Bently Nevada 21000-16-10-00-124-03-02 Proximity Probe Assembly – 21000 Series

Bently Nevada 21000-16-10-00-124-03-02: Eddy-Current Proximity Probe Assembly for Rotating Machinery Protection

The Bently Nevada 21000-16-10-00-124-03-02 is a 16 mm eddy-current proximity probe housing assembly with a 10-metre armored extension cable, engineered for continuous shaft displacement and radial vibration measurement in turbomachinery protection systems. Within a machinery protection loop, this assembly occupies the sensing layer between the rotating shaft and the signal conditioning monitor — its output voltage directly determines whether a machine trips, alarms, or continues operation. The probe converts mechanical gap variation into a DC voltage signal at a nominal sensitivity of −200 mV/mil (−7.87 V/mm), feeding the Bently Nevada 3300 or 3500 series monitor cards that execute protection logic in real time.

Unlike general-purpose inductive sensors, the 21000 series is factory-calibrated against AISI 4140 steel targets to maintain sensitivity linearity across the full operating gap range of 0–2.54 mm (0–100 mil). This calibration traceability is a prerequisite for API 670 compliance, which mandates that each transducer system — probe, extension cable, and proximitor — be characterized as a matched set. The -16-10-00-124-03-02 suffix encodes the probe tip diameter (16 mm), cable length (10 m), and connector/termination variant, ensuring the assembly integrates without recalibration into any 3500/42M or 3300/16 monitor slot pre-configured for this transducer set.

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Technical Parameters

Hardware Logical Analysis

The 21000-16-10-00-124-03-02 operates on the eddy-current (electromagnetic induction) principle. The probe tip houses a flat coil driven by a high-frequency oscillator (typically 1.0 MHz) located in the paired proximitor. When the conductive target shaft enters the probe’s electromagnetic field, eddy currents are induced on the shaft surface, loading the oscillator circuit and reducing its output amplitude. This amplitude reduction is demodulated into a DC voltage proportional to the gap distance — a fundamentally passive, contact-free measurement with no mechanical wear mechanism.

EMC Design: The armored coaxial cable construction provides continuous 360° shielding from the probe tip to the monitor input, suppressing capacitively coupled interference from adjacent power cables, VFDs, and high-current bus bars common in turbomachinery enclosures. The shield is grounded at the monitor end only (single-point grounding), preventing ground-loop currents that would appear as low-frequency noise on the displacement signal. The probe body itself is constructed from non-magnetic stainless steel, which eliminates permeability variation artifacts that would otherwise introduce measurement error when the probe is mounted near ferromagnetic structural members.

Thermal Stability: The coil former material and potting compound are selected for low thermal coefficient of inductance. Across the rated −35°C to +177°C range, sensitivity drift is maintained within ±1% of nominal — a specification critical for steam turbine bearing housings where probe body temperatures can exceed 120°C during sustained full-load operation. This thermal stability eliminates the need for temperature compensation corrections in the monitor’s alarm setpoint calculations.

Matched-Set Calibration Logic: The 21000 series is calibrated as a three-component set: probe + extension cable + proximitor. The extension cable’s distributed capacitance and inductance are factored into the oscillator tuning at the factory. Substituting a cable of different length or impedance characteristic without recalibration will shift the sensitivity curve, producing systematic measurement error. The -10- segment of the part number (10 m cable) is therefore a functional parameter, not merely a dimensional descriptor.

System Integration Benefits

• Zero-recalibration drop-in replacement: The complete part number encodes all transducer set parameters, allowing direct substitution into an existing 3500 or 3300 monitor slot without field recalibration, reducing planned maintenance downtime to the time required for mechanical installation and gap setting only.
• Deterministic alarm response: The DC output signal is continuously present at the monitor input — there is no polling latency. The 3500/42M processes the analog input at its internal scan rate (typically 1 ms), enabling alarm-to-relay response times well within API 670’s 2-second maximum requirement for machinery protection.
• Diagnostic transparency via gap voltage: The DC bias voltage at the monitor input (nominally −10.4 VDC at 1.27 mm gap) serves as a direct diagnostic indicator. Technicians can verify probe installation gap, detect probe-to-shaft contact, and identify cable open-circuit or short-circuit faults without removing the probe from service.
• API 670 compliance pathway: Using the OEM-calibrated assembly preserves the documented sensitivity tolerance (±1%) required for API 670 Annex A transducer system qualification, avoiding the re-qualification testing burden associated with third-party substitutes.
• Broad monitor platform compatibility: The −200 mV/mil sensitivity and −24 VDC supply requirement are the standard Bently Nevada transducer interface, compatible with 3300/16, 3500/42M, 3500/42E, and ADAPT.wind monitor cards without hardware modification.
• High-temperature process suitability: The 177°C probe body rating covers the majority of steam turbine and gas compressor bearing housing environments, eliminating the need for thermal standoff brackets or probe cooling provisions in most installations.
• Reduced installation error risk: The M10 × 1 thread and 16 mm tip diameter are mechanically constrained to the correct probe bracket bore, preventing cross-installation with 8 mm or 25 mm probe variants that share the same monitor card type but require different gap settings and sensitivity factors.
• Long-term parts availability: The 21000 series has been in continuous production for over two decades and remains the standard transducer for Bently Nevada monitor platforms. OEM and verified surplus stock are available through established distribution channels, supporting 20+ year plant lifecycle requirements.

Quality Assurance & Global Logistics

Every unit of the Bently Nevada 21000-16-10-00-124-03-02 offered through siemensplc.com is sourced from authorized distributors or verified surplus channels with full traceability documentation. Pre-shipment inspection covers visual examination of the probe tip, cable armor integrity, connector condition, and coaxial continuity verification. Calibration certificates and OEM documentation are available upon request and are provided as standard for orders requiring API 670 documentation packages.

Shipments originate from our Xiamen, China operations center. Domestic China orders are dispatched via SF Express or JD Logistics with next-day delivery coverage to major industrial hubs including Shanghai, Guangzhou, Chengdu, and Wuhan. International orders are handled via DHL Express, FedEx International Priority, or UPS Worldwide Expedited, with typical transit times of 3–5 business days to Europe, North America, and Southeast Asia. Export documentation — including commercial invoice, packing list, certificate of origin, and ECCN classification — is prepared in-house to minimize customs clearance delays. All units are packed in anti-static foam-lined cartons with individual serialized labels to maintain traceability through the logistics chain.

Contact Information

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