Product Overview
When a thrust bearing malfunction threatens critical rotating machinery, the Bently Nevada 991-06-50-03-00 provides immediate fault detection and signal defeat. This probe vibration transmitter is designed specifically for axial thrust monitoring, converting proximity probe input into a standard 4-20 mA current loop signal. Its integrated Not OK / Signal Defeat function forces the output below 3.6 mA within 100 µs of a fault condition, protecting downstream control systems from erroneous data. The 991-06-50-03-00 mounts easily on a DIN rail and operates from +12 to +35 Vdc, making it a reliable choice for continuous vibration monitoring in industrial environments.
Technical Specifications
The following key parameters define the performance of the Bently Nevada 991-06-50-03-00:
| Parameter |
Value |
| Full-scale Range |
0.6-0-0.6 mm (axial) |
| System Length |
5.0 meters (16.4 feet) |
| Mounting |
DIN rail with clips and screws |
| Output Signal |
4-20 mA (2-wire) |
| Power Input |
+12 to +35 Vdc at transmitter terminal |
| Linear Range (Prox Out) |
0.25 to 1.65 mm |
| Loop Accuracy |
Within ±1.5% full scale (typical) |
| Maximum Loop Resistance |
1,000 Ω including cable at 35 Vdc |
| Current Limiting |
23 mA typical |
| Not OK Response Time |
Signal <3.6 mA within 100 µs |
| Operating Temperature |
-35°C to +85°C (-31°F to +185°F) |
| Weight |
0.43 kg (0.9 lbm) |
Industry Applications
The 991-06-50-03-00 excels in axial thrust monitoring for steam turbines, centrifugal compressors, and large pumps. In a power generation plant, a sudden increase in axial displacement can indicate bearing wear or misalignment. The transmitter's fast Not OK signal defeat immediately alerts the control system, allowing operators to initiate protective shutdown before catastrophic damage occurs. Similarly, in oil and gas compressor stations, the 4-20 mA output provides continuous trend data for predictive maintenance, while the defeat function ensures safety during fault events.
Installation & Setup
Mount the Bently Nevada 991-06-50-03-00 on a standard DIN rail using the included clips and screws. Connect a single non-contacting 3300 NSv proximity probe and extension cable to the input. Wire the 4-20 mA loop in a 2-wire configuration to your monitor or PLC. Power must be supplied between +12 and +35 Vdc at the transmitter terminal. Ensure the loop resistance does not exceed 1,000 Ω at 35 Vdc to maintain accuracy. The unit provides non-interacting external zero and span adjustments for calibration.
Maintenance & Reliability
The 991-06-50-03-00 is designed for long-term operation in harsh environments. With an operating temperature range of -35°C to +85°C and storage capability from -51°C to +100°C, it withstands extreme conditions. The sealed DIN rail enclosure protects against dust and moisture. Periodic visual inspection and loop calibration verification every 12 months ensure sustained performance. The Not OK/Signal Defeat feature eliminates the risk of false readings during sensor or transmitter faults, enhancing overall system reliability.
Selection Guide & Purchasing Advice
When ordering, confirm the full-scale option and system length match your application. The 991-06-50-03-00 includes a 5.0-meter cable; for different lengths, verify compatibility with the -50 option. This model does not require agency approval (Option 00). For a reliable supply of genuine Bently Nevada parts, PLC Source PRO (available at ubest101.myshopify.com) stocks the 991-06-50-03-00 with fast shipping and expert support.