Bently Nevada 330909-00-25-50-02-05 Proximity Probe – 3300 XL Series

Bently Nevada 330909-00-25-50-02-05 — Eddy-Current Proximity Probe for Continuous Shaft Displacement Monitoring

The 330909-00-25-50-02-05 is a 25 mm active-length, 5.0 m integral-cable eddy-current proximity probe belonging to Bently Nevada’s 3300 XL Proximity Transducer System. Its operating principle relies on the impedance change induced in a coil wound at the probe tip when a conductive target surface enters the electromagnetic field — a field generated by a high-frequency oscillator housed in the companion Proximitor® sensor. The resulting DC output voltage is linearly proportional to the gap between probe face and target, delivering a continuous, wear-free displacement signal with a nominal sensitivity of 7.87 V/mm (200 mV/mil).

Within a rotating-machinery protection architecture, this probe occupies the first link in the measurement chain: mechanical displacement → electromagnetic field perturbation → conditioned DC voltage → monitor card input. Because the transduction occurs without physical contact, the probe imposes zero mechanical load on the shaft and introduces no friction-induced measurement error. The 3300 XL series was designed to satisfy API 670 Fifth Edition requirements for machinery protection systems, making it the standard selection for steam turbines, gas turbines, centrifugal compressors, and large motor-driven pumps in hydrocarbon processing, power generation, and LNG facilities.

The M10 × 1.0 threaded body allows precise axial positioning within a standard proximity probe holder. The integral armored cable — 5.0 m in this configuration — routes the signal from the probe tip to the Proximitor® sensor without an intermediate extension cable, reducing connector count and the associated failure modes. The cable jacket is rated for continuous exposure to lubricating oils, process fluids, and the thermal gradients typical of bearing pedestals and seal housings.

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

Technical Parameters

Hardware Logical Analysis

Oscillator-Coil Coupling Architecture. The 3300 XL probe tip houses a precision-wound ferrite-core coil connected via the integral cable to the Proximitor® sensor’s internal oscillator, which operates at a fixed carrier frequency in the radio-frequency range (typically 1.0–1.5 MHz). The coil’s effective inductance and resistance — collectively its impedance — shift as a conductive target enters the near-field zone. The Proximitor® demodulates this impedance change into a DC voltage with a transfer function of 7.87 V/mm. The 25 mm active length in this SKU defines the coil geometry and, consequently, the linear range endpoint of 2.25 mm gap. Probes with shorter active lengths (e.g., 8 mm) produce a compressed linear range; the 25 mm variant is selected when larger gap clearances or higher shaft runout amplitudes must be accommodated.

EMC Design and Shielding. The armored integral cable provides a continuous coaxial shield from probe tip to Proximitor® input, suppressing capacitively coupled interference from adjacent power cables, variable-frequency drives, and high-current bus bars — all common in turbomachinery enclosures. The shield is grounded at the Proximitor® end only (single-point grounding), preventing ground-loop currents that would appear as low-frequency noise on the displacement signal. The 316 stainless steel probe body acts as a Faraday enclosure for the coil assembly, attenuating radiated EMI ingress from the bearing housing environment.

Thermal Stability and Compensation. Eddy-current sensitivity is a function of target material resistivity, which varies with temperature. The 3300 XL system’s Proximitor® sensor incorporates a temperature-compensation network calibrated for AISI 4140 steel targets (the API 670 reference material). For installations where target material deviates from 4140 — such as 17-4 PH stainless or Inconel shaft sleeves — a material correction factor must be applied during commissioning. The probe’s −35 °C to +177 °C rating covers the full range of bearing-pedestal temperatures encountered in steam-turbine exhaust ends and gas-turbine hot sections.

Signal Integrity Over 5 m Cable Run. The 5.0 m integral cable length is the maximum recommended for the 3300 XL system without an extension cable. Cable capacitance accumulates at approximately 100 pF/m; at 5 m, the total shunt capacitance remains within the Proximitor® oscillator’s drive capability, preserving the −3 dB bandwidth at 10,000 Hz. Installations requiring longer runs must use a matched 3300 XL extension cable and a recalibrated Proximitor® to maintain sensitivity accuracy within ±1%.

System Integration Benefits

• Zero-wear measurement chain: Non-contact transduction eliminates probe-to-shaft contact, removing the primary wear mechanism present in LVDT and contacting displacement sensors. Mean time between replacement intervals are measured in years under continuous operation.
• Deterministic DC output: The Proximitor® delivers a DC voltage proportional to gap with no sampling latency. The 3500 Series monitor reads this signal at its full A/D conversion rate, enabling alarm response times below 1 ms — critical for overspeed and high-vibration trip logic.
• API 670 system-level compliance: Using the 330909-00-25-50-02-05 within a 3300 XL / 3500 Series architecture satisfies the transducer system requirements of API 670 Fifth Edition without additional field calibration, simplifying insurance and regulatory documentation for new installations.
• Direct 3500 monitor compatibility: The probe’s output range (−2 VDC to −18 VDC at −24 VDC supply) maps directly to the 3500/40M and 3500/42M monitor card input specifications, eliminating signal conditioning adapters and the associated failure points.
• Diagnostic transparency via gap voltage: The DC gap voltage is continuously available on the Proximitor® output connector, allowing maintenance technicians to verify probe-to-shaft gap with a standard voltmeter during commissioning and periodic checks — no specialized test equipment required.
• Plug-compatible replacement: The M10 × 1.0 thread, 2-pin MIL-C-5015 connector, and 7.87 V/mm sensitivity are identical across the 3300 XL 25 mm probe family. A failed probe can be replaced without recalibrating the Proximitor® or reconfiguring the monitor card, minimizing planned-outage duration.
• Broad target material compatibility: While calibrated for AISI 4140, the probe operates with correction factors on 304/316 stainless, Inconel 718, and titanium alloy shafts — covering the full range of turbomachinery rotor materials encountered in petrochemical and aerospace-derivative applications.
• Hazardous-area variants available: ATEX Zone 1 and IECEx-certified versions of the 3300 XL probe are available for installations in classified areas (gas groups IIA/IIB, temperature class T4), enabling the same measurement architecture in offshore platforms and onshore hydrocarbon processing units.

Quality Assurance & Global Logistics

Every 330909-00-25-50-02-05 unit supplied by siemensplc.com is sourced through verified Bently Nevada (Baker Hughes) authorized distribution channels. Incoming inspection covers physical marking authentication, coil impedance measurement against factory test data, cable continuity and insulation resistance (≥100 MΩ at 500 VDC), and connector pin integrity. A Certificate of Conformance (CoC) with lot traceability is issued with each shipment and retained in our quality records for a minimum of five years.

Shipments originate from our warehouse in Xiamen, China. In-stock orders are dispatched within 1–3 business days under DHL Express, FedEx International Priority, or UPS Worldwide Expedited, with typical transit times of 3–5 business days to Europe, the Middle East, and Southeast Asia. For bulk procurement (10+ units), sea freight consolidation via FOB Xiamen is available with full export documentation: commercial invoice, packing list, CoC, and HS code 8543.70.9000. All units are packed in anti-static foam inserts within double-wall cartons to prevent transit damage to the probe tip and cable armor.

A 12-month warranty covers defects in materials and workmanship from the date of shipment. Warranty claims are processed within 5 business days of receipt of the returned unit, with replacement or credit issued upon confirmation of the defect.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
© 2026 siemensplc.com. All rights reserved.