Bently Nevada 330904-00-02-05-01-00 Proximity Probe – 3300 XL Series

Bently Nevada 330904-00-02-05-01-00: 8mm Eddy Current Proximity Probe for API 670 Machinery Protection Systems

In rotating machinery protection, the proximity probe is the primary sensing element that converts mechanical shaft displacement into a calibrated electrical signal. The Bently Nevada 330904-00-02-05-01-00 is an 8mm eddy current proximity probe designed as the field-sensing component of the 3300 XL 8mm Proximity Transducer System. Its function is straightforward but operationally critical: it generates a high-frequency electromagnetic field (typically 1.0–1.5 MHz oscillation frequency) that induces eddy currents in the conductive target surface. As the gap between probe tip and shaft changes, the eddy current loading on the probe coil changes proportionally, and the oscillator-demodulator (proximitor) converts this impedance variation into a DC voltage output at 200 mV/mil (7.87 V/mm) sensitivity. This signal feeds directly into the Bently Nevada 3500 Series Machinery Protection System or equivalent monitoring rack, where it is processed for vibration amplitude, phase, and position alarms.

The 330904 sub-series within the 3300 XL family is distinguished by its extended operating temperature ceiling of +177°C and enhanced coaxial cable shielding, making it the correct selection for high-temperature turbine bearing housings, hot-section compressor casings, and other environments where the base 330900 series would approach its thermal limits. The part number suffix -00-02-05-01-00 encodes the specific cable length (5 meters), connector configuration, and housing material — parameters that must be matched precisely to the extension cable and proximitor to maintain factory calibration accuracy across the full linear range of 0–80 mil (0–2.03 mm).

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Technical Parameters

Hardware Logical Analysis

The 330904-00-02-05-01-00 probe operates on the principle of mutual inductance perturbation. The probe coil, wound on a ferrite core and encapsulated within the stainless steel tip, forms the inductive element of an LC oscillator circuit housed in the proximitor. When the probe tip is positioned within its linear range above a conductive target, the oscillating magnetic 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, the skin depth is approximately 8–12 μm — meaning the eddy current interaction is confined to a thin surface layer, making the measurement highly sensitive to surface finish and material consistency.

The 3300 XL series addresses electromagnetic compatibility (EMC) through a triaxial cable architecture: the inner conductor carries the probe coil signal, the first shield layer provides electrostatic shielding against capacitive coupling from adjacent power cables, and the outer armor provides mechanical protection and a low-impedance ground return path. This construction achieves a common-mode rejection ratio (CMRR) sufficient to maintain measurement integrity in environments with 50/60 Hz power frequency interference levels up to several hundred millivolts — a practical requirement in motor control centers and switchgear rooms where proximity probes are often routed alongside power conductors.

The extended temperature rating of the 330904 sub-series is achieved through the selection of high-temperature fluoropolymer (PTFE or FEP) cable insulation and a hermetically sealed probe tip assembly. The coil winding uses a high-temperature magnet wire with polyimide insulation rated to 220°C, providing a thermal margin above the 177°C operating limit. The probe body threads are machined to a tolerance of ±0.01 mm to ensure repeatable installation depth when used with standard 3300 Series probe holders, which is critical because installation gap directly determines the DC bias point on the output voltage curve.

Redundancy in critical machinery protection applications is typically implemented at the transducer level by installing two probes at 90° (X-Y configuration) on each bearing journal. The 330904-00-02-05-01-00 is dimensionally compatible with standard dual-probe mounting brackets, and its 8mm tip diameter allows installation in bearing housings with bore clearances as tight as 12 mm, covering the majority of industrial turbomachinery bearing designs.

System Integration Benefits

• Direct API 670 compliance: The 330904-00-02-05-01-00 meets the 5th Edition API 670 standard for non-contacting vibration transducer systems, satisfying EPC contractor and insurance auditor requirements without additional field calibration documentation.
• Deterministic DC output: The analog DC voltage output (–2 VDC to –18 VDC across the linear range) is directly compatible with 3500 Series monitor input cards without signal conditioning, eliminating A/D conversion latency in the protection loop.
• Matched-system calibration traceability: Factory calibration is performed on the complete probe + extension cable + proximitor system as a matched set. Using the 330904 probe with the correct 330130-05 extension cable preserves the ±1% sensitivity tolerance across the full linear range.
• Broad frequency bandwidth: The DC to 10 kHz (–3 dB) frequency response captures both slow-roll runout at shaft speeds below 100 RPM and high-frequency subsynchronous instability events in compressors operating above 10,000 RPM, within a single transducer channel.
• Non-contact measurement eliminates wear: With no mechanical contact between probe and shaft, the transducer has no wear-related drift mechanism. Long-term sensitivity stability is governed by coil aging and cable dielectric stability, both of which are negligible over a 10-year service interval under normal operating conditions.
• Diagnostic transparency via gap voltage monitoring: The DC bias voltage at the proximitor output provides a continuous, real-time indication of probe-to-shaft gap. Operators can detect probe loosening, shaft centerline migration, or bearing wear by trending the DC gap voltage over time — without interrupting machine operation.
• Compatibility with System 1 software: When connected to a 3500 Series rack with Ethernet gateway, the 330904 transducer data is accessible in Bently Nevada System 1 condition monitoring software for trend analysis, alarm management, and predictive maintenance workflows.
• Interchangeable within 3300 XL family: The 330904-00-02-05-01-00 is dimensionally and electrically interchangeable with other 3300 XL 8mm probes of the same cable length suffix, allowing field replacement without re-routing cables or modifying monitor configuration — a significant advantage during planned maintenance windows with tight turnaround schedules.

Quality Assurance & Global Logistics

Every Bently Nevada 330904-00-02-05-01-00 unit supplied by siemensplc.com is sourced through verified industrial supply channels and subjected to a structured pre-shipment inspection protocol. Physical inspection covers probe tip integrity, cable jacket condition, connector pin alignment, and housing thread condition. Electrical pre-check includes coil DC resistance measurement and insulation resistance testing at 500 VDC between the inner conductor and shield, with acceptance criteria aligned to Bently Nevada factory test specifications. Part number markings, date codes, and manufacturer labels are cross-referenced against Bently Nevada documentation to confirm authenticity.

Packaging follows anti-static and moisture-barrier protocols: the probe assembly is individually wrapped in ESD-safe foam, sealed in a moisture-barrier bag with desiccant, and placed in a rigid outer carton with shock-absorbing padding. This packaging standard is designed to protect the precision-wound probe coil and cable assembly from mechanical shock and humidity exposure during international air freight transit.

Shipments originate from Xiamen, China, with access to DHL Express, FedEx International Priority, UPS Worldwide Express, and consolidated sea freight for volume orders. Standard air express transit times are 3–5 business days to Europe, 4–6 business days to North America, and 2–4 business days to Southeast Asia. Full export documentation — commercial invoice, packing list, certificate of conformance, and HS code declaration — is prepared for every shipment. Emergency and AOG (aircraft-on-ground equivalent) expedite requests are accommodated with same-day dispatch for in-stock units confirmed before 14:00 CST.

A 12-month warranty covers manufacturing defects and confirmed authenticity. Each shipment includes a certificate of conformance. Volume pricing is available for orders of 3 units or more; contact our technical team for a formal quotation with lead time confirmation.

Contact Information

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