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Product Overview
The Bently Nevada 991-25-50-03-05 991 Thrust Sensor is a precision, loop-powered transmitter engineered for monitoring thrust position in rotating machinery. It provides a 4–20 mA output proportional to the shaft thrust position, enabling reliable integration into control and protection systems without the need for complex rack-based monitoring.
Key Features
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2-wire, loop-powered thrust sensor
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4–20 mA output proportional to shaft thrust position
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Compatible with Bently Nevada proximity probes and extension cables
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PROX OUT terminal provides access to vibration and gap signals
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Field calibration with zero and span adjustments
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Fault detection with “Not OK” indication
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Flexible mounting: DIN rail or bulkhead
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Rugged construction for demanding industrial conditions
Technical Specifications
| Item | Specification |
|---|---|
| Manufacturer | Bently Nevada |
| Part Number | 991-25-50-03-05 |
| Series | 991 Thrust Sensor |
| Product Type | Thrust Position Transmitter |
| Dimensions | 100.1 x 73.9 x 53.3 mm |
| Weight | 0.43 kg |
| Power Supply | +12 to +35 V DC |
| Output | 4–20 mA proportional to thrust position |
| Measurement Range | 0–2 mm (depending on probe configuration) |
| Frequency Response | DC to 600 Hz |
| Loop Accuracy | ±1.5% of full scale |
| Max Loop Resistance | 1,000 Ω at 35 V DC |
| Probe Compatibility | Bently Nevada proximity probes and extension cables |
| Operating Temperature – Transmitter | –35 °C to +85 °C |
| Operating Temperature – Probe | –52 °C to +177 °C |
| Relative Humidity | 0–100%, condensing |
| Mounting Options | DIN rail or bulkhead mounting |
Industry Applications
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Steam turbines and gas turbines
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Compressors and centrifugal pumps
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Electric motors and generators
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Thrust position monitoring in rotating machinery
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Oil & gas and petrochemical facilities
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Power generation and utilities
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OEM machinery protection systems
Frequently Asked Questions (FAQ)
Q1: What does the 991-25-50-03-05 measure?
It measures shaft thrust position and provides a 4–20 mA proportional output.
Q2: Which probes are compatible with this transmitter?
It is compatible with Bently Nevada proximity probes and extension cables.
Q3: How is this sensor powered?
It is loop-powered with a DC supply of +12 to +35 V.
Q4: Does it include fault detection?
Yes, it has “Not OK” indication circuitry for probe or cable faults.
Q5: Can it provide vibration signals?
Yes, the PROX OUT terminal allows access to vibration and gap signals.
Q6: What mounting options are available?
It supports DIN rail and bulkhead mounting.
Q7: What industries use this device?
Commonly used in oil & gas, turbines, compressors, power generation, and OEM machinery.
Q8: Can it replace a full rack-based system?
Yes, it offers a cost-effective alternative to rack-based monitoring for thrust.
Related Bently Nevada Modules
| Model | Description |
|---|---|
| 991-01-XX-01-05 | Standard 991 thrust sensor transmitter |
| 991-06-70-03-RU | High-performance 991 thrust sensor |
| 991-03-XX-01-05 | Extended range thrust sensor |
| 991-04-XX-01-05 | OEM version thrust sensor |
| 990-05-XX-01-00 | Standard 990 vibration transmitter |
| 330930 Extension Cable | Compatible extension cable for proximity probes |
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