Configured for shaft displacement sensing in legacy machinery protection systems, the Bently Nevada 21747-080-01 (21747-080-01 Proximitor Probe) provides direct physical/electrical execution of eddy-current signal generation for rotor position monitoring.

Model Identification Matrix

The 21747 series utilizes a specific configuration code to denote physical probe dimensions and electrical compatibility. The -080-01 suffix dictates the thread size, case length, and cable configuration required for integration into the 7200 series Proximitor transducer platform.

Hardware Specifications

Transducer Electrical and Mechanical Dynamics

Reliable rotor dynamics monitoring requires consistent eddy-current probe scaling to ensure the voltage output maintains a linear correlation with the measured gap. During site commissioning, technicians must conduct gap voltage validation (-10 VDC targets) at the Proximitor sensor output to confirm the probe is centered within its linear operating range. Maintaining cross-talk suppression is mandatory; coaxial shields must be continuous and grounded exclusively at the monitor interface to prevent electromagnetic noise and ground loops from compromising the vibration signal.

Ordering Information

• 21747-080-01 Proximitor Probe

• Integral coaxial cable assembly

• Stainless steel mounting jam nuts

• Technical installation data sheet

Field Installation Protocols

• Surface Conditioning: Ensure the target shaft area is free of non-conductive coatings, oxidation, or debris to allow uniform eddy-current field penetration.

• Mounting Mechanics: Thread the probe body into the mounting bracket; verify the gap is set to the machine-specific distance after tightening the lock nuts.

• Cabling and Shielding: Route coaxial cable leads away from high-current power conduits to prevent induction; maintain shield continuity throughout the cable run.

• Connector Integrity: Keep coaxial connector interfaces clean and protected from moisture; utilize provided caps until the final mating sequence.

• Signal Validation: Perform a post-installation static gap check to confirm the transducer output voltage is within the specified -10 VDC operational range.

Frequently Asked Questions

• Can this probe be used in modern 3300 XL systems? No, the 7200 series probes are designed for legacy Proximitor electronics; intermixing with XL components results in signal calibration errors.

• How do I verify a cable short? A drop in gap voltage to 0 VDC or a shift in the baseline noise floor suggests a coaxial dielectric breakdown or connector failure.

• Is the probe housing field-repairable? No, internal transducer coils are encapsulated for durability; structural damage or electrical failure necessitates total unit replacement.

• How does hydrogen cooling affect probe performance? The probe materials are rated for hydrogen-cooled environments; verify that O-ring seals are maintained to prevent gas leakage.

• What signifies a damaged PPS probe tip? Any cracking, heavy pitting, or deformation of the tip disrupts field linearity and warrants immediate replacement.

• Why is the shield grounded at only one end? Grounding the shield at both the probe and the monitor creates a ground loop, introducing 50/60 Hz noise into the signal path.

• Can I shorten the integral cable? No, the probe-cable assembly is factory-tuned to a specific capacitance; modifying cable length alters frequency response and sensitivity.

• What is the nominal output sensitivity? The probe maintains a fixed sensitivity of 200 mV/mil (7.87 V/mm) when paired with a compatible 7200 series Proximitor.