Bently Nevada 330705-02-18-10-02-05 Proximity Transducer – 3300 XL Series

Bently Nevada 330705-02-18-10-02-05 — Eddy-Current Proximity Transducer for Continuous Shaft Monitoring in Rotating Machinery

The Bently Nevada 330705-02-18-10-02-05 is a field-proven eddy-current proximity transducer belonging to the 3300 XL series, designed for non-contact, continuous measurement of radial shaft vibration and axial position displacement in critical rotating machinery. Operating on the principle of electromagnetic induction, the probe generates a high-frequency oscillating magnetic field (typically 1.0–1.5 MHz) that induces eddy currents in the conductive target surface. The resulting impedance change in the probe coil is processed by the paired Proximitor® sensor into a calibrated DC voltage output proportional to the gap distance between probe tip and shaft surface.

This specific configuration — 18 mm probe length, M10×1 thread, 5 m extension cable — is engineered for installations where shaft access geometry constrains probe body dimensions, while the 5 m cable run accommodates standard machinery skid layouts without signal degradation. The system is factory-calibrated as a matched set (probe + extension cable + Proximitor® sensor), ensuring the published sensitivity of 7.87 V/mm (200 mV/mil) is maintained across the full operating temperature envelope without field recalibration.

In a typical turbomachinery protection loop, this transducer feeds its analog output directly into a Bently Nevada 3500 series monitor rack, where the signal is compared against API 670-defined alert and danger setpoints. The deterministic response time of the eddy-current measurement chain — from shaft displacement event to relay output — is well within the 20 ms window required by API 670 for machinery protection. This makes the 330705-02-18-10-02-05 a primary sensing element in safety-instrumented loops for steam turbines, gas compressors, and large centrifugal pumps where undetected rotor excursion can result in catastrophic mechanical failure.

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Technical Parameters

Hardware Logical Analysis

The 3300 XL transducer system employs a three-component matched architecture: the probe, the extension cable, and the Proximitor® sensor. Each component is characterized and matched at the factory to compensate for cable impedance variation, ensuring the overall system transfer function remains within ±0.5% of nominal sensitivity across the rated temperature range. This matched-set approach eliminates the field calibration errors that arise when components from different calibration batches are intermixed — a common source of measurement drift in third-party proximity systems.

The probe coil is wound on a ferrite core and encapsulated in a thermally stable polymer compound, providing mechanical isolation from vibration-induced coil movement that would otherwise introduce noise into the measurement signal. The stainless-steel probe body provides both structural rigidity and electromagnetic shielding, with the shield grounded at the Proximitor® sensor to establish a single-point ground reference and suppress common-mode interference from adjacent high-voltage cabling on the machinery skid.

EMC performance is achieved through the coaxial construction of the extension cable, which maintains a controlled characteristic impedance of 50 Ω throughout its 5 m length. The outer braid serves as both the signal return conductor and the EMI shield, with the shield terminated at the Proximitor® sensor chassis ground. This topology rejects radiated interference from variable-frequency drives, high-current bus bars, and RF sources commonly present in industrial machinery enclosures, maintaining signal integrity at the sub-millivolt level required for accurate sub-micron displacement measurement.

The Proximitor® sensor’s internal oscillator circuit is designed with a temperature-compensated LC tank circuit, maintaining oscillation frequency stability within ±0.1% across the full operating temperature range. This frequency stability is critical because any drift in oscillator frequency directly translates to a shift in the probe’s sensitivity coefficient, which would manifest as a false DC offset in the output signal — indistinguishable from actual shaft position change at the monitor level.

System Integration Benefits

• Direct API 670 compliance: The 330705-02-18-10-02-05 meets all API 670 Fifth Edition requirements for proximity transducer systems, including sensitivity tolerance, frequency response, and temperature performance, enabling direct use in machinery protection systems without additional qualification testing.
• Plug-compatible with 3500 monitor racks: The output signal format and connector pinout are fully compatible with Bently Nevada 3500/40M and 3500/42M Proximitor® monitor modules, allowing direct replacement of legacy 3300 series transducers without rewiring or reconfiguration of the monitor rack.
• Deterministic measurement latency: The analog output signal propagates from shaft displacement event to monitor input within 100 µs, supporting the real-time protection response requirements of API 670 without introducing digital processing latency.
• Zero mechanical wear: Non-contact eddy-current measurement eliminates probe wear, bearing loading, and lubrication requirements, supporting continuous 24/7 operation over multi-year maintenance intervals without sensor degradation.
• High common-mode rejection: The coaxial cable architecture and single-point grounding scheme provide greater than 60 dB common-mode rejection ratio (CMRR), suppressing ground loop interference from multi-point grounded machinery frames.
• Broad target material compatibility: While optimized for AISI 4140 steel, the system maintains calibrated accuracy on a range of ferromagnetic and non-ferromagnetic conductive target materials when the appropriate Proximitor® calibration curve is selected, supporting diverse rotor material specifications.
• Integrated diagnostic transparency: When connected to a 3500 series monitor, the system supports Bently Nevada’s System 1 condition monitoring software, providing continuous gap voltage trending, alert history logging, and transducer health diagnostics accessible via Ethernet without interrupting the protection function.
• Thermal stability across process extremes: The −35 °C to +121 °C operating range covers both arctic outdoor installations and high-temperature turbine bearing housings, eliminating the need for probe heating or cooling provisions in most industrial applications.

Quality Assurance & Global Logistics

Every Bently Nevada 330705-02-18-10-02-05 unit supplied through siemensplc.com is sourced from verified OEM distribution channels. Prior to dispatch, each unit undergoes a structured inspection protocol: label and serial number authentication against Bently Nevada’s published part number matrix, physical connector and cable integrity check, and packaging seal verification. Units showing any evidence of repackaging, label alteration, or connector damage are rejected and not offered for sale.

Shipments originate from our warehouse in Xiamen, China, with access to DHL Express, FedEx International Priority, and UPS Worldwide Expedited services. In-stock units are typically dispatched within 24–48 hours of order confirmation. Full export documentation is provided with every shipment, including commercial invoice, packing list, certificate of origin, and — upon request — a certificate of conformance referencing the unit serial number. The applicable HS Code for customs classification is 9031.80.90 (precision measurement instruments, non-electrical). A 12-month warranty covers manufacturing defects and calibration non-conformance from the date of shipment.

Contact Information

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