Bently Nevada 3300 XL Proximity Probe System Modules – 21504-12-28-10-02

Technical Dossier

Product Details And Specifications

Bently Nevada 3300 XL Series Technical Notes

The Bently Nevada 3300 XL Proximity Probe System is one of the most widely deployed eddy-current-based vibration measurement platforms in global heavy industry. Installed across petrochemical refineries, nuclear power stations, LNG terminals, offshore platforms, and rotating machinery in steel mills, the 3300 XL system provides continuous, non-contact measurement of shaft radial vibration, axial position, and differential expansion. Its architecture conforms to API 670 (5th Edition) machinery protection standards, making it the de facto specification for turbomachinery OEM packages and retrofit projects worldwide. The system operates on a modular backplane design, allowing field replacement of individual probes, extension cables, and signal conditioning monitors without full system shutdown in most configurations.

The Evolution of 3300 XL Architecture

Bently Nevada introduced the original 3300 Series in the early 1980s as a successor to the 7200 Series proximity system. The 3300 XL designation was formalized in the mid-1990s to reflect enhanced electromagnetic compatibility (EMC) shielding, tighter sensitivity tolerances (±0.5% full scale), and compatibility with the then-emerging 3500 Series rack-based monitoring platform. Key architectural milestones include:

Compatibility note: 3300 XL probes use a standard 5/16-32 UNF thread mount and are interchangeable within the XL family provided cable length and target material specifications are matched.

3300 XL Full Catalog & Functionalities (SKU List)

The following SKUs represent verified, commonly stocked models within the Bently Nevada 3300 XL Proximity Probe System. Models are organized by functional category.

Proximity Probes (8mm)

• 21504-12-28-10-02: 8mm XL probe, 12-inch (305mm) armored cable, -24V, 200 mV/mil sensitivity, standard target.
• 21504-12-28-10-01: 8mm XL probe, 12-inch cable, -24V, metric connector variant, standard target.
• 21504-24-28-10-02: 8mm XL probe, 24-inch (610mm) armored cable, -24V, extended reach configuration.
• 21504-36-28-10-02: 8mm XL probe, 36-inch (914mm) armored cable, -24V, for large-bore bearing housings.
• 21504-48-28-10-02: 8mm XL probe, 48-inch (1219mm) armored cable, -24V, turbine pedestal applications.

Proximity Probes (5mm)

• 21500-12-28-10-02: 5mm XL probe, 12-inch cable, -24V, 200 mV/mil, compact bearing housing use.
• 21500-24-28-10-02: 5mm XL probe, 24-inch cable, -24V, standard compressor train application.
• 21500-36-28-10-02: 5mm XL probe, 36-inch cable, -24V, extended installation depth.

Extension Cables

• 330130-045-00-CN: 3300 XL extension cable, 4.5m (15 ft), standard coaxial, field-terminated.
• 330130-080-00-CN: 3300 XL extension cable, 8m (26 ft), armored jacket, high-vibration environments.
• 330130-100-00-CN: 3300 XL extension cable, 10m (33 ft), standard coaxial, general purpose.
• 330130-150-00-CN: 3300 XL extension cable, 15m (49 ft), for remote monitor rack installations.

Signal Conditioning / Drivers (Proximitors)

• 3300/16-02-01-01-00-00-00: 3300 XL Proximitor, 8mm, -24V, DIN rail mount, single-channel output.
• 3300/20-02-01-01-00-00-00: 3300 XL Proximitor, 8mm, -24V, panel mount, dual-channel output.
• 3300/55-01-01-00-00-00: 3300 XL Proximitor, 5mm, -24V, compact housing, OEM turbine packages.

Mounting Hardware & Accessories

• 21504-000-000: 8mm probe mounting bracket, stainless steel, API 670 compliant, standard bore.
• 21500-000-000: 5mm probe mounting bracket, stainless steel, compact pedestal configuration.

Sourcing Hard-to-Find & Obsolete 3300 XL Parts

The 3300 XL system entered end-of-active-production status, with Bently Nevada (a Baker Hughes company) directing new installations toward the 3500 Series platform. This creates a well-documented supply gap for operators running legacy 3300 XL-based machinery protection systems who require like-for-like replacement parts without undertaking a full system migration.

Quality Control for the 3300 XL Range

The 3300 XL proximity probe system presents specific quality verification challenges due to its analog signal chain architecture and sensitivity to cable impedance matching. DriveKNMS applies the following test protocol to all 3300 XL inventory prior to shipment:

• Probe Sensitivity Calibration: Each probe is tested against an AISI 4140 steel target at the manufacturer-specified gap range (0.25mm to 2.54mm). Output linearity is verified at 200 mV/mil (7.87 V/mm) ±5% across the full measurement range.
• Cable Impedance Verification: Extension cables are tested for characteristic impedance (50Ω nominal) using a TDR (Time Domain Reflectometer) to detect any internal damage, moisture ingress, or connector degradation not visible externally.
• Insulation Resistance: Minimum 100 MΩ at 500 VDC between signal conductor and shield, per IEC 60228 Class 5 requirements.
• Connector Inspection: All BNC and coaxial connectors are inspected under 10× magnification for pin deformation, corrosion, and thread integrity.
• Proximitor Functional Test: Signal conditioning drivers (Proximitors) are bench-tested with a calibrated probe and target fixture to verify output voltage range, bias voltage stability (-24 VDC ±0.5V), and frequency response up to 10 kHz.
• Documentation: Each shipped unit is accompanied by a test record including serial number, test date, technician ID, and measured values. Traceability documentation is available on request for nuclear and safety-critical applications.