Introduction to the 990-04-70-03-00 Vibration Transmitter
When machinery vibration threatens uptime, the 990-04-70-03-00 from Bently Nevada provides a dependable solution. This 990 Vibration Transmitter converts proximity probe signals into a standard 4-20 mA output, enabling seamless integration with PLCs and DCS systems. With a full-scale range of 0-4 mils pp (0-100 μm pp), it suits applications requiring precise vibration monitoring.
Manufactured in the U.S.A., this transmitter accepts one non-contacting 3300 NSv Proximity Probe and extension cable, simplifying installation. Its compact design and DIN clip mounting option (Option 03) make it easy to retrofit into existing panels. The 7.0-meter system length (Option 70) provides flexibility in probe placement.
Key Features and Technical Specifications
The 990-04-70-03-00 offers several features that enhance its performance and reliability:
- 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 (from TEST signal to voltage across 250 Ω loop).
- 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.
One distinctive spec is the NOT OK/signal defeat feature: the output goes to less than 3.6 mA within 100 µs after a Not OK condition, and restores within 2-3 seconds after removal. This fast response helps prevent false readings during fault conditions.
Comparison with Similar Vibration Transmitters
Compared to other vibration transmitters, the 990-04-70-03-00 stands out due to its specific full-scale option (0-4 mils) and system length (7.0 meters). While many transmitters offer adjustable ranges, this model is factory-set for a narrow span, ensuring consistent accuracy. Its 2-wire configuration simplifies wiring, and the 4-20 mA output is universally accepted by monitoring systems.
Below is a comparison of key parameters:
- Full-scale range: 0-4 mils pp (0-100 μm pp) – ideal for low-vibration applications.
- Power supply: +12 to +35 Vdc – flexible for various control panels.
- Loop resistance: 1,000 Ω max – supports long cable runs.
- Frequency response: 5 Hz to 6,000 Hz – covers typical machinery vibration frequencies.
Installation and Setup
Mounting the 990-04-70-03-00 is straightforward with DIN clips and screws (Option 03). Ensure the probe is gapped between 0.5 and 1.75 mm (20 and 55 mils) from the target to achieve full-scale range. The transmitter accepts one 3300 NSv probe and extension cable; the maximum leadwire length for the Proximitor Sensor Output (BNC connector) is 3 meters (10 feet).
Power the transmitter with +12 to +35 Vdc at the terminal. The 4-20 mA output connects in a 2-wire loop, with maximum loop resistance of 1,000 Ω at 35 Vdc. Non-interacting external zero and span adjustments allow fine calibration without affecting each other.
Maintenance and Reliability
Regular inspection of the probe gap and cable connections ensures consistent performance. The transmitter’s current limiting (23 mA typical) protects against overcurrent conditions. Since the unit is designed for non-hazardous, Zone 2, or Div 2 hazardous areas (with 28 V power supply), follow manufacturer guidelines for safe operation.
Periodic verification of the 4-20 mA output against a known reference can detect drift. The ±1.5% accuracy ensures reliable monitoring over time. For any maintenance, always refer to the official Bently Nevada manual.
Support and Availability
The 990-04-70-03-00 is available from AutoDCSTech. Contact us for current lifecycle status and availability before ordering. Our team can assist with technical inquiries and ensure you receive the right vibration monitoring solution.
