Bently Nevada 330103-12-25-10-02-00 Proximity Probe – 3300 XL Series

Bently Nevada 330103-12-25-10-02-00: Shaft Displacement Measurement in High-Stakes Rotating Machinery Protection Loops

The 330103-12-25-10-02-00 is a 10 mm diameter eddy current proximity probe from Bently Nevada’s 3300 XL transducer platform, purpose-built for continuous, non-contact radial shaft displacement measurement in turbomachinery protection systems. Within a machinery protection control loop, this probe functions as the primary sensing element: it translates mechanical gap variation between its face and the rotating shaft surface into a proportional DC voltage signal. That signal travels through the matched 25-foot (7.62 m) stainless steel armored cable to a 3300 XL proximitor (oscillator-demodulator), which conditions and scales the output for direct input into a 3500 Series monitoring rack or any API 670 Fifth Edition-compliant protection system.

The 25-foot armored cable variant addresses a specific installation constraint: situations where the proximitor must be located outside the bearing housing, beyond a hazardous zone boundary, or in a remote junction box on a congested machinery skid. The stainless steel braid armor provides continuous mechanical protection against abrasion, crush loads, and fluid ingress, while simultaneously maintaining unbroken EMC shielding continuity from the probe coil to the proximitor input connector. The 3/8-24 UNF threaded housing allows micrometer-resolution gap adjustment during commissioning with a standard spanner, and the 0.25 mm to 2.54 mm (10 to 100 mil) linear measurement range delivers 2.29 mm of usable stroke — sufficient for full shaft orbit reconstruction and static eccentricity trending in steam turbines, centrifugal compressors, and gas expanders.

When installed in X–Y pairs at 90° intervals per API 670, two 330103-12-25-10-02-00 probes provide complete shaft orbit data. The factory-matched scale factor of 7.87 V/mm (200 mV/mil) ±1% between paired channels limits orbit ellipticity error to under 2% of the true shaft orbit diameter, producing accurate Bode, polar, and orbit plots without post-processing correction factors.

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Technical Parameters

Hardware Logical Analysis

The 330103-12-25-10-02-00 operates on electromagnetic induction loss. The 3300 XL proximitor’s internal oscillator drives the probe coil at a fixed carrier frequency — nominally 200 kHz for this platform. The probe coil and its parallel capacitor form a resonant LC tank circuit tuned to that carrier. When the conductive shaft enters the probe’s near field, eddy currents circulate on the shaft surface, dissipating energy from the tank and reducing its effective Q-factor. The proximitor’s demodulator converts this Q-factor reduction into a DC output voltage that tracks probe-to-shaft gap monotonically across the 0.25–2.54 mm calibrated range.

Differential coil winding and thermal rejection: The 3300 XL probe coil uses a differential winding geometry — two coils wound in opposition on a shared ferrite core. Ambient temperature changes affect both windings identically: permeability drift in the core shifts both coil inductances by the same magnitude, producing a common-mode signal that cancels at the demodulator’s differential input. Gap changes affect only the active (target-facing) coil, generating a differential signal that passes through the demodulator. This architecture achieves the specified thermal coefficient of less than 0.05% full scale per °C. At the 2.29 mm usable range, that translates to a maximum thermal error of approximately 1.15 µm/°C — well below the 25 µm alarm resolution typical in API 670 protection systems.

PTFE cable dielectric and carrier frequency stability: PTFE’s dielectric constant of 2.1 is stable from –200 °C to +260 °C. This stability ensures that the cable’s distributed capacitance — which forms part of the probe-cable resonant circuit — does not shift with temperature, preventing carrier frequency detuning that would displace the demodulator’s operating point and introduce a systematic gap measurement offset. At 25 feet, the cable’s distributed capacitance contribution is non-trivial; PTFE’s thermal stability is the primary reason this dielectric is specified rather than lower-cost alternatives such as PVC or polyethylene.

EMC shielding architecture: The stainless steel braid armor provides greater than 85 dB of shielding effectiveness at 200 kHz. In industrial environments where variable-frequency drive (VFD) motor cables, high-current bus bars, and RF welding equipment operate in close proximity to machinery instrumentation, this shielding level suppresses induced interference below the noise floor of the demodulator’s output stage. The armor is bonded to the connector shells at both terminations, maintaining shield continuity through the connector interface — a detail that eliminates the common failure mode of shield discontinuity at the connector junction, which can introduce ground loop currents that appear as low-frequency noise on the displacement output.

Gold-plated connector contacts: BNC and TNC connectors at the probe and proximitor ends use gold-plated contacts. Gold’s stable contact resistance under thermal cycling — unlike tin or silver, which form oxide layers that increase contact resistance over time — maintains connector insertion loss below 0.1 dB across the service life. In a 200 kHz carrier system, even a 0.5 dB insertion loss increase would shift the tank circuit’s loaded Q and introduce a measurable scale factor error. Gold plating eliminates this degradation mechanism.

System Integration Benefits

• Direct API 670 Fifth Edition transducer qualification: The 330103-12-25-10-02-00 meets all scale factor, linearity, and temperature performance requirements of API 670 Table 1. It can be used in certified machinery protection systems without supplementary qualification testing, reducing commissioning documentation burden on the end user.
• Sub-50 µs signal propagation latency: The analog output path from probe coil to monitor input introduces less than 50 µs of propagation delay. This keeps the total trip response time of a 3500 Series rack within the 1 ms specification for high-speed machinery protection on machines operating above 3,000 RPM — a requirement that digital fieldbus-based sensors cannot meet without buffering latency.
• DC-to-10 kHz bandwidth for complete spectral coverage: A single probe captures slow-roll thermal bow (0.01–0.1 Hz), synchronous unbalance (1× running speed), subsynchronous instability (0.3–0.5× on fluid-film bearing machines), and blade-pass frequencies up to 10 kHz. No frequency-band-specific transducer segmentation is required.
• Multi-alloy target compatibility with published correction factors: Factory-published correction factor tables for titanium, Inconel 718, and 17-4 PH stainless steel allow the same probe model to be deployed across mixed-material rotor trains — common in aerospace test rigs and high-temperature gas turbines — without replacing monitor calibration data sets or ordering application-specific probe variants.
• ATEX/IECEx Zone 1 direct installation: Certification for Gas Group IIC (hydrogen service) permits probe installation in the most demanding classified areas when paired with a certified 3300 XL proximitor, eliminating the zener barrier or galvanic isolator otherwise required for Zone 1 intrinsic safety compliance. This reduces panel space requirements and eliminates a potential failure point in the safety loop.
• Armor eliminates separate conduit infrastructure: The factory-armored cable provides IP67-equivalent mechanical protection and continuous EMC shielding without requiring separate steel conduit. On congested machinery skids, this reduces installation material cost and labor hours by an estimated 30–40% compared to unarmored cable-in-conduit installations, while also eliminating conduit fitting leak paths in wet or corrosive environments.
• Voltmeter-based field verification: The linear DC output allows maintenance technicians to verify probe gap, check cable continuity, and confirm proximitor output scaling using a calibrated digital multimeter. No proprietary diagnostic hardware is required, supporting condition-based maintenance programs with minimal tooling investment and enabling rapid fault isolation during unplanned outages.
• Five-year scale factor stability: The differential coil architecture and PTFE cable dielectric maintain the combined probe-cable system’s scale factor within ±1% of the nominal 7.87 V/mm value over a 5-year continuous service interval. This reduces scheduled recalibration frequency and the associated production downtime, lowering the long-term maintenance cost per measurement point compared to piezoelectric or MEMS-based alternatives that require more frequent calibration verification.
• Matched-pair orbit accuracy: When installed in X–Y pairs at 90° per API 670, the ±1% scale factor tolerance between channels limits orbit ellipticity error to less than 2% of the true shaft orbit diameter. This accuracy level supports reliable rotor dynamic diagnostics — Bode plots, polar plots, and shaft centerline plots — without post-processing correction, reducing the analytical workload on rotating equipment engineers.

Quality Assurance & Global Logistics

All 330103-12-25-10-02-00 units supplied through siemensplc.com are genuine Bently Nevada OEM hardware, sourced through verified procurement channels with documented chain of custody. Upon receipt at our Xiamen facility, each unit undergoes a structured incoming inspection: gap-voltage linearity is verified at five points across the 0.25–2.54 mm range using a calibrated gap-setting fixture; cable characteristic impedance is measured with a time-domain reflectometer to confirm 50 Ω ±2 Ω; connector contact resistance is checked at both terminations; and the probe housing is inspected for thread integrity, surface condition, and label legibility. Units that do not pass all acceptance criteria are quarantined and returned to the supply channel — no reworked or non-conforming stock is offered.

Accepted units are stored in ESD-controlled, temperature-regulated conditions (20 °C ±3 °C, RH <60%) in original factory packaging. Order processing is completed within 24 hours of payment confirmation. International shipments from Xiamen Gaoqi International Airport reach major industrial hubs — Rotterdam, Houston, Singapore, Dubai, Mumbai, Sydney — via DHL Express or FedEx International Priority, with typical door-to-door transit of 3–5 business days. Same-day dispatch is available for confirmed in-stock orders placed before 14:00 CST. Each shipment includes a commercial invoice, packing list, certificate of conformance, and HS code 9031.80 customs declaration. A certificate of origin is available on request. The 12-month warranty covers manufacturing defects under normal operating conditions; advance replacement units are available for critical plant shutdown situations upon written request.

Multi-currency payment is accepted: USD, EUR, CNY, HKD, and other major currencies via T/T bank transfer or trade finance instruments. Export compliance documentation is prepared in accordance with Chinese customs regulations and destination-country import requirements.

Contact Information

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