Bently Nevada 21000-16-10-00-106-03-02 Proximity Probe Housing Assembly – 21000 Series

Bently Nevada 21000-16-10-00-106-03-02 — Precision Proximity Probe Housing for Continuous Machinery Protection

The Bently Nevada 21000-16-10-00-106-03-02 is a factory-assembled proximity probe housing unit from the 21000 Series eddy-current transducer system, engineered specifically for continuous, non-contact vibration and displacement monitoring of rotating shafts in critical industrial machinery. This housing assembly integrates a 5/16-28 UNF threaded probe body with a pre-terminated, PTFE-insulated coaxial cable, forming a mechanically stable and electrically consistent transducer front-end for use with Bently Nevada Proximitor® signal conditioners and 3300/3500 Series monitoring racks.

The 21000 Series was developed to address the mechanical and thermal stresses inherent in turbomachinery environments — steam turbines, gas compressors, centrifugal pumps, and expanders — where shaft radial vibration, axial position, and Keyphasor® phase reference must be measured with sub-micron resolution and zero signal interruption. The 21000-16-10-00-106-03-02 variant specifies a 1.0 m integral cable, standard stainless steel housing, and a probe tip geometry calibrated for ferromagnetic steel targets at a nominal gap of 1.0 mm, producing a –10.0 VDC ± 0.5 VDC output at the Proximitor® input under standard conditions.

Unlike generic eddy-current sensors, this assembly is factory-matched to Bently Nevada’s proprietary calibration curves, ensuring that the probe-extension-conditioner system meets the ±1% full-scale accuracy specification required by API 670 (Machinery Protection Systems) without field recalibration. The housing is rated IP67 for dust ingress and temporary water immersion, and the operating temperature envelope of –35°C to +177°C covers the majority of turbine bearing housing and compressor seal area installations without derating.

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Technical Parameters

Hardware Logical Analysis

The eddy-current operating principle of the 21000-16-10-00-106-03-02 relies on a high-frequency oscillator circuit embedded within the Proximitor® conditioner, which drives an alternating magnetic field through the probe coil wound at the tip of this housing assembly. When a conductive target (typically low-alloy steel shaft) enters the field, eddy currents are induced on the target surface, loading the oscillator and producing a measurable impedance change. The Proximitor® converts this impedance shift into a DC voltage proportional to the gap distance — a fundamentally contactless, wear-free measurement mechanism with no moving parts and no mechanical hysteresis.

The 21000 Series housing is designed with a coaxial cable geometry that maintains a controlled characteristic impedance (nominally 50 Ω) from the probe coil to the Proximitor® input. Any impedance discontinuity — caused by cable damage, connector corrosion, or improper extension cable length — directly degrades the calibration accuracy. The factory-matched cable length of 1.0 m in this variant is therefore not arbitrary: it is part of the calibrated system, and the total cable length (probe + extension) must match the Proximitor® calibration table to maintain the ±1% accuracy specification.

EMC performance is achieved through the coaxial shielding of the integral cable, which provides continuous 360° coverage from the probe body to the BNC connector. The 316 stainless steel housing acts as a Faraday shield around the probe coil, attenuating external RF interference that could otherwise modulate the oscillator frequency and introduce measurement noise. In high-EMI environments — such as variable-frequency drive (VFD) motor rooms or switchgear areas — this shielding architecture maintains signal integrity without requiring additional external conduit or ferrite suppression.

The PTFE cable insulation is selected for its dielectric stability across the full operating temperature range. Unlike PVC or polyethylene insulations, PTFE maintains a consistent dielectric constant (εr ≈ 2.1) from cryogenic temperatures to +260°C, ensuring that the cable’s electrical characteristics do not drift with thermal cycling — a critical requirement in steam turbine applications where bearing housing temperatures can vary by 80°C between cold start and full-load operation.

The 5/16-28 UNF thread on the probe body is a Bently Nevada proprietary standard that provides a fine-pitch engagement for precise axial positioning during installation. The thread pitch of 0.907 mm per revolution allows gap adjustment resolution of approximately 0.9 mm per full turn, enabling field technicians to set the nominal gap to within ±0.05 mm using a standard feeler gauge — sufficient to place the probe within the linear range without requiring a gap meter during initial commissioning.

System Integration Benefits

• API 670 compliance out of the box: The 21000-16-10-00-106-03-02 is factory-calibrated to meet API 670 5th Edition accuracy requirements, eliminating the need for site-level calibration verification before commissioning in machinery protection applications.
• Plug-and-play compatibility with 3500 Series racks: The probe interfaces directly with 3500/40M, 3500/42M, and 3500/44M monitor modules without conditioner re-tuning, reducing installation time and eliminating configuration errors associated with third-party probe substitution.
• Deterministic signal latency: The eddy-current measurement chain from probe coil to Proximitor® output introduces less than 100 µs of signal delay, ensuring that the 3500 Series monitor’s trip response time remains within the 20 ms specification required for overspeed and high-vibration protection logic.
• Dual-use measurement capability: A single 21000 Series probe installation can simultaneously provide radial vibration (AC component) and average shaft centerline position (DC component) data to the monitor, reducing the number of penetrations required in the bearing housing and simplifying mechanical installation.
• Keyphasor® phase reference integration: When installed in the Keyphasor® position, this probe provides the once-per-revolution trigger signal required for synchronous vibration analysis (1X, 2X amplitude and phase), enabling identification of unbalance, misalignment, and resonance conditions without additional instrumentation.
• DCS/SIS interoperability: The Proximitor® output (–24 VDC to 0 VDC range) is directly compatible with 4–20 mA transmitter modules for DCS integration (Emerson DeltaV, Honeywell Experion, ABB 800xA) and with SIL-rated safety instrumented system inputs when installed per IEC 61511 functional safety requirements.
• Diagnostic transparency via System 1: When connected to a 3500 rack managed by Bently Nevada System 1 software, the probe’s gap voltage is continuously logged, enabling trend analysis of bearing wear (progressive shaft centerline shift) and early detection of probe fouling or cable degradation before measurement accuracy is compromised.
• Reduced maintenance interval dependency: The non-contact measurement principle eliminates probe wear as a failure mode. Combined with the IP67 housing and PTFE cable, the 21000-16-10-00-106-03-02 is designed for continuous service intervals exceeding 5 years in clean bearing environments, with inspection limited to connector integrity and gap verification during scheduled outages.

Quality Assurance & Global Logistics

Every unit of the Bently Nevada 21000-16-10-00-106-03-02 supplied by siemensplc.com is sourced from verified channels with full traceability documentation. Pre-shipment inspection covers visual examination of the housing and cable assembly, dimensional verification of the probe thread and tip geometry, electrical continuity and insulation resistance testing of the coaxial cable, and BNC connector integrity check. Serial numbers are cross-referenced against Bently Nevada / Baker Hughes records where applicable to confirm authenticity and rule out counterfeit components — a critical step given the prevalence of non-genuine proximity probes in the surplus market.

Units are packaged in ESD-safe protective foam inserts within rigid outer cartons, with the BNC connector capped and the probe tip protected by a machined thread guard to prevent damage during transit. For air freight shipments, the coaxial cable is coiled to a minimum bend radius of 50 mm to prevent dielectric deformation.

Logistics operations are based in Xiamen, China, with direct access to Xiamen Gaoqi International Airport (XMN) and Xiamen Port for sea freight. In-stock units are dispatched within 1–3 business days of order confirmation. Standard international delivery via DHL Express or FedEx International Priority reaches most destinations in Europe, Southeast Asia, the Middle East, and the Americas within 3–7 business days. Expedited same-day dispatch is available for urgent plant maintenance requirements — contact us directly to confirm cut-off times.

All shipments are accompanied by a commercial invoice, packing list, and certificate of origin. Test reports and calibration documentation are available upon request at the time of order. A 12-month warranty covers manufacturing defects and electrical performance against the published specification from the date of shipment.

Contact Information

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