The 991-25-70-01-CN is a 2-wire, loop-powered thrust transmitter designed to provide a proportional 4 to 20 mA axial displacement signal for rotating machinery monitoring applications. It accepts input from a 3300 NSv proximity probe and matching extension cable, then conditions the signal into engineering units proportional to shaft axial position for machinery control and protection systems.
The 991 Thrust Transmitter integrates the Proximitor Sensor within the transmitter housing, eliminating the need for an external unit. It provides non-isolated PROX OUT and COM outputs for dynamic vibration and gap voltage diagnostics, supporting machinery analysis and troubleshooting.
The transmitter is suitable for centrifugal air compressors, pumps, motors, and fans where compact installation space and continuous thrust position indication are required. Compatibility with the 3300 NSv proximity probe allows installation in small clearance areas typical of centrifugal compressor systems.
| Model Code | Description |
|---|---|
| 991 | Thrust Transmitter |
| -25 | 25-0-25 mils |
| -70 | 7.0 metres (23.0 feet) |
| -01 | 35 mm DIN-rail clips |
| -CN | China explosion-proof certification NEPSI/CCC/ATEX/IECEx |
| Category | Specification |
|---|---|
| Manufacturer | Bently Nevada |
| Product Model | 991-25-70-01-CN |
| Product Type | Thrust Transmitter |
| Series | 991 |
| Input Type | 1 non-contacting 3300 NSv Proximity Probe and extension cable |
| Power Requirement | +12 to +35 Vdc |
| Signal Output | 4 to 20 mAdc |
| Configuration | 2-wire |
| Loop Accuracy | Within +/-1.5% full scale typical |
| Maximum Loop Resistance | 1000 ohm including cable at 35 Vdc |
| Current Limiting | 23 mA typical |
| Zero and Span Adjustment | Non-interacting external adjustments |
| Not OK/Signal Defeat Response | Output less than 3.6 mA within 100 us |
| Signal Recovery Time | Restored within 0.1 seconds |
| Output Impedance | 10 kohm |
| Linear Range | 0.25 to 1.65 mm (10 to 65 mils) |
| Prox Out Incremental Scale Factor | 7.87 mV/um (200 mV/mil) +/-6.5% typical |
| Temperature Stability | Within +/-10% from 0 degC to +70 degC |
| Minimum Target Size | 9.5 mm diameter |
| Leadwire Length | 3 metres maximum |
| Maximum Distance Non-Hazardous Areas | 13 km |
| Maximum Distance Intrinsically Safe Areas | 68 metres |
| Operating Temperature | -35 degC to +85 degC |
| Storage Temperature | -51 degC to +100 degC |
| Probe Operating Temperature | -35 degC to +177 degC |
| Probe Storage Temperature | -51 degC to +177 degC |
| Relative Humidity | 100% condensing non-submerged |
| Transducer Tip Material | Polyphenylene sulfide (PPS) |
| Transducer Case Material | AISI 303 or 304 stainless steel |
| Probe Cable Type | 75 ohm coaxial FEP insulated |
| Cable Armor | Flexible AISI 302 SST optional |
| Tensile Strength | 222 N maximum |
| Transmitter Weight | 0.43 kg |
| Total System Weight | 0.82 kg typical |
| Dimensions (H x W x D) | 53.3 mm x 73.9 mm x 100.1 mm |
| Body Height Without DIN Clip | 42.6 mm |
| Mounting Hole Distance (W x L) | 63.5 mm x 69.9 mm |
| Mounting Hole Diameter | 5.8 mm |
| Electrical Classification | CSA/NRTL/C approval in North America and VDE approval in Europe |
| Europe Marking | CE |
| Country of Origin | U.S.A |
| Connector Pin | Function |
|---|---|
| PROX OUT | Dynamic vibration and gap voltage signal output |
| COM | Common terminal |
| Test Input | Loop signal verification input |
| BNC Connector | Proximitor Sensor diagnostic output |
| Certification | Description |
|---|---|
| CSA/NRTL/C | General Purpose Approval for North America |
| VDE | Europe approval |
| CE | European CE marking |
| NEPSI | China explosion-proof certification |
| CCC | China Compulsory Certification |
| ATEX | Hazardous area certification |
| IECEx | International hazardous area certification |
What is the primary function of this transmitter?
It converts axial shaft displacement into a proportional 4 to 20 mA signal.
Which probe system is compatible with this model?
The transmitter is designed for use with the 3300 NSv proximity probe system.
Does the transmitter require an external Proximitor unit?
No. The Proximitor Sensor is integrated into the transmitter.
What output signal does the device provide?
It provides a 4 to 20 mAdc industry-standard signal.
Can the PROX OUT signal be used for diagnostics?
Yes. The PROX OUT connection supports vibration and gap voltage diagnostics.
What mounting method does this configuration use?
This model uses 35 mm DIN-rail clips.
Is the transmitter suitable for humid environments?
Yes. The potted construction supports 100% condensing environments.
What happens during a Not OK condition?
The output drops below 3.6 mA within 100 microseconds.
Can grounded test equipment connect directly to PROX OUT?
The manual recommends using the 122115-01 Test Adapter for signal isolation.
What industries commonly use this transmitter?
Oil and gas, power generation, and industrial rotating machinery applications.
Global Express Shipping
Returns & Warranty
Manufacturer: Bently Nevada
Product No.: 991-25-70-01-CN
Country of origin:United States
Product Type: 991 Thrust Transmitter
Payment: T/T, Western Union
Weight: 430g
Dimensions: 53.3 mm x 73.9 mm x 100.1 mm
Shipping port: Xiamen
Warranty: 12 months
The 991-25-70-01-CN is a 2-wire, loop-powered thrust transmitter designed to provide a proportional 4 to 20 mA axial displacement signal for rotating machinery monitoring applications. It accepts input from a 3300 NSv proximity probe and matching extension cable, then conditions the signal into engineering units proportional to shaft axial position for machinery control and protection systems.
The 991 Thrust Transmitter integrates the Proximitor Sensor within the transmitter housing, eliminating the need for an external unit. It provides non-isolated PROX OUT and COM outputs for dynamic vibration and gap voltage diagnostics, supporting machinery analysis and troubleshooting.
The transmitter is suitable for centrifugal air compressors, pumps, motors, and fans where compact installation space and continuous thrust position indication are required. Compatibility with the 3300 NSv proximity probe allows installation in small clearance areas typical of centrifugal compressor systems.
| Model Code | Description |
|---|---|
| 991 | Thrust Transmitter |
| -25 | 25-0-25 mils |
| -70 | 7.0 metres (23.0 feet) |
| -01 | 35 mm DIN-rail clips |
| -CN | China explosion-proof certification NEPSI/CCC/ATEX/IECEx |
| Category | Specification |
|---|---|
| Manufacturer | Bently Nevada |
| Product Model | 991-25-70-01-CN |
| Product Type | Thrust Transmitter |
| Series | 991 |
| Input Type | 1 non-contacting 3300 NSv Proximity Probe and extension cable |
| Power Requirement | +12 to +35 Vdc |
| Signal Output | 4 to 20 mAdc |
| Configuration | 2-wire |
| Loop Accuracy | Within +/-1.5% full scale typical |
| Maximum Loop Resistance | 1000 ohm including cable at 35 Vdc |
| Current Limiting | 23 mA typical |
| Zero and Span Adjustment | Non-interacting external adjustments |
| Not OK/Signal Defeat Response | Output less than 3.6 mA within 100 us |
| Signal Recovery Time | Restored within 0.1 seconds |
| Output Impedance | 10 kohm |
| Linear Range | 0.25 to 1.65 mm (10 to 65 mils) |
| Prox Out Incremental Scale Factor | 7.87 mV/um (200 mV/mil) +/-6.5% typical |
| Temperature Stability | Within +/-10% from 0 degC to +70 degC |
| Minimum Target Size | 9.5 mm diameter |
| Leadwire Length | 3 metres maximum |
| Maximum Distance Non-Hazardous Areas | 13 km |
| Maximum Distance Intrinsically Safe Areas | 68 metres |
| Operating Temperature | -35 degC to +85 degC |
| Storage Temperature | -51 degC to +100 degC |
| Probe Operating Temperature | -35 degC to +177 degC |
| Probe Storage Temperature | -51 degC to +177 degC |
| Relative Humidity | 100% condensing non-submerged |
| Transducer Tip Material | Polyphenylene sulfide (PPS) |
| Transducer Case Material | AISI 303 or 304 stainless steel |
| Probe Cable Type | 75 ohm coaxial FEP insulated |
| Cable Armor | Flexible AISI 302 SST optional |
| Tensile Strength | 222 N maximum |
| Transmitter Weight | 0.43 kg |
| Total System Weight | 0.82 kg typical |
| Dimensions (H x W x D) | 53.3 mm x 73.9 mm x 100.1 mm |
| Body Height Without DIN Clip | 42.6 mm |
| Mounting Hole Distance (W x L) | 63.5 mm x 69.9 mm |
| Mounting Hole Diameter | 5.8 mm |
| Electrical Classification | CSA/NRTL/C approval in North America and VDE approval in Europe |
| Europe Marking | CE |
| Country of Origin | U.S.A |
| Connector Pin | Function |
|---|---|
| PROX OUT | Dynamic vibration and gap voltage signal output |
| COM | Common terminal |
| Test Input | Loop signal verification input |
| BNC Connector | Proximitor Sensor diagnostic output |
| Certification | Description |
|---|---|
| CSA/NRTL/C | General Purpose Approval for North America |
| VDE | Europe approval |
| CE | European CE marking |
| NEPSI | China explosion-proof certification |
| CCC | China Compulsory Certification |
| ATEX | Hazardous area certification |
| IECEx | International hazardous area certification |
What is the primary function of this transmitter?
It converts axial shaft displacement into a proportional 4 to 20 mA signal.
Which probe system is compatible with this model?
The transmitter is designed for use with the 3300 NSv proximity probe system.
Does the transmitter require an external Proximitor unit?
No. The Proximitor Sensor is integrated into the transmitter.
What output signal does the device provide?
It provides a 4 to 20 mAdc industry-standard signal.
Can the PROX OUT signal be used for diagnostics?
Yes. The PROX OUT connection supports vibration and gap voltage diagnostics.
What mounting method does this configuration use?
This model uses 35 mm DIN-rail clips.
Is the transmitter suitable for humid environments?
Yes. The potted construction supports 100% condensing environments.
What happens during a Not OK condition?
The output drops below 3.6 mA within 100 microseconds.
Can grounded test equipment connect directly to PROX OUT?
The manual recommends using the 122115-01 Test Adapter for signal isolation.
What industries commonly use this transmitter?
Oil and gas, power generation, and industrial rotating machinery applications.
Global Express Shipping
Returns & Warranty
Orders are processed and delivered Monday-Friday (excluding public holidays).
For full eligibility, restocking fees, and international return details, please view our official Refund & Return Policy .
| Color pattern |
White
|
| Country of origin |
United States
|
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