Bently Nevada 21509-02-12-10-02 Eddy Current Proximity Probe Product Specification
21509-02-12-10-02 is a factory pre-calibrated reverse-mounted 5 mm eddy current proximity probe belonging to Bently Nevada 7200 series transducer family, which is designed to work cooperatively with matched 2155/00 proximitor preamplifier and certified 75-ohm extension cable to form a complete non-contact displacement measuring system complying with API 670 machinery protection specification. Based on eddy current induction principle, the probe converts clearance fluctuation between sensing tip and metallic rotating target into proportional linear voltage signal, and the output signal is delivered to 7200 or 3500 rack monitoring modules for continuous measurement of rotor radial vibration, axial thrust displacement and Keyphasor rotational speed signal of critical rotating equipment. Widely applied on steam turbines, gas turbines, centrifugal compressors and large turbo-generators in power, petrochemical and metallurgical industries, this probe supports threshold alarming and emergency shutdown interlock functions to secure unit running safety. All finished probes undergo strict linearity calibration, high-low temperature cycling aging and hermetic encapsulation inspection before factory shipment to guarantee stable measurement precision under complicated working conditions with high ambient temperature, oil mist and strong electromagnetic interference from on-site high-power electrical equipment.
Description
Bently Nevada 21509-02-12-10-02 Eddy Current Proximity Probe Product Specification
1. Product Overview
21509-02-12-10-02 is a factory pre-calibrated reverse-mounted 5 mm eddy current proximity probe belonging to Bently Nevada 7200 series transducer family, which is designed to work cooperatively with matched 2155/00 proximitor preamplifier and certified 75-ohm extension cable to form a complete non-contact displacement measuring system complying with API 670 machinery protection specification. Based on eddy current induction principle, the probe converts clearance fluctuation between sensing tip and metallic rotating target into proportional linear voltage signal, and the output signal is delivered to 7200 or 3500 rack monitoring modules for continuous measurement of rotor radial vibration, axial thrust displacement and Keyphasor rotational speed signal of critical rotating equipment. Widely applied on steam turbines, gas turbines, centrifugal compressors and large turbo-generators in power, petrochemical and metallurgical industries, this probe supports threshold alarming and emergency shutdown interlock functions to secure unit running safety. All finished probes undergo strict linearity calibration, high-low temperature cycling aging and hermetic encapsulation inspection before factory shipment to guarantee stable measurement precision under complicated working conditions with high ambient temperature, oil mist and strong electromagnetic interference from on-site high-power electrical equipment.
2. Part Number Coding Definition
Each segment of 21509-02-12-10-02 follows Bently’s standard part numbering rule for 7200 series proximity probes. The base code 21509 represents core specification of 5 mm reverse installation proximity probe with 3/8 inch threaded body structure, differing from standard front-mounted 21515 series probe in mechanical installation layout. The second segment 02 stands for internal coil configuration, built-in wiring layout and fixed factory electrical calibration parameter setting for reverse mount structure. The third segment 12 defines 12 mm total threaded body length of probe main body, which matches reserved installation hole dimension of bearing pedestal and customized mounting fixture. The fourth segment 10 indicates fixed integral coaxial cable length of 1.0 meter pre-molded with probe body during production. The final segment 02 denotes miniature coaxial MS connector equipped at cable terminal for standard connection with original matched extension cable. Any field cutting, jointing or replacement of original integral cable and connector is prohibited, as any physical damage will invalidate factory preset calibration data and cause whole measurement loop out of specification.
3. Product Structural & Material Features
The probe threaded body and sensing head are manufactured with high-strength anti-corrosion stainless steel material, featuring excellent oil resistance and vapor-proof property to adapt long-term service inside closed bearing housing filled with lubricating oil steam. Internal induction coil is fully sealed and fixed by high-temperature resistant epoxy resin potting compound without internal air clearance, effectively avoiding coil displacement or short-circuit failure triggered by long-time equipment vibration and ambient temperature variation. Attached integral cable adopts standard 75-ohm impedance controlled coaxial wire with dense copper braided outer shielding layer, which effectively restrains external electromagnetic interference during signal transmission and improves anti-noise performance of the whole transducer system. Reverse mounting design enables the probe to be installed from backside of equipment bearing seat, which is applicable for narrow installation space where front threading access is unavailable, solving space restriction problem of compact unit structure. Only full set matching of original probe, designated extension cable and corresponding 2155 series proximitor can maintain original linear conversion characteristic calibrated at factory.
4. Electrical Performance Specifications
The complete transducer system requires negative DC power supply ranging from -17.5 VDC to -26 VDC via matched proximitor, and -24 VDC is the conventional operating voltage for field practical application. Factory fixed nominal sensitivity is 7.87 V/mm (200 mV/mil) calibrated with standard AISI4140 steel target material, with full-span linearity deviation controlled within ±5% as per API670 industrial standard. Valid linear measuring range covers 0~1.27 mm (50 mil), which satisfies regular measurement requirement of small-gap radial vibration and short-stroke axial displacement of most industrial rotating shafts. Effective frequency response spans DC to 10 kHz to capture both slow thermal expansion static displacement signal and high-frequency dynamic shaft vibration signal synchronously. The probe supports open/short circuit fault diagnosis via abnormal output voltage drift, which greatly simplifies daily on-site circuit troubleshooting work.
5. Environmental Operating Parameters
Continuous working temperature range of probe sensing part is from -35°C up to +120°C to fit high-temperature installation environment nearby turbine bearing housing and cylinder casing. Spare storage temperature scope is -55°C ~ +85°C under dry non-condensation storage condition, with applicable working relative humidity between 5%RH and 100%RH; persistent immersion into liquid oil or condensed water is forbidden to protect internal insulation integrity of coil and cable. The probe can withstand regular industrial vibration of 10 Hz to 2 kHz generated by adjacent operating rotating machines, while long-term exposure to strong corrosive gas and continuous high-temperature steam environment should be avoided to extend component service life. For installation positions over 1000 meters altitude, shorten periodic inspection cycle to check mounting tightness and cable insulation integrity regularly.
6. Installation & Maintenance Instructions
Cut off total power supply of the entire monitoring loop before field installation, install the probe reversely from rear side of bearing pedestal reserved threaded hole or customized mounting bracket, adjust pre-installation gap to middle position of linear range and lock fastening nut to prevent looseness caused by long-term equipment running vibration. During cabling construction, separate probe signal cable routing from high-current AC power cable and frequency converter output wiring to reduce cross electromagnetic coupling interference. In routine maintenance period, regularly inspect outer cable insulation for oil corrosion, cracking and mechanical abrasion damage, and check locking status of terminal connector. When probe needs field replacement due to breakdown, only spare part with identical full part number 21509-02-12-10-02 can be used for direct replacement; all replacement probes complete full electrical test and alternating temperature aging screening before factory delivery to guarantee complete interchangeability inside original vibration monitoring circuit.
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