Product Introduction
In axial thrust monitoring applications, the Bently Nevada 991-25-50-01-00 provides reliable 4-20 mA output for real-time machine protection. This Thrust Transmitter accepts one non-contacting 3300 NSv proximity probe and integrates directly with your control system. The 991-25-50-01-00 is designed for continuous operation in harsh industrial environments, offering a Not OK signal defeat feature that alerts operators within 100 µs of a fault condition.
Technical Specifications
| Parameter |
Value |
| Full-scale range |
25-0-25 mils (0.6-0-0.6 mm) |
| System length |
5.0 meters (16.4 feet) |
| Mounting |
35 mm DIN-rail clips |
| Output signal |
4-20 mAdc, 2-wire |
| Power supply |
+12 to +35 Vdc at transmitter terminal |
| Loop accuracy |
Within ±1.5% of full scale (typical) |
| Max loop resistance |
1,000 ohms at 35 Vdc |
| Current limiting |
23 mA typical |
| Operating temperature |
-35°C to +85°C (-31°F to +185°F) |
| Storage temperature |
-51°C to +100°C (-60°F to +212°F) |
| Weight |
0.43 kg (0.9 lbm) |
Industry Applications
The Bently Nevada 991-25-50-01-00 is ideal for axial thrust monitoring in turbines, compressors, and large rotating machinery. Its 4-20 mA loop output integrates with PLCs, DCS, and plant monitoring systems. The -25 full-scale option (25-0-25 mils) suits common thrust bearing clearances. The Not OK/Signal Defeat function ensures fast fault detection: output drops below 3.6 mA within 100 µs of a probe failure or power loss, and restores within 0.1 seconds after the fault clears.
Installation & Setup Guidance
Mount the Bently Nevada 991-25-50-01-00 on a standard 35 mm DIN rail using the included clips. Connect the 3300 NSv proximity probe and extension cable (up to 5.0 meters total system length). Wire the 4-20 mA loop in a 2-wire configuration, observing polarity. The transmitter accepts +12 to +35 Vdc at its terminals. Adjust zero and span externally using non-interacting potentiometers. Verify that the full-scale range matches your application: 25-0-25 mils or 0.6-0-0.6 mm current loop linear range.
Maintenance & Reliability
Designed for continuous duty, the Bently Nevada 991-25-50-01-00 operates reliably from -35°C to +85°C. The Not OK/Signal Defeat circuit provides automatic safety shutdown in case of probe damage or wiring faults. No routine calibration is required; however, periodically verify the loop accuracy (±1.5%) using a test signal across a 250 ohm resistor. The transmitter housing is sealed against industrial contaminants. Ensure the DIN-rail clips are secure to prevent vibration-induced disconnection.
Selection Guide & Purchasing Advice
Verify the full-scale option (-25), system length (-50), mounting option (01 for DIN rail), and agency approval (00). The Bently Nevada 991-25-50-01-00 is supplied from stock by PLC Source PRO. For applications requiring different full-scale ranges or probe types, contact our technical team at ubest101. Ensure your 3300 NSv probe cable length does not exceed the specified 5.0 meters to maintain loop resistance under 1,000 ohms.