Description
The Bently Nevada 991-01-50-01-00 is a two-wire, loop-powered thrust position transmitter from Bently Nevada (Baker Hughes), designed for continuous monitoring of axial shaft displacement in rotating machinery. As part of the 991 Series, the 991-01-50-01-00 converts the signal from a single 3300 NSv proximity probe into an industry-standard 4-20 mA output proportional to axial shaft position, providing a simple and cost-effective thrust position signal for PLC, DCS, or SCADA integration.
The unit integrates the Proximitor sensor electronics directly into its housing, accepting a 3300 NSv probe and matching extension cable without requiring an external Proximitor module or rack-based monitoring system. Built for a 5.0-meter system length, the 991-01-50-01-00 mounts on standard 35mm DIN-rail clips, making it ideal for OEM machinery skids and applications where space and wiring simplicity are priorities .
Application Scenarios
In a packaged centrifugal air compressor installation, the OEM skid control panel needs to know one critical thing about the rotor: is the shaft sitting where it should be axially, or is the thrust bearing being consumed? The machine is not critical enough to justify a full 3500 monitoring rack, but losing a thrust bearing means a rotor rub, a damaged impeller, and an unplanned shutdown. The Bently Nevada 991-01-50-01-00 fills this gap precisely. Without axial position feedback, the first sign of a failing thrust bearing is often metal in the oil or a seized rotor—by then, the damage is done. With the 991-01-50-01-00 wired into the compressor PLC, its 4-20 mA signal provides a continuous trend that operators can alarm on, transforming a slow drift in rotor position from a catastrophic failure into a planned inspection . The same logic applies to small pumps, motors, fans, and turbine auxiliary systems where a simple proportional signal is all the control system needs. In power generation applications, the 991-01-50-01-00 monitors thrust position on steam turbine rotors, providing early warning of bearing wear that could otherwise lead to costly rotor damage.
Parameter
| Parameter | Value/Description |
|---|---|
| Product Model | 991-01-50-01-00 (Internal Part: 288865-01) |
| Manufacturer | Bently Nevada (Baker Hughes) |
| Product Category | Two-Wire Thrust Position Transmitter |
| Input | 1 × 3300 NSv Proximity Probe with matching extension cable |
| System Length | 5.0 m (16.4 ft) total calibrated length |
| Full-Scale Range | Platform measures up to 1.2 mm (50 mils) total thrust travel; confirm unit nameplate |
| Power Requirement | +12 to +35 V DC at transmitter terminal |
| Output Signal | 4 – 20 mA DC, two-wire, proportional to axial position |
| Loop Accuracy | Within ±1.5% of full scale (typical) |
| Max Loop Resistance | 1,000 Ω including cable at 35 V DC |
| Fault Output | < 3.6 mA within 100 µs of fault; restores within 0.1 s |
| Mounting | 35 mm DIN-rail clips |
| Operating Temperature | -35°C to +85°C (typical for 991 series) |