Bently Nevada 330881-28-04-034-06-02 Proximity Transducer – PROXPAC XL

Bently Nevada 330881-28-04-034-06-02 PROXPAC XL — Integrated Eddy-Current Transducer Assembly for Continuous Shaft Monitoring

The Bently Nevada 330881-28-04-034-06-02 is a factory-integrated PROXPAC XL proximity transducer assembly that consolidates the eddy-current probe, extension cable, and proximitor driver into a single pre-calibrated unit. This architecture eliminates the three-component field assembly required by conventional 3300 XL systems, removing a primary source of calibration error and connector-induced signal degradation in critical machinery protection loops.

In a standard eddy-current measurement chain, the probe tip generates an oscillating electromagnetic field at approximately 1.0 MHz. When a conductive target — typically AISI 4140 or 4340 steel — enters the sensing field, eddy currents are induced on the target surface, loading the oscillator circuit and producing a proportional change in output voltage. The PROXPAC XL proximitor conditions this signal to a linear DC output of 200 mV/mil (7.87 V/mm) across a calibrated range of 0 to 90 mil (0 to 2.286 mm). The integrated design ensures that the probe-to-proximitor cable impedance is factory-matched, preserving the calibration curve without field trimming.

This assembly is deployed in API 670-governed machinery protection systems on steam turbines, gas turbines, centrifugal compressors, and large motor-driven pumps. It provides the radial shaft vibration, axial position, and differential expansion signals required by Bently Nevada 3300 and 3500 Series monitor modules, as well as System 1 condition monitoring software.

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

Technical Parameters

Hardware Logical Analysis

Oscillator Impedance Matching: The PROXPAC XL proximitor is factory-paired with the probe and extension cable as a matched impedance set. In field-assembled systems, cable length variation shifts the resonant frequency of the LC tank circuit, requiring re-calibration. The 330881-28-04-034-06-02 eliminates this variable entirely — the 4 m extension cable is characterized and compensated at the factory, and the calibration coefficients are locked into the proximitor’s internal reference network.

EMC Design: The proximitor housing employs a multi-layer shielding architecture: an inner copper foil layer attenuates high-frequency radiated interference above 100 MHz, while an outer braided steel shield provides low-impedance grounding continuity along the full cable run. The probe tip coil is wound on a ferrite core with a controlled permeability tolerance of ±3%, ensuring consistent field geometry across production batches. This design maintains signal integrity in environments with variable-frequency drive (VFD) switching noise, which typically generates conducted interference in the 2–20 kHz range.

Thermal Drift Compensation: The proximitor incorporates a temperature-compensated oscillator (TCXO-class reference) that limits sensitivity drift to less than ±0.5% across the full –35°C to +85°C operating range. In uncompensated designs, thermal expansion of the probe tip coil former can shift the resonant frequency by 2–5 kHz per 10°C, introducing a measurable DC offset error in the gap voltage output. The PROXPAC XL’s compensation network corrects for this effect using a thermistor-referenced voltage divider in the signal conditioning stage.

Connector Integrity: The MIL-spec connector (06 variant) uses gold-plated contacts with a contact resistance below 10 mΩ, rated for 500 mating cycles. The bayonet locking mechanism provides a positive retention force of 45 N minimum, preventing intermittent disconnection under vibration loads up to 20 g (10–2,000 Hz per MIL-STD-810G). This is a critical design consideration in turbine bearing housings where structural vibration can exceed 15 g during transient events.

System Integration Benefits

• Zero field calibration: Factory-matched probe-cable-proximitor set ships pre-calibrated to 200 mV/mil; no gap voltage trimming required at commissioning, reducing installation time by an estimated 40–60 minutes per channel.
• Direct monitor compatibility: Plug-compatible with Bently Nevada 3500/40M, 3500/42M, 3500/44M, 3500/45, 3500/46M, 3300/16, 3300/20, and 3300/25 monitor modules without channel reconfiguration.
• Deterministic signal latency: The DC-to-10,000 Hz flat frequency response ensures that shaft vibration events at sub-synchronous, synchronous, and super-synchronous frequencies are captured without phase distortion, supporting accurate orbit plot generation in System 1.
• Reduced wiring complexity: Single-cable assembly replaces three separate field-routed cables (probe, extension, proximitor power/output), reducing junction box termination count by 6 per channel and lowering the probability of wiring-induced common-mode noise injection.
• Diagnostic transparency: The –24 VDC supply current draw (typically 12–15 mA) is within the monitor’s built-in current monitoring window, enabling the 3500 Series to detect open-circuit probe faults and short-circuit conditions without external test equipment.
• API 670 out-of-box compliance: The assembly meets API 670 5th Edition requirements for radial vibration, axial position, and differential expansion measurement without supplementary documentation or field verification testing.
• Hazardous area suitability: FM and CSA certifications cover Class I, Division 1, Groups A–D installations, permitting deployment in gas turbine enclosures and compressor buildings without additional barrier hardware in most North American jurisdictions.
• Long-term parts availability: The PROXPAC XL platform maintains backward compatibility with 3300 Series monitor infrastructure, protecting capital investment in existing DCS and machinery protection architectures during phased plant upgrades.

Quality Assurance & Global Logistics

Every 330881-28-04-034-06-02 unit dispatched from our Xiamen, China facility undergoes a structured pre-shipment verification protocol. Visual inspection confirms probe tip geometry, cable jacket integrity, and connector seating. Where test equipment permits, output voltage at a reference gap of 50 mil is verified against the factory calibration certificate (nominal –10.0 VDC ± 0.5 VDC). Original Bently Nevada packaging, including the calibration data sheet and traceability label, is preserved and included with each shipment.

Sourcing traceability is maintained through documented supply chain records. Units are procured from authorized distribution channels or verified industrial surplus sources with full lot traceability. No remanufactured or counterfeit components are accepted into inventory.

Logistics from Xiamen cover all major international freight lanes. Standard air freight to Europe, North America, Southeast Asia, and the Middle East typically achieves 3–7 business day transit. Express DHL/FedEx options are available for critical plant maintenance requirements with next-flight-out capability. Export documentation, including commercial invoice, packing list, and certificate of origin, is prepared in compliance with Chinese customs regulations and destination country import requirements.

Contact Information

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