Bently Nevada 330104-00-05-20-12-CN Proximity Transducer System – 3300 XL Series

330104-00-05-20-12-CN: Non-Contact Shaft Displacement Measurement in High-Speed Rotating Machinery Protection Loops

The Bently Nevada 330104-00-05-20-12-CN is a factory-matched, three-component eddy-current proximity transducer system from the 3300 XL Series, designed for continuous non-contact measurement of radial shaft vibration, axial position displacement, and differential thermal expansion in turbomachinery and critical rotating equipment. The system integrates an 8 mm diameter probe body (M12 × 1 thread), a 5-metre armored integral probe cable, and a 20-metre coaxial extension cable terminated with a CN-type connector. All three elements are calibrated as a matched set at the factory, locking the system scale factor to 7.87 V/mm (200 mV/mil) across the full measurement chain — a figure that cannot be reliably reproduced by mixing components from different part number configurations.

Within a machinery protection architecture, this transducer occupies the primary sensing node of the signal chain. The probe coil generates a high-frequency electromagnetic field at approximately 1.0 MHz. When the conductive shaft surface — typically AISI 4140 low-alloy steel or equivalent — enters the field, eddy currents are induced on the target surface, loading the oscillator circuit housed in the paired driver module. The driver converts the resulting impedance shift into a DC voltage proportional to the physical gap between probe tip and shaft surface. This DC output feeds directly into monitor modules such as the 3500/42M Proximitor I/O Module or the 3300/16 Dual Vibration Monitor, where alarm and trip thresholds are evaluated in real time. The linear measurement range spans 0.25 mm to 2.26 mm, corresponding to a DC output window of approximately −2.0 V to −18.0 V at the driver output terminal.

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Technical Parameters

Hardware Logical Analysis

Oscillator Loading and Impedance Modulation: The 8 mm probe coil forms the inductive arm of an LC tank circuit within the driver module. At the nominal installation gap of 1.0 mm, the tank circuit operates at its design Q-factor, and the oscillator sustains a stable carrier at approximately 1.0 MHz. As the shaft surface displaces toward or away from the probe tip, the mutual coupling between the coil field and the conductive target changes the effective inductance seen by the oscillator. The driver’s demodulation stage — a precision envelope detector — extracts the amplitude modulation imposed by this impedance shift and converts it to a DC voltage with a group delay below 1 ms at 1 kHz. This sub-millisecond latency is essential for capturing high-speed transient events such as rub-impact at shaft speeds above 3,000 RPM, where a 1 ms delay corresponds to 18° of shaft rotation.

Cable Impedance Architecture and Matching: The 5 m probe cable and 20 m extension cable are impedance-matched as a pair to the driver input. The coaxial geometry maintains a controlled characteristic impedance throughout the signal path, preventing reflections that would manifest as standing-wave artifacts in the DC output — particularly relevant at high shaft speeds where the vibration signal contains frequency components above 5 kHz. Field substitution of either cable segment with an unmatched component introduces a systematic DC offset of up to 0.15 mm in the apparent gap reading, which can shift alarm thresholds by a corresponding margin. The factory-matched configuration of the 330104-00-05-20-12-CN eliminates this error source by design.

EMC Shielding Architecture: The probe cable employs a dual-layer shielding construction: an inner braid shield over the signal conductor and an outer foil-plus-braid shield bonded to the driver chassis ground. This arrangement provides greater than 60 dB of common-mode rejection against radiated interference from variable-frequency drives (VFDs), high-current bus bars, and RF sources prevalent in turbomachinery enclosures. The CN connector’s precision-machined body maintains shield continuity at the cable junction, preventing ground loop injection at the connection point — a failure mode that commonly introduces 50/60 Hz hum into proximity measurements in electrically noisy plant environments.

Thermal Compensation of Scale Factor: The probe coil is wound with a temperature-compensated alloy conductor, and the ferrite core material is selected for minimal permeability drift across the −35 °C to +177 °C probe tip operating range. This design holds the scale factor within ±1% across the full thermal envelope — a specification that matters in steam turbine bearing housings where probe tip temperatures routinely exceed 140 °C during sustained base-load operation. Without thermal compensation, a 100 °C rise in probe tip temperature would shift the scale factor by 3–5% in an uncompensated coil design, introducing a proportional error in the vibration amplitude reading.

Mechanical Sealing and Chemical Resistance: The 316L stainless steel probe body with IP67 sealing resists ingress of turbine oil, steam condensate, and hydrocarbon-based lubricants. The armored probe cable jacket withstands continuous mechanical flexing at the bearing housing entry port without cracking or shield degradation, eliminating the need for additional conduit protection in most standard installations. The M12 × 1 thread provides a secure, vibration-resistant mounting in standard proximity probe bosses machined per API 670 dimensional requirements.

System Integration Benefits

• API 670 Fifth Edition compliance out of the box: The 330104-00-05-20-12-CN satisfies the electrical, mechanical, and calibration requirements of API Standard 670 without supplementary field verification, reducing commissioning time during plant acceptance testing by eliminating a dedicated transducer compliance step.
• Sub-millisecond signal latency for transient capture: The DC-coupled eddy-current output with <1 ms group delay at 1 kHz ensures that high-speed mechanical transients — rub-impact, blade loss, sudden unbalance — are captured without phase distortion in the downstream monitor module, preserving the integrity of time-waveform and orbit plot analysis.
• Cross-platform compatibility with 3300 and 3500 monitor architectures: The CN connector and cable impedance specification are compatible with both the legacy 3300 XL driver and the current-generation 3500/42M Proximitor I/O module, allowing the same transducer system to serve across mixed-generation monitoring infrastructure without adapter hardware or recalibration.
• Continuous gap voltage diagnostics without process interruption: The driver DC output provides a real-time gap voltage that can be trended independently of the vibration signal. Gradual drift in the gap voltage baseline indicates probe fouling, target surface wear, or mechanical loosening of the probe mounting — all detectable during normal machinery operation without requiring a shutdown inspection.
• 10 kHz bandwidth for higher-order spectral analysis: The −3 dB bandwidth extending to 10,000 Hz supports blade-pass frequency monitoring in axial compressors, gear-mesh frequency analysis in gearboxes, and sub-synchronous instability detection in fluid-film bearing machines — extending the transducer’s utility beyond basic 1× and 2× vibration protection into full-spectrum condition monitoring.
• X-Y orbital redundancy configuration: Two units mounted at 90° intervals on a single bearing journal provide full shaft orbital analysis and dual-channel redundant protection per API 670, enabling the monitor to maintain protection coverage during single-channel maintenance without a machinery shutdown.
• Remote driver placement via 20 m extension cable: The 20 m extension cable allows the driver module to be installed in a temperature-controlled instrument enclosure remote from the bearing housing, reducing driver exposure to heat, vibration, and chemical contamination — factors that are the primary causes of driver module failure in direct-mount configurations.
• Minimal cross-axis interference in combined radial-axial motion: Cross-axis sensitivity below 3% of primary sensitivity ensures that axial shaft displacement — common in machines with combined thrust and journal bearings — does not introduce false amplitude contributions into the radial vibration channel, maintaining measurement integrity in multi-axis motion environments.
• Factory-matched calibration eliminates field trim requirement: Because the probe, probe cable, and extension cable are calibrated as a set, the published scale factor is valid immediately upon installation without field adjustment of the driver gain potentiometer, reducing commissioning labor and eliminating the risk of calibration error introduced during field trimming.

Quality Assurance & Global Logistics

Each 330104-00-05-20-12-CN unit dispatched from siemensplc.com is sourced through verified Bently Nevada (Baker Hughes) supply channels and passes a structured pre-shipment inspection before leaving our Xiamen warehouse:

• OEM serial number authentication: Probe serial number is cross-referenced against the manufacturer’s production records to confirm unit authenticity and exclude refurbished or non-OEM assemblies.
• Thread and dimensional verification: M12 × 1 thread pitch, probe tip diameter, and CN connector geometry are checked against OEM dimensional drawings.
• Three-point scale factor verification: Gap voltage output is measured at 0.5 mm, 1.0 mm, and 1.5 mm reference gaps using a calibrated test fixture. Scale factor must fall within ±0.5% of 7.87 V/mm at all three points before the unit is cleared for shipment.
• Cable insulation resistance test: Shield-to-conductor insulation resistance is verified at >100 MΩ at 500 VDC to detect any cable damage sustained during storage or inbound transit.
• Original OEM packaging: Units ship in factory packaging with calibration documentation, product datasheet, and installation guide enclosed.
• 12-month replacement warranty: Covers manufacturing defects and calibration drift beyond the published ±0.5% tolerance from the date of shipment.

International shipments are dispatched from Xiamen, China via DHL Express or FedEx International Priority, with standard transit times of 3–7 business days to most global destinations. Air freight consolidation is available for multi-unit procurement orders. All shipments include a commercial invoice, packing list, and certificate of origin to support customs clearance. In-stock units ordered before 14:00 CST are eligible for same-day dispatch.

Contact Information

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