The Bently Nevada 330881-28-08-050-03-02, also cataloged as the 330881 PROXPAC XL Assembly, operates as a dedicated hardware component for integrated displacement measurement within 3300 XL monitoring platforms. This assembly combines the probe, extension cable, and Proximitor sensor into a unified housing, executing direct physical signal transduction to capture instantaneous relative motion between the sensor tip and a conductive target.

Model Suffix Breakdown

• 330881: PROXPAC XL Proximity Transducer Assembly

• 28: Total Case Length (metric)

• 08: Probe Tip Style (8 mm)

• 050: Cable Length (5.0 meters)

• 03: Connector Type (Miniature coaxial ClickLoc)

• 02: Agency Approval (Multiple approvals)

Hardware Specifications

Mechanical Monitoring & Eddy-Current Dynamics

The PROXPAC XL system utilizes standard eddy-current probe scaling to convert target displacement into a linear voltage signal. To ensure accurate rotor dynamics analysis, installers must perform gap voltage validation, targeting a -10 VDC setpoint at the monitor output. Cross-talk suppression is critical in multi-probe installations; maintain a minimum clearance of 40 mm between adjacent probe tips to prevent 1 MHz carrier frequency interference, which could otherwise introduce harmonic noise into the vibration data stream.

Ordering Information

• 1 x 330881-28-08-050-03-02 PROXPAC XL Assembly

• 1 x Mounting accessory kit

• 1 x Technical documentation

Field Installation Guidelines

• Mechanical Mounting: Secure the integrated housing to a rigid, vibration-isolated surface to prevent structural resonance within the transducer assembly.

• Signal Cabling: Utilize grounded metallic conduit for the output signal cable to provide robust shielding against electromagnetic interference.

• Connection Integrity: Verify all internal connections are factory-sealed; ensure the external output connector is fully seated and locked.

• Grounding: Establish a low-impedance connection to the machine instrument earth to prevent ground loop currents that affect signal stability.

• Gap Adjustment: Use a feeler gauge to set the initial probe gap, then verify the voltage reading at the Proximitor test point during cold-state commissioning.

Frequently Asked Questions

• Q: Why is the PROXPAC XL considered an "integrated" system?

  A: It houses the Proximitor sensor and probe interface within a single protective enclosure, reducing field wiring complexity and environmental exposure.

• Q: Can the probe tip be replaced if damaged?

  A: No. The PROXPAC XL is a factory-calibrated assembly; any mechanical damage to the tip or cable requires replacement of the entire unit.

• Q: Is the system sensitive to target material?

  A: Yes, calibration is optimized for 4140 steel. Using materials with different magnetic permeability requires specific scale factor recalibration.

• Q: What is the purpose of the 12 mA power consumption?

  A: This constant current draw is required by the internal Proximitor circuitry to drive the 1 MHz carrier frequency signal used in eddy-current detection.

• Q: Can the assembly be used in hazardous locations?

  A: Yes, provided the "02" agency approval suffix matches the requirements for the site hazardous area classification and is used with approved barriers.

• Q: How does cable length affect performance?

  A: The system is factory-calibrated for the specified cable length; modifying the cable introduces impedance mismatches and phase errors.

• Q: What indicates a system failure?

  A: A failure usually manifests as a hard-scale voltage (e.g., -24 VDC) at the output, signaling an internal component fault or cable break.

• Q: How do I verify the gap voltage?

  A: Measure the DC voltage between the "OUT" and "COM" terminals on the output connector while the machine is at rest.