The Bently Nevada 330903-04-10-10-01-00, also cataloged as the 330903 Proximity Probe, serves as a high-precision sensing element for the 3300 NSv (Near-field) Transducer System. Specifically engineered for small-shaft rotating machinery, this 5 mm diameter probe utilizes eddy-current induction to provide high-resolution displacement data. Unlike standard 8 mm XL probes, the 330903 is optimized for tighter clearances and lower-vibration amplitude environments, ensuring accurate radial vibration and axial position measurement in compact industrial equipment.

Suffix Breakdown & Model Matrix

The 330903-04-10-10-01-00 assembly is configured to meet specific installation requirements:

• 04: Thread size/style (5/8-24 UN-2A)

• 10: Overall case length (100 mm)

• 10: Total length (1.0 meter)

• 01: Connector type (Miniature coaxial, non-armored)

• 00: Agency approval (Standard)

Hardware Specifications

Mechanical Monitoring & TSI Characteristics

The 3300 NSv system is designed for machinery where space constraints or small shaft diameters preclude the use of larger 8 mm transducers. The system's sensitivity is factory-tuned to 7.87 V/mm (200 mV/mil), providing the high gain necessary to detect subtle rotor dynamics. During commissioning, the probe must be gapped to the mid-point of the linear range, typically verified by observing a -10 VDC output at the Proximitor sensor. Proper installation is critical for signal linearity; any mechanical resonance in the probe mounting bracket or proximity to metallic surfaces can induce unwanted signal artifacts.

Ordering Info

• 330903 5 mm NSv Proximity Probe

• Installation hardware package (Locknut and washer)

• Product technical data sheet

• Note: This probe requires a matched 3300 NSv Proximitor to function within specified accuracy limits.

Field Installation Guidelines

• Gap Setting: Use a precision feeler gauge to set the gap. Verify that the Proximitor output voltage is -10 VDC before finalizing the locknut position.

• Torque Application: Tighten the locknut to the recommended torque specifications to prevent sensor migration during thermal cycling.

• Cable Management: Secure the coaxial cable to minimize movement; use industrial-grade ties and avoid tight bends that could stress the miniature connector.

• Grounding: Ensure the probe case has a clean, low-resistance path to the machine ground to minimize electromagnetic interference (EMI).

• Surface Inspection: Confirm the target shaft area is smooth and free from magnetic inclusions, as these will affect eddy-current field uniformity.

Frequently Asked Questions

• Q: Can this probe be used with a standard 8 mm 3300 XL Proximitor?

• A: No, 3300 NSv probes have different electrical characteristics and must be paired exclusively with 3300 NSv Proximitors.

• Q: Why is the linear range limited to 1.5 mm?

• A: The 1.5 mm range is optimized for small-clearance machinery to provide higher resolution and sensitivity than larger 8 mm probes.

• Q: Is the 1.0 meter cable replaceable?

• A: No, the cable length is an integral part of the system’s tuned impedance; it cannot be replaced or altered without compromising calibration.

• Q: What is the primary advantage of the 5 mm tip?

• A: The smaller tip diameter allows for installation in tight spaces and improves spatial resolution for measuring vibration on narrow shaft journals.

• Q: Can I use this probe in a vacuum environment?

• A: Yes, the probe construction materials are compatible with vacuum environments, provided the temperature remains within the -35 to +177 deg C range.

• Q: What indicates a malfunctioning probe?

• A: A DC gap voltage outside the normal operating range (e.g., near -24 VDC or 0 VDC) or significant signal noise typically indicates a fault.

• Q: Are these probes suitable for steam turbine applications?

• A: They are suitable, provided the temperature and pressure limits are respected. They are often used on smaller auxiliary turbines.

• Q: How do I prevent signal interference?

• A: Keep signal cables away from high-voltage AC lines and ensure all connections are tight and protected in a grounded junction box.