Product Introduction
When unexpected vibration threatens machinery uptime, the Bently Nevada 990-05-50-02-05 delivers precise shaft vibration monitoring. This 990 Vibration Transmitter accepts a 3300 NSv proximity probe and provides a 4-20 mA output proportional to peak-to-peak displacement. Designed for reliability, it includes a NOT OK/signal defeat function that drives output below 3.6 mA within 100 µs of a fault, enabling quick shutdown actions.
Technical Specifications Breakdown
The Bently Nevada 990-05-50-02-05 comes with a full-scale option of 05 (0-5 mils pp, 0-125 μm pp) and a system length option of 50 (5.0 meters, 16.4 feet). It is mounted using bulkhead screws (option 02). Key specifications include:
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Power Supply: +12 to +35 Vdc input at the transmitter terminal.
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4-20 mA Output: Over specified full-scale range in a 2-wire configuration.
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Loop Accuracy: Within ±1.5% over full-scale range (additional to Prox Out Incremental Scale Factor).
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Maximum Loop Resistance: 1,000 Ω including cable at 35 Vdc.
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Current Limiting: 23 mA typical.
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Frequency Response: 5 Hz to 6,000 Hz +0, -3 dB.
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Probe Gap: Must be set between 0.5 and 1.75 mm (20 to 55 mils).
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Minimum Target Size: 9.5 mm (0.375 in) diameter.
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Weight: 0.43 kg (0.9 lbm).
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Agency Approvals: CSA Division 2, ATEX Zone 0, ATEX Zone 2, and ABS maritime approval.
The unit also features non-interacting external adjustments for zero and span, and the NOT OK/signal defeat circuit ensures output drops below 3.6 mA within 100 µs of a fault condition, automatically restoring 2-3 seconds after the fault clears.
Industry Applications
In turbomachinery, compressors, and pumps, the Bently Nevada 990-05-50-02-05 provides continuous vibration monitoring. With ATEX Zone 0 and Zone 2 approvals, it suits hazardous environments such as oil and gas refineries and chemical plants. The system length option of 5.0 meters allows flexible probe placement even in large machinery trains. The 4-20 mA output integrates directly with DCS, PLCs, or vibration monitoring systems for real-time condition monitoring and predictive maintenance.
Installation & Setup Guidance
Mount the Bently Nevada 990-05-50-02-05 using the bulkhead screws provided. Ensure the proximity probe (3300 NSv) is gapped between 0.5 and 1.75 mm from the target shaft to achieve full-scale range. Connect the probe and extension cable to the transmitter. Power the unit with a +12 to +35 Vdc supply at the transmitter terminal. For the Proximitor Sensor Output (BNC connector), limit the leadwire length to 3 meters (10 feet). After installation, perform a calibration check via the TEST input to verify accuracy across the specified loop resistance (250 Ω recommended for test).
Troubleshooting & Common Issues
If the output signal drops below 3.6 mA, the Bently Nevada 990-05-50-02-05 has detected a Not OK condition. Common causes include excessive probe gap, cable faults, or target surface irregularities. Verify probe gap is within 0.5-1.75 mm and that the extension cable is properly seated. The unit automatically restores output 2-3 seconds after the fault clears. For zero drift, use the external non-interacting adjustments. If the loop resistance exceeds 1,000 Ω at 35 Vdc, the transmitter may not drive the full 20 mA; reduce loop resistance or increase supply voltage up to 35 Vdc.
Selection Guide & Purchasing Advice
Before purchasing the Bently Nevada 990-05-50-02-05, verify that the full-scale option (05), system length (50), and mounting option (02) match your application requirements. Confirm agency approval needs: CSA Division 2, ATEX Zone 0, ATEX Zone 2, or ABS maritime. For replacement units, ensure compatibility with existing 3300 NSv probes and extension cables. PLC Source PRO offers genuine Bently Nevada parts with fast shipping. Contact ubest101 for availability and technical support regarding the 990-05-50-02-05.