Bently Nevada 21504-00-60-05-02 Eddy Current Proximity Probe Product Specification
21504-00-60-05-02 is a factory pre-calibrated front-mounted 8 mm eddy current proximity probe for Bently Nevada 7200 series transducer system. Matched with original 2155/00 proximitor preamplifier and certified 75-ohm calibrated extension cable, it forms a complete non-contact measurement system compliant with API 670 rotating machinery protection standards. Based on eddy current induction principle, the probe converts tiny clearance fluctuations 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 for continuous online measurement of rotor radial vibration, short-stroke axial displacement and Keyphasor rotational pulse signals. Widely used on steam turbines, gas turbines, centrifugal compressors and large turbo-generators in power, petrochemical and metallurgical industries for over-limit alarm triggering and emergency shutdown interlock control. Every finished probe passes linearity calibration, high-low temperature cyclic aging test and full hermetic epoxy encapsulation inspection before factory delivery to maintain stable measuring accuracy under harsh field conditions including high bearing housing temperature, lubricating oil mist and complex electromagnetic interference from high-current power cables and variable frequency drives.
Description
Bently Nevada 21504-00-60-05-02 Eddy Current Proximity Probe Product Specification
1. Product Overview
21504-00-60-05-02 is a factory pre-calibrated front-mounted 8 mm eddy current proximity probe for Bently Nevada 7200 series transducer system. Matched with original 2155/00 proximitor preamplifier and certified 75-ohm calibrated extension cable, it forms a complete non-contact measurement system compliant with API 670 rotating machinery protection standards. Based on eddy current induction principle, the probe converts tiny clearance fluctuations 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 for continuous online measurement of rotor radial vibration, short-stroke axial displacement and Keyphasor rotational pulse signals. Widely used on steam turbines, gas turbines, centrifugal compressors and large turbo-generators in power, petrochemical and metallurgical industries for over-limit alarm triggering and emergency shutdown interlock control. Every finished probe passes linearity calibration, high-low temperature cyclic aging test and full hermetic epoxy encapsulation inspection before factory delivery to maintain stable measuring accuracy under harsh field conditions including high bearing housing temperature, lubricating oil mist and complex electromagnetic interference from high-current power cables and variable frequency drives.
2. Part Number Definition Breakdown
Each code segment follows Bently’s standard coding rules for 7200-series front-install proximity probes. Base code 21504 stands for core series of standard front-thread 8 mm proximity probe exclusively designed 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 60 specifies extra-long threaded body dimension for deep-hole installation on thick bearing pedestals; segment 05 indicates factory pre-molded integral coaxial cable fixed length of 0.5 meter permanently bonded to probe main body; final segment 02 means standard miniature coaxial terminal connector fitted at cable end for plug connection with certified original extension cable. Probes with altered digit segments have different mechanical dimensions or calibrated electrical parameters and cannot be arbitrarily replaced on-site; improper substitution invalidates full-loop factory calibration and causes measurement deviation or unexpected protection trip of the monitoring channel.
3. Core Functional Characteristics
The probe threaded housing and sensing tip are precision fabricated from high-strength corrosion-resistant stainless steel with excellent resistance against lubricant erosion and corrosive vapor inside confined oil-filled bearing chambers. Internal induction coil is fully potted with high-temperature epoxy resin to eliminate inner air gaps, effectively preventing coil shifting or inter-turn short-circuit triggered by long-term equipment vibration and ambient temperature swings. The attached 0.5-meter integral cable adopts controlled 75-ohm impedance coaxial structure with dense tinned copper braided shielding over 95% coverage to suppress external electromagnetic crosstalk during signal transmission. Field cutting, splicing or replacement of original integral cable and end connector is strictly prohibited; any physical alteration permanently voids factory preset calibration data. Front screw-in mounting design with extra-long thread fits deep reserved mounting holes and thick-wall bearing seats which short-size probes cannot reach. Built-in open/short-circuit fault diagnosis quickly identifies abnormal wiring via obvious output voltage drift to facilitate daily field troubleshooting. Stable linear performance of the whole measuring system is only secured by full original matching of the probe, matched extension cable and designated 2155/00 proximitor.
4. Electrical and Metrological Specifications
The supporting 2155/00 proximitor supplies regulated negative DC power ranging from -17.5 VDC to -26 VDC, with -24 VDC as the standard field operating voltage. Factory fixed calibrated sensitivity is 7.87 V/mm (200 mV/mil) referenced to standard AISI4140 carbon steel target, and full-range linearity tolerance is controlled within ±5% per API 670 requirements. Valid linear measuring range covers 0 mm to 2.0 mm for small-gap radial vibration and short-travel axial displacement monitoring of industrial rotating shafts. Effective frequency response spans DC up to 10 kHz to capture both low-frequency static thermal expansion drift and high-frequency dynamic shaft vibration signals synchronously. Recommended pre-installation gap is set near the midpoint of linear range to maintain a 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 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 above 1000 meters altitude, shorten periodic inspection interval appropriately.
6. Installation and Routine Maintenance Guidance
Cut off power supply of the entire monitoring loop before installation, screw the extra-long threaded probe into deep 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 lines 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 21504-00-60-05-02 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.
Get a Quote