Bently Nevada 20929-04 190 Series Eddy Current Proximitor Product Specification
20929-04 is a standalone 190-type proximitor belonging to Bently Nevada classic 20929 serial discrete eddy-current signal conditioning unit under the 3000 series transducer system, factory pre-calibrated exclusively for 0.190 inch (4.83mm) diameter proximity probe with total 20 feet (6.10m) system cable length. Developed as a core signal conversion component for traditional TSI machinery protection systems, it applies eddy-current working principle to convert tiny coil inductance variation induced by clearance change between probe tip and rotating metal target into standardized linear negative DC output signal, to monitor radial shaft vibration, axial thrust displacement, rotor eccentricity and Keyphasor rotational phase signal on large rotating equipment including steam turbines, gas turbines, industrial centrifugal compressors and heavy-duty feed pumps within thermal power, petrochemical and metallurgical industries. The unit adopts solid die-cast aluminum alloy sealed housing with three brass screw terminal posts for field wiring, conformal protective coating is covered over internal printed circuit board to resist cabinet dust, damp ambient air and trace corrosive industrial gas for long-term uninterrupted fixed installation. It shares identical outer mechanical dimension layout with 20929-06 and 20929-07 variants in the same product family for partial spare part interchangeability.
Description
Bently Nevada 20929-04 190 Series Eddy Current Proximitor Product Specification
1. Product Overview
20929-04 is a standalone 190-type proximitor belonging to Bently Nevada classic 20929 serial discrete eddy-current signal conditioning unit under the 3000 series transducer system, factory pre-calibrated exclusively for 0.190 inch (4.83mm) diameter proximity probe with total 20 feet (6.10m) system cable length. Developed as a core signal conversion component for traditional TSI machinery protection systems, it applies eddy-current working principle to convert tiny coil inductance variation induced by clearance change between probe tip and rotating metal target into standardized linear negative DC output signal, to monitor radial shaft vibration, axial thrust displacement, rotor eccentricity and Keyphasor rotational phase signal on large rotating equipment including steam turbines, gas turbines, industrial centrifugal compressors and heavy-duty feed pumps within thermal power, petrochemical and metallurgical industries. The unit adopts solid die-cast aluminum alloy sealed housing with three brass screw terminal posts for field wiring, conformal protective coating is covered over internal printed circuit board to resist cabinet dust, damp ambient air and trace corrosive industrial gas for long-term uninterrupted fixed installation. It shares identical outer mechanical dimension layout with 20929-06 and 20929-07 variants in the same product family for partial spare part interchangeability.
2. Main Application Scope
This proximitor is mostly mounted inside on-site machinery protection control cabinets and local field junction boxes, forming a complete three-element measuring loop with matched 4.83mm diameter eddy-current probe and dedicated 6.10m extension cable to continuously collect real-time gap value between probe and conductive target surface made of standard AISI4140 steel as specified by factory calibration. After built-in multi-stage amplification, linear correction and EMI high-frequency noise filtering processing, the conditioned analog DC signal is transmitted to local field indicator meters, DCS analog input modules or legacy rack-based monitor equipment for real-time parameter display, over-limit alarm activation and equipment emergency trip interlock control. Apart from conventional power and refining sectors, it is widely configured for critical large industrial blowers and high-pressure process pumps on continuous chemical production lines for online condition monitoring and protection interlock logic execution.
3. Detailed Electrical Performance Specifications
3.1 Input and Output Electrical Parameters
Factory fixed scale factor is defined as 200 mV/mil (equivalent to 8 V/mm), which matches 0.190-inch diameter probe linear measuring range and generates proportional 0 VDC ~ -24 VDC negative linear output corresponding to physical gap distance. Internal integrated low-pass filter circuit effectively suppresses electromagnetic interference generated by surrounding frequency converters, high-voltage distribution cabinets and large AC motors to stabilize measuring precision under complicated industrial electromagnetic environment. Every finished product undergoes strict factory linearity calibration test to restrict full-system measuring deviation within industry permitted tolerance standard for rotating machinery monitoring. The target material for calibration is standard AISI4140 alloy steel, and measuring accuracy will deviate slightly when applied on other metal target materials without on-site recalibration.
3.2 Power Supply Specification
The proximitor requires regulated external negative DC auxiliary power input within standard rated voltage range, with built-in reverse polarity protection and transient surge suppression circuit at power terminal to prevent internal circuit damage caused by wrong wiring during field installation, commissioning and regular maintenance. Optimized internal power consumption design controls continuous operating heat generation to satisfy 24-hour non-stop running working mode of critical heavy industrial equipment.
3.3 Onboard Fault Diagnostic Function
No digital communication diagnostic bus interface is equipped for this discrete standalone proximitor model; on-site fault troubleshooting depends on abnormal drift of output DC voltage value. Detectable common field faults cover probe inner conductor open circuit, extension cable core wire breakage, terminal short-circuit failure and over-range gap exceeding valid probe measuring distance, all above faults will trigger obvious abnormal deviation of output voltage for maintenance staff to rapidly locate defective component.
4. Mechanical Structure and Environmental Operating Ratings
4.1 Mechanical Structure and Installation
Full die-cast aluminum alloy shell delivers outstanding anti-shock and anti-vibration capability to adapt vibration-prone cabinet installation environment. Three independent brass screw terminals are arranged on one side of housing respectively for power supply access, probe input connection and conditioned signal output wiring, differing from coaxial connector configuration adopted on 20929-07 model. Pre-punched fixed mounting holes on housing base support direct screw-type panel installation on cabinet guide rails without rack plug-in structure, compact overall outline effectively saves limited inner cabinet installation space; single unit net weight is consistent with other 20929 series proximitor specifications around 0.53~0.55kg.
4.2 Ambient Temperature and Humidity Ratings
Rated continuous on-site cabinet operating temperature spans from -29℃ to +66℃ as factory labeled parameter; allowable spare part storage and cross-region transportation temperature ranges from -51℃ to +107℃ to accommodate diverse seasonal climate during logistics and spare inventory storage. Rated working ambient relative humidity is controlled within 5%~95% non-condensing condition to avoid internal PCB short circuit induced by cabinet internal dew condensation and moisture accumulation.
5. Core Product Technical Advantages
First, unified serial dimension standard enables partial interchange with 20929-06, 20929-07 and other models of 20929 series, reducing on-site spare part stocking varieties and lowering later-period equipment maintenance cost for end users. Second, dedicated internal signal linearization circuit is customized for matched 4.83mm diameter 190-series probe to guarantee stable long-term measuring accuracy for critical machinery protection monitoring under continuous heavy-duty operation. Third, robust screw terminal wiring structure improves connection stability under long-term cabinet vibration compared with coaxial connection type, lowering loose wiring failure probability on industrial site. Fourth, mature classic analog circuit design with decades of field application experience ensures long service life and reliable running performance adapting uninterrupted industrial working conditions.
6. Quality Certification and Warranty Provisions
20929-04 is original USA-manufactured product complying with Bently Nevada internal industrial component quality management standards and corresponding CE electrical safety certification for global industrial automation market supply. When operated under specified rated environmental condition without artificial physical damage, improper power supply wiring or overvoltage misuse, the product provides standard 12-month limited factory warranty covering inherent original manufacturing defects calculated from formal delivery date.
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