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Technical Specifications
| Parameter | Value |
|---|---|
| Product Model | 990-04-XX-01-CN (MOD 165335-01) |
| Manufacturer | Bently Nevada (Baker Hughes / GE) |
| Product Type | 2-Wire Loop-Powered Vibration Transmitter |
| Compatible Probe | 3300 NSv Proximity Probe + Extension Cable |
| Output Signal | 4-20 mA DC (proportional to vibration) |
| Loop Accuracy | ±1.5% of full-scale range |
| Frequency Response | 5 Hz to 6,000 Hz (+0, -3 dB) |
| Probe Gap Range | 0.5 to 1.75 mm (20 to 55 mils) |
| Supply Voltage | +12 to +35 VDC |
| Maximum Loop Resistance | 1,000 Ω (at 35 VDC) |
| Current Limiting | 23 mA typical |
| Prox Out Scale Factor | 7.87 mV/μm (200 mV/mil) ± 6.5% |
| Prox Out Linear Range | 1.4 mm |
| Zero/Span Adjustment | Non-interacting external potentiometers |
| Mounting Options | 35 mm DIN Rail Clip or Bulkhead |
| Enclosure Rating | IP66 / NEMA 4X (316L Stainless Steel) |
| Operating Temperature | -30°C to +100°C |
| Storage Temperature | -40°C to +85°C |
| Weight | Approx. 0.5 kg |
Main Features and Advantages
Integrated Proximitor and Compact Design: The Bently Nevada 990-04-XX-01-CN integrates the Proximitor sensor directly into the transmitter housing, eliminating the need for a separate external unit . This compact, potted construction allows installation in tight spaces with minimal clearance, making it particularly suitable for centrifugal air compressors and other machinery with limited access .
Simplified 2-Wire Loop-Powered Installation: As a loop-powered device, the Bently Nevada 990-04-XX-01-CN requires only two wires for both power and signal transmission, significantly reducing cabling complexity and installation costs compared to traditional multi-wire sensors . The 4-20 mA industry-standard output enables direct connection to any standard analog input card on a PLC, DCS, or SCADA system without expensive interface hardware .
Comprehensive Protection and Diagnostic Features: The Bently Nevada 990-04-XX-01-CN incorporates a Not OK/Signal Defeat circuit that forces the output below 3.6 mA within 100 microseconds of detecting a faulty probe or loose connection . This prevents false alarms and high outputs that could cause spurious machine trips. Additionally, a Power-up Inhibit circuit suppresses the output for 2-3 seconds during startup, eliminating errors caused by line voltage transients . Non-interacting zero and span potentiometers allow easy loop adjustment without affecting other calibration points .
Diagnostic Signal Access: The Bently Nevada 990-04-XX-01-CN provides a non-isolated “PROX OUT” coaxial connector that outputs the raw dynamic vibration and gap voltage signals for diagnostic purposes . This allows maintenance personnel to connect portable test equipment for detailed machinery analysis using battery-powered or isolated instruments. For use with AC-powered oscilloscopes and analyzers, the 990/991 Test Adapter is strongly recommended to maintain signal isolation and system integrity .
