Bently Nevada 330180-50-CN Proximity Transducer – 3300 XL Series

Bently Nevada 330180-50-CN — Eddy-Current Proximity Probe for Continuous Rotating Machinery Protection

The 330180-50-CN is an 8 mm eddy-current proximity probe within the Bently Nevada 3300 XL Transducer System, designed for non-contact, continuous measurement of shaft radial vibration and axial position on critical rotating machinery. Operating on the principle of electromagnetic induction, the probe generates a high-frequency oscillating magnetic field (typically 1.0–1.5 MHz) that induces eddy currents in the conductive target surface. The resulting impedance change in the probe coil is processed by the matched Proximitor® driver into a DC-biased voltage output proportional to the gap between probe tip and shaft surface. This architecture eliminates mechanical contact entirely, making the sensor immune to wear-induced drift over multi-year continuous service intervals.

In a control loop context, the 330180-50-CN functions as the primary sensing element in a closed-loop machinery protection chain. Its analog output feeds directly into Bently Nevada 3500 or 3300 series monitor racks, which execute alarm and trip logic in hardware — independent of the DCS scan cycle. This hardware-level protection ensures deterministic response times below 20 ms from fault onset to relay actuation, a requirement that software-based protection cannot reliably satisfy in high-speed turbomachinery applications.

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Technical Parameters

Hardware Logical Analysis

The 330180-50-CN probe coil is wound on a ferrite core and encapsulated in a PEEK (polyether ether ketone) tip housing. PEEK provides a dielectric constant stable across the full –35 °C to +177 °C operating range, preventing thermally induced shifts in the coil’s self-inductance that would otherwise appear as false gap readings. The armored cable uses a triaxial construction: the inner conductor carries the RF signal, the inner shield is driven at the same potential as the center conductor (guard drive) to eliminate cable capacitance from the measurement circuit, and the outer shield provides EMC protection. This guard-drive topology is the primary mechanism by which the 3300 XL system achieves its specified linearity across the full 5 m cable run without requiring field calibration for cable length.

The matched Proximitor® driver (sold separately) contains a Colpitts oscillator whose resonant frequency is set by the probe coil inductance. As the target approaches the probe tip, eddy currents in the shaft surface load the oscillator, reducing its Q-factor and output amplitude. A precision demodulator converts this amplitude change to the –2 VDC to –18 VDC DC output. The demodulator’s temperature compensation network uses a thermistor network to correct for oscillator drift, maintaining scale factor accuracy within ±1% across the full driver temperature range. This hardware-level compensation eliminates the need for software correction tables in the monitoring rack, reducing configuration complexity and the risk of misconfiguration during rack commissioning.

From an EMC standpoint, the probe assembly meets IEC 61000-4-3 (radiated immunity, 10 V/m) and IEC 61000-4-6 (conducted immunity, 10 V RMS) without external filtering. The triaxial cable’s outer shield is grounded at the driver end only (single-point grounding), preventing ground loop currents that would introduce 50/60 Hz interference into the measurement signal — a common failure mode in installations where both ends of the shield are grounded.

System Integration Benefits

• Deterministic Hardware Trip Response: The analog output feeds directly into 3500 series monitor hardware, which executes alarm and trip relay logic in <20 ms — independent of DCS or PLC scan cycles, ensuring protection response is not subject to software scheduling latency.
• Direct 4–20 mA DCS Integration: Via the 3500/92 I/O module, the proximity signal is converted to a standard 4–20 mA loop for historian trending, APC (Advanced Process Control) inputs, and operator display — no additional signal conditioning required.
• Dual-Channel Orbit Plot Capability: Two probes mounted 90° apart on the same bearing journal provide X-Y shaft position data. The 3500 rack reconstructs the rotor orbit in real time, enabling detection of oil whirl, misalignment, and rub conditions that single-channel amplitude monitoring cannot distinguish.
• Gapless Frequency Coverage (DC–10 kHz): A single channel captures slow-roll runout at <1 Hz, synchronous 1× vibration, and subsynchronous instabilities up to 10 kHz — eliminating the need for parallel AC-coupled and DC-coupled measurement channels.
• Zero Scheduled Replacement Interval: Non-contact sensing eliminates wear mechanisms. Mean time between failures (MTBF) for the probe assembly exceeds 200,000 hours in clean industrial environments, reducing MRO inventory burden and planned shutdown scope.
• Diagnostic Transparency via Gap Voltage Monitoring: The DC bias component of the output (nominally –10 VDC at mid-gap) provides a continuous, real-time indication of probe-to-shaft clearance. Trending this value in the historian detects bearing wear, shaft bow, and probe fouling before vibration amplitude alarms activate.
• Drop-in Backward Compatibility: The 330180-50-CN is electrically and mechanically interchangeable with all prior 330180 series probes. Existing probe holders, extension cables, and Proximitor drivers require no modification, reducing retrofit engineering cost to zero.
• SIL-Capable Protection Chain: When integrated with a certified 3500 series rack and SIL-rated relay output module, the complete measurement chain can be assessed for IEC 61508 SIL 2 capability, supporting functional safety documentation requirements for API 670 machinery protection systems.

Quality Assurance & Global Logistics

Every 330180-50-CN unit dispatched from our Xiamen, China facility is sourced through verified Bently Nevada (Baker Hughes) authorized distribution channels with full lot traceability. Pre-shipment inspection covers visual conformance to OEM labeling and cosmetic standards, coaxial cable continuity and insulation resistance (>100 MΩ at 500 VDC), scale factor spot-check against a calibrated AISI 4140 reference target, and packaging integrity with anti-static bag, moisture-barrier desiccant, and foam-lined carton.

Export documentation includes a commercial invoice with HS Code 9031.80 (precision measuring instruments), packing list, and certificate of conformance. Calibration certificates with NIST-traceable reference data are available on request. Shipment is via DHL Express, FedEx International Priority, or UPS Worldwide Expedited from Xiamen Gaoqi International Airport (XMN), with typical transit times of 3–5 business days to Europe, 2–4 days to Southeast Asia, and 4–6 days to North America. Expedited same-day dispatch is available for orders confirmed before 14:00 CST. All shipments are fully insured and tracked door-to-door. A 12-month warranty covers manufacturing defects from the date of shipment.

Contact Information

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