Bently Nevada 330881-28-00-150-03-02 Proximity Transducer – PROXPAC XL

Bently Nevada 330881-28-00-150-03-02: Shaft Displacement Measurement in Critical Rotating Machinery

The 330881-28-00-150-03-02 is a factory-assembled eddy-current proximity transducer from Bently Nevada’s PROXPAC XL platform. It integrates a probe tip, 28-foot (8.53 m) armored extension cable, and a driver oscillator/demodulator into a single calibrated assembly. This architecture eliminates the three-component field-assembly process required by discrete probe/cable/driver configurations, removing a primary source of calibration drift in continuous machinery protection loops.

The assembly outputs a DC voltage proportional to the gap between the probe face and the target shaft surface. At the nominal scale factor of 200 mV/mil (7.87 V/mm), the 150-mil (3.81 mm) linear range produces a full-scale output swing of approximately 30 VDC — sufficient to resolve sub-mil shaft displacements while accommodating the large static eccentricities present in sleeve-bearing machines operating at low speed during startup and coast-down.

Real-time Stock & RFQ: [email protected] | WhatsApp: +86 18359268345

Technical Parameters

Hardware Logical Analysis

The PROXPAC XL architecture addresses three hardware-level failure modes that are endemic to discrete three-component eddy-current systems:

1. Impedance Matching and Cable Capacitance Compensation
In a conventional probe/extension cable/driver arrangement, the extension cable introduces distributed capacitance that attenuates the oscillator signal and shifts the resonant frequency of the probe coil circuit. The PROXPAC XL integrates the driver electronics at the factory-calibrated cable terminus, ensuring the oscillator operates into a known, fixed impedance. This eliminates the cable-length-dependent frequency shift that would otherwise require field recalibration when cable runs are modified.

2. EMC Shielding Architecture
The 28-foot armored cable uses a triaxial construction: the inner conductor carries the probe coil signal, the intermediate shield is driven at the same potential as the inner conductor (guard drive), and the outer stainless steel braid provides a low-impedance path to chassis ground. This guard-drive topology reduces the effective cable capacitance seen by the oscillator by a factor of 10–100×, extending the usable cable length without degrading the –3 dB bandwidth. In environments with high-frequency switching noise from variable-frequency drives (VFDs) operating at 2–20 kHz carrier frequencies, the triaxial shield provides >60 dB of common-mode rejection across the measurement bandwidth.

3. Thermal Stability of the Oscillator Circuit
The driver oscillator uses a temperature-compensated LC tank circuit. The inductance of the probe coil varies with temperature due to changes in the ferrite core permeability and copper winding resistance. Bently Nevada’s compensation network introduces a complementary reactance that maintains the oscillator frequency within ±0.5% across the full –35°C to +85°C driver operating range. This is critical in steam turbine applications where bearing housing temperatures can cycle between ambient and 120°C during load changes, as an uncompensated scale factor drift of 1–2% per 10°C would introduce false alarm conditions in a 3500 series monitor configured with tight alert setpoints.

4. Mechanical Robustness of the Probe Tip
The 8 mm probe tip uses a ceramic-filled epoxy encapsulant over the coil winding, rated to withstand continuous immersion in turbine lube oil at 177°C. The stainless steel probe body is machined to a thread tolerance of ±0.025 mm to ensure repeatable installation depth when used with Bently Nevada probe holders, maintaining the factory gap calibration without requiring a gap meter at installation.

System Integration Benefits

The 330881-28-00-150-03-02 delivers the following measurable advantages when integrated into a 3500 series machinery protection system:

• Zero field calibration overhead: Factory-calibrated assembly ships with a calibration certificate traceable to NIST standards. Installation requires only gap setting to the nominal 50-mil (1.27 mm) center-of-range gap — no oscilloscope or signal generator needed on-site.
• Direct 3500 monitor compatibility: The –24 VDC supply and 200 mV/mil scale factor are natively recognized by 3500/40M, 3500/42M, and 3500/45 monitor modules without requiring custom scale factor programming, reducing configuration error risk during commissioning.
• 150-mil range supports large-bore sleeve bearings: Machines with journal diameters above 200 mm typically exhibit static eccentricities of 60–80 mil at operating speed. The 150-mil range provides a 35–45 mil margin above the static offset, preserving full dynamic measurement range for vibration amplitudes up to API 670 danger setpoints.
• 28-foot cable eliminates junction boxes: In turbine pedestals where the monitor rack is located 6–8 meters from the bearing, the integral 28-foot cable reaches the rack directly, removing the intermediate junction box that is a common source of ground loops and moisture ingress.
• Deterministic frequency response to 10 kHz: Flat response to 10,000 Hz enables detection of sub-synchronous instabilities (oil whirl at 0.43–0.48×), synchronous (1×), and high-order harmonics (up to 16× on a 600 RPM machine) within a single measurement channel, without anti-aliasing filter artifacts.
• ATEX/IECEx certification reduces zone classification paperwork: Pre-certified assemblies allow direct installation in Zone 1 classified areas without requiring a separate intrinsic safety barrier or Zener barrier, simplifying the hazardous area equipment schedule and reducing installed cost.
• Stainless steel armored cable withstands mechanical abuse: The outer braid is rated for a minimum bend radius of 50 mm and a pull force of 500 N, allowing the cable to be routed through cable trays and conduit without risk of insulation damage that would introduce ground faults detectable as DC offset errors in the monitor.
• 12-month warranty with traceable documentation: Each unit ships with a material certificate (EN 10204 3.1 or equivalent) and a factory test report confirming scale factor, linearity, and frequency response. This documentation satisfies the quality records requirements of ISO 55001 asset management programs and API 670 Annex D inspection checklists.

Quality Assurance & Global Logistics

Every 330881-28-00-150-03-02 unit stocked at our Xiamen, China facility is sourced through verified Bently Nevada (Baker Hughes) authorized distribution channels. Upon receipt, each assembly undergoes a structured incoming inspection protocol:

• Part number and date code verification against Bently Nevada’s serialization database
• Visual inspection of probe tip encapsulant, cable armor integrity, and connector termination condition
• DC resistance measurement of the probe coil (nominal 5–8 Ω) to confirm coil continuity and absence of winding shorts
• Driver output voltage check at nominal 50-mil gap using a calibrated target fixture
• Anti-static packaging in moisture-barrier bags with desiccant, sealed in rigid foam-lined cartons

Shipments from Xiamen are dispatched via DHL Express, FedEx International Priority, or UPS Worldwide Expedited, with typical transit times of 3–5 business days to Europe, 4–6 days to North America, and 2–3 days to Southeast Asia. Export documentation includes a commercial invoice, packing list, and certificate of origin. ATEX/IECEx certificates and Bently Nevada factory calibration reports are included in the shipment package. For orders requiring expedited customs clearance, we provide HS code 9026.80.90 pre-classification documentation to minimize border delays.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
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