Product Introduction
When axial thrust monitoring is critical to preventing catastrophic machinery failure, the Bently Nevada 991-25-70-01-CN provides reliable, continuous measurement. This probe vibration transmitter converts non-contacting proximity probe signals into a 4-20 mA output, engineered specifically for thrust position monitoring in rotating equipment. Designed in the USA, the 991-25-70-01-CN integrates seamlessly into existing control systems via DIN rail mounting.
Technical Specifications Breakdown
| Parameter |
Value |
| Full-Scale Option |
-25: 25-0-25 mils |
| System Length |
-70: 7.0 meters (23.0 feet) |
| Mounting |
DIN rail |
| Output Signal |
4-20 mA |
| Power |
+12 to +35 Vdc |
| Linear Range (Prox Out) |
0.25 to 1.65 mm |
| Operating Temperature |
-35°C to +85°C |
| Storage Temperature |
-51°C to +100°C |
| Weight |
0.43 kg (0.9 lbm) |
| Input |
1 non-contacting 3300 NSv probe and cable |
| 4-20 mA Loop Accuracy |
±1.5% typical |
| Maximum Loop Resistance |
1000 Ω at 35 Vdc |
| Current Limiting |
23 mA typical |
| Not OK/Signal Defeat |
<3.6 mA within 100 µs, restored in 0.1 s |
Each specification ensures dependable operation in harsh industrial environments. The 991-25-70-01-CN offers non-interacting zero and span adjustments, simplifying calibration.
Industry Applications
The Bently Nevada 991-25-70-01-CN excels in axial thrust monitoring for steam turbines, centrifugal compressors, and large pumps. In a typical turbine application, the transmitter provides a 4-20 mA signal proportional to shaft position, enabling early detection of thrust bearing wear. The built-in Not OK/Signal Defeat feature drops the output below 3.6 mA within 100 µs during fault conditions, triggering alarms without delay.
Installation & Setup Guidance
Mount the Bently Nevada 991-25-70-01-CN on a standard DIN rail. Connect the 3300 NSv proximity probe and extension cable to the input terminals. Power the transmitter with +12 to +35 Vdc at the terminal block. The 4-20 mA loop wiring uses a simple two-wire configuration. Adjust zero and span using the non-interacting potentiometers. Ensure the system length option -70 (7.0 meters) matches your cable requirements.
Maintenance & Reliability
The 991-25-70-01-CN operates reliably from -35°C to +85°C, with storage capability down to -51°C. The transmitter's robust design minimizes drift; periodic verification of loop accuracy (±1.5%) is recommended. The Not OK/Signal Defeat circuit ensures failsafe operation, automatically restoring output within 0.1 seconds after the fault clears. No routine component replacement is needed under normal conditions.
Selection Guide & Purchasing Advice
Before purchasing the Bently Nevada 991-25-70-01-CN, verify the full-scale option (-25 for 25-0-25 mils) and system length (-70 for 7.0 meters). Confirm DIN rail availability and power supply range (+12 to +35 Vdc). For reliable sourcing, contact PLC Source PRO at ubest101.myshopify.com to ensure genuine Bently Nevada 991-25-70-01-CN units with proper agency approvals (-CN).