Bently Nevada 330904-00-11-10-02-05/CN Proximity Probe – 3300 NSv

Bently Nevada 330904-00-11-10-02-05/CN — Eddy-Current Proximity Probe for Turbomachinery Shaft Monitoring

The 330904-00-11-10-02-05/CN is an 8 mm eddy-current non-contacting proximity probe with a 5-metre integral cable assembly, designed for the Bently Nevada 3300 NSv measurement platform. It operates as the primary sensing element in API 670-compliant machinery protection systems, converting shaft-to-probe gap changes into a proportional DC voltage signal with a nominal scale factor of 7.87 V/mm (200 mV/mil). The probe is engineered for continuous, unattended operation in the bearing housings of steam turbines, gas turbines, centrifugal compressors, and large rotating machinery where shaft radial vibration and axial position must be measured simultaneously on a single channel.

Unlike piezoelectric accelerometers, which respond only to dynamic acceleration, the eddy-current probe delivers a true DC-coupled output. This means the same channel captures both static gap (rotor position) and dynamic vibration amplitude without signal conditioning compromises. For machinery protection engineers, this dual-function characteristic eliminates the need for a separate position sensor on each bearing plane, reducing wiring complexity and potential failure points in the measurement loop.

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Technical Parameters

Hardware Logical Analysis

The 330904-00-11-10-02-05/CN operates on the principle of Faraday induction: the driver/oscillator energizes the probe coil at a carrier frequency typically between 500 kHz and 2 MHz. When a conductive target enters the electromagnetic field, eddy currents are induced on the target surface, loading the coil and reducing its effective inductance. The driver circuit detects this impedance shift and converts it to a proportional DC output voltage. The 5-metre cable in this variant introduces a defined distributed capacitance and inductance that is factory-compensated in the matched driver calibration — substituting a non-matched cable length will shift the scale factor and invalidate API 670 compliance.

EMC Design: The armored cable construction provides a continuous Faraday shield from the probe tip to the driver input, attenuating radiated interference from adjacent high-voltage cables, variable-frequency drives, and RF sources common in turbomachinery environments. The shield is grounded at the driver end only (single-point grounding) to prevent ground-loop currents that would appear as low-frequency noise on the vibration channel.

Thermal Stability: The probe coil former is wound on a ceramic mandrel with a low coefficient of thermal expansion. This minimizes thermally induced gap offset errors in hot-section installations where bearing housing temperatures can exceed 150 °C during steady-state operation. The –35 °C lower limit accommodates cold-climate outdoor installations and cold-start conditions without probe sensitivity drift.

Target Material Sensitivity: Factory calibration is performed against AISI 4140 steel per API 670 Annex D. For non-standard shaft alloys — Inconel 718, 17-4 PH stainless, or titanium — the effective scale factor deviates due to differences in electrical conductivity and magnetic permeability. Field recalibration or application of a published material correction factor is mandatory for these cases to maintain measurement accuracy within ±1%.

Matched System Architecture: The probe, extension cable, and driver form a three-element matched measurement chain. The 330904-00-11-10-02-05/CN is calibrated as a unit with its 5 m cable; the driver (e.g., 3300 XL 8 mm) is then calibrated against this probe-cable assembly. Replacing any single element without recalibrating the chain introduces a systematic scale factor error that will not be detected by the monitor’s self-test routines.

System Integration Benefits

• Single-channel dual measurement: DC-coupled output captures both static shaft position and dynamic vibration amplitude simultaneously, eliminating the need for a dedicated position sensor on each bearing plane.
• Direct rack compatibility: Electrically and mechanically compatible with Bently Nevada 3300 NSv, 3500, and 3701 monitor racks without hardware modification or re-ranging of the monitor card.
• Deterministic signal latency: Analog output with no digital conversion delay; the monitor receives a real-time continuous signal, enabling alarm and trip response within the monitor’s configured time constant — typically <1 ms for trip functions.
• Diagnostic transparency: The –2 VDC to –18 VDC output range provides clear out-of-range indication: a reading above –2 V indicates probe-to-target gap too small (contact risk); below –18 V indicates gap too large or open-circuit cable fault, both detectable by the monitor’s OK relay logic.
• Zero mechanical wear: Non-contacting measurement principle eliminates sensor wear regardless of shaft speed or vibration amplitude, supporting continuous online monitoring without scheduled sensor replacement intervals.
• High-frequency bandwidth: 10 kHz flat response captures sub-synchronous instabilities (oil whirl, oil whip), synchronous 1× imbalance, and super-synchronous harmonics up to the 10th order on a 60,000 RPM machine — all within a single sensor channel.
• Hazardous area compatibility: The probe body is intrinsically safe when paired with an approved Zener barrier or galvanic isolator, enabling deployment in ATEX Zone 1 / IECEx Zone 1 classified areas without additional enclosure requirements.
• Reduced commissioning time: Factory-matched calibration record supplied with each unit allows direct verification of scale factor at the monitor input during loop check, eliminating the need for a field calibration rig at installation.
• Long-term measurement stability: Ceramic coil former and stainless steel body resist creep and dimensional change over multi-year service intervals, maintaining scale factor within specification without periodic recalibration of the probe itself.

Quality Assurance & Global Logistics

Every 330904-00-11-10-02-05/CN unit dispatched from our Xiamen facility undergoes a structured pre-shipment verification protocol. Electrical checks include scale factor measurement at three gap points within the linear range, frequency response spot-check at 1 kHz and 5 kHz, and insulation resistance verification on the cable shield. Physical inspection covers probe tip concentricity, cable armor integrity, and connector seating. Units that do not meet the original Bently Nevada factory specification are quarantined and not offered for sale.

Documentation supplied with each shipment includes the original datasheet, a pre-shipment inspection record with measured scale factor, and a certificate of conformance (CoC) available on request. Packaging uses an anti-static foam insert inside a moisture-barrier sealed bag, with the outer carton rated for international air freight handling per ISTA 2A.

Logistics from Xiamen, China: standard dispatch via DHL Express or FedEx International Priority with typical transit times of 3–5 business days to Europe, North America, and Southeast Asia. EXW Xiamen and CIF destination Incoterms are both available. Export documentation — commercial invoice, packing list, and HS code declaration — is prepared for each shipment to facilitate customs clearance. For urgent plant shutdowns or unplanned outages, same-day dispatch is available for orders confirmed before 14:00 CST.

A 12-month warranty covers manufacturing defects and out-of-specification performance from the date of shipment. Warranty claims are processed with a replacement unit dispatched before the defective unit is returned, minimizing plant downtime exposure.

Contact Information

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