990-08-70-02-00 Vibration Transmitter Overview
When machine vibration threatens uptime, the 990-08-70-02-00 from Bently Nevada delivers a precise, loop-powered solution. This 990-series transmitter accepts one non-contacting 3300 NSv proximity probe and extension cable, converting dynamic shaft vibration into a standard 4-20 mA signal. Designed for continuous condition monitoring, it helps maintenance teams detect developing faults before they cause unplanned downtime.
With a full-scale range of 0-8 mils pp (0-200 μm pp), the 990-08-70-02-00 suits applications requiring high-resolution vibration measurement. Its 7.0-meter system length option provides installation flexibility, while bulkhead screw mounting simplifies secure attachment. This transmitter is manufactured in the U.S.A. and carries the Bently Nevada brand, known for reliability in industrial rotating machinery protection.
Key Features and Technical Specifications
The 990-08-70-02-00 offers several features that make it a practical choice for vibration monitoring. Its two-wire 4-20 mA output integrates easily with existing control systems, reducing wiring complexity. The transmitter operates from a wide DC supply range, accommodating various plant power architectures.
- Input: Accepts 1 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 250 Ω loop resistance).
- 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.
- Probe Gap: Must be gapped between 0.5 and 1.75 mm (20 and 55 mils) from target.
- NOT OK/Signal Defeat: Output goes to less than 3.6 mA within 100 µs after a Not OK condition; restored within 2-3 seconds after removal.
- Leadwire Length: Maximum 3 meters (10 feet) for Proximitor Sensor Output (BNC connector).
- Mounting: Bulkhead screws.
- Weight: 0.43 kg (0.9 lbm).
The 990-08-70-02-00 stands out for its fast NOT OK response, ensuring that a fault condition is communicated immediately. This rapid signal drop helps protect downstream monitoring systems from false data, a critical feature for safety-conscious operations.
Applications and Use Cases
The 990-08-70-02-00 is well-suited for monitoring vibration on rotating machinery such as pumps, motors, fans, and compressors. Its 4-20 mA output allows direct connection to PLCs, DCS, or standalone vibration monitors. In predictive maintenance programs, the transmitter provides continuous data that supports trend analysis and early fault detection. For example, a plant engineer could use the 990-08-70-02-00 to monitor a critical cooling fan, receiving an immediate alarm if vibration exceeds the 0-8 mils range, enabling timely intervention.
Installation and Setup
Proper installation is essential for accurate vibration measurement. The proximity probe must be gapped between 0.5 and 1.75 mm (20 and 55 mils) from the target to ensure full-scale range. The transmitter requires a +12 to +35 Vdc power supply at its terminal, and the maximum loop resistance is 1,000 Ω at 35 Vdc. Mount the unit using the bulkhead screws provided, ensuring a secure mechanical connection. The probe leadwire length should not exceed 3 meters (10 feet) for the Proximitor Sensor Output. For detailed wiring and configuration, refer to the Bently Nevada installation manual.
Maintenance and Reliability
Regular inspection of the probe and cable is recommended to maintain measurement integrity. Check that the probe gap remains within the specified range, as thermal expansion or mechanical shift can alter it. Verify the loop power supply voltage stays within +12 to +35 Vdc. Periodically test the NOT OK function to ensure the output drops below 3.6 mA when a fault is simulated. Following the manufacturer's maintenance guidelines helps ensure long-term reliability.
Compatibility and Integration
The 990-08-70-02-00 is designed to work with Bently Nevada 3300 NSv proximity probes and extension cables. Its 4-20 mA output is universally compatible with most industrial control systems, including PLCs and DCS platforms. The transmitter can be used in non-hazardous, Zone 2, or Div 2 hazardous area locations, with a power supply of 28 V. This flexibility makes it a versatile component in both new installations and retrofits.
Support and Availability
The 990-08-70-02-00 is available through AutoDCSTech, an industrial automation parts supplier. Please verify current lifecycle status and availability with AutoDCSTech before ordering. For technical support, contact AutoDCSTech for assistance.
