve. The
position sensor measures the valve movement. The control
algorithm modulates the I/P converter control signal until
the control valve position matches the input signal.
Service
Port
mA
HART
DO
µC
Pos 50.2
P1
P2
Pos
T
S
EXH1
EXH2
PCB
LUI
Prestage
Output stage
Pneumatic actuator
PT/DO
Ps
Fig. 2 Operating principle of double acting valve controller (NDX2512_).
3.4
OPTIONS
Following options are available for NDX valve controller:
•
Internal position transmitter
•
Digital output (namur)
•
Gauge block
3.4.1
Internal position transmitter
Optional position transmitter connection is part of the
electronics module. Position transmitter is connected to
the 2pole OUT terminal as shown in figure 4. Position
transmitter requires an external power supply.
Fig. 3
3
PRODUCT SUMMARY
GENER
AL
INFO
