Configured for casing vibration monitoring, the Bently Nevada 990-04-XX-01-05 MOD:165335-01 (990-04-XX-01-05 Vibration Transmitter) provides direct physical signal processing and 4-20 mA output transmission for machine protection.

Configuration Matrix

• 990: Base Model (Vibration Transmitter)
• 04: 0-4 mils pp (0-100 um pp) range
• XX: System length (5.0 m or 7.0 m dependent on install)
• 01: 35 mm DIN-rail mounting clips
• 05: Hazardous area approval (CSA Div 2, ATEX Zone 0/2, ABS maritime)
• MOD: 165335-01 factory configuration

Hardware Specifications

Mechanical Monitoring and Signal Conditioning

The 990 transmitter facilitates accurate eddy-current probe scaling for vibration velocity measurement. System commissioning requires gap voltage validation against -10 VDC targets to ensure linear measurement within the transducer loop. Signal fidelity is maintained through internal filtering and cross-talk suppression circuitry, which mitigates interference in multi-channel installations. The non-interacting external zero and span adjustments allow for rapid calibration to site-specific rotor dynamics, ensuring that the processed 4-20 mA output accurately reflects machine vibration behavior.

Ordering Info

• 1 x 990-04-XX-01-05 Vibration Transmitter
• 1 x 35 mm DIN-rail mounting hardware kit

Installation Guidelines

• Mechanical Mounting: Mount the transmitter on a 35 mm DIN rail in a clean, dry location protected from direct environmental exposure.
• Electrical Termination: Ensure correct polarity for all connections. Use shielded cabling to connect the proximity probe input and the 4-20 mA current loop output.
• Grounding: Connect the transmitter case to a verified system ground to minimize EMI and common-mode noise on the signal output.
• Configuration: Adjust the non-interacting zero and span controls using a high-impedance (10 MOhm) digital multimeter for precise signal mapping.

Frequently Asked Questions

• Can this transmitter be used in hazardous locations?

  Yes, the -05 suffix provides ratings for CSA Division 2 and ATEX Zone 0/2. Verify installation drawings for specific intrinsic safety barrier requirements.

• How is the Prox Out signal used?

  The Prox Out port provides a buffered raw signal for diagnostic analysis, such as waveform viewing on an oscilloscope or vibration analyzer.

• What is the effect of a load impedance lower than 10 MOhm on Prox Out?

  Loading the output below 10 MOhm will cause signal attenuation and phase shift, leading to errors in diagnostic data interpretation.

• Are the zero and span adjustments interlinked?

  No, the internal design is non-interacting, allowing for independent adjustment of the 4-20 mA endpoints without iterative calibration cycles.

• Is this transmitter compatible with all Bently Nevada probes?

  It is designed for standard 8 mm 3300 XL probe systems. Compatibility with other probe series should be verified via technical documentation.

• What is the purpose of the 23 mA current limiting?

  This circuit protects the transmitter circuitry and the downstream control system input from high-current damage during fault conditions.

• How does the transmitter handle frequency responses outside of 5 Hz to 6,000 Hz?

  Signals outside this range are attenuated. Operation near the 6,000 Hz limit will experience roll-off according to the -3 dB specification.

• Can I replace the mounting clips in the field?

  Yes, the 35 mm DIN-rail clips are mechanical components and can be replaced if damaged, provided the unit housing remains intact.