The Bently Nevada 21505-00-40-10-02, also cataloged as the 21505 Proximity Probe, operates as a dedicated hardware component for non-contacting displacement and vibration measurements within 7200 Series Transducer Systems.

Suffix Code Definitions

The mechanical configurations of this 7200 Series proximity probe are defined by the following suffix options:

• 21505: Base model designation for the 5 mm / 8 mm Standard Mount Proximity Probe with 3/8-24 UNF threads.
• -00: Selects an unthreaded case length of 0.0 inches.
• -40: Configures an overall case length of 4.0 inches.
• -10: Selects a total cable length of 1.0 meter (39 inches).
• -02: Selects a miniature male coaxial connector interface.

Hardware Specifications

Eddy-Current Probe Scaling and Rotor Dynamics Integration

The 21505-00-40-10-02 probe utilizes eddy-current probe scaling to monitor dynamic changes in the distance between the probe tip and the rotating shaft. The system relies on a gap-to-voltage transducer loop where target proximity changes directly alter the high-frequency magnetic field, generating a proportional voltage output. For accurate rotor dynamics mapping, a gap voltage validation must be executed during physical installation.

Adjusting the probe position until the sensor loop generates a nominal target voltage of -10 VDC centers the sensor precisely in its 80 mil (2 mm) linear range. This setup minimizes signal distortion and maintains the integrity of high-frequency TSI (Turbine Supervisory Instrumentation) data paths.

Ordering Info

• 1 x Bently Nevada 21505-00-40-10-02 Proximity Probe
• 2 x 3/8-24 Hexagonal jam nuts
• 1 x Lock washer
• 1 x Plastic thread protection sleeve

Field Installation Guidelines

• Thread Engagement and Torquing

  Ensure clean, debris-free threads prior to insertion. The 4.0 inch threaded body must be tightened with the provided jam nuts to 35 ft-lb (48 N-m) of torque to prevent loosening from continuous machinery casing vibration.

• Zero Unthreaded Length Clearance

  Since this model features a 0.0 inch unthreaded length option, the threads extend to the base of the probe tip. Avoid bottoming out the threaded body against internal shoulders or counterbores within the bracket assembly.

• Cable Routing and Connection Security

  Keep the coaxial cable clear of sharp metal edges and maintain a minimum bend radius of 25.4 mm (1.0 inch). Secure the miniature male coaxial connector to the extension cable and shield the connection with a Teflon connector insulator sleeve to prevent grounding faults.

Frequently Asked Questions

• How is the target gap voltage validated during the installation of this 7200 series probe?

  Hook up a voltmeter to the Proximitor loop and rotate the probe in its mounting thread until the output matches the nominal -10 VDC calibration target.

• Can this 7200 Series probe be used with a 3300 XL Proximitor sensor?

  No, 7200 Series probes are electrically tuned to 7200 Proximitors and are incompatible with 3300 XL electronics due to differing scale factor profiles.

• What occurs if the 1.0 meter cable is bent past its minimum bend radius?

  Bending the coaxial cable too tightly can damage the internal copper shield and core, leading to impedance mismatch or calibration drift in the loop.

• Does this model feature physical mechanical armor on the cable?

  No, this specific configuration relies on an unarmored coaxial cable jacket and requires conduit or external trays for mechanical routing protection.

• Is the 21505 probe body capable of withstanding exposure to high-pressure oil?

  The front tip of the probe is sealed against process gases and fluids, but the rear cable exit is unsealed and must not be submerged.

• What target material is required to ensure accurate eddy-current scaling?

  The system is calibrated for AISI 4140 steel. Using other metals will alter the linear range and require custom system calibration.

• Why is the frequency response rated down to 0 Hz (DC)?

  The 0 Hz (DC) measurement capability is required to detect slow thrust displacement, thermal expansion, and static shaft position offsets.

• How should the miniature male coaxial connector be handled to prevent signal loss?

  Ensure the connector contacts remain free of oil, moisture, and grease; use clean contact cleaner before mating the connector with the extension cable.