Bently Nevada 330904-00-03-10-02-05/CN Proximity Probe – 3300 NSv

Bently Nevada 330904-00-03-10-02-05/CN — Eddy-Current Proximity Probe for Critical Rotating Machinery Protection

The Bently Nevada 330904-00-03-10-02-05/CN is a factory-calibrated, 8 mm eddy-current proximity probe from the 3300 NSv Series, designed for continuous, non-contact measurement of shaft radial vibration, axial position, and eccentricity in turbomachinery and other critical rotating equipment. The “/CN” suffix designates a MIL-C-5015 style bayonet connector, selected for applications requiring sealed, vibration-resistant terminations in harsh-environment junction boxes and explosion-proof enclosures.

Within a machinery protection loop, this probe functions as the primary transducer in a three-component measurement chain: probe body → extension cable (330130 series) → proximitor/driver (330180 series). The probe generates a high-frequency oscillating electromagnetic field at its tip. When a conductive target — typically AISI 4140 steel shaft — enters the field, eddy currents are induced on the target surface, loading the oscillator circuit and producing a DC output voltage linearly proportional to the gap distance. The 3300 NSv driver conditions this signal to a calibrated sensitivity of 200 mV/mil (7.87 V/mm) across a linear range of 0–90 mil (0–2.29 mm), delivering a deterministic analog output directly compatible with Bently Nevada 3500 Series monitor inputs.

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Technical Parameters

Hardware Logical Analysis

The 330904-00-03-10-02-05/CN operates on a Colpitts-type LC oscillator embedded in the probe tip. The oscillator runs at approximately 1.0 MHz carrier frequency, chosen to balance penetration depth into the target material against sensitivity to surface conductivity variation. At this frequency, the eddy-current skin depth in AISI 4140 steel is approximately 0.08 mm — shallow enough to make the measurement insensitive to sub-surface metallurgical variation while remaining robust against surface oxidation layers up to 5 µm.

The MIL-C-5015 (CN) connector provides a hermetically sealable, bayonet-locking interface rated to IP67 when mated. This is a deliberate design choice for installations in petrochemical bearing housings where hydrocarbon vapor ingress into the signal path would introduce dielectric loading on the coaxial cable, shifting the oscillator’s resonant frequency and producing a calibration offset. The bayonet lock also eliminates the risk of partial-mating under vibration — a failure mode documented in installations using standard BNC connectors in high-vibration environments above 2 g RMS.

The integral cable uses a low-loss, semi-rigid coaxial construction with a characteristic impedance of 50 Ω, matched to the proximitor input. The armored outer jacket provides mechanical protection against abrasion and hydrocarbon fluid exposure, while the cable’s capacitance per unit length is tightly controlled to ±2 pF/ft — a specification that directly governs the accuracy of the gap-voltage calibration curve when the probe is paired with a 330180 proximitor. Deviation beyond this tolerance requires field recalibration of the driver’s zero and span potentiometers.

From an EMC perspective, the probe body’s 316 stainless steel housing acts as a Faraday shield for the oscillator coil, attenuating external RF interference above 100 MHz by greater than 40 dB. The coaxial cable’s braided shield is grounded at the proximitor end only (single-point grounding), preventing ground-loop currents that would appear as low-frequency noise on the DC output — a critical consideration in large turbine installations where ground potential differences between bearing pedestals can reach several hundred millivolts.

System Integration Benefits

• Direct API 670 compliance: The probe meets the 5th Edition API 670 standard for machinery protection instrumentation, eliminating the need for additional engineering justification when specifying into new or retrofit turbomachinery protection systems.
• Zero-reconfiguration installation: Factory calibration to 200 mV/mil is stored in the paired proximitor’s EEPROM. Replacing a probe of the same part number requires only gap re-setting — no driver recalibration or DCS scaling changes.
• Deterministic analog output: The DC voltage output has a settling time of less than 10 µs for a step change in gap, supporting vibration frequency analysis up to 10,000 Hz without phase distortion — adequate for blade-pass frequency monitoring on high-speed compressors running at 15,000 RPM with 8 blades (2,000 Hz blade-pass).
• Broad system compatibility: Electrically compatible with Bently Nevada 3300 XL, 3500/42M, 3500/45, 3500/46M, and Orbit 60 monitor modules without signal conditioning adapters.
• Diagnostics transparency: The proximitor’s OK relay output monitors oscillator amplitude continuously. A gap outside the linear range (under 5 mil or over 90 mil) drives the OK output low, providing a hardware-level diagnostic signal to the safety PLC without requiring software polling.
• Harsh-environment durability: Rated to −35°C to +177°C, the probe operates through cold-start conditions in outdoor installations and sustained high-temperature environments adjacent to steam turbine casings without drift in sensitivity.
• Reduced installation error risk: The CN bayonet connector’s keyed mating interface prevents incorrect polarity connection, a common source of commissioning errors in multi-probe installations where cable routing obscures connector orientation.
• Long-term metrology stability: The oscillator coil is wound on a ceramic former with a thermal expansion coefficient matched to the stainless steel housing, limiting sensitivity drift to less than ±0.5% over the full operating temperature range — a specification that supports 12-month calibration intervals without interim verification.

Quality Assurance & Global Logistics

Every 330904-00-03-10-02-05/CN unit supplied by siemensplc.com is sourced through verified channels with full documentation traceability. Incoming inspection covers visual examination of the probe tip and connector, dimensional verification of the probe body length and tip diameter, and functional gap-voltage verification at 25 mil, 50 mil, and 75 mil against the factory calibration curve. Units that deviate more than ±1% from the nominal 200 mV/mil sensitivity at any test point are rejected.

Packaging follows anti-static and moisture-barrier protocols: the probe is individually bagged in ESD-protective film, placed in a rigid foam-lined carton, and sealed with desiccant. The calibration certificate and lot documentation accompany each shipment. Export documentation, including HS code classification and certificate of origin, is prepared for each order to support customs clearance in the EU, Southeast Asia, and the Middle East.

Logistics are managed from Xiamen, China, with access to DHL Express, FedEx International Priority, and sea freight consolidation services. Standard in-stock orders ship within 1–3 business days. Express delivery to major industrial hubs in Europe and the Middle East typically achieves door-to-door transit in 3–5 business days. All shipments are fully insured and tracked from dispatch to delivery confirmation.

Contact Information

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