Bently Nevada 330104-00-06-50-01-00 Proximity Probe – 3300 XL Series

Bently Nevada 330104-00-06-50-01-00: 8mm Eddy Current Proximity Probe for Rotating Machinery Protection

The 330104-00-06-50-01-00 is an 8mm diameter eddy current proximity probe belonging to the Bently Nevada 3300 XL transducer series, manufactured by Baker Hughes. This probe is engineered for continuous, non-contact displacement measurement in rotating machinery protection systems, operating as the primary sensing element in a three-component measurement chain that includes an extension cable and a proximitor/oscillator driver. Its core function within a control loop is to convert mechanical shaft displacement — radial vibration, axial thrust position, or differential expansion — into a proportional DC voltage signal that feeds directly into machinery protection monitors such as the Bently Nevada 3500 series rack.

The probe generates a high-frequency electromagnetic field at approximately 1 MHz from its tip coil. When a conductive target (typically AISI 4140 carbon steel) enters this field, eddy currents are induced on the target surface. These eddy currents create a counter-magnetic field that loads the oscillator circuit in the proximitor, reducing the oscillation amplitude in direct proportion to the probe-to-target gap. The proximitor demodulates this amplitude-modulated RF signal into a linear DC voltage output ranging from –2 VDC (maximum gap, far position) to –18 VDC (minimum gap, near position), with a nominal sensitivity of 7.87 V/mm (200 mV/mil). This voltage is then sampled by the monitor at rates sufficient to resolve shaft vibration frequencies up to 10,000 Hz (–3 dB bandwidth), covering the full spectrum of interest for most turbomachinery applications including subsynchronous instabilities, synchronous unbalance, and blade-pass frequencies.

The 330104-00-06-50-01-00 carries a 0.6 m integral cable, calibrated for use with a 5.0 m extension cable (part series 330130-xx-xx), yielding a total system cable length of 5.6 m. This total length is a calibration-critical parameter: the distributed capacitance and inductance of the cable form part of the oscillator tank circuit. Substituting a non-matched extension cable length will shift the output voltage curve and invalidate the factory calibration, introducing measurement error that cannot be corrected at the monitor level without recalibration.

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Technical Parameters

Hardware Logical Analysis

Oscillator Tank Circuit & Cable Impedance Matching: The 3300 XL probe tip houses a precision-wound coil embedded in a ferrite-backed housing. This coil, together with the distributed capacitance of the integral and extension cables, forms the resonant tank circuit of the Colpitts-type oscillator inside the proximitor. The 5.6 m total cable length is not arbitrary — it is the exact electrical length at which the tank circuit was factory-tuned to achieve the specified 7.87 V/mm sensitivity and ±0.5% linearity across the 0.25–2.54 mm range. Any deviation in cable length alters the tank impedance, shifting the oscillation frequency and compressing or expanding the output voltage curve. This is why Bently Nevada specifies matched cable systems rather than field-adjustable lengths.

EMC Design & Shielding Architecture: The integral cable uses a double-layer coaxial construction: an inner conductor carrying the RF oscillator signal, surrounded by a polytetrafluoroethylene (PTFE) dielectric, enclosed in a braided copper shield, and jacketed in a chemically resistant outer sheath. The double-braid shield provides greater than 85 dB of RF attenuation across the 1 MHz operating frequency, suppressing interference from variable-frequency drives (VFDs), high-voltage bus bars, and adjacent instrumentation cables. The gold-plated coaxial connector at the probe-to-extension cable junction maintains shield continuity and prevents galvanic corrosion in humid or chemically aggressive environments.

Thermal Stability & Probe Tip Construction: The probe tip is hermetically sealed using a ceramic-filled epoxy compound rated to +177°C continuous. The coil winding uses a temperature-stable alloy wire with a low temperature coefficient of resistance, limiting sensitivity drift to less than ±0.5% across the full –35°C to +177°C operating range. This thermal stability is critical in steam turbine applications where bearing housing temperatures can exceed 150°C during sustained full-load operation.

Target Material Sensitivity & Correction Factors: The factory calibration curve is established using AISI 4140 steel targets with a surface resistivity of approximately 20 µΩ·cm. Targets with significantly different electrical resistivity — such as 17-4PH stainless steel (~80 µΩ·cm) or Inconel 718 (~125 µΩ·cm) — will produce a different eddy current density for the same gap, shifting the output voltage. Bently Nevada publishes target material correction curves; these must be applied at the monitor configuration level when non-standard target materials are used.

System Integration Benefits

• API 670 Measurement Chain Compliance: The 330104-00-06-50-01-00 is a certified component of an API 670-compliant measurement chain. When paired with the matched 330130-series extension cable and 330180-series proximitor, the complete system meets the linearity, sensitivity, and frequency response requirements of API 670 §5 without additional field calibration, reducing commissioning time on new machinery protection installations.
• Direct Monitor Compatibility: The –2 VDC to –18 VDC output is natively compatible with Bently Nevada 3500/42M, 3500/40M, 3500/45, and legacy 7200-series monitor input cards. No signal conditioning or scaling is required at the monitor input, preserving the full 16-bit ADC resolution of the 3500 rack for alarm and danger setpoint discrimination.
• Deterministic Real-Time Response: The DC-coupled output with 10 kHz bandwidth ensures that the monitor receives a continuous, latency-free signal. Unlike HART or fieldbus-based sensors, there is no protocol overhead or sampling jitter in the signal path between probe tip and monitor input, which is essential for machinery protection systems where trip response times must be less than 1 ms.
• Diagnostic Transparency via Gap Voltage: The DC component of the output voltage directly encodes the average probe-to-shaft gap. Operators can read the gap voltage at the monitor front panel or via Bently Nevada System 1 software to detect shaft centerline migration, bearing wear, or probe mounting looseness without removing the probe from service — a key advantage for condition-based maintenance programs.
• Redundant Measurement Architectures: The probe’s compact 8mm tip diameter allows installation in tight bearing housings where dual-probe redundant configurations (X-Y radial vibration per API 670 §5.3) are required. Two probes can be mounted at 90° ± 5° without mechanical interference in most standard bearing housings designed for 3300 XL probes.
• Hazardous Area Suitability: When the complete measurement chain is configured with an appropriate Zener barrier or galvanic isolator, the system can be certified for ATEX Zone 1 / IECEx Group IIC hazardous areas, enabling deployment in hydrogen-rich or hydrocarbon processing environments without additional intrinsic safety hardware at the probe level.
• Long-Term Calibration Stability: The absence of moving parts, combined with the hermetically sealed probe body and stable coil alloy, results in a calibration drift of less than ±1% per year under normal operating conditions. This stability reduces the frequency of mandatory calibration verification outages compared to contact-type displacement sensors.
• Backward Compatibility with Legacy 3300 Systems: The 3300 XL probe is electrically and mechanically backward-compatible with the earlier 3300 series (non-XL) proximitors and monitors, provided the total cable length is matched. This allows direct replacement of aging 3300 probes in existing installations without modifying cable routing, conduit, or monitor rack configuration.

Quality Assurance & Global Logistics

Every 330104-00-06-50-01-00 unit supplied by siemensplc.com is sourced as a genuine Baker Hughes / Bently Nevada component through verified industrial supply channels. Units undergo incoming inspection including coil resistance verification, output voltage linearity check at three gap points (0.5 mm, 1.27 mm, and 2.0 mm), and connector integrity test before being listed as available stock. A 12-month warranty against manufacturing defects is provided on all units; RMA processing is initiated within 48 hours of a confirmed fault report.

Shipments originate from our warehouse in Xiamen, China — a major international logistics hub with direct access to DHL Express, FedEx International Priority, and UPS Worldwide Expedited services. Standard transit times are 3–5 business days to Southeast Asia, 5–7 business days to Europe and the Middle East, and 5–8 business days to North America. All shipments include a commercial invoice, packing list, and certificate of conformance. ATEX/IECEx certificates and calibration records are available on request and can be included with the shipment documentation for regulatory compliance purposes.

Export classification and customs documentation are prepared in accordance with Chinese export regulations and the destination country’s import requirements. HS code 9031.80 applies to this product category in most jurisdictions. Customers requiring specific documentation formats for their procurement or customs clearance processes are encouraged to contact us prior to order placement.

Contact Information

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