Configured for high-frequency displacement monitoring in 3500 Machinery Protection Systems, the Bently Nevada 330908-39-71-05-01-00 (330908 Proximity Probe) provides direct physical/electrical execution. This component is engineered for small-diameter shaft applications, converting the gap between the probe tip and target into a linear voltage signal. The system is designed to provide high-resolution measurement of rotor position and vibration where standard 8 mm probes are physically constrained or lack the required measurement range for small-target geometry.

Suffix Breakdown & Model Matrix

• 330908: 3300 NSv Proximity Probe

• -39: Thread option (3/8-24 UNF thread, non-armored)

• -71: Unthreaded Length option (71 mm length)

• -05: Total Length option (0.5 meter system length)

• -01: Connector option (Miniature coaxial connector)

• -00: Agency Approval option (Not required/Standard version)

Hardware Specifications

Mechanical Monitoring & Rotor Dynamics

The 3300 NSv system requires specific eddy-current probe scaling to ensure accuracy, particularly when monitoring low-amplitude vibrations on small-diameter shafts. Field engineers must perform gap voltage validation to maintain the -10 VDC target at the mechanical center of the probe linear range. This ensures that dynamic signals remain within the optimum response window of the monitoring module. Additionally, cross-talk suppression is vital; maintain adequate spacing between probe tips to prevent inductive coupling, which can otherwise introduce false phase-angle data or erroneous vibration readings into the protection logic.

Ordering Information

• One (1) 330908-39-71-05-01-00 Proximity Probe

• Two (2) 3/8-24 UNF hex locknuts

• One (1) silicone connector protector sleeve

• Compliance and factory calibration documentation

Installation Guidelines

• Thread Engagement: Ensure at least five (5) full thread turns of engagement within the mounting bracket to secure the probe against process vibrations.

• Gap Calibration: Use a feeler gauge to establish the initial mechanical gap prior to operation, confirming the target is within the linear 1.5 mm range.

• Shield Grounding: Terminate the coaxial shield exclusively at the designated ground terminal within the Proximitor housing to prevent circulating ground-loop currents.

• Cable Handling: Maintain a minimum bend radius of 25.4 mm (1.0 inch) and secure the cable at regular intervals to prevent structural fatigue.

Logistics & Transit

• Delivery time: 2-7 days when payment finish.

• Shipped via DHL/FEDEX/UPS.

• Anti-static industrial packaging used to prevent ESD and impact damage during global transit.

Frequently Asked Questions

• Can the 330908 probe be used with standard 3300 XL Proximitors?

  No. The NSv probe is designed specifically for the 3300 NSv Proximitor sensor due to different carrier frequencies and impedance characteristics.

• What is the consequence of exceeding the linear range?

  Exceeding the 1.5 mm linear range results in signal non-linearity, causing distortion of the vibration waveform and inaccurate amplitude readings.

• Is this probe suitable for submerged oil service?

  Yes, provided the coaxial connector is protected by the silicone sleeve to prevent conductive fluids from bridging the connector pins.

• Why does the probe output voltage increase with distance?

  The probe uses an inductive oscillator; as the target moves away, the loading on the coil decreases, shifting the output voltage closer to the supply voltage (-24 VDC).

• Can the probe cable be shortened in the field?

  No. Altering the cable length changes the impedance of the tuned circuit, which invalidates the calibration and significantly degrades measurement accuracy.

• How is probe health monitored in the 3500 system?

  The monitor constantly checks the gap voltage. Values outside the -1 VDC to -21 VDC range trigger a NOT OK status, indicating a fault.

• Does the probe tip diameter affect the measurement?

  Yes. The 3300 NSv tip is optimized for smaller targets than standard 8 mm probes, providing better resolution for small-diameter shaft applications.

• Is there a limit to how many probes can be mounted near each other?

  Yes. To prevent cross-talk, probes must be separated by at least 25 mm if they are not shielded or oriented such that their fields do not overlap.