Product Overview
When axial thrust monitoring in rotating machinery requires high reliability, the Bently Nevada 991-25-50-03-05 Probe Vibration Transmitter delivers precise displacement measurement. Designed for thrust applications, this 4-20 mA output transmitter mounts on a DIN rail and accepts a single non-contacting 3300 NSv proximity probe. Its Not OK/Signal Defeat feature quickly identifies sensor faults, minimizing downtime. Made in the USA, the 991-25-50-03-05 carries CSA Division 2, ATEX Zone 0, ATEX Zone 2, and ABS maritime approvals.
Technical Specifications
| Parameter |
Value |
| Full-Scale Option |
25-0-25 mils |
| System Length Option |
5.0 meters (16.4 ft) |
| Mounting |
DIN rail with clips and screws |
| Agency Approvals |
CSA Division 2, ATEX Zone 0, ATEX Zone 2, ABS maritime |
| Output Signal |
4-20 mA |
| Power Requirement |
+12 to +35 Vdc at transmitter terminal |
| Linear Range (Prox Out) |
0.25 to 1.65 mm |
| 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 lb) |
| Loop Accuracy |
±1.5% over specified full scale (typical) |
| Maximum Loop Resistance |
1,000 Ω including cable at 35 Vdc |
| Current Limiting |
23 mA typical |
| Not OK Signal |
Less than 3.6 mA within 100 µs; restores within 0.1 s after condition cleared |
| Zero and Span |
Non-interacting external adjustments |
Typical Applications
The Bently Nevada 991-25-50-03-05 is ideal for axial thrust monitoring in steam turbines, compressors, and large pumps. It provides a 4-20 mA signal proportional to shaft displacement, enabling integration with PLCs and DCS systems. The rugged design withstands harsh industrial environments with operating temperatures from -35°C to +85°C.
Installation Guide
Mount the 991-25-50-03-05 on a standard DIN rail using the included clips and screws. Connect a compatible 3300 NSv proximity probe and extension cable to the transmitter input. Apply +12 to +35 Vdc power. The 2-wire configuration simplifies wiring. Ensure the loop resistance does not exceed 1,000 Ω. Adjust zero and span using the non-interacting external potentiometers.
Troubleshooting Common Issues
If the output remains at less than 3.6 mA, check for a Not OK condition. Verify probe and cable integrity. Ensure power supply is within +12 to +35 Vdc. Loop resistance exceeding 1,000 Ω may cause accuracy degradation. Use the non-interacting zero and span adjustments to calibrate if needed. The 991-25-50-03-05's fast response aids in quick diagnosis.
Selection Guide
When selecting the Bently Nevada 991-25-50-03-05, verify the full-scale option, system length, and agency approvals match your application. This transmitter works with standard DIN rail and requires a compatible 3300 NSv probe. For genuine automation spares, contact PLC Source PRO at ubest101.myshopify.com.