Bently Nevada 330104-00-20-50-02-00 Proximity Transducer – 3300 Series

Bently Nevada 330104-00-20-50-02-00: Non-Contact Shaft Measurement in High-Demand Rotating Machinery Protection

The Bently Nevada 330104-00-20-50-02-00 is a 20 mm diameter eddy current proximity transducer probe assembly within the 3300 Series platform, configured with a 5-metre armored integral cable and a 5-metre extension cable for standard –24 VDC oscillator-demodulator driver systems. Its function within a machinery protection loop is precise and non-negotiable: it converts the physical gap between the probe tip and a conductive target shaft into a proportional DC voltage signal, delivering continuous, real-time data on radial shaft vibration, axial thrust position, and differential expansion to the connected monitor rack.

In a rotating machinery protection architecture, the proximity transducer occupies the first node in the measurement chain. Signal fidelity at this node determines the accuracy of every downstream decision — from alarm setpoint evaluation to automatic trip relay actuation. The 330104-00-20-50-02-00 achieves this through a tightly controlled eddy current field generated by the probe coil, driven at a fixed frequency by the paired oscillator-demodulator. When the conductive target (typically AISI 4140 steel or equivalent) enters the probe’s electromagnetic field, eddy currents are induced on the target surface, loading the probe coil and shifting the oscillator’s output voltage in direct proportion to the gap distance. The resulting output is a linear –24 VDC signal with a nominal sensitivity of 7.87 V/mm (200 mV/mil), calibrated against the standard Bently Nevada target material specification.

The 5-metre armored integral cable is a critical design element, not merely a mechanical convenience. The coaxial cable between probe and driver forms part of the tuned LC circuit; its electrical length and impedance characteristics are matched at the factory to the specific probe coil inductance. Substituting a non-matched cable or splicing the integral cable will detune the system and introduce calibration error. The 330104-00-20-50-02-00’s armored construction provides mechanical protection against abrasion, crush loads, and chemical exposure in turbine bearing housings and compressor pedestals, while the coaxial shield maintains signal integrity against radiated EMI from adjacent motor drives, switchgear, and high-current bus bars.

This assembly is fully compatible with the Bently Nevada 3300 XL monitor family and legacy 3300 series racks, and meets the requirements of API 670 Fifth Edition for machinery protection systems. It is one of the most widely deployed proximity transducer configurations in global rotating machinery installations, covering steam turbines, gas turbines, centrifugal compressors, expanders, and large pump trains across power generation, oil and gas, petrochemical refining, and heavy industrial sectors.

Real-time Stock & RFQ: [email protected] | WhatsApp: +86 18359268345

Technical Parameters

Hardware Logical Analysis

The 330104-00-20-50-02-00 operates on a resonant LC circuit principle. The probe coil, integral cable, and extension cable together form a tuned network that the oscillator-demodulator drives at a fixed carrier frequency — typically in the range of 1.0 MHz to 1.5 MHz for 3300 Series drivers. At this frequency, the electromagnetic field penetration depth into the target material (skin depth) is on the order of 50–80 µm for AISI 4140 steel, which means the eddy current losses are concentrated at the target surface and are highly sensitive to gap variation rather than bulk material properties. This shallow skin depth is what gives the system its sub-micron displacement resolution.

The 20 mm probe diameter determines the effective sensing area and, consequently, the linear measurement range. Larger diameter probes generate a broader electromagnetic field, extending the linear gap range but reducing spatial resolution for small-diameter shafts. The 20 mm format is the standard selection for shaft diameters above approximately 50 mm, covering the majority of turbine and compressor rotor applications. For smaller shafts or tighter installation envelopes, the 8 mm and 11 mm probe variants in the 3300 Series are used instead.

EMC performance is achieved through two mechanisms. First, the coaxial cable construction provides continuous 360° shielding of the signal conductor from the probe tip to the driver input, with the shield grounded at the driver end only — a single-point ground topology that prevents shield current loops from inducing noise on the signal conductor. Second, the armored outer jacket provides mechanical isolation that prevents the cable from acting as an antenna for radiated interference. In installations near variable-frequency drives or high-current switchgear, this shielding architecture is the primary defense against common-mode noise that would otherwise appear as false vibration signals in the monitor.

The –24 VDC supply architecture is a deliberate design choice for intrinsic safety compatibility. Negative supply rails are more easily protected by Zener barriers in hazardous area installations (Zone 1, Zone 2 per IEC 60079) because the barrier diodes clamp the supply negative rail to a safe energy level without requiring complex active circuitry. This means the 330104-00-20-50-02-00 can be deployed in gas turbine enclosures and offshore compressor modules with classified atmospheres by adding the appropriate 3300/20 Zener barrier in the driver circuit — no modification to the probe or cable assembly is required.

System Integration Benefits

• Direct rack compatibility: The 330104-00-20-50-02-00 connects directly to 3300/16 and 3300/20 oscillator-demodulator modules without adapter hardware, preserving the factory-calibrated sensitivity curve and eliminating field calibration risk at installation.
• Monitor interoperability: Compatible with 3300 XL 8mm, 3300 XL 11mm, 3500/40M, and 3500/42M monitor cards, allowing the probe assembly to remain in service during monitor rack upgrades — a significant cost advantage in brownfield retrofit projects.
• Deterministic signal latency: The analog output architecture delivers gap-to-voltage conversion with no digital processing delay. The monitor receives a continuous analog signal that is sampled at the monitor’s internal ADC rate (typically 20 kHz or higher for 3500 series), ensuring that high-frequency vibration events above 10 kHz are captured without aliasing artifacts.
• Diagnostic transparency: The DC bias voltage at the driver output provides a direct, measurable indicator of probe gap. Maintenance technicians can verify probe installation gap with a standard voltmeter without removing the probe from service — a –10.4 VDC output corresponds to the nominal 1.27 mm (50 mil) installation gap for standard 3300 Series calibration.
• Hazardous area deployment: The –24 VDC supply architecture is directly compatible with Zener barrier intrinsic safety circuits for Zone 1 and Zone 2 classified areas, requiring no modification to the probe assembly.
• API 670 compliance: Meets the transducer performance requirements of API 670 Fifth Edition, including sensitivity tolerance, linearity, and temperature coefficient specifications, supporting machinery protection system certification for critical service applications.
• Non-contact wear immunity: The absence of mechanical contact between probe and shaft means sensor performance does not degrade with shaft rotation cycles. Field service intervals are driven by cable condition and connector integrity, not probe wear — typical service life exceeds 10 years in clean installations.
• Multi-parameter measurement: A single probe assembly can provide radial vibration, shaft centerline position, and — when installed in the axial plane — thrust position data to the monitor, reducing the total sensor count required for a complete API 670 protection system.
• Standardized spare parts management: The 330104-00-20-50-02-00 configuration (20 mm, 5 m + 5 m, –24 VDC) is the most common 3300 Series assembly globally, meaning it is stocked by authorized distributors and specialist suppliers worldwide, minimizing lead time risk for emergency replacements.
• Thermal stability: The probe coil assembly is rated to +177°C continuous, covering the bearing housing temperatures encountered in high-pressure steam turbine and gas turbine applications without requiring thermal isolation hardware.

Quality Assurance & Global Logistics

Every 330104-00-20-50-02-00 unit dispatched from our Xiamen, China facility undergoes a structured pre-shipment verification process. Physical inspection confirms probe tip condition, connector integrity, cable armor continuity, and part number label authenticity against the manufacturer’s marking specification. Units sourced from authorized distribution channels carry full traceability documentation including manufacturer lot codes and date codes.

Packaging is engineered for international transit: the probe assembly is secured in a formed foam insert within a rigid outer carton, with the cable coiled to the manufacturer’s minimum bend radius specification to prevent coaxial dielectric damage. Moisture barrier bags with desiccant are used for ocean freight shipments. Each shipment includes a commercial invoice, packing list, and certificate of origin. Additional documentation — including material test reports, calibration certificates, or MSDS — is available on request for project-specific requirements.

Xiamen’s port infrastructure supports direct container services to major global hubs including Rotterdam, Los Angeles, Singapore, and Dubai, with typical transit times of 18–25 days for sea freight. Air freight via Xiamen Gaoqi International Airport reaches most destinations within 3–5 business days. For urgent plant shutdown requirements, same-day dispatch on confirmed orders received before 14:00 CST is available for in-stock units. All shipments are tracked end-to-end with documentation provided for customs clearance in the destination country.

A 12-month warranty covers manufacturing defects from the date of dispatch. Warranty claims are processed with replacement unit dispatch or full refund, subject to inspection of the returned unit. Our technical team — with direct experience in Bently Nevada 3300 and 3500 Series system architecture — is available to support installation verification, compatibility confirmation, and troubleshooting throughout the warranty period and beyond.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
© 2026 siemensplc.com. All rights reserved.

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