Bently Nevada 330903-00-24-10-01-00 Proximity Transducer – 3300 XL Series

Bently Nevada 330903-00-24-10-01-00 — Eddy-Current Proximity Transducer in Rotating Machinery Protection Loops

The 330903-00-24-10-01-00 is an 8 mm eddy-current proximity transducer manufactured by Bently Nevada as part of the 3300 XL product family. Its primary function within a machinery protection loop is to convert the physical gap between the probe tip and a conductive target surface into a proportional DC voltage signal, delivering continuous, non-contact measurement of radial shaft vibration, axial thrust position, and differential expansion across a broad frequency spectrum. The transducer operates as the sensing element of a three-component system — probe, extension cable, and Proximitor® driver — and is the field-mounted component most directly exposed to the mechanical and thermal environment of the monitored machine.

In a typical API 670-compliant installation, the probe is threaded into a bracket welded or bolted to the bearing housing, positioned perpendicular to the shaft journal. The eddy-current field generated by the probe tip oscillator interacts with the shaft surface; any change in gap modulates the oscillator loading, which the Proximitor® driver converts to a calibrated voltage output at 200 mV/mil (7.87 V/mm). This signal is routed to a Bently Nevada 3500 series monitor card — typically the 3500/40M or 3500/42M — where it is compared against alarm and danger setpoints in real time. The 330903-00-24-10-01-00 is the standard 24-inch integral cable variant, suited for installations where the junction box or conduit entry is within approximately 610 mm of the probe mounting point.

Deployment environments for this transducer span the full range of rotating machinery in process industries: steam turbines in power generation, centrifugal and axial compressors in gas processing, boiler feed pumps in thermal plants, and integrally geared compressors in air separation units. Its ATEX, FM, and CSA certifications permit installation in Zone 1 / Division 1 classified areas without additional barriers when used with the appropriate Proximitor® driver configuration.

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Technical Parameters

Hardware Logical Analysis

The 330903-00-24-10-01-00 probe operates on the Lenz’s law eddy-current principle. The Proximitor® driver supplies a high-frequency oscillator signal — nominally 1 MHz — through the coaxial cable to the probe coil wound at the tip. When the probe tip is positioned within its linear range of a conductive target, the oscillating magnetic field induces eddy currents in the target surface. These eddy currents create a counter-magnetic field that loads the oscillator circuit, reducing its amplitude in proportion to the gap distance. The Proximitor® driver demodulates this amplitude-modulated carrier and outputs a DC voltage linearly proportional to gap: at 90 mil (2.29 mm) gap the output is approximately −18 VDC; at 0 mil (contact) it approaches 0 VDC.

The 24-inch armored integral cable is a critical design element. The cable forms part of the tuned LC circuit between probe coil and Proximitor® driver; its characteristic impedance and capacitance per unit length are matched to the driver’s oscillator design. Substituting a non-OEM cable of different capacitance shifts the resonant frequency and degrades sensitivity calibration. The armor jacket — typically stainless steel braid over PTFE dielectric — provides mechanical protection against abrasion and vibration fatigue at the probe-to-cable junction, which is the highest-stress point in the assembly during machine operation.

EMC performance is achieved through the coaxial cable geometry itself: the shield conductor carries the return current and attenuates external RF interference before it reaches the probe coil. The Proximitor® driver’s internal filtering further rejects common-mode noise on the supply rail. In installations near variable-frequency drives or high-current bus bars, additional shielded conduit is recommended per Bently Nevada installation guidelines to maintain signal integrity below 1 mV RMS noise floor at the monitor input.

The probe tip material — typically a non-magnetic, non-conductive housing with a ferrite-core coil — ensures that the eddy-current field is confined to the axial direction, minimizing sensitivity to lateral electromagnetic interference from adjacent probes. In dual-probe configurations (X-Y radial vibration), the 90° angular separation combined with the probe’s directional field geometry prevents cross-coupling between channels, maintaining channel-to-channel isolation above 40 dB across the operating frequency band.

System Integration Benefits

• Direct 3500 Rack Compatibility: The 330903-00-24-10-01-00 is the factory-specified input transducer for Bently Nevada 3500/40M and 3500/42M monitor cards. No signal conditioning adapter or impedance matching network is required; the probe-cable-driver system presents a calibrated −24 VDC output directly to the monitor’s BNC or terminal block input.
• Zero-Wear Measurement Principle: Non-contact eddy-current sensing eliminates mechanical contact between sensor and shaft. There is no wear mechanism, no lubrication requirement, and no scheduled replacement interval driven by sensor degradation — only periodic calibration verification per API 670 Annex D.
• Deterministic Frequency Response: The flat frequency response from DC to 10,000 Hz ensures that the monitor card receives an undistorted representation of shaft motion across all relevant frequency components: 1× (unbalance), 2× (misalignment), sub-synchronous (fluid instability), and high-frequency blade-pass events — all within a single measurement channel.
• Slow-Roll Runout Compensation: The DC-coupled output allows the 3500 monitor to capture slow-roll waveform data at shaft speeds below 600 RPM during startup and coast-down. This data is used to subtract mechanical and electrical runout from the vibration vector, improving alarm accuracy at operating speed.
• Axial Position Dual-Use: The same probe model, when mounted against a thrust collar target, measures axial shaft position with the same 200 mV/mil sensitivity. This eliminates the need for a separate sensor family for thrust monitoring, reducing spare parts inventory and simplifying technician training.
• Hazardous Area Deployment: FM, CSA, and ATEX certifications allow direct installation in Zone 1 / Division 1 classified areas when paired with the appropriate Proximitor® driver configuration. No additional Zener barriers or galvanic isolators are required in the standard intrinsically safe configuration, reducing panel wiring complexity.
• Diagnostic Transparency via Gap Voltage: The Proximitor® driver’s DC output voltage at any operating condition directly indicates the physical probe-to-shaft gap. Technicians can verify correct probe installation gap (typically 50 mil / 1.27 mm nominal) with a standard DC voltmeter without removing the probe or interrupting machine operation.
• Drop-in Field Replacement: The 330903-00-24-10-01-00 is dimensionally and electrically interchangeable with all previous 3300 XL 8 mm probes of the same cable length. No recalibration of the 3500 monitor card is required after replacement, provided the same Proximitor® driver model is retained — a critical operational advantage during unplanned maintenance windows.

Quality Assurance & Global Logistics

Every 330903-00-24-10-01-00 unit dispatched from our Xiamen facility is sourced from verified supply channels and subjected to a structured pre-shipment inspection protocol. Each probe undergoes visual examination of the tip housing, armored cable jacket, and MIL-C-5015 connector body for mechanical damage, corrosion, or contamination. The part number label and date code are cross-referenced against Bently Nevada factory markings. Electrical continuity of the probe coil and cable shield is verified, and insulation resistance between the center conductor and shield is measured to confirm cable dielectric integrity.

Units are dispatched in ESD-safe packaging with desiccant to prevent moisture ingress during transit. Export documentation — commercial invoice, packing list, and certificate of origin — is prepared for all international shipments. Customs HS code 9026.80 is applied for proximity transducer exports. Standard international transit time from Xiamen to major industrial hubs is 3–7 business days via DHL Express or FedEx International Priority. For project-critical deliveries, same-day dispatch is available for orders confirmed before 14:00 CST. All units carry a 12-month warranty from the date of shipment against manufacturing defects and calibration drift beyond OEM tolerance.

Contact Information

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