Bently Nevada 21504-00-52-10-02 Eddy Current Proximity Probe Product Specification
21504-00-52-10-02 is factory pre-calibrated front-mounted 8 mm eddy current proximity probe designed for Bently Nevada 7200 series transducer system. When matched with original 2155/00 proximitor preamplifier and certified 75-ohm calibrated extension cable, it forms a complete non-contact measurement system complying with API 670 rotating machinery protection standards. Based on eddy-current induction principle, the probe converts minor clearance variations between sensing tip and conductive metallic rotor target into linear analog voltage signals. These output signals are transmitted to 7200 or 3500 rack-mounted monitor modules to realize continuous online measurement of rotor radial vibration, short-stroke axial displacement and Keyphasor rotational pickup signals. Widely deployed on steam turbines, gas turbines, centrifugal compressors and large turbo-generators across power, petrochemical and metallurgical industries for over-limit alarm activation and emergency shutdown interlock protection. Every finished probe undergoes linearity calibration, high-low temperature cyclic aging and full hermetic epoxy encapsulation inspection prior to factory shipment to maintain stable measuring accuracy under harsh field conditions including high bearing housing temperature, pervasive lubricant oil mist and complex electromagnetic interference from high-current power cables and variable frequency drive equipment.
Description
Bently Nevada 21504-00-52-10-02 Eddy Current Proximity Probe Product Specification
1. Product Overview
21504-00-52-10-02 is factory pre-calibrated front-mounted 8 mm eddy current proximity probe designed for Bently Nevada 7200 series transducer system. When matched with original 2155/00 proximitor preamplifier and certified 75-ohm calibrated extension cable, it forms a complete non-contact measurement system complying with API 670 rotating machinery protection standards. Based on eddy-current induction principle, the probe converts minor clearance variations between sensing tip and conductive metallic rotor target into linear analog voltage signals. These output signals are transmitted to 7200 or 3500 rack-mounted monitor modules to realize continuous online measurement of rotor radial vibration, short-stroke axial displacement and Keyphasor rotational pickup signals. Widely deployed on steam turbines, gas turbines, centrifugal compressors and large turbo-generators across power, petrochemical and metallurgical industries for over-limit alarm activation and emergency shutdown interlock protection. Every finished probe undergoes linearity calibration, high-low temperature cyclic aging and full hermetic epoxy encapsulation inspection prior to factory shipment to maintain stable measuring accuracy under harsh field conditions including high bearing housing temperature, pervasive lubricant oil mist and complex electromagnetic interference from high-current power cables and variable frequency drive equipment.
2. Part Number Definition Breakdown
Each coded segment follows Bently’s standard coding specification for 7200-series front-install proximity probes. Base code 21504 stands for core series of standard front-thread 8 mm proximity probe exclusively developed for the 7200 transducer platform; segment 00 defines fixed internal coil structure, inner wiring layout and factory-locked original calibration parameters without customized electrical modification; segment 52 specifies medium-long threaded body dimension for medium-depth hole installation on thick bearing pedestals; segment 10 represents factory pre-molded integral coaxial cable fixed length of 1.0 meter permanently bonded to probe main body; final segment 02 indicates standard miniature coaxial terminal connector fitted at cable end for plug-in connection with certified original extension cable. Probes with altered segment digits have different mechanical dimensions or calibrated electrical characteristics and cannot be arbitrarily replaced on-site; improper substitution invalidates full-loop factory calibration and results in measurement deviation or unexpected protection trip of the monitoring channel.
3. Core Functional Characteristics
The probe threaded housing and sensing tip are precision manufactured from high-strength corrosion-resistant stainless steel with outstanding resistance against lubricant erosion and corrosive vapor inside confined sealed bearing compartments. Internal induction coil is fully potted with high-temperature epoxy resin to eliminate inner air gaps, effectively preventing coil displacement or inter-turn short-circuit caused by long-term equipment vibration and ambient temperature fluctuation. The attached 1-meter integral cable adopts standard 75-ohm controlled-impedance coaxial structure with dense tinned copper braided shielding over 95% coverage to suppress external electromagnetic crosstalk during signal transmission. Any field cutting, splicing or manual replacement of original integral cable and end connector is strictly prohibited, as physical modification permanently voids factory preset calibration data. Front screw-in mounting design with medium-long thread fits medium-depth mounting holes of conventional bearing seats conveniently. Built-in open/short-circuit fault diagnosis identifies abnormal wiring via obvious output voltage drift to simplify daily field troubleshooting. Consistent linear performance of the entire measuring system is only maintained by full original matching of the probe, certified extension cable and designated 2155/00 proximitor.
4. Electrical and Metrological Specifications
The matched 2155/00 proximitor provides regulated negative DC supply ranging from -17.5 VDC to -26 VDC, and -24 VDC is the standard field operating voltage. 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 specification. Valid linear measuring range covers 0 mm to 2.0 mm for small-gap radial vibration and short-travel axial displacement measurement of industrial rotating shafts. Effective frequency response spans DC up to 10 kHz to collect both low-frequency static thermal expansion drift signals and high-frequency dynamic shaft vibration signals simultaneously. Recommended pre-installation gap is set near the midpoint of linear range to secure a stable bias working point for continuous long-term equipment operation.
5. Environmental Working Parameters
Permissible continuous operating temperature of probe sensing part ranges from -35°C to +120°C to adapt 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 storage 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 positions above 1000 meters altitude, shorten periodic inspection interval appropriately.
6. Installation and Routine Maintenance Guidance
Cut off power supply of the whole monitoring loop before installation, screw the medium-long threaded probe into medium-depth reserved threaded hole of bearing pedestal or custom mounting fixture, adjust pre-set installation gap to rated design value and lock fastening nut against operational loosening. 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 internal core breakage and 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 21504-00-52-10-02 is permitted 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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