Bently Nevada 330104-12-18-50-02-00 Proximity Transducer – 3300 XL Series

Bently Nevada 330104-12-18-50-02-00: Eddy-Current Proximity Transducer for Continuous Shaft Displacement Monitoring

The Bently Nevada 330104-12-18-50-02-00 is a 5 mm eddy-current proximity transducer forming part of the 3300 XL Proximity Transducer System — a three-component measurement chain comprising probe, extension cable, and Proximitor sensor. This specific configuration ships with a 12 mm probe body, an 18-inch (457 mm) extension cable, and a 50-foot (15.24 m) interconnect cable terminated with a standard coaxial connector (suffix -02-00). The system operates on the eddy-current principle: a high-frequency oscillator within the Proximitor sensor drives an electromagnetic field through the probe tip coil; when a conductive target surface enters this field, induced eddy currents attenuate the oscillator amplitude, and the resulting voltage shift is linearized to produce a DC output proportional to gap distance.

In rotating machinery protection architectures, this transducer serves as the primary sensing element for radial shaft vibration and relative shaft position measurement. It feeds continuous analog voltage data — ranging from -1 VDC at minimum gap to -21 VDC at maximum gap — to Bently Nevada 3500 series monitor cards such as the 3500/40M and 3500/42M. These monitors apply alert and danger setpoints against the incoming signal, triggering protective relay outputs when shaft displacement exceeds safe operating thresholds. The 330104-12-18-50-02-00 is therefore not a passive sensor but an active participant in the machinery protection control loop, where measurement latency and signal fidelity directly determine the speed and accuracy of protective response.

The 50-foot interconnect cable length addresses the physical separation between machine bearing housings and remote instrument cabinets common in power plant and compressor station layouts. The 18-inch extension cable provides the mechanical standoff needed to route the probe through bearing housing walls while maintaining the required gap to the shaft surface — typically 50 mil (1.27 mm) for a 5 mm probe operating at the center of its linear range. The M8 × 1 thread on the probe body allows precise gap adjustment using a standard locknut assembly, with each full rotation changing the gap by 1 mm.

This part number is widely deployed in API 670-compliant machinery protection systems across power generation, oil and gas, petrochemical, and heavy manufacturing sectors. Its compatibility with the Bently Nevada 3500 rack infrastructure — the dominant platform for turbomachinery protection globally — means it functions as a direct replacement component in existing installations without requiring monitor reconfiguration or recalibration, provided the target material is AISI 4140 steel or an equivalent ferromagnetic alloy.

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Technical Parameters

Hardware Logical Analysis

The 3300 XL measurement chain is built around a Colpitts-type LC oscillator housed within the Proximitor sensor. The probe tip coil — wound on a ferrite core and encapsulated in a chemically resistant tip material — acts as the inductive element of this oscillator circuit. At nominal operating frequency (approximately 1.0 MHz for the 5 mm probe), the electromagnetic field penetrates the target surface to a depth governed by the skin effect formula: δ = √(2ρ / ωμ), where ρ is target resistivity, ω is angular frequency, and μ is magnetic permeability. For AISI 4140 steel at 1 MHz, this skin depth is approximately 8–12 μm — meaning the eddy-current interaction is confined to the immediate surface layer, making the measurement insensitive to shaft core metallurgy variations.

The Proximitor sensor’s demodulation circuit converts the oscillator amplitude envelope into a DC voltage with a transfer function of 200 mV/mil across the calibrated linear range. This linearity is maintained within ±1% of full-scale over the specified temperature range through internal temperature compensation circuitry. The coaxial cable construction of both the extension and interconnect cables provides continuous electromagnetic shielding, with the shield grounded at the Proximitor end only — a single-point grounding topology that eliminates ground loop currents that would otherwise appear as low-frequency noise on the output signal.

The –02 connector suffix designates a standard BNC-compatible coaxial termination, which maintains 50 Ω characteristic impedance along the cable run. At the 50-foot interconnect length, signal attenuation at 10 kHz remains below 0.1 dB — negligible relative to the DC-coupled output architecture. The probe body’s M8 × 1 thread pitch provides 1 mm of gap adjustment per revolution, allowing field technicians to set the nominal gap to 50 mil (1.27 mm) — the midpoint of the linear range — with a resolution of approximately 2.8 mil per 10° of rotation, sufficient for precise gap setting without specialized tooling.

EMC performance is achieved through the coaxial shielding architecture combined with the Proximitor sensor’s internal filtering. The output impedance of the Proximitor is low enough (typically <100 Ω) to drive long cable runs to monitor card inputs without susceptibility to capacitive loading or induced interference from adjacent power cables in cable trays. This is particularly relevant in power plant environments where 6.6 kV and 11 kV motor feeder cables may share cable routes with instrumentation wiring.

System Integration Benefits

• Direct 3500 Monitor Compatibility: The 330104-12-18-50-02-00 interfaces natively with Bently Nevada 3500/40M and 3500/42M monitor cards. No jumper changes, no software reconfiguration — the monitor reads the –200 mV/mil transfer function as a factory default, enabling like-for-like replacement without recalibration downtime.
• Deterministic DC-Coupled Output: The DC-to-10 kHz frequency response with a DC-coupled output means the monitor receives both static position data (shaft centerline position, thermal growth) and dynamic vibration data (1× and 2× running speed components) on a single channel, eliminating the need for separate position and vibration transducers on each bearing.
• API 670 Compliance: The 3300 XL system meets API Standard 670 (Machinery Protection Systems) requirements for proximity transducer systems, including sensitivity tolerance, temperature performance, and electrical safety. This simplifies compliance documentation for new installations and replacement projects in regulated industries.
• Non-Contact Measurement Eliminates Wear: With no physical contact between probe and shaft, there is zero mechanical wear on the sensing element. Mean time between replacement is determined by environmental factors (chemical exposure, thermal cycling) rather than mechanical fatigue, supporting multi-year maintenance intervals in clean environments.
• Shaft Orbit Analysis Capability: When installed in X–Y pairs at 90° orientation on a bearing housing, two 330104-series probes provide the orthogonal displacement signals required for shaft orbit plotting in Bently Nevada System 1 or equivalent condition monitoring software. Orbit analysis identifies rotor imbalance, misalignment, rub, and fluid instability from the shape and precession direction of the orbit pattern.
• Diagnostic Transparency via Gap Voltage: The DC output voltage at any operating condition directly indicates the probe-to-shaft gap. A technician can read the Proximitor output with a standard voltmeter and calculate the actual gap without removing the probe — a significant advantage during commissioning and troubleshooting without requiring the monitor to be online.
• Thermal Growth Tracking: The DC position component of the output tracks slow thermal expansion of the rotor during startup and shutdown transients. This data feeds into differential expansion calculations in the 3500 monitor, providing early warning of abnormal thermal behavior before vibration amplitudes increase.
• Standardized Cable Lengths Reduce Field Errors: The 18-inch extension + 50-foot interconnect configuration covers the majority of standard turbomachinery installations. Using factory-assembled, tested cable assemblies eliminates field-spliced connections — a common source of impedance discontinuities and moisture ingress that degrade signal integrity over time.

Quality Assurance & Global Logistics

Every 330104-12-18-50-02-00 unit supplied by siemensplc.com is sourced as genuine Bently Nevada (Baker Hughes) original equipment. Units are verified against OEM part number markings, connector specifications, and cable assembly dimensions prior to dispatch. Functional verification includes output voltage linearity checks across the calibrated gap range using calibrated gap simulation fixtures, confirming the 200 mV/mil transfer function within the specified ±1% tolerance band.

Packaging follows anti-static and mechanical protection protocols: probe tip and connector terminations are individually capped, cable assemblies are coiled to manufacturer-specified bend radius minimums, and the complete assembly is sealed in moisture-barrier packaging with desiccant. Each shipment includes a packing list and commercial invoice with full part number traceability for customs clearance.

Logistics operations are based in Xiamen, China — a major international port city with direct air freight connections to Singapore, Dubai, Frankfurt, Los Angeles, and Tokyo. Standard export documentation (commercial invoice, packing list, certificate of origin) is prepared for all international shipments. Air freight to Southeast Asia typically clears in 3–5 business days; to Europe and the Middle East, 5–7 business days; to North America, 5–8 business days. DHL, FedEx, and UPS express services are available for urgent replacement requirements. For large-volume orders, sea freight via Xiamen Port is coordinated with established freight forwarders.

Contact Information

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