Bently Nevada 330908-00-18-10-02-05 Proximity Transducer – 3300 XL Series

Bently Nevada 330908-00-18-10-02-05 — Eddy-Current Proximity Transducer System for Critical Rotating Machinery

The 330908-00-18-10-02-05 is a factory-matched, three-component proximity transducer system manufactured by Bently Nevada under the 3300 XL platform. It is designed for continuous, non-contact measurement of radial shaft vibration and axial position displacement in high-speed rotating machinery. The system operates on the eddy-current principle: a high-frequency oscillator signal (nominally 1 MHz) is driven through the probe coil, inducing eddy currents in the conductive target surface. As the gap between probe tip and shaft changes, the reflected impedance modulates the oscillator, and the driver demodulates this signal into a calibrated DC voltage output proportional to displacement. This architecture eliminates mechanical contact, wear, and the signal latency inherent in contact-type sensors, making it the preferred transducer topology for API 670-compliant machinery protection systems in petrochemical, power generation, and heavy industrial facilities.

The 18-inch (457 mm) extension cable variant in this configuration is specified for installations where the bearing housing geometry requires an intermediate cable segment between the probe body and the driver/oscillator-demodulator unit. The 5-meter (16.4 ft) armored extension cable provides the signal path from driver to the monitor rack, with stainless steel armor providing mechanical protection against abrasion, crush loads, and chemical exposure typical of plant environments. All three components — probe, extension cable, and driver — are factory-calibrated as a matched set to the same target material (AISI 4140 steel, standard), ensuring system accuracy within the published specification without field recalibration of the monitor.

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Technical Parameters

Hardware Logical Analysis

Oscillator-Demodulator Architecture: The driver unit (330180-series) houses a Colpitts-type LC oscillator tuned to approximately 1 MHz. The probe coil forms part of the tank circuit. When the conductive target approaches the probe face, eddy currents dissipate energy from the oscillator, reducing oscillation amplitude. The demodulator stage rectifies and filters this amplitude-modulated signal, producing the –1 to –21 VDC output. The DC-coupled output means the system responds to static position (gap) as well as dynamic vibration — a critical requirement for combined radial vibration and thrust position monitoring on the same channel.

EMC Design: The armored extension cable uses a coaxial construction with a braided shield terminated at the driver chassis. This configuration provides greater than 60 dB of common-mode rejection against plant-frequency interference (50/60 Hz) and high-frequency switching noise from variable-frequency drives (VFDs) operating in the 2–20 kHz range. The stainless steel armor adds a second mechanical and electrostatic shield layer, reducing capacitive coupling from adjacent power cables routed in the same cable tray.

Thermal Stability: The probe coil is wound on a ceramic bobbin with a low thermal coefficient of inductance. Over the probe’s rated temperature range (–35°C to +121°C), sensitivity drift is maintained within ±1% of nominal (200 mV/mil), eliminating the need for temperature compensation circuitry in the monitor for standard applications. This is particularly relevant in steam turbine bearing pedestals where probe ambient temperatures can reach 90–110°C during full-load operation.

Matched-Set Calibration: Each 330908 system is calibrated as a three-component set (probe + extension cable + driver) against a certified AISI 4140 steel target on a precision gap bench. The calibration data is encoded in the driver’s serial number suffix, allowing the 3300 XL monitor to apply the correct scale factor without manual entry. Substituting components from different calibration lots introduces a systematic sensitivity error that is not detectable by the monitor’s self-test routines — a common source of false alarms and missed trips in field installations using mixed-lot spares.

Connector Integrity: The probe-to-extension cable connector uses a threaded coupling with a gold-plated center pin and PTFE dielectric. Contact resistance is specified at less than 10 mΩ, and the connector is rated for 500 mating cycles. In high-vibration environments, the threaded coupling prevents intermittent contact that would appear as broadband noise in the vibration spectrum, masking real machinery faults.

System Integration Benefits

• Direct 3300 XL Monitor Compatibility: The –24 VDC supply and –1 to –21 VDC output are natively accepted by all 3300 XL series monitor input cards (3300/16, 3300/20, 3300/25, 3300/46, 3300/55). No signal conditioning, shunt resistors, or input range adjustment is required at the monitor terminal block.
• API 670 Compliance for EPC Acceptance: The system is documented to API 670 (5th edition) requirements for sensitivity, linear range, frequency response, and temperature rating. This eliminates the need for third-party compliance testing during plant commissioning and simplifies EPC contractor acceptance procedures.
• DC-Coupled Output for Dual-Purpose Measurement: The DC-coupled output allows a single channel to simultaneously provide radial vibration (AC component, filtered by the monitor) and average shaft centerline position (DC component). This reduces channel count and wiring cost compared to systems requiring separate vibration and position transducers.
• 10 kHz Bandwidth for Sub-Synchronous Fault Detection: The flat frequency response to 10,000 Hz captures sub-synchronous instabilities (oil whirl at 0.43–0.48× running speed), synchronous imbalance, and super-synchronous blade-pass frequencies in a single measurement channel without aliasing or bandwidth-related phase error.
• IP67 Probe for Wet and Contaminated Environments: The IP67-rated probe assembly withstands direct oil spray, water washdown, and condensation without signal degradation. This is essential for bearing housings in wet-gas compressors and steam turbines where bearing oil mist is present at the probe installation point.
• Wide Operating Temperature for Multi-Zone Installation: The probe’s –35°C to +121°C rating covers both cryogenic service (LNG expanders, cold-box compressors) and high-temperature service (steam turbine HP sections, hot-gas expanders) within a single spare part number, reducing spare inventory complexity.
• Armored Cable for Mechanical Protection Without Conduit: The stainless steel armor eliminates the need for rigid conduit in many installations, reducing installation labor and allowing the cable to follow curved routing paths around bearing pedestals and baseplate structures without signal degradation.
• Deterministic Diagnostic Output for Monitor Self-Test: The 3300 XL monitor continuously checks the driver output voltage against the expected range for a properly gapped probe. An open circuit, short circuit, or out-of-gap condition drives the output outside the –1 to –21 VDC window, triggering a Not-OK (NOK) relay output within 100 ms. This deterministic fault detection ensures that a failed transducer is identified before it can mask a real machinery trip condition.
• Traceability for Regulated Industries: Each factory-matched set carries a unique serial number traceable to the calibration record. This supports the documentation requirements of ISO 55000 asset management programs and regulatory inspection regimes in nuclear, offshore, and refinery applications.

Quality Assurance & Global Logistics

Every 330908-00-18-10-02-05 unit supplied by siemensplc.com is sourced from verified distribution channels with full traceability to Bently Nevada’s manufacturing records. Incoming inspection covers visual examination of probe tip and connector surfaces, cable armor continuity, driver output voltage verification at a known gap, and connector mating force check. Units that do not meet the original manufacturer’s acceptance criteria are quarantined and not offered for sale.

Documentation supplied with each unit includes a Certificate of Conformance (CoC) referencing the original part number and serial number, the current Bently Nevada product datasheet, and — where available from new production stock — the factory calibration certificate. B2B customers requiring additional documentation (material test reports, country-of-origin certificates, export control classification) should specify requirements at the time of inquiry.

Shipments originate from Xiamen, China, with access to DHL Express, FedEx International Priority, and UPS Worldwide Express services. Standard in-stock orders are dispatched within 1–3 business days of payment confirmation. Export documentation — commercial invoice, packing list, CoC, and HS code 903180 declaration — is prepared for each shipment to facilitate customs clearance in the destination country. For orders requiring air freight to the Americas, Europe, Southeast Asia, or the Middle East, transit times of 3–7 business days are typical under normal customs conditions. Packing uses anti-static foam inserts with desiccant packs; armored cable is coiled to a minimum bend radius of 10× cable diameter and secured to prevent kinking during transit.

A 12-month warranty covers manufacturing defects in materials and workmanship from the date of shipment. Warranty claims are processed with return merchandise authorization (RMA) and replacement dispatch within 5 business days of confirmed defect verification.

Contact Information

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