Product Introduction
When undetected bearing faults or rotor imbalances threaten critical machinery, the Bently Nevada 990-08-70-02-CN provides reliable vibration monitoring to prevent catastrophic failures. This 990 Vibration Transmitter accepts one non-contacting 3300 NSv Proximity Probe and extension cable, converting probe signals into a 4-20 mA loop output. With a full-scale range of 0-8 mils pp (0-200 μm pp) and a system length of 7.0 meters (23.0 feet), it is designed for continuous vibration monitoring in demanding industrial environments.
Technical Specifications Breakdown
| Parameter |
Value |
| Full-Scale Option |
0-8 mils pp (0-200 μm pp) |
| System Length |
7.0 meters (23.0 feet) |
| Mounting Option |
Bulkhead screws |
| Input |
1 non-contacting 3300 NSv Proximity Probe and extension cable |
| Power |
+12 to +35 Vdc at transmitter terminal |
| Maximum Loop Resistance |
1000 Ω including cable at 35 Vdc |
| Current Limiting |
23 mA typical |
| 4-20 mA Loop Accuracy |
Within ±1.5% over full-scale range |
| Probe Gap |
0.5 to 1.75 mm (20 to 55 mils) |
| Frequency Response |
5 Hz to 6000 Hz +0, 3 dB |
| Weight |
0.43 kg (0.9 lbm) |
Industry Applications
The Bently Nevada 990-08-70-02-CN excels in rotating machinery applications such as turbines, centrifugal pumps, compressors, and motors. In a petrochemical plant, for example, continuous vibration monitoring with this transmitter can detect imbalance or misalignment early, reducing unplanned downtime. Its 4-20 mA output integrates seamlessly with PLCs, DCS systems, and standalone vibration monitors, enabling proactive maintenance strategies.
Installation & Setup Guidance
Mount the Bently Nevada 990-08-70-02-CN using the bulkhead screw option in a suitable enclosure near the monitored machinery. The probe must be gapped between 0.5 and 1.75 mm (20 and 55 mils) from the target to ensure full-scale range. Use a shielded cable for the probe and extension; the leadwire from the transmitter to the power supply should not exceed 3 meters (10 feet) for proximity output (BNC connector). Power the unit with +12 to +35 Vdc, observing polarity. After installation, perform a zero and span adjustment using the non-interacting external potentiometers.
Troubleshooting & Common Issues
If the signal output drops below 3.6 mA, the Bently Nevada 990-08-70-02-CN has detected a NOT OK condition (e.g., probe gap out of range or internal fault). The output will go low within 100 µs and restore within 2-3 seconds after the fault clears. To diagnose loop issues, measure voltage across a 250 Ω resistor and compare with expected 4-20 mA values. Verify the probe gap using a dial gauge; adjust if outside 0.5-1.75 mm. For persistent current limiting at 23 mA, check cable resistance and ensure total loop resistance (including cable) does not exceed 1000 Ω at 35 Vdc.
Selection Guide & Purchasing Advice
Before ordering the Bently Nevada 990-08-70-02-CN, confirm your full-scale requirement (0-8 mils pp), system length (7.0 meters), mounting preference (bulkhead screws), and agency approval (CN for country-specific approvals). The transmitter requires a compatible 3300 NSv proximity probe and extension cable – ensure these are sourced separately if not included. For reliable supply of this industrial automation module, contact ubest101, a trusted source for PLC and DCS spares.