Bently Nevada 330703-000-100-10-02-00 Proximity Probe – 3300 XL 8mm

Bently Nevada 330703-000-100-10-02-00 — Eddy-Current Proximity Probe in the 3300 XL 8mm Transducer System

The 330703-000-100-10-02-00 is a non-contact eddy-current displacement transducer manufactured by Bently Nevada (Baker Hughes) as part of the 3300 XL 8mm Proximity Transducer System. Its primary function within a machinery protection control loop is to convert the physical air gap between the probe tip and a conductive target surface — typically the shaft journal — into a proportional DC voltage signal. This voltage is then processed by a matched Proximitor® sensor to produce a calibrated output used for radial vibration, axial position, and differential expansion monitoring in accordance with API 670.

The probe operates on the eddy-current principle: a high-frequency oscillator within the Proximitor® driver energizes a coil embedded in the probe tip, generating an alternating electromagnetic field. When a conductive target enters this field, eddy currents are induced on the target surface, loading the oscillator circuit and reducing its amplitude. The Proximitor® linearizes this amplitude change into a voltage output with a nominal sensitivity of 200 mV/mil (7.87 V/mm), providing a continuous, real-time analog representation of shaft position relative to the bearing centerline.

In a typical turbomachinery protection architecture, two probes are mounted 90° apart in the X–Y plane at each bearing journal. Their outputs feed into a 3500 Series monitoring rack, where the vector sum of the two channels yields the shaft orbit — a two-dimensional trajectory of the rotor centerline. Deviations from the baseline orbit pattern are the earliest detectable indicators of rotor instability, oil whirl, rub, or bearing degradation. The 330703-000-100-10-02-00 is the OEM-specified probe for this measurement chain, and its dimensional and electrical characteristics are factory-matched to the 3300 XL Proximitor® to ensure system-level calibration accuracy without field adjustment.

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Technical Parameters

Hardware Logical Analysis

The 330703-000-100-10-02-00 probe tip houses a precision-wound ferrite-core coil encapsulated in a thermally stable polymer compound. The encapsulant is selected for its low coefficient of thermal expansion, maintaining coil geometry — and therefore sensitivity — across the full operating temperature range of −35°C to +177°C. Dimensional stability of the coil geometry is critical: a 1% change in coil inductance translates directly into a calibration error at the Proximitor® output, which in a machinery protection context can mean the difference between a valid alarm threshold and a nuisance trip or, worse, a missed event.

The coaxial cable assembly uses a double-shielded construction: an inner braid shield referenced to the Proximitor® common, and an outer foil shield connected to the system ground at a single point. This topology suppresses both capacitively coupled interference from adjacent high-voltage cables and magnetically induced noise from motor stator fields and transformer leakage flux — both of which are present in the cable trays of a typical turbomachinery installation. The characteristic impedance of the cable is matched to the Proximitor® oscillator output impedance, preventing reflections that would introduce standing-wave errors in the high-frequency carrier signal.

The probe body is machined from 316L stainless steel, providing corrosion resistance in environments where bearing lube oil, process gas condensate, or steam leakage may contact the probe housing. The thread form and tip-to-shoulder dimension are held to tight tolerances to ensure that the installed gap — set during commissioning with a feeler gauge or gap voltage measurement — corresponds precisely to the midpoint of the linear range, maximizing the usable dynamic range for shaft displacement measurement.

EMC performance is further enhanced by the Proximitor®’s internal architecture, which uses a differential measurement technique: the oscillator amplitude is compared against an internal reference, and only the differential signal is amplified and linearized. This common-mode rejection suppresses power-supply noise and ground-loop interference that would otherwise appear as a DC offset or low-frequency modulation on the output signal — a particularly important characteristic in offshore and petrochemical installations where ground potential differences between equipment skids can reach several volts.

System Integration Benefits

• Zero-recalibration replacement: The 330703-000-100-10-02-00 is factory-calibrated as a matched set with the 3300 XL Proximitor®. Replacing a failed probe with an identical part number restores the original calibration curve without requiring a field sensitivity verification, reducing maintenance downtime to the time required for mechanical installation and gap setting.
• Deterministic analog output: The DC-coupled output with a flat frequency response from 0 Hz to 10 kHz ensures that both static position (axial thrust, differential expansion) and dynamic vibration data are captured on a single channel without phase distortion across the measurement bandwidth — a requirement for accurate orbit analysis and 1X/2X vector extraction.
• API 670 compliance without additional qualification: EPC contractors and end-users specifying API 670 machinery protection systems can incorporate this probe without additional type-testing, as the 3300 XL system holds third-party certification to the standard. This eliminates qualification lead time from project schedules.
• Broad target material compatibility: While optimized for AISI 4140 steel per API 670 Annex D, the probe can be recalibrated for alternative shaft materials (e.g., 17-4 PH stainless, Inconel 718) using the Bently Nevada material correction procedure, extending applicability to aerospace-derivative and high-alloy turbomachinery.
• Diagnostic transparency via 3500 rack integration: When connected to a Bently Nevada 3500 Series monitoring rack, the probe’s gap voltage is continuously monitored by the rack’s internal diagnostics. An out-of-range gap voltage — indicating probe damage, target loss, or cable fault — triggers a Not OK (NOK) relay output and a front-panel alarm, providing unambiguous fault localization without requiring a technician to physically inspect the probe.
• Redundant measurement architecture support: The probe’s low output impedance allows its signal to be split and fed simultaneously to a primary protection channel and a condition monitoring channel (e.g., a GE System 1 or OSIsoft PI data historian interface) without signal loading errors, supporting dual-use protection and predictive maintenance architectures.
• Long cable runs without signal degradation: The matched impedance coaxial cable system supports total probe-plus-extension cable lengths up to 9 meters (standard configurations) with negligible sensitivity deviation, enabling probe placement in confined bearing housings while routing the Proximitor® to an accessible junction box outside the hot zone.
• Intrinsically safe and ATEX-compatible configurations: Zone 1 and Zone 2 hazardous area installations are supported through the use of approved Zener barriers or galvanic isolators in the Proximitor® supply circuit, with the probe itself requiring no modification — simplifying ATEX documentation and zone classification compliance for offshore and onshore hydrocarbon processing facilities.

Quality Assurance & Global Logistics

Every 330703-000-100-10-02-00 unit dispatched from our Xiamen, China facility undergoes a structured pre-shipment inspection protocol. Coil resistance is measured and compared against the OEM specification band; values outside tolerance indicate winding damage or moisture ingress and result in unit rejection. Insulation resistance between the coil circuit and the probe body is verified at 500 VDC to confirm cable jacket integrity. Where test equipment permits, probe sensitivity is verified against a calibrated AISI 4140 target at the nominal gap distance, with the measured sensitivity recorded on the inspection certificate accompanying the shipment.

Units are individually packaged in anti-static, moisture-barrier pouches with desiccant, then placed in rigid foam-lined cartons to protect the probe tip and cable connector during transit. Each shipment includes a commercial invoice, packing list, and certificate of origin — documentation required for customs clearance in most import jurisdictions. Export from Xiamen is handled via DHL Express, FedEx International Priority, or consolidated sea freight depending on order volume and customer timeline. Transit times to major industrial hubs: Southeast Asia 2–4 days, Middle East 3–5 days, Europe 4–6 days, Americas 5–7 days (air freight). All shipments are tracked end-to-end with proactive status updates provided to the buyer.

Stock availability is maintained for the most common 3300 XL probe configurations. For less common cable length variants or high-temperature versions, lead times are confirmed at the time of quotation. A 12-month warranty against defects in materials and workmanship is provided on all units, covering failure under normal operating conditions as defined by the Bently Nevada installation and maintenance manual.

Contact Information

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