Introduction to the 990-05-50-01-00 Vibration Transmitter
When machine vibration threatens uptime, the 990-05-50-01-00 from Bently Nevada delivers a precise, loop-powered solution. This 990 Vibration 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 industrial use, it provides a direct interface to PLCs, DCSs, and SCADA systems without additional signal conditioning.
With a full-scale range of 0-5 mils pp (0-125 μm pp), the transmitter is calibrated for fine vibration measurement. The system length option of 5.0 metres (16.4 feet) accommodates typical installation distances. Mounting is simplified with 35 mm DIN rail clips, and the unit is manufactured in the U.S.A.
Key Features and Technical Specifications
The 990-05-50-01-00 offers several engineering-critical parameters that ensure accurate and reliable operation.
- 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 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.
- Mounting: 35 mm DIN rail clips.
- Weight: 0.43 kg (0.9 lbm).
One distinctive feature is the non-interacting external zero and span adjustments. This allows field calibration without affecting the other parameter, reducing setup time and improving accuracy.
Real-World Applications and Use Cases
In rotating machinery monitoring, the 990-05-50-01-00 excels at providing continuous vibration data. Typical applications include pumps, fans, compressors, and turbines where shaft vibration indicates mechanical health. Because the transmitter outputs a standard 4-20 mA signal, it integrates easily with existing control systems.
For example, in a petrochemical plant, a 990-05-50-01-00 mounted on a cooling tower fan can send vibration trends to a DCS. Operators can then schedule maintenance before a failure occurs, avoiding unplanned downtime. The fast NOT OK response (less than 3.6 mA within 100 µs) ensures that a faulty probe or cable is immediately detected, preventing false safety actions.
Installation and Setup Guidance
Proper installation is critical for accurate vibration measurement. The probe must be gapped between 0.5 and 1.75 mm (20 and 55 mils) from the target. Use the 35 mm DIN rail clips for secure mounting in an enclosure. Connect the power supply (+12 to +35 Vdc) to the transmitter terminals, and wire the 4-20 mA loop to your monitoring system.
Ensure the maximum loop resistance does not exceed 1,000 Ω at 35 Vdc. For longer cable runs, verify that the total resistance stays within this limit. The leadwire length for the Proximitor Sensor Output (BNC connector) is a maximum of 3 meters (10 feet).
Maintenance and Reliability Tips
Regular inspection of the probe and cable is recommended to ensure reliable operation. Check that the probe gap remains within the specified range, as thermal expansion or mechanical wear can alter it. Verify that the transmitter's output responds correctly to known vibration levels.
Because the 990-05-50-01-00 is loop-powered, it has minimal heat dissipation and long-term stability. The current limiting at 23 mA typical protects the loop from overcurrent conditions. For hazardous area installations, the unit is rated for NonHazardous, Zone 2 or Div 2 locations with a power supply of 28 V.
Troubleshooting Common Issues
If the output is stuck at a low value (below 3.6 mA), a Not OK condition may be present. Check the probe connection and gap. If the output is saturated at 20 mA, the vibration may exceed the full-scale range, or the probe gap may be incorrect.
For accuracy issues, verify that the loop resistance is within the 1,000 Ω limit. Use a 250 Ω resistor for calibration checks, as the accuracy specification is rated across this resistance. If the problem persists, consult the Bently Nevada manual or contact AutoDCSTech for support.
Product Support and Availability
The 990-05-50-01-00 is available from AutoDCSTech. Please verify current lifecycle status and availability before ordering. Contact our team for technical support and pricing.
