Description
1. At-A-Glance Executive Brief
- Model: 990-05-50-01-CN
- Brand: Bently Nevada (Baker Hughes)
- Part Type: 2-Wire Vibration Transmitter
- System Compatibility: 3300 NSv Proximity Probe and Extension Cable
- Lifecycle Status: Active / Legacy Support Tier
- Weight: 0.82 kg
2. Technical Introduction
Monitoring vibration on compact centrifugal air compressors, small motors, or specialized pumps often introduces mechanical clearance hurdles that traditional rack-based monitoring systems cannot accommodate. The Bently Nevada 990-05-50-01-CN solves this layout challenge by integrating the Proximitor sensor directly into a rugged, loop-powered housing. This transmitter scales raw gap signals from a matched 3300 NSv probe setup into a proportional 4-20 mA current loop, feeding machinery protection logic straight into the local automation controller without requiring intermediate rack modules.
3. Core Technical Specifications
| Parameter | Value |
| Input Power Requirements | +12 Vdc to +35 Vdc at transmitter terminals |
| Signal Output | Proportional 4-20 mA current loop |
| Full-Scale Range Option (-05) | 0 to 5 mils pp (0 to 125 micrometers pp) |
| System Length Option (-50) | 5.0 meters (16.4 feet total matched length) |
| Mounting Option (-01) | 35 mm DIN rail clips |
| Agency Approval Option (-CN) | ATEX / IECEx and Chinese NEPSI hazardous area markings |
| Frequency Response | 5 Hz to 6,000 Hz (+0, -3 dB) |
| Loop Accuracy | Within plus or minus 1.5% over specified full-scale range |
4. Field Engineer’s Tech Notes
- Transducer Gap Verification: Ensure the probe tip is mechanically gapped between 0.5 mm and 1.75 mm from the shaft target surface during initial cold alignment. Failing to hit this strict voltage offset window causes premature saturation of the internal demodulator circuit, resulting in clipped 4-20 mA loop outputs or constant fault tripping.
- Shield Grounding Discipline: Terminate the signal cable shield strictly at the control system cabinet ground reference, leaving the transmitter housing side floating. Grounding both ends creates ground loops that inject high-frequency electrical noise into the dynamic PROX OUT terminals, corrupting portable diagnostic data collection.
5. Adaptive QA & Testing Protocol
Every 990-05-50-01-CN unit undergoes bench calibration verification using a precision signal generator to simulate probe gap variations and shaft vibration amplitudes. Testing validates the exact 4-20 mA current loop scaling across the 0-5 mils pp full-scale window, alongside response checks on the Not OK/Signal Defeat circuit to ensure output drops below 3.6 mA during simulated probe faults. Dynamic signal output integrity is verified via the coaxial BNC connection. Inspection test sheets and functional sign-off records are available upon request.
6. Buyer’s FAQ
- What warranty is provided with this vibration transmitter?All New Surplus and factory-refurbished transmitters include a standard 12-month replacement warranty from the invoice date.
- Does this part include the proximity probe and extension cable?The part number designates the transmitter unit only; 3300 NSv probes and matching 5-meter extension cables must be sourced separately or verified as an existing machine installation.
- How is the unit protected against moisture in harsh operating environments?The internal electronics feature a completely potted construction rated for continuous deployment in up to 100% condensing humidity enclosures.
