The Bently Nevada 330881-28-04-090-03-02, also cataloged as the 330881 Proximity Transducer, operates as a dedicated hardware component for integrated displacement sensing and signal conditioning within turbine monitoring platforms.

Model Configuration Matrix

• 330881: PROXPAC XL integrated proximity transducer.

• 28: Probe diameter and thread specification.

• 04: Unthreaded length.

• 090: Case length (90 mm).

• 03: Connector type.

• 02: Agency approval and configuration option.

Technical Specifications

Mechanical Monitoring Characteristics

The system provides eddy-current probe scaling within an integrated package to ensure signal linearity over the target displacement range. Commissioning requires gap voltage validation; the transducer must be adjusted to a nominal -10 VDC operational setpoint at the monitor input to maintain performance within the linear sensing region. The internal design incorporates cross-talk suppression circuitry to preserve signal integrity in multi-transducer configurations. The integrated nature of this unit removes the requirement for remote Proximitor enclosures, reducing interconnection complexity in rotor dynamics and shaft centerline monitoring applications.

Ordering Information

• One (1) 330881-28-04-090-03-02 PROXPAC XL Transducer.

• Required mounting nuts and lock washers.

• Technical compliance and installation documentation.

• Note: Operation requires a stable -24 VDC power source for specified electrical output.

Installation Guidelines

• Mechanical Mounting: Mount the transducer through the machine casing; use a rigid bracket to prevent mechanical resonance that could bias vibration data.

• Gap Setting: Utilize a depth micrometer to verify the mechanical gap; monitor the DC output voltage at the signal terminal until the -10 VDC target is achieved.

• Cabling: Install signal cabling in shielded conduit or dedicated cable trays to prevent induction from high-voltage AC lines.

• Grounding: Secure a low-impedance machine ground to the transducer housing to ensure consistent shielding of the internal signal circuit.

• Torque Management: Tighten jam nuts to prevent loosening during harmonic machine operation; verify lock washers are seated correctly.

Frequently Asked Questions

• What is the primary operational advantage of the PROXPAC XL design?

  The integration of probe and signal conditioner eliminates external extension cables, reducing installation space and simplifying the signal path to the monitor.

• Can this transducer function without a Proximitor?

  The signal conditioning electronics are already integrated within the housing, effectively making the unit a self-contained transducer system.

• What is the target gap voltage for this transducer?

  The nominal gap is centered at -10 VDC to ensure the eddy-current sensing circuit operates in the center of its linear range.

• Is the 90 mm case length field-adjustable?

  No. The length is a fixed mechanical parameter determined at the factory; physical modification will invalidate the calibration.

• Can I replace the internal probe if the tip is damaged?

  No. The PROXPAC XL is a factory-sealed, integrated unit; structural damage to the tip or body requires complete assembly replacement.

• How is operational health verified?

  Health is monitored via the DC gap voltage; drifts outside of acceptable ranges typically indicate probe failure or electrical discontinuity.

• Does the transducer require a specific target material?

  Factory calibration is based on 4140 steel; usage on alternative materials necessitates a scale factor adjustment to maintain linearity.

• Are there specific grounding requirements?

  The transducer housing must maintain a low-impedance connection to the machine chassis to ensure effective EMI/RFI shielding of the internal components.