Introduction to the 990-04-50-02-01 Vibration Transmitter
When machine vibration threatens uptime, the 990-04-50-02-01 from Bently Nevada provides a direct 4-20 mA signal for your PLC or DCS. This 990 Vibration Transmitter accepts one non-contacting 3300 NSv Proximity Probe and extension cable, converting shaft vibration into a standardized current loop. With a full-scale range of 0-4 mils pp (0-100 μm pp), it suits a wide variety of rotating machinery monitoring tasks.
Key Features and Technical Specifications
The 990-04-50-02-01 is engineered for reliability and ease of integration. Its 4-20 mA output is proportional to vibration amplitude, and it operates in a two-wire configuration. The transmitter requires +12 to +35 Vdc input at the terminal, and the maximum loop resistance is 1,000 Ω including cable at 35 Vdc. Current limiting is 23 mA typical, protecting the loop. The unit includes non-interacting external zero and span adjustments, simplifying calibration. Frequency response is 5 Hz to 6,000 Hz +0, 3 dB, covering typical machine vibration ranges. The minimum target size is 9.5 mm (0.375 in) diameter, and the probe gap must be set between 0.5 and 1.75 mm (20 and 55 mils) for full-scale operation. The transmitter weight is 0.43 kg (0.9 lbm).
Performance and Accuracy
Loop accuracy is within ±1.5% over the specified full-scale range, rated from the TEST signal input to the voltage measured across a 250 Ω loop resistance. This error is in addition to the Prox Out Incremental Scale Factor. The signal output goes to less than 3.6 mA within 100 µs after a Not OK condition, and restores within 2-3 seconds after the condition is removed. This fast response helps protect downstream monitoring systems.
Installation and Setup
Mounting uses bulkhead screws (Mounting Option 02). The system length is 5.0 metres (16.4 feet), which includes the probe and extension cable. Ensure the probe is properly gapped between 0.5 and 1.75 mm (20 and 55 mils) from the target. The maximum leadwire length for the Proximitor Sensor Output (BNC connector) is 3 meters (10 feet). Power supply is 28 V, within the required +12 to +35 Vdc range. Follow the manufacturer's manual for precise wiring and configuration.
Applications and Use Cases
This vibration transmitter is ideal for monitoring pumps, fans, motors, and other rotating equipment in industrial plants. Its 4-20 mA output integrates directly with existing control systems, enabling continuous vibration monitoring without additional signal conditioning. The CSA Division 2 approval (Agency Approval Option 01) makes it suitable for non-hazardous and Zone 2 or Div 2 hazardous area locations, expanding its deployment flexibility. Maintenance engineers can use the real-time vibration data to detect imbalance, misalignment, or bearing wear early, reducing unplanned downtime.
Maintenance and Reliability
For long-term reliability, periodically inspect the probe and cable for damage. Verify the probe gap remains within the specified range, as thermal expansion or mechanical shifts can alter it. Check the loop current and power supply voltage to ensure they stay within limits. Since the transmitter has no moving parts, routine maintenance is minimal. Always follow the manufacturer's safety manual for any inspection or service procedures.
Compatibility and Integration
The 990-04-50-02-01 works with any 4-20 mA input module, PLC, or DCS. It accepts one 3300 NSv Proximity Probe and extension cable, which are standard Bently Nevada components. The two-wire configuration simplifies wiring, and the non-interacting zero and span adjustments allow quick calibration. For detailed integration guidance, refer to the official Bently Nevada documentation or contact AutoDCSTech.
Product Support and Availability
The Bently Nevada 990-04-50-02-01 is available through AutoDCSTech. Please verify current lifecycle status and availability with AutoDCSTech before ordering. For technical questions, consult the official Bently Nevada manual or contact our team.
