Introduction to the Bently Nevada 990-08-50-01-CN
The Bently Nevada 990-08-50-01-CN is a precision 990 Vibration Transmitter designed for continuous monitoring of rotating machinery. It accepts a 3300 NSv proximity probe and outputs a 4-20 mA signal proportional to vibration displacement. With a full-scale range of 0-8 mils pp (0-200 µm pp) and integrated Not OK/signal defeat functionality, this transmitter offers reliable machine protection in harsh industrial environments.
Technical Specifications Breakdown
| Parameter |
Value |
| Input |
1 non-contacting 3300 NSv Proximity Probe with extension cable |
| Power |
+12 to +35 Vdc at transmitter terminal |
| Output |
4-20 mAdc over full-scale range (0-8 mils pp) |
| Loop Accuracy |
Within ±1.5% of full scale (additional to Prox Out Incremental Scale Factor) |
| Maximum Loop Resistance |
1,000 Ω including cable at 35 Vdc |
| Current Limiting |
23 mA typical |
| Frequency Response |
5 Hz to 6,000 Hz +0, -3 dB |
| Probe Gap |
0.5 to 1.75 mm (20 to 55 mils) from target |
| Not OK Response |
Output drops below 3.6 mA within 100 µs; restores within 2-3 seconds after fault cleared |
| Weight |
0.43 kg (0.9 lbm) |
| Mounting |
35 mm DIN rail clips |
| Agency Approvals |
Country-specific (CN option) |
Industry Applications
The Bently Nevada 990-08-50-01-CN serves in critical rotating machinery like steam turbines, centrifugal compressors, and large pumps. In a power generation plant, this vibration transmitter monitors shaft vibration and triggers an alarm or shutdown if displacement exceeds safe limits. Its fast Not OK detection (within 100 µs) helps prevent catastrophic bearing failures. The 5 Hz to 6,000 Hz frequency response captures both low-speed runout and high-speed blade pass vibrations.
Installation & Setup Guidance
Mount the 990-08-50-01-CN on a 35 mm DIN rail using the provided clips. Ensure the proximity probe is gapped between 0.5 and 1.75 mm from the target surface. Connect the probe to the transmitter via the BNC connector, keeping the leadwire length within 3 meters (10 feet) for best performance. Power the unit with +12 to +35 Vdc at the transmitter terminal. The non-interacting zero and span adjustments allow quick calibration without signal disruption.
Troubleshooting & Common Issues
A key failure mode is loss of signal due to a Not OK condition. The 990-08-50-01-CN automatically forces the output below 3.6 mA within 100 µs when a probe fault or power anomaly occurs. Check probe gap and cable connections if the transmitter enters this state. Verify loop resistance does not exceed 1,000 Ω at 35 Vdc; excessive resistance reduces output linearity. The current limiter (23 mA typical) protects against short circuits. For reliable performance, use the recommended 250 Ω loop resistance for accuracy testing. When replacing an older vibration transmitter, ensure the full-scale option matches your machinery's vibration tolerance. For purchasing this genuine Bently Nevada 990-08-50-01-CN, trust ubest101 as your partner for industrial automation spares.