Product Overview
The Bently Nevada 991-06-50-02-05 Probe Vibration Transmitter is a precision axial thrust transmitter designed for critical rotating machinery. In the event of a sensor fault or abnormal condition, this module's Not OK/Signal Defeat function forces the output below 3.6 mA within 100 µs, preventing false readings and triggering protective actions. Built for harsh environments, it operates reliably from -35°C to +85°C and stores from -51°C to +100°C. The 991-06-50-02-05 accepts one non-contacting 3300 NSv proximity probe and extension cable, making it a direct upgrade for older thrust monitoring systems.
Technical Specifications
| Parameter |
Value |
| Model |
991 - Thrust Transmitter |
| Full-scale Option |
06: 0.6-0-0.6 mm |
| System Length Option |
-50: 5.0 meters (16.4 feet) |
| Mounting Option |
02: Bulkhead screws |
| Agency Approvals |
CSA Division 2, ATEX Zone 0, ATEX Zone 2, ABS maritime |
| Mounting |
DIN rail |
| Output Signal |
4-20 mA (2-wire) |
| Use |
Axial |
| Power Input |
+12 to +35 Vdc at transmitter terminal |
| Linear Range (Prox Out) |
0.25 to 1.65 mm |
| Current Loop Linear Ranges |
0.6-0-0.6 mm or 25-0-25 mils |
| Accuracy |
±1.5% over full scale (typical) |
| Max Loop Resistance |
1,000 Ω including cable at 35 Vdc |
| Current Limiting |
23 mA typical |
| Zero and Span |
Non-interacting external adjustments |
| Not OK/Signal Defeat |
<3.6 mA within 100 µs; restores in 0.1 s |
| Operating Temperature |
-35°C to +85°C (-31°F to +185°F) |
| Storage Temperature |
-51°C to +100°C (-60°F to +212°F) |
| Weight |
0.43 kg (0.9 lbm) |
Industry Applications
The Bently Nevada 991-06-50-02-05 thrives in axial vibration monitoring for steam turbines, gas compressors, and large pumps. In a typical turbine train, a fault in the thrust bearing can cause rapid damage; this transmitter's Not OK/Signal Defeat ensures the control system receives an unambiguous low-current alarm within 100 µs, initiating a safe shutdown. The ±1.5% accuracy over the 0.6-0-0.6 mm range provides reliable data for predictive maintenance programs, reducing unplanned downtime.
Installation and Setup
Mount the Bently Nevada 991-06-50-02-05 on a standard DIN rail using the bulkhead screw option (option 02). Connect a compatible 3300 NSv proximity probe and extension cable to the input. The 5.0 meter system length (option -50) accommodates typical machine train distances. Power the transmitter with +12 to +35 Vdc at its terminal. Adjust zero and span using the non-interacting external potentiometers — no internal calibration required. Once configured, verify the 4-20 mA loop response and Not OK signal defeat behavior with a test input.
Maintenance and Reliability
Routine inspection of the Bently Nevada 991-06-50-02-05 focuses on the probe and cable integrity. The transmitter's wide operating temperature range (-35°C to +85°C) ensures consistent performance in both arctic and tropical environments. The current limiting feature (23 mA typical) protects the loop from overcurrent conditions. Due to its robust design and ±1.5% accuracy, the 991-06-50-02-05 delivers long service life with minimal drift, reducing total cost of ownership.
Buying Guide and Selection Advice
When ordering the Bently Nevada 991-06-50-02-05, verify the full-scale option (06 = 0.6-0-0.6 mm) and system length (-50 = 5.0 m) match your application. Ensure your existing proximity probe is a 3300 NSv type. The transmitter carries CSA Division 2, ATEX Zone 0/2, and ABS maritime approvals, making it suitable for hazardous and marine environments. For reliable sourcing, contact ubest101 — a trusted supplier of industrial automation spares — to confirm stock and availability.