Bently Nevada 21000-28-10-00-094-04-02 Proximity Probe Housing Assembly – 3300 XL Series

Bently Nevada 21000-28-10-00-094-04-02 — 8 mm Proximity Probe Housing Assembly for Continuous Shaft Displacement Measurement

The Bently Nevada 21000-28-10-00-094-04-02 is an 8 mm proximity probe housing assembly belonging to the 3300 XL Proximity Transducer System product family. Its primary function within a machinery protection control loop is to convert rotor-to-casing gap distance into a proportional DC voltage signal, which is then conditioned by a paired Proximitor and processed by a 3300 XL or 3500-series monitor rack. The assembly operates on the eddy-current principle: a high-frequency oscillator (typically 1.0 MHz) drives the probe tip coil, and the impedance change induced by a conductive target surface is demodulated into a linear voltage output of 7.87 V/mm (200 mV/mil) across a calibrated linear range of 0.25 mm to 2.54 mm (10 to 100 mil).

In a turbine or compressor protection architecture, this probe housing is mounted at the bearing journal, oriented radially at 45° X–Y to the shaft centerline per API 670 §5.3. The differential signal from two orthogonally mounted probes feeds the monitor’s orbit computation engine, enabling real-time shaft centerline position tracking, 1× and 2× vibration amplitude extraction, and alarm/trip setpoint enforcement — all within the deterministic scan cycle of the connected monitor card.

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Technical Parameters

Hardware Logical Analysis

The 21000-28-10-00-094-04-02 housing assembly integrates three mechanically distinct sub-systems that collectively determine measurement fidelity under industrial operating conditions:

1. Coil-and-Ferrite Probe Tip Architecture
The 8 mm probe tip houses a precision-wound coil embedded in a thermally stable ferrite core. The coil geometry is matched to the 3300 XL Proximitor’s oscillator circuit to maintain a defined Q-factor across the full temperature range. Thermal expansion of the stainless steel housing is compensated by the coil winding pitch, limiting sensitivity drift to less than ±0.5% across the −40 °C to +177 °C envelope. This is critical in hot-section turbine bearing housings where ambient temperatures can exceed 150 °C during steady-state operation.

2. EMC Shielding and Cable Routing
The integral 1.0 m cable uses a coaxial construction with a braided copper shield terminated at the probe body ground. This topology suppresses common-mode noise induced by high-voltage motor drives, variable-frequency drives (VFDs), and bus-bar switching transients — all of which are present in the same cable trays in typical power plant environments. The shield continuity is maintained through the M10 × 1.0 locknut interface, ensuring the probe body and machine casing share a common ground reference without creating a ground loop through the signal return path.

3. Mechanical Mounting and Vibration Isolation
The M10 × 1.0 thread with jam-nut locking arrangement provides a defined axial preload that prevents probe tip migration under sustained vibration loads up to 20 g (per API 670 Annex D mounting requirements). The stainless steel housing resists galvanic corrosion when mounted in aluminum or carbon steel bearing housings, and the 316 SS grade provides adequate resistance to H₂S partial pressures encountered in sour gas compressor applications. The housing geometry also accommodates standard API 670 probe holders, eliminating the need for custom machined adapters in retrofit installations.

System Integration Benefits

• Direct 3300 XL Monitor Compatibility: The probe-Proximitor-monitor chain is factory-characterized as a matched set, eliminating field calibration uncertainty. The monitor’s internal scale factor is pre-loaded for 7.87 V/mm sensitivity, so engineering units (µm or mil) are displayed without manual offset correction.
• API 670 Fifth Edition Compliance: The assembly meets all dimensional, electrical, and documentation requirements of API 670 (5th Ed.), the globally accepted standard for turbomachinery protection. This simplifies EPC contractor approval and insurance underwriter acceptance on new-build projects.
• Deterministic Alarm Response: When paired with a 3300 XL or 3500-series monitor, the probe signal is sampled at a fixed scan rate (typically 10 ms per channel), ensuring that alarm and trip relay outputs respond within one scan cycle of a threshold crossing — a requirement for machinery protection systems where trip delay directly affects mechanical damage extent.
• Orbit and Centerline Diagnostics: Two probes mounted at 90° X–Y provide the orthogonal displacement data required for shaft orbit plots and centerline position tracking. This enables differentiation between unbalance (circular orbit), misalignment (elliptical orbit), and rub (truncated orbit) without additional instrumentation.
• Hazardous Area Deployment: ATEX and IECEx certifications allow installation in Zone 1 and Zone 2 classified areas (gas group IIC, temperature class T4 or better, subject to datasheet confirmation), covering the majority of petrochemical and offshore platform applications.
• Non-Contact, Zero-Wear Operation: The eddy-current measurement principle involves no physical contact with the rotating shaft. There is no probe wear mechanism, and the measurement loop remains stable across the full machinery lifecycle — typically 20+ years for baseload turbines — without scheduled probe replacement.
• Diagnostic Transparency via Gap Voltage Monitoring: The DC gap voltage (nominally −10 VDC at 50 mil) is continuously available at the Proximitor output. Slow drift in gap voltage over time indicates shaft centerline migration due to bearing wear, providing a leading indicator of bearing degradation before vibration amplitude alarms are triggered.
• Standardized Spare Parts Inventory: The 8 mm, M10 × 1.0 form factor is the most widely deployed proximity probe standard in the 3300 XL ecosystem. A single spare housing assembly covers multiple measurement points across a turbine train, reducing spare parts inventory carrying cost and simplifying maintenance planning.

Quality Assurance & Global Logistics

Every Bently Nevada 21000-28-10-00-094-04-02 unit supplied through siemensplc.com is sourced from verified industrial distribution channels with full traceability to the original Baker Hughes / Bently Nevada manufacturing lot. Incoming inspection at our Xiamen, China facility includes dimensional verification against OEM drawings, sensitivity and linearity functional check (200 mV/mil ± 1%), and review of the certificate of conformance. Original manufacturer packaging is preserved where possible to maintain ESD and mechanical protection integrity during transit.

Shipments originate from Xiamen, China and are dispatched via DHL Express, FedEx International Priority, or UPS Worldwide Expedited depending on destination and urgency. Standard in-stock orders are processed within 1–2 business days. Export documentation — including commercial invoice, packing list, and HS code 9031.80.9090 classification — is prepared in compliance with Chinese customs regulations and destination country import requirements. For project quantities or shutdown-critical orders, contact our logistics team directly for dedicated freight coordination.

Contact Information

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