Bently Nevada 21000-02-36-00-120-03-02 Armored Eddy Current Probe Assembly Product Specification

The 21000-02-36-00-120-03-02 belongs to Bently Nevada 21000 series heavy-duty armored eddy current proximity probe assembly with factory pre-calibration. Designed for deep-hole embedded installation inside bearing pedestals under severe operating conditions of high ambient temperature, dense lubricating oil mist and complicated assembly stress, this integrated unit is built with a standard 3300XL 5 mm sensing core encapsulated inside a full metal protective armored sleeve. When paired with matched original proximitor transducer and certified extension cable, it forms a complete non-contact measuring system compliant with API 670 international standard for critical rotating machinery protection. Widely applied on large steam turbines, heavy-duty gas turbines, oversized centrifugal compressors and high-capacity turbo-generator sets in power, petrochemical and metallurgical industries, the probe performs continuous online measurement of shaft radial vibration and axial thrust displacement, as well as keyphasor rotational speed pickup. It delivers over-limit alarm and emergency shutdown interlock signals to safeguard production units against catastrophic mechanical failures. Each finished probe undergoes full-scale linearity calibration, high-low temperature cyclic aging test and comprehensive hermetic sealing inspection before ex-factory delivery to retain consistent measurement accuracy over long-term harsh field operation.

The seven-segment part coding follows Bently Nevada unified naming specification for armored proximity probes. The prefix 21000 denotes heavy-duty integrated armored probe series with anti-impact, oil-proof metal outer casing structure; the second digit 02 specifies the probe core configuration for standard 5 mm diameter 3300XL sensing element and matched customized aluminum alloy armored housing; the third code 36 stands for factory pre-molded integral coaxial cable with fixed total length of 36 meters, and on-site cutting, splicing or arbitrary modification to original cable is forbidden to protect preset factory calibration parameters; the fourth segment 00 means fully recessed sensing tip design with zero tip extension out of armored sleeve front face to avoid collision damage during installation and equipment running; the fifth code 120 refers to overall armored sleeve length of 12 inches for deep bore mounting on thick heavy-duty bearing housings; the sixth code 03 represents standard 3/4-14 NPT tapered pipe mounting thread for bearing pedestal threaded installation holes; the final suffix 02 indicates standard rear-end general industrial sealing structure and miniature coaxial male connector without special explosion-proof rating, supplied under original factory calibrated configuration. Random replacement with mismatched part number probes will destroy factory matching calibration and cause measurement deviation or unintended protection channel tripping.

The armored sleeve and front protection structure are precision processed from high-strength anti-corrosion stainless steel, featuring excellent resistance against lubricant erosion, high-temperature oil vapor and mechanical collision inside closed bearing cavities. Internal induction coil of the sensing core is fully potted with high-temperature resistant epoxy resin to eliminate internal air gaps, effectively preventing coil shifting and inter-turn short-circuit faults triggered by long-period equipment vibration and fluctuating working temperature. The attached 36-meter original integral coaxial cable adopts standard 75-ohm controlled-impedance shielding design with over 95% coverage tinned copper braided screen to restrain external electromagnetic interference during long-distance signal transmission. Any unauthorized cutting or connector replacement on site will permanently invalidate the full-set factory calibration of the whole transducer system. The fully recessed tip plus long armored sleeve design is specially optimized for deep embedded installation of thick-wall heavy-duty bearing seat, isolating assembly extrusion stress and avoiding probe core abrasion. Built-in open-circuit and short-circuit self-diagnosis function reflects abnormal wiring status via obvious output voltage offset, facilitating daily field troubleshooting. Stable linear measurement performance of the complete monitoring system can only be ensured by original matching of this probe, designated extension cable and compatible proximitor.

The matched proximitor accepts regulated negative DC input voltage ranging from -17.5 VDC to -26 VDC, with -24 VDC as nominal standard operating voltage for industrial field application. Factory preset sensitivity is fixed at 7.87 V/mm (200 mV/mil) calibrated on standard AISI4140 carbon steel target, and full-range linearity error is controlled within ±5% in accordance with API 670 specification. Valid linear measuring range covers 0 mm ~ 1.27 mm to satisfy regular radial vibration and axial clearance measurement of medium and small-diameter high-speed rotating shafts. Frequency response spans DC to 10 kHz to capture both low-frequency static thermal drift and high-frequency dynamic vibration signals simultaneously. Recommended installation gap is arranged near the midpoint of linear range to maintain steady DC bias working point for continuous long-time equipment operation.

The sensing section supports continuous working temperature from -35°C to +120°C to adapt high-temperature installation near heated bearing housings and turbine casings. Storage temperature for spare probes is maintained between -55°C and +85°C under dry non-condensing storage environment; applicable operating relative humidity ranges from 5%RH to 95%RH without dew accumulation on probe casing and cable outer jacket. The probe withstands regular equipment vibration of 10 Hz ~ 2 kHz generated by adjacent running rotating machinery. Long-term immersion or continuous exposure to corrosive liquid, acid mist and persistent high-temperature steam is prohibited to prevent outer shell corrosion and premature aging of internal insulating materials. For installation locations above 1000 meters altitude, regular inspection cycle shall be shortened appropriately.

Cut off full power of the monitoring loop prior to field installation, screw the probe threaded body into pre-machined deep threaded hole of bearing pedestal or customized fixture via 3/4-14 NPT thread, adjust installation clearance to rated design value and fasten lock nut tightly to avoid loosening induced by long-term running vibration. During cable routing, separate probe signal cable from high-current AC power cables and inverter output lines to reduce cross electromagnetic coupling interference. Avoid sharp small-radius bending, overstretching and heavy compression on cable body to prevent inner conductor breakage and abnormal impedance shift. Within fixed maintenance cycles, periodically inspect cable outer sheath for oil corrosion, abrasion and cracking, and check fastening tightness of rear terminal connector. Once probe fails and needs replacement, only spare part with identical part number 21000-02-36-00-120-03-02 is allowed for direct swap. All replacement probes pass complete electrical performance test and alternating temperature aging screening before factory delivery to guarantee full interchangeability within original vibration monitoring loops.