Bently Nevada 330703-000-026-10-01-05 Proximity Probe – 3300 XL Series

Bently Nevada 330703-000-026-10-01-05 — 3300 XL 11mm Eddy-Current Proximity Probe for Critical Machinery Protection

The 330703-000-026-10-01-05 is a factory-calibrated, 11mm eddy-current proximity probe belonging to Bently Nevada’s 3300 XL platform — a measurement system that has established the reference standard for API 670-compliant shaft monitoring in turbomachinery and rotating equipment. This specific configuration carries a 0.26 m integral cable paired with a 10 ft (3.05 m) extension cable, a standard MIL-spec connector (code 01), and a standard probe body housing (code 05). The probe operates as one leg of a three-component matched system: probe body, integral cable, and extension cable are characterized together at the factory to produce a defined gap-voltage transfer function. Substituting any single element without recalibration shifts the output curve and introduces measurement error that cannot be corrected at the monitor level.

In a radial vibration measurement loop, the probe tip is positioned 1.0–1.5 mm from the shaft surface — within the linear region of the eddy-current field — and held in place by a threaded probe holder. The Proximitor® driver (e.g., 330180-X1-05) supplies a regulated −24 VDC excitation, generates a 1 MHz oscillator signal through the coil, and demodulates the impedance change caused by shaft proximity into a DC-coupled output at 200 mV/mil (7.87 V/mm) sensitivity. This output feeds directly into a 3500 or 3300 Series monitor channel, where gap DC voltage, 1× and 2× vibration amplitude, and phase angle are extracted in real time. The DC component simultaneously serves as a continuous gap health indicator: a drift beyond ±10% of the nominal gap voltage triggers a Not OK (NOK) relay state without any additional sensor.

The 330703-000-026-10-01-05 is deployed across gas turbines, steam turbines, centrifugal compressors, boiler feed pumps, and large induction motors where API 670 mandates non-contacting measurement with a frequency response flat from DC to at least 10 kHz. Its −35 °C to +177 °C operating envelope covers both arctic-rated outdoor installations and high-temperature bearing housings adjacent to steam paths. The AISI 4140 steel target specification is embedded in the calibration; installations on stainless or non-ferrous shafts require a separate calibration curve and are not interchangeable with standard 4140-based gap tables.

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Technical Parameters

Hardware Logical Analysis

The 3300 XL 11mm probe coil is wound on a ferrite core and encapsulated in a thermally stable polymer tip. The coil geometry is optimized for an 11mm target diameter, producing a field depth of approximately 2× the tip diameter — roughly 22 mm — which defines the minimum shaft diameter for valid measurement. Below this threshold, field fringing introduces nonlinearity at the extremes of the measurement range.

EMC performance is achieved through a coaxial cable construction with a continuous shield bonded at the Proximitor end only (single-point grounding). This topology eliminates ground-loop currents that would otherwise appear as low-frequency noise on the output signal. The shield is floating at the probe end, which prevents capacitive coupling from high-voltage motor windings or adjacent power cables from injecting common-mode interference into the measurement path. In installations where the probe cable runs parallel to power conductors for more than 0.5 m, Bently Nevada specifies a minimum 150 mm separation or the use of a grounded metallic conduit — not because the probe is inherently susceptible, but because the shield’s floating end can act as an antenna if the separation is insufficient.

The integral cable (0.26 m) is a fixed-length, factory-characterized segment. Its distributed capacitance and inductance are part of the resonant circuit that determines the Proximitor’s oscillator loading. Replacing the integral cable — even with an electrically identical cable of the same length — requires re-characterization because the probe-cable assembly is calibrated as a unit. The extension cable (10 ft, 330130-045-00-00 or equivalent) adds a defined capacitive load that the Proximitor’s output stage is designed to drive without gain error. Exceeding the specified extension cable length increases cable capacitance, reduces the high-frequency bandwidth of the output, and can cause the Proximitor to oscillate if the load impedance falls below the driver’s stability margin.

Thread engagement on the probe body (standard M14×1.5 or 3/8-24 UNF depending on variant) must achieve a minimum of 5 full turns into the probe holder to prevent vibration-induced loosening. Bently Nevada specifies a torque of 2.3 N·m (20 in·lb) for the locknut — insufficient torque allows micro-movement of the probe tip, which appears as a low-frequency modulation of the gap signal indistinguishable from actual shaft motion at sub-1 Hz frequencies.

System Integration Benefits

• Direct API 670 compliance path: When installed as a matched probe-cable-driver system, the 330703-000-026-10-01-05 satisfies API 670 Fifth Edition requirements for non-contacting vibration measurement without additional field calibration, reducing commissioning time on regulated assets.
• Deterministic gap health monitoring: The DC gap voltage output provides a continuous, real-time indication of probe-to-shaft clearance. Any mechanical shift — probe loosening, shaft thermal growth, or bearing wear — is immediately visible as a DC offset change, enabling predictive maintenance before vibration amplitude thresholds are reached.
• Flat DC-to-10 kHz frequency response: The measurement bandwidth covers sub-synchronous instabilities (oil whirl at 0.43–0.48×), synchronous 1× unbalance, and super-synchronous blade-pass frequencies up to 10,000 Hz, eliminating the need for separate sensors at different frequency ranges on a single measurement plane.
• Plug-and-play compatibility with 3500/3300 monitor racks: The 200 mV/mil sensitivity is the native input scaling of all 3300 XL-compatible monitor channels. No scaling factor entry or field adjustment is required; the monitor reads engineering units (mil pk-pk or µm pk-pk) directly from the probe output.
• Single-point grounding for noise immunity: The coaxial shield architecture eliminates ground loops in multi-probe installations where probe holders are at different electrical potentials — a common condition in large turbine pedestals with multiple bearing housings connected to different structural ground points.
• Wide thermal operating range for harsh environments: The −35 °C to +177 °C rating allows installation in both cryogenic service compressors and high-temperature steam turbine bearing housings without derating or special probe variants, reducing spare-parts inventory complexity.
• Traceability for regulated industries: Genuine Bently Nevada units carry factory calibration documentation and serial number traceability, satisfying quality management requirements in power generation, oil & gas, and petrochemical facilities operating under ISO 55000 asset management frameworks.
• Minimal installation footprint: The 11mm tip diameter and standard probe body allow installation in existing probe holders designed for the 3300 XL platform without machining modifications, preserving the mechanical integrity of the bearing housing.
• Keyphasor® phase reference compatibility: When used in conjunction with a Keyphasor probe on the same shaft, the 330703 series provides the amplitude and phase data required for vector-based balancing and orbit plot generation in the System 1 software environment.
• Redundant measurement architecture support: X–Y probe pairs installed 90° apart on the same measurement plane provide full orbit reconstruction. The matched sensitivity of both probes (200 mV/mil) ensures that the orbit plot is geometrically accurate without per-channel scaling correction.

Quality Assurance & Global Logistics

Every unit of the 330703-000-026-10-01-05 supplied through siemensplc.com is sourced from verified channels with full part traceability. Pre-shipment inspection covers visual examination of the probe tip and cable jacket for mechanical damage, dimensional verification of the thread engagement length, and electrical continuity and insulation resistance checks on the coaxial cable assembly. Units are packaged in anti-static bags within foam-lined boxes to prevent tip damage and cable kinking during transit — the most common cause of field failures in proximity probe assemblies.

Shipments originate from our warehouse in Xiamen, China, a major logistics hub with direct access to international freight forwarders serving North America, Europe, Southeast Asia, the Middle East, and Australia. Standard export documentation — commercial invoice, packing list, and certificate of origin — is prepared for each shipment. For projects requiring expedited delivery, DHL Express and FedEx International Priority services are available with typical transit times of 3–5 business days to major destinations. For bulk orders, sea freight consolidation from Xiamen Port is coordinated on request.

All supplied units carry a 12-month warranty from the date of shipment, covering manufacturing defects and calibration drift beyond the published tolerance band. Warranty claims are processed with replacement dispatch within 5 business days of defect confirmation. Counterfeit risk is mitigated through serial number verification against Bently Nevada’s published part number structure and label authentication checks prior to dispatch.

Contact Information

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