Bently Nevada 330709-000-120-10-02-00 Proximity Probe – 3300 XL Series

Bently Nevada 330709-000-120-10-02-00 — 5 mm Eddy-Current Proximity Probe in the 3300 XL Transducer System

The 330709-000-120-10-02-00 is a 5 mm diameter eddy-current proximity probe manufactured by Bently Nevada (Baker Hughes) as part of the 3300 XL transducer platform. It functions as the primary sensing element in a three-component non-contact measurement chain — probe, extension cable, and proximitor/oscillator-demodulator — used to measure shaft radial vibration, axial position, and differential expansion on critical rotating machinery. The 120 mm armored integral cable variant is specified for installations where the probe-to-junction-box distance is short and mechanical protection of the coaxial line is required from the probe tip outward.

In a machinery protection architecture compliant with API 670 (5th Edition), this probe connects to a matched extension cable (total system cable length must equal the proximitor calibration length) and terminates at a 3300 XL proximitor driver. The proximitor supplies –24 VDC to the probe’s internal oscillator coil, which generates a radio-frequency electromagnetic field at approximately 1 MHz. When a conductive target — typically an AISI 4140 steel journal — enters the field, eddy currents are induced on the target surface, loading the oscillator and reducing field amplitude. The proximitor demodulates this amplitude change into a calibrated DC voltage output ranging from –2 VDC (near gap) to –18 VDC (far gap), with a nominal scale factor of 7.87 V/mm (200 mV/mil) at a 1.27 mm (50 mil) nominal air gap.

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Technical Parameters

Hardware Logical Analysis

The 330709-000-120-10-02-00 probe body houses a precision-wound sensing coil embedded in a thermoplastic tip, potted with epoxy compound rated to 177 °C. The coil geometry is optimized for a 5 mm tip diameter, which defines the effective sensing field diameter — approximately 2× the tip diameter, or roughly 10 mm. This field diameter governs the minimum shaft diameter for accurate measurement (shaft OD must be ≥ 5× probe tip diameter per API 670 guidance, i.e., ≥ 25 mm) and the spatial resolution of the gap measurement.

The armored integral cable on this variant uses a stainless steel braid over the coaxial dielectric, providing mechanical protection against abrasion from turbine bearing pedestal hardware, oil splash, and steam condensate. The 120 mm length is intentionally short — it positions the first coaxial connector junction at a point where the cable can transition to a standard 330130 or 330180 extension cable routed through conduit to the junction box. This architecture isolates the mechanically vulnerable probe-tip region from the longer, more accessible cable run.

EMC performance is governed by the coaxial construction throughout the signal chain. The shield continuity from probe tip to proximitor input suppresses common-mode interference from variable-frequency drives, high-voltage bus bars, and RF sources common in turbine halls. The proximitor’s internal demodulation circuit operates at the fixed ~1 MHz carrier, which sits above the frequency band of most industrial EMI sources (50/60 Hz harmonics, VFD switching at 2–20 kHz), providing inherent rejection of low-frequency electrical noise without additional filtering. The DC-to-10 kHz flat frequency response ensures that sub-synchronous instabilities (oil whirl at 0.43–0.48× running speed), synchronous 1× unbalance, and super-synchronous blade-pass frequencies are all captured within a single measurement channel without aliasing.

The M10 × 1.0 probe body thread provides fine-pitch adjustment for gap setting during commissioning. Each full rotation of the probe body changes the gap by 1.0 mm, allowing precise positioning to the 1.27 mm nominal gap with a calibrated gap tool. The locknut design prevents gap drift under vibration, maintaining measurement accuracy over extended operating periods between scheduled outages.

System Integration Benefits

• Direct 3300 XL platform compatibility: The 330709-000-120-10-02-00 is factory-calibrated for use with 3300 XL proximitor drivers (e.g., 330180-X1-05). No field calibration is required for standard AISI 4140 targets when total system cable length matches the proximitor specification, reducing commissioning time and eliminating calibration error as a source of measurement uncertainty.
• API 670 machinery protection compliance: The probe’s electrical characteristics — scale factor, frequency response, and output range — satisfy the transducer performance requirements of API 670 (5th Edition) for radial vibration, axial position, and differential expansion channels. This simplifies third-party safety system audits and insurance inspections.
• DC-coupled output for static position measurement: The DC-to-10 kHz frequency response allows simultaneous measurement of dynamic vibration (AC component) and static shaft position (DC component) from a single probe channel. This eliminates the need for separate position sensors on machines where both parameters must be monitored (e.g., axial thrust on compressors).
• Non-contact operation eliminates mechanical wear: With no physical contact between probe tip and rotating shaft, the sensing element has no wear mechanism. Mean time between replacement is governed by thermal degradation of the tip potting compound and cable jacket, not by mechanical fatigue — extending maintenance intervals compared to contact-type sensors.
• Wide operating temperature range for hot-section installations: The –35 °C to +177 °C rating covers bearing housing temperatures on gas turbines, steam turbines, and high-speed compressors without requiring probe cooling or thermal isolation hardware, simplifying installation design.
• Armored cable for harsh bearing pedestal environments: The stainless steel braid armor resists cutting and abrasion from turbine hardware, oil mist, and steam, reducing cable failure as a cause of spurious trips or false alarms in the machinery protection system.
• Deterministic scale factor for system-level accuracy: The 7.87 V/mm (200 mV/mil) scale factor is consistent across the 3300 XL probe family, allowing monitoring system (e.g., Bently Nevada 3500 rack, System 1) alarm and trip setpoints to be configured in engineering units (µm or mil) without per-probe calibration data entry.
• Compatibility with non-Bently monitoring systems: The –24 VDC supply / DC voltage output interface is an open standard used by multiple machinery monitoring platforms. The 330709-000-120-10-02-00 can be integrated with third-party systems (e.g., Emerson AMS 6500, Metrix ST5484E) provided the monitoring system input impedance and voltage range are compatible, protecting the instrumentation investment if the monitoring platform is upgraded.
• Traceable documentation chain: Each unit ships with original Bently Nevada / Baker Hughes labeling, part number markings, and batch traceability. Calibration certificates and material test records are available on request, supporting quality management system requirements (ISO 9001, IATF 16949) at the end-user facility.

Quality Assurance & Global Logistics

Every 330709-000-120-10-02-00 unit dispatched from our Xiamen, China facility is sourced from authorized Bently Nevada / Baker Hughes distribution channels or verified OEM-surplus inventory. Prior to dispatch, each probe undergoes a pre-shipment inspection covering connector pin integrity, coaxial cable continuity (measured with a calibrated LCR meter), tip condition (visual and dimensional check), and label/part-number verification against the purchase order. Units that do not pass inspection are quarantined and not shipped.

Packaging follows anti-static and moisture-barrier protocols: the probe is placed in a conductive foam insert, sealed in a moisture-barrier poly bag with desiccant, and packed in a rigid outer carton labeled with the full part number, serial number (where available), and shipment date. This packaging standard protects the coaxial connector and probe tip during international air freight handling.

From Xiamen, we ship via DHL Express, FedEx International Priority, and UPS Worldwide Express to destinations across Europe, North America, Southeast Asia, the Middle East, and Australia. In-stock units are dispatched within 1–3 business days of order confirmation. For urgent plant shutdowns or unplanned outages, same-day dispatch is available for orders confirmed before 14:00 CST — contact us directly to arrange. All shipments include a tracking number and commercial invoice with HS code pre-filled for customs clearance. A 12-month warranty covers manufacturing defects; warranty claims are processed with replacement dispatch within 5 business days of defective unit receipt.

Contact Information

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