The 990-05-XX-01-CN MOD: 165335-01 is a high-reliability, two-wire 990 Vibration Transmitter engineered by Bently Nevada to supply continuous machinery protection monitoring directly to plant control networks. This industrial component integrates the processing circuitry of a standard proximity sensor into a compact field-mount transmitter package. It accepts inputs from a non-contacting 3300 XL 8mm eddy-current proximity probe and extension cable, processing raw high-frequency micro-gap changes into a linear, proportional 4 to 20 mA current output loop. This analog signal interfaces directly with standard Distributed Control Systems (DCS), Programmable Logic Controllers (PLC), or simple process data recorders without requiring a separate rack system monitor.
This precise hardware configuration features a factory-calibrated full-scale measurement option of 0-5 mils pp (0-125 um pp), designed for direct tracking of radial shaft vibration amplitudes. The physical casing comes integrated with 35 mm DIN rail clips to allow fast, secure snap-on mounting into field marshalling junctions. This variant is engineered with the CN agency option, which provides global and local industrial compliance covering ATEX/IECEx and Chinese NEPSI hazardous area safety certifications. The assignment MOD: 165335-01 designates a specialized factory modification code that ensures specific internal processing tweaks or precise component matching parameters tailored to targeted machinery requirements while preserving full base-model compatibility.
Features
Two-wire loop-powered architecture providing direct 4 to 20 mA analog output integration into host PLC or DCS loops.
Factory-calibrated full-scale range measuring 0-5 mils peak-to-peak (0-125 um peak-to-peak) for high-accuracy shaft vibration logging.
Integral 35 mm DIN rail mounting clips allowing rapid, toolless snap-fit structural deployment on enclosure racks.
Robust hazardous area safety design certified with combined ATEX/IECEx and local Chinese NEPSI industrial markings.
Dedicated factory configuration label designated under MOD: 165335-01 for precise system architecture synchronization.
Onboard BNC buffered output connector providing unconditioned dynamic eddy-current waveforms for local machinery diagnostics.
Built-in non-interacting zero and span adjustments allowing clean precision calibration touch-ups under field conditions.
Applications
Direct radial vibration tracking on fluid-filmed bearings of industrial centrifugal air compressors and process fans.
Continuous asset health processing loop monitoring on medium-sized balance-of-plant electric motor or pump skids.
Distributed, standalone field instrumentation integration on specialized gas or water utility infrastructure pumps.
Option String Breakdown
Option Code Slot
Selected Option Value
Technical Detail
Model Number
990
990 Vibration Transmitter Product Line
A: Full-scale Option
-05
0-5 mils peak-to-peak (0-125 um peak-to-peak) measurement scale
B: System Length Option
-XX
Configurable system loop length option (Matches probe/cable design)
C: Mounting Option
-01
35 mm DIN rail clips installed
D: Agency Approval
-CN
Combined ATEX/IECEx and Chinese NEPSI hazardous area approvals
0 to 5 mils pp (0 to 125 um pp) peak-to-peak displacement
Output Signaling Loop
Linear 4 to 20 mAdc proportional current
Buffered Output Impedance
10 kohm nominal (Protected against continuous short circuit)
Buffered Output Scale
Nominal 7.87 V/mm (200 mV/mil) corresponding to the probe gap
Supply Voltage Range
+12 Vdc to +35 Vdc loop power required at the terminal links
Transducer Core Matching
Calibrated for 3300 XL 8mm proximity probe and extension cable loops
Field Wiring Connector Size
Pin terminals accepting wire cross-sections up to 1.5 mm squares
Enclosure Framework Build
Polycarbonate body structure with integrated aluminum mounting plate
Net Component Weight
0.43 kg (0.9 lbm) typical
Operating Temperature Bounds
-35 degC to +85 degC
Storage Temperature Bounds
-51 degC to +100 degC
Relative Humidity Index
95% maximum, non-condensing exposure boundaries
Connections/Interfaces
Terminal Connection
Function Assignment
PROBE
Miniature coaxial port linking to the incoming proximity transducer extension cable
+ (SIG)
Positive loop terminal interface receiving incoming +12 to +35 Vdc power inputs
- (COM)
Negative loop connection returning the regulated 4 to 20 mA measurement signal
BUF
Dedicated front coaxial BNC socket providing unconditioned voltage waveforms
Installation Guidelines
DIN Rail Alignment: Position the transmitter housing directly over standard 35 mm DIN rail tracking. Apply firm downward pressure until the integrated plastic clips snap tightly over the rail flanges.
Chassis Frame Isolation: Ensure the internal ground planes remain isolated from bare electrical conduit paths. The transmitter plate must remain isolated from structural rack frames to eliminate low-voltage ground loops.
System Length Verification: Verify that the system length option (Option -XX) perfectly matches the combined physical length of the connected 3300 XL 8mm probe and extension cable to maintain proper scaling.
Dynamic Signal Diagnostic Check: Use the front-facing coaxial BNC connector to patch into local signal analyzers. This buffered port provides a raw voltage wave (200 mV/mil) without altering the primary 4-20 mA control loop tracking.
FAQ
What does the 'CN' agency option signify on this 990 transmitter module?
The 'CN' suffix indicates that the unit is fully compliant with combined ATEX/IECEx safety directives along with official Chinese NEPSI hazardous area marking certifications for dangerous processing zones.
Does a short circuit on the front BNC buffered output disrupt the 4-20 mA DCS system signal?
No. The buffered BNC diagnostic interface is electronically isolated. A temporary or permanent short circuit on the diagnostic connector will not impact or interrupt the primary 4 to 20 mA loop processing.
What measurement metric corresponds to the 4 to 20 mA scaling on this specific model?
This specific variant features the -05 option, meaning a 4 mA output represents 0 mils of shaft vibration, while a full 20 mA output represents a peak-to-peak vibration amplitude of 5 mils (125 um).
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