Bently Nevada 21504-000-032-10-02 Eddy Current Proximity Probe Product Specification
21504-000-032-10-02 is factory pre-calibrated front-mounted 8 mm eddy current proximity probe exclusively developed for Bently Nevada 7200 series transducer system. When paired with original 2155/00 proximitor preamplifier and factory-calibrated 75-ohm matched extension cable, the assembly forms a complete non-contact measuring system conforming to API 670 standard for critical rotating machinery protection. 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 signals are transmitted to 7200 or 3500 rack-mounted monitoring modules to conduct continuous online measurement of shaft radial vibration, short-stroke axial displacement and Keyphasor rotational pickup pulses. Widely deployed on steam turbines, gas turbines, centrifugal compressors and large turbo-generators in power, petrochemical and metallurgical industries, it supplies over-limit alarm and emergency shutdown interlock signals to ensure unit safe 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 severe field conditions including high bearing housing temperature, persistent lubricant oil mist and complex electromagnetic interference from high-current power cables and variable frequency drive equipment.
Description
Bently Nevada 21504-000-032-10-02 Eddy Current Proximity Probe Product Specification
1. Product Overview
21504-000-032-10-02 is factory pre-calibrated front-mounted 8 mm eddy current proximity probe exclusively developed for Bently Nevada 7200 series transducer system. When paired with original 2155/00 proximitor preamplifier and factory-calibrated 75-ohm matched extension cable, the assembly forms a complete non-contact measuring system conforming to API 670 standard for critical rotating machinery protection. 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 signals are transmitted to 7200 or 3500 rack-mounted monitoring modules to conduct continuous online measurement of shaft radial vibration, short-stroke axial displacement and Keyphasor rotational pickup pulses. Widely deployed on steam turbines, gas turbines, centrifugal compressors and large turbo-generators in power, petrochemical and metallurgical industries, it supplies over-limit alarm and emergency shutdown interlock signals to ensure unit safe 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 severe field conditions including high bearing housing temperature, persistent lubricant 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 rules for 7200-series front-install proximity probes. Base code 21504 represents standard 8 mm diameter front-threaded proximity probe series dedicated to the 7200 transducer platform; segment 000 means zero exposed unthreaded tip length with fixed internal coil structure and factory-locked original calibration parameters without customized electrical modification; segment 032 stands for medium full-threaded body dimension designed for regular medium-depth mounting holes on standard bearing pedestals; segment 10 refers to factory pre-molded integral coaxial cable fixed at 1.0 meter and 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. Any modification to part code digits leads to changed mechanical size or calibrated electrical parameters, and random on-site replacement with non-identical part will invalidate full-loop factory calibration, resulting in measurement deviation or unexpected protective trip of the monitoring channel.
3. Core Functional Characteristics
The probe threaded housing and sensing tip are precision processed 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, effectively preventing coil displacement and inter-turn short-circuit caused by long-term equipment vibration and ambient temperature fluctuation. The attached 1.0-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, and all physical alteration permanently voids factory preset calibration data of the whole transducer set. Medium full-thread front mounting design is optimized for conventional medium-depth pre-drilled mounting holes and regular medium-thickness 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 performance of the entire measuring system can only be maintained by complete 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 use. 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 ~ 2.0 mm to satisfy regular radial vibration and short-travel axial clearance measurement for most 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 continuous 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 medium full-thread 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 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 required after probe failure, only spare part with identical full part number 21504-000-032-10-02 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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