Compact Axial Displacement Transmitter for Reliable Machinery Protection
The Bently Nevada 991-01-XX-01-00 (Part No. 284318-01) 991 Thrust Transmitter is a compact, two-wire axial displacement transmitter designed to provide continuous thrust position monitoring for rotating machinery. As part of the trusted 991 Thrust Transmitter family, it accepts input from a compatible 3300 NSv proximity probe system and converts shaft axial movement into a standard 4–20 mA proportional output, allowing straightforward integration with PLC, DCS, SCADA, and machinery protection systems. It is widely used by OEM manufacturers and end users operating compressors, pumps, motors, and industrial fans.
The 991-01-XX-01-00 configuration features a configurable measurement range, DIN-rail mounting, integrated Proximitor® electronics, and the 284318-01 hardware revision. Its compact design reduces installation complexity while providing dependable long-term monitoring for critical rotating assets.
Technical Specifications
| Parameter | Specification |
|---|
| Manufacturer | Bently Nevada |
| Model Number | 991-01-XX-01-00 |
| Part Number | 284318-01 |
| Product Type | 991 Thrust Transmitter |
| Measurement Function | Shaft axial displacement (thrust position) |
| Measurement Range | Configurable (depends on ordered XX option) |
| Compatible Probe | Bently Nevada 3300 NSv Proximity Probe |
| Output Signal | 4–20 mA proportional analog output |
| Power Supply | 12–35 VDC loop powered |
| Wiring | Two-wire |
| Mounting Method | 35 mm DIN-rail |
| Signal Conditioning | Integrated Proximitor® electronics |
| Diagnostic Outputs | PROX OUT and COM |
| Operating Temperature | -35°C to +85°C |
| Storage Temperature | -52°C to +177°C |
| Humidity | Up to 100% condensing (non-submerged) |
| Dimensions | Approx. 82 × 35 × 75 mm |
| Weight | Approx. 0.43 kg |
Typical Applications
The 991-01-XX-01-00 is developed for continuous thrust position monitoring across a wide range of rotating equipment.
| Industry | Typical Equipment |
|---|
| Oil & Gas | Centrifugal compressors, process pumps |
| Petrochemical | Rotating process machinery |
| Power Generation | Steam and gas turbine auxiliaries |
| Manufacturing | Motors, blowers, industrial fans |
| Water Treatment | High-capacity pumps |
| OEM Equipment | Compressor and pump packages |
Typical applications include:
-
Shaft axial displacement monitoring
-
Thrust bearing protection
-
Machinery health monitoring
-
Predictive maintenance systems
-
PLC/DCS process feedback
-
Alarm and shutdown protection
Product Advantages
Integrated Proximitor® Electronics
The transmitter incorporates Bently Nevada's integrated Proximitor® technology, eliminating the need for a separate signal conditioning module. This simplifies installation, reduces wiring, and minimizes cabinet space requirements.
Flexible Measurement Configuration
The configurable XX measurement option allows the transmitter to be matched to different machinery thrust requirements, making it suitable for various OEM and retrofit applications.
Fast DIN-Rail Installation
The 01 mounting configuration supports standard 35 mm DIN-rail installation, enabling quick integration into industrial control cabinets and packaged machinery panels.
Industry-Standard 4–20 mA Output
The transmitter delivers a stable 4–20 mA analog signal, allowing compatibility with virtually all modern industrial automation and machinery protection platforms.
Reliable Continuous Operation
Designed specifically for continuous-duty rotating equipment, the 991 Series provides dependable monitoring performance in demanding industrial environments with high humidity and wide temperature variations.
Simplified Maintenance
Integrated diagnostic outputs provide convenient access to vibration and gap voltage signals, allowing maintenance personnel to verify probe performance and troubleshoot the monitoring system efficiently.
Technical FAQs
1. What is the Bently Nevada 991-01-XX-01-00 used for?
It continuously measures shaft axial displacement and converts the signal into a 4–20 mA output for machinery monitoring and protection.
2. What does "XX" represent?
The XX identifies the factory-configured measurement range selected when ordering the transmitter. Different applications require different axial displacement ranges.
3. What is Part Number 284318-01?
284318-01 is the associated Bently Nevada part number for this transmitter configuration.
4. Which proximity probe is compatible?
The transmitter is designed to operate with the Bently Nevada 3300 NSv proximity probe and the corresponding extension cable.
5. Does this model require an external Proximitor module?
No. The Proximitor® electronics are integrated into the transmitter enclosure.
6. What power supply is required?
The unit operates from a 12–35 VDC loop-powered supply.
7. What mounting method does this model use?
The 01 option specifies installation on a standard 35 mm DIN rail.
8. Are diagnostic outputs available?
Yes. PROX OUT and COM terminals provide access to dynamic vibration and gap voltage signals for commissioning and troubleshooting.
9. Which industries commonly use this transmitter?
It is widely used in oil & gas, petrochemical, power generation, manufacturing, water treatment, and OEM rotating equipment applications.
10. What are the main benefits of the 991 Series?
The 991 Series offers integrated signal conditioning, compact installation, reliable 4–20 mA output, simplified maintenance, and proven performance for machinery protection.
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