Description
Bently Nevada 74712‑03‑10‑02‑00
3300‑XL 8 mm Keyphasor Eddy‑Current Probe Assembly (Standard‑Temperature, Non‑Hazardous‑Area)
Product Overview
The 74712‑03‑10‑02‑00 is a dedicated Keyphasor eddy‑current proximity probe from Bently Nevada 3300‑XL 8 mm Microdot transducer family. Optimized for once‑per‑revolution phase mark detection on rotating shafts, it generates a sharp pulse signal when observing a shaft notch or keyway. It is primarily used for rotational speed measurement, phase angle reference, vibration phase analysis and rotor balance monitoring for turbomachinery. This unit complies with API‑670 standards for rotating‑machinery protection. The suffix ‑00 denotes no hazardous‑area agency certifications, intended for installation within non‑explosive general‑purpose industrial zones.
Critical Compatibility Warning
- This is legacy Microdot‑interface Keyphasor probe. Works exclusively with 3300‑XL standard‑temperature Microdot‑type extension cables (330130 series). Not compatible with NSv ClickLoc (330930 series) or ETR‑qualified 330190 high‑temperature cables.
- Total calibrated transducer loop length = probe integral pigtail length + matched standard‑grade Microdot extension‑cable length. Summated length must match the length setting of paired Microdot‑type proximitor. Mismatched length results in signal distortion and inaccurate speed / phase reading.
- Termination: straight Microdot 10‑32 coaxial connector. Do not cut, splice or modify factory‑molded integral pigtail assembly. This probe shall only be deployed in non‑hazardous general‑purpose areas.
Part Number Decoding
- 74712：Base model, 3300‑XL 8 mm dedicated Keyphasor proximity probe
- ‑03：Mounting thread specification: 1/4‑28 UNF
- ‑10：Probe housing overall length: 100 mm
- ‑02：Integral non‑armored pigtail cable length: 2.0 meters
- ‑00：Certification option: No ATEX / IECEx / CSA hazardous‑area approvals
Key Specifications
| Parameter | Value |
|---|---|
| Part Number | 74712‑03‑10‑02‑00 |
| Series | 3300‑XL 8 mm Microdot Keyphasor Probe Transducer |
| Measurement Principle | Non‑contact eddy‑current displacement for phase‑mark triggering |
| Nominal Sensitivity | 7.87 V/mm (200 mV/mil), ±5 % tolerance |
| Linear Measurement Range | 0.25 mm ~ 2.0 mm (10‑80 mil) |
| Probe Tip Diameter | 8 mm |
| Mounting Thread | 1/4‑28 UNF |
| Housing Overall Length | 100 mm |
| Integral Pigtail | 2.0 m, non‑armored standard‑grade FEP insulation |
| Connector Type | Straight Microdot 10‑32 coaxial |
| Frequency Response | 0 Hz‑10 kHz |
| Operating Temperature Range | ‑52 °C ~ +121 °C (standard temperature rating) |
| Housing Material | 316 stainless steel |
| Certifications | API‑670 compliant; No hazardous‑area intrinsic‑safety approvals |
| Country of Origin | USA |
| Weight | ≈0.23 kg |
Main Features
- Specialized Keyphasor triggering design: Optimized for detecting shaft keyways or notches to generate once‑per‑revolution reference pulse, supports speed reading, vibration‑phase calculation and rotor dynamic balancing analysis.
- Compact 100 mm housing with 1/4‑28 UNF thread: Small‑form‑factor mechanical interface widely used for phase‑reference mounting positions on turbine and compressor bearing housings.
- 2.0 m factory‑calibrated standard‑temperature non‑armored integral pigtail with straight Microdot connector: Pairs with 330130‑series standard‑grade tri‑axial extension cables to build required total transducer‑loop length.
- Standard‑temperature performance rating: Reliable performance under general‑purpose plant ambient‑temperature conditions; not suitable for continuous high‑radiant‑heat locations that require ETR‑rated components.
- Robust mechanical construction: Resists oil‑mist, humidity and normal machinery vibration, satisfies API‑670 phase‑reference requirements for critical rotating equipment.
- Full interoperability within legacy 3300‑XL standard‑temperature Microdot transducer ecosystem.
Typical Application Scenarios
| Application Scenarios |
|---|
| Once‑per‑revolution phase‑mark detection for steam turbines, gas turbines and centrifugal compressors within non‑hazardous industrial areas |
| Rotational speed monitoring, vibration‑phase angle measurement and rotor balancing reference for fluid‑film‑bearing rotating machinery |
| General‑purpose power‑plant and machinery‑house installations without explosive‑zone classification |
| System integration with Bently Nevada 3500 rack Microdot‑compatible Keyphasor proximitor input channels |
| Spare‑part replacement for existing standard‑temperature Microdot Keyphasor measurement loops |
Related & Recommended Alternative Models
| Model | Description |
|---|---|
| 74712‑03‑10‑02‑05 | 2.0 m pigtail Keyphasor probe, multi‑hazardous‑area intrinsic‑safety approvals |
| 74712‑03‑10‑10‑00 | 1.0 m integral pigtail Keyphasor probe, non‑hazardous‑area version |
| 330130‑075‑00‑05 | 7.5 m non‑armored standard‑grade extension cable, dual‑end right‑angle Microdot |
| 330190‑085‑00‑05 | 8.5 m ETR high‑temperature extension cable (ETR only, not interchangeable) |
| 330105‑02‑12‑05‑02‑05 | NSv ClickLoc reverse‑mount proximity probe (incompatible, reference‑only) |
Compatible Components & Accessories
- Extension Cables: 330130 series standard‑temperature Microdot tri‑axial extension cables (straight / right‑angle variants)
- Monitoring Hardware: Standard‑temperature Microdot‑type proximitor modules, Bently Nevada 3500 rack Keyphasor‑enabled Microdot monitor channels
- Mechanical Accessories: Probe mounting lock‑nut, probe mounting shell assembly, 43501‑02‑04‑02 low‑pressure cable‑seal assembly, 43574‑04 multi‑hole grommet
- Installation Consumables: Anti‑seize compound for mounting threads, cable clamps for strain‑relief, high‑temperature cable ties
- Tooling: Specified‑torque Microdot connector tightening tool
- Calibration Tool: 8 mm 3300‑XL Microdot static gap calibration fixture
Installation and Configuration Guide
Warning: Installation shall be performed by qualified instrument technicians. Always reference the original Bently Nevada 3300‑XL Microdot transducer‑system manual as primary technical source. This model has no hazardous‑area certifications and must not be installed in explosive classified zones.
- Pre‑installation Total‑Length Calculation
- Calculate total transducer loop length = probe integral pigtail (2.0 m) + selected standard‑grade Microdot extension‑cable length.
- Confirm total length strictly matches calibrated‑length requirement of paired Microdot proximitor. Length mismatch leads to distorted Keyphasor pulse and erroneous speed / phase data.
- Keyphasor Mechanical Mounting
- Install matching probe mounting shell onto bearing housing.
- Apply anti‑seize compound to 1/4‑28 UNF probe thread. Screw probe into mounting shell, adjust working gap targeting optimal trigger gap for shaft notch / keyway geometry, fasten lock‑nut to specified torque.
- Verify probe tip maintains safe clearance; no physical contact with rotating‑shaft surface during full operational speed range. Validate clear pulse trigger from shaft notch via gap‑voltage observation.
- Cable Routing & Microdot Connector Mating
- Route tri‑axial transducer cable separately from high‑power AC, VFD and contactor wiring to minimize EMI‑induced signal noise.
- Maintain minimum static bending radius ≥50 mm; avoid sharp kinks. Never pull cable assembly by Microdot connector housing.
- Clean Microdot contact pins; align keyway and tighten to manufacturer‑specified torque value. Do not over‑torque connector assembly.
- Fit strain‑relief clamps adjacent to connector joint. Where cable penetrates machine casing, deploy approved cable‑seal fitting.
- System Commissioning
- Complete full transducer‑loop assembly and power‑up proximitor / monitoring rack.
- Observe Keyphasor pulse waveform and static gap voltage to validate mechanical gap setting. Perform static‑gap calibration test with 8 mm Microdot calibration fixture to confirm system scale‑factor.
- Clear Not‑OK fault status; configure speed alarm thresholds and phase‑monitor parameters according to project machinery specification.
- Maintenance & Troubleshooting
- During machinery turnaround, inspect probe locking torque, examine Microdot connector for oil contamination and corrosion; inspect pigtail outer jacket for abrasion or cracking damage.
- Missing or unstable Keyphasor pulse, signal noise or persistent Not‑OK faults may originate from improper trigger gap, shaft notch wear, loose Microdot joint, cable damage or incorrect total transducer‑loop length.
- Replace complete factory probe assembly upon pigtail or probe‑tip damage; field‑splicing of integral probe pigtail cable is strictly prohibited.
Supplementary Remark
74712‑03‑10‑02‑00 is a dedicated 3300‑XL 8 mm Microdot Keyphasor proximity probe with 1/4‑28 UNF thread, 100 mm housing and 2.0 m standard‑temperature integral pigtail. Without hazardous‑area certifications, it is designed for phase‑mark detection, rotational‑speed and vibration‑phase measurement within non‑explosive industrial environments. It only pairs with standard‑temperature Microdot‑system components and cannot interoperate with ETR high‑temperature cables or NSv ClickLoc hardware. Before commissioning, cross‑check Keyphasor mechanical mounting requirements, total transducer‑loop length, Microdot interface and area classification against project BOM and mechanical drawings.
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