Bently Nevada 21500-00-20-05-02 Eddy Current Proximity Probe Product Specification
21500-00-20-05-02 is factory pre-calibrated front-mounted 14 mm eddy current proximity probe designed exclusively for Bently Nevada 7200 series transducer system. When paired with original 2155/00 proximitor preamplifier and factory-calibrated 75-ohm matched extension cable, the complete assembly forms a full non-contact measurement system compliant with API 670 industry standards for critical heavy-duty rotating machinery protection. Based on eddy-current induction principle, the probe converts minor clearance variations between its sensing tip and conductive metallic rotor target into linear analog voltage signals. These analog signals are transmitted to 7200 or 3500 rack-mounted monitoring modules to realize continuous online measurement of large-diameter shaft radial vibration, long-travel axial displacement and Keyphasor rotational pickup pulse signals. Widely applied on heavy-duty steam turbines, large gas turbines, oversize centrifugal compressors and big turbo-generators across power, petrochemical and metallurgical industries, it provides over-limit alarm trigger and emergency shutdown interlock signals to ensure secure unit operation. Every finished probe undergoes full-range linearity calibration, high-low temperature cyclic aging test and full hermetic epoxy encapsulation inspection prior to factory shipment to retain stable measuring accuracy under harsh field conditions including high bearing housing temperature, persistent lubricating oil mist and complex electromagnetic interference from high-current power cables and variable frequency drive equipment.
Description
Bently Nevada 21500-00-20-05-02 Eddy Current Proximity Probe Product Specification
1. Product Overview
21500-00-20-05-02 is factory pre-calibrated front-mounted 14 mm eddy current proximity probe designed exclusively for Bently Nevada 7200 series transducer system. When paired with original 2155/00 proximitor preamplifier and factory-calibrated 75-ohm matched extension cable, the complete assembly forms a full non-contact measurement system compliant with API 670 industry standards for critical heavy-duty rotating machinery protection. Based on eddy-current induction principle, the probe converts minor clearance variations between its sensing tip and conductive metallic rotor target into linear analog voltage signals. These analog signals are transmitted to 7200 or 3500 rack-mounted monitoring modules to realize continuous online measurement of large-diameter shaft radial vibration, long-travel axial displacement and Keyphasor rotational pickup pulse signals. Widely applied on heavy-duty steam turbines, large gas turbines, oversize centrifugal compressors and big turbo-generators across power, petrochemical and metallurgical industries, it provides over-limit alarm trigger and emergency shutdown interlock signals to ensure secure unit operation. Every finished probe undergoes full-range linearity calibration, high-low temperature cyclic aging test and full hermetic epoxy encapsulation inspection prior to factory shipment to retain stable measuring accuracy under harsh field conditions including high bearing housing temperature, persistent lubricating oil mist and complex electromagnetic interference from high-current power cables and variable frequency drive equipment.
2. Part Number Definition Breakdown
All coding segments follow Bently’s unified part coding specification for 7200-series front-install proximity probes. Base code 21500 stands for standard 14 mm diameter front full-thread proximity probe series dedicated to the 7200 transducer platform; segment 00 represents zero exposed unthreaded tip length, fixed internal coil structure and factory-locked original calibration parameters without customized electrical modification; segment 20 defines short full-threaded body dimension for shallow standard mounting holes on thin or medium-thickness heavy-duty bearing pedestals; segment 05 refers to factory pre-molded integral coaxial cable with fixed 0.5-meter length permanently bonded to probe main body during production; final suffix 02 denotes standard miniature male coaxial terminal connector fitted at cable tail for plug-in connection with certified original extension cable. Random replacement with probes of different part codes changes mechanical dimensions or calibrated electrical characteristics, invalidates factory full-loop matching calibration and leads to measurement deviation or unexpected protective tripping of relevant monitoring channel.
3. Core Functional Characteristics
The probe threaded housing and sensing tip are precision machined from high-strength corrosion-resistant stainless steel with excellent resistance against lubricant erosion and corrosive vapor inside sealed bearing chambers. Internal induction coil is fully potted with high-temperature resistant epoxy resin to eliminate inner air gaps and effectively avoid coil displacement or inter-turn short-circuit caused by long-term equipment vibration and ambient temperature fluctuation. The attached 0.5-meter integral cable adopts standard 75-ohm controlled-impedance coaxial construction with over 95% coverage dense tinned copper braided shielding to suppress external electromagnetic crosstalk during signal transmission. On-site cutting, splicing or arbitrary replacement of original cable and end connector is strictly prohibited; any physical alteration permanently voids factory preset calibration data of the whole transducer assembly. Short full-thread front screw-in design is optimized for conventional shallow pre-drilled mounting holes and regular thin-to-medium thickness heavy-duty bearing pedestal structures. Built-in open/short-circuit fault diagnosis identifies abnormal wiring via obvious output voltage drift to simplify daily field troubleshooting. Stable linear measuring performance of the whole system can only be guaranteed by full original matching of this probe, certified extension cable and designated 2155/00 proximitor preamplifier.
4. Electrical and Metrological Specifications
Matching 2155/00 proximitor provides regulated negative DC supply ranging from -17.5 VDC to -26 VDC, and -24 VDC is the standard nominal operating voltage for field application. Factory fixed calibrated sensitivity is 7.87 V/mm (200 mV/mil) referenced to standard AISI4140 carbon steel target, with full-range linearity tolerance controlled within ±5% per API 670 requirements. Valid linear measuring range covers 0 mm ~ 2.54 mm to satisfy regular radial vibration and long-travel axial clearance measurement for large industrial rotating shafts. Effective frequency response spans DC up to 10 kHz to synchronously collect low-frequency static thermal expansion drift and high-frequency dynamic shaft vibration signals. Recommended pre-installation gap is set near midpoint of linear range to keep stable bias working point for long-term uninterrupted equipment operation.
5. Environmental Working Parameters
Permissible continuous operating temperature of probe sensing part ranges from -35°C to +120°C to fit high-temperature installation near heated bearing housings and turbine casings. Spare storage temperature is kept between -55°C and +85°C under dry non-condensing environment; applicable working relative humidity is 5%RH~95%RH without dew condensation on probe housing and cable outer jacket. The probe withstands routine industrial vibration of 10 Hz ~ 2 kHz generated by adjacent running rotating equipment. Long-term continuous immersion in corrosive liquid, acid mist and persistent high-temperature steam is forbidden to avoid outer casing corrosion and inner insulation aging damage. For installation above altitude 1000 meters, shorten periodic inspection interval appropriately.
6. Installation and Routine Maintenance Guidance
Cut off full power of the whole monitoring loop before installation, screw the short full-thread probe into shallow reserved threaded hole of bearing pedestal or custom mounting fixture, adjust pre-set installation gap to rated design value and lock fastening nut tightly against loosening from long-term operational vibration. During cabling construction, separate probe signal cable routing away from high-current AC power cables and inverter output wiring to reduce cross electromagnetic coupling interference. Avoid sharp small-radius bending, overstretching and heavy squeezing on cable body to prevent inner core breakage and abnormal impedance shift. Within regular maintenance cycles, periodically inspect cable outer sheath for oil corrosion, abrasion and cracking, and check locking tightness of terminal connector. When replacement is needed after probe failure, only spare part with identical full part number 21500-00-20-05-02 is allowed for direct swap. All replacement probes complete impedance testing and calibration matching before factory outbound delivery to guarantee full interchangeability inside original vibration monitoring loops.
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