Overview of the 990-10-70-02-CN Vibration Transmitter
When machinery vibration threatens uptime, the 990-10-70-02-CN from Bently Nevada provides a direct path to actionable data. This 990 Vibration Transmitter accepts one non-contacting 3300 NSv Proximity Probe and extension cable, converting dynamic shaft motion into a standard 4-20 mA signal. Designed for continuous duty in industrial environments, it supports full-scale ranges of 0-10 mils pp (0-250 μm pp) and operates from a +12 to +35 Vdc supply. For maintenance engineers, this unit simplifies vibration monitoring by integrating directly into existing control loops.
Built in the U.S.A., the 990-10-70-02-CN includes a system length option of 7.0 meters (23.0 feet) and mounts via bulkhead screws. Its compact transmitter weight of 0.43 kg (0.9 lbm) allows flexible placement near the measurement point. With a maximum loop resistance of 1,000 Ω at 35 Vdc, it can drive long cable runs without signal degradation. This model is tailored for users who need reliable, loop-powered vibration sensing without complex configuration.
Key Features and Technical Specifications
The 990-10-70-02-CN delivers several features that enhance both performance and serviceability. Each specification below is drawn directly from the manufacturer's data to ensure accuracy.
- Input: Accepts one non-contacting 3300 NSv Proximity Probe and extension cable.
- Power: Requires +12 to +35 Vdc input at the transmitter terminal.
- Output: 4 to 20 mAdc over specified full-scale range in 2-wire configuration.
- Accuracy: Within ±1.5% over specified full-scale range, rated from TEST signal input to voltage across a 250 Ω loop resistance.
- Probe gap: Must be gapped between 0.5 and 1.75 mm (20 and 55 mils) from target to ensure full-scale range.
- 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.
- Minimum target size: 9.5 mm (0.375 in) diameter.
- Leadwire length: Maximum for Proximitor Sensor Output (BNC connector) is 3 meters (10 feet).
One distinctive spec is the NOT OK/signal defeat function: the signal output drops to less than 3.6 mA within 100 µs after a Not OK condition, and restores within 2-3 seconds after the condition clears. This fast response helps maintenance teams quickly identify probe or system faults, reducing diagnostic time.
Real-World Applications
In rotating machinery monitoring, the 990-10-70-02-CN fits naturally into vibration monitoring systems for pumps, motors, fans, and compressors. Its 4-20 mA output integrates with PLCs, DCS, and SCADA systems, enabling continuous trend analysis. For example, in a petrochemical plant, the transmitter can monitor a critical pump's shaft vibration, alerting operators before bearing damage occurs. The wide frequency response (5 Hz to 6,000 Hz) covers common machine vibration frequencies, making it versatile across different rotating speeds.
Because it accepts a standard 3300 NSv probe, the transmitter works with existing Bently Nevada sensor installations, simplifying retrofits. The non-hazardous, Zone 2 or Div 2 hazardous area locations rating (with 28 V power supply) allows installation in many industrial areas without special enclosures. This makes the 990-10-70-02-CN a practical choice for both new projects and upgrades.
Installation and Setup
Proper installation is critical for accurate vibration readings. The probe must be gapped between 0.5 and 1.75 mm (20 and 55 mils) from the target shaft. Use the bulkhead mounting option to secure the transmitter, and ensure the system length (7.0 meters) matches your cable run. Connect the probe and extension cable to the transmitter input, then wire the 4-20 mA loop to your monitoring system. Power the transmitter with +12 to +35 Vdc, and verify the loop resistance does not exceed 1,000 Ω at 35 Vdc.
For best results, follow the manufacturer's manual for torque specifications and cable routing. Avoid running signal cables near high-voltage power lines to prevent interference. After installation, perform a gap check and verify the output signal corresponds to the expected vibration level.
Maintenance and Reliability
Regular inspection of the probe and cable is essential for long-term reliability. Check the probe tip for wear or contamination, and ensure the gap remains within the specified range. Verify the transmitter's output responds correctly to known vibration changes. Because the 990-10-70-02-CN uses a 2-wire loop, it is less prone to wiring errors, but periodic loop checks are still recommended.
From a maintenance engineer's perspective, the fast Not OK response (less than 3.6 mA within 100 µs) is a valuable diagnostic tool. It immediately signals a fault, allowing quick troubleshooting. The current limiting at 23 mA typical protects the loop from overcurrent, reducing the risk of damage to downstream devices. With proper care, this transmitter can provide years of reliable service.
Compatibility and Integration
The 990-10-70-02-CN is designed to work with Bently Nevada's 3300 NSv proximity probe system. It outputs a standard 4-20 mA signal, which is universally accepted by most industrial control systems. This allows easy integration into existing PLC or DCS analog input modules. The transmitter also supports a BNC connector for the Proximitor Sensor Output, with a maximum cable distance of 3 meters (10 feet).
For hazardous area installations, the unit is rated for NonHazardous, Zone 2 or Div 2 locations when powered at 28 V. Always verify local codes and the specific agency approval option (CN Approvals country specific) before installation.
Troubleshooting Common Issues
If the output signal is erratic or missing, check the probe gap first. A gap outside 0.5-1.75 mm will cause incorrect readings. Next, verify the supply voltage is within +12 to +35 Vdc and that loop resistance is below 1,000 Ω. If the signal goes below 3.6 mA, the transmitter is in a Not OK state—check the probe and cable for damage. After clearing the fault, the output should restore within 2-3 seconds.
For persistent issues, consult the Bently Nevada manual or contact AutoDCSTech for technical support. Do not attempt internal repairs; replace the unit if necessary.
Product Support and Availability
The 990-10-70-02-CN is available from AutoDCSTech, a trusted supplier of industrial automation parts. For current lifecycle status and availability, please contact AutoDCSTech before ordering. Our team can assist with technical questions and ensure you receive the correct Bently Nevada vibration transmitter for your application.
