Product Overview

The Bently Nevada 3300703-000-050-10-02-00 is a 3300 XL 11 mm proximity probe used for non-contact measurement of shaft vibration and displacement in rotating machinery. It belongs to the 3300 XL proximity transducer family, which is widely used in machinery condition monitoring for equipment fitted with fluid-film bearings. The probe detects changes in the distance between its sensing tip and a conductive shaft surface, producing an electrical response that can be processed by compatible monitoring equipment.

The 3300 XL 11 mm system is particularly useful when an application requires a longer linear measurement range than the standard 8 mm proximity system provides. Its nominal linear range is 4 mm, with a scale factor of 3.94 V/mm (100 mV/mil). These characteristics make the system suitable for measurements involving relative shaft vibration, axial position, and other displacement-related parameters in compatible machinery.

This model uses an M14 × 1.5 mounting thread and a 50 mm probe case length. Its unarmored construction allows the probe cable to be routed through the designated machine installation without the additional armored cable arrangement used by other variants. The probe is supplied with an integral cable and connects to a compatible extension cable and Proximitor sensor to form the complete measurement circuit.

In a centrifugal compressor, for example, proximity probes installed near bearing locations measure shaft movement as operating speed and load change. The resulting signals allow the machinery monitoring system to track vibration trends and identify changes from established operating conditions. Similar measurements are used on turbines, generators, industrial pumps, and other rotating equipment where shaft displacement provides useful condition information.

The probe does not independently analyze vibration or determine the cause of a mechanical fault. Its role is to detect shaft movement and provide the corresponding measurement signal. Monitoring hardware interprets that signal, while maintenance personnel use the resulting measurements alongside other operating data to investigate imbalance, misalignment, bearing-related movement, and other possible conditions.

For correct operation, the probe must be paired with a compatible 3300 XL 11 mm extension cable and Proximitor sensor. The complete transducer circuit must maintain the specified electrical configuration because cable length and signal-conditioning characteristics affect measurement performance.

Technical Specifications

Product Features

• 11 mm sensing tip: Provides the sensing geometry used in the 3300 XL 11 mm proximity transducer system.
• 4 mm linear measurement range: Supports shaft-displacement measurements across the specified linear operating region.
• Eddy-current technology: Detects changes in the gap between the probe tip and a conductive target without physical contact.
• M14 × 1.5 mounting thread: Supports installation in compatible metric probe mounting arrangements.
• 50 mm case length: Defines the probe body configuration for the specified installation.
• Unarmored cable construction: Supports cable routing in installations that do not require an armored probe lead.
• Integrated cable: Connects the sensing element to the remaining transducer circuit.
• Defined scale factor: Provides a nominal output sensitivity of 3.94 V/mm when used in the specified system configuration.
• Rotating machinery monitoring: Supports shaft vibration, relative displacement, and position measurements.
• 3300 XL system compatibility: Works as part of a matched probe, extension cable, and Proximitor sensor arrangement.
• Continuous measurement capability: Supplies displacement-related signals for compatible monitoring channels.
• Industrial condition monitoring: Supports trend analysis and machinery protection when integrated into an appropriate monitoring system.

Working Principle

The 3300703-000-050-10-02-00 operates through eddy-current sensing. An alternating electromagnetic field generated by the proximity transducer circuit interacts with the conductive shaft surface. Changes in the distance between the probe tip and the target alter the electrical characteristics of the circuit, allowing the connected Proximitor sensor to produce an output related to shaft displacement.

Rotating Shaft → 3300 XL 11 mm Probe → Extension Cable → Proximitor Sensor → Machinery Monitoring System

When a shaft moves toward or away from the probe, the gap changes. The transducer system converts that change into an electrical signal that represents the shaft’s relative movement. The monitoring channel can then process the signal for vibration, position, or other configured displacement measurements.

The nominal scale factor is 3.94 V/mm, equivalent to 100 mV/mil. This relationship allows the monitoring equipment to convert voltage changes into displacement values within the specified linear measurement range. The nominal 4 mm linear range provides the operating span over which the system is specified to measure displacement linearly.

The reference target material is AISI 4140 steel. Target material and surface characteristics affect the electrical response of an eddy-current system, so the sensing arrangement and calibration must be consistent with the intended measurement application.

The initial probe gap is an important commissioning parameter. Setting the probe within its specified linear region allows the monitoring system to measure movement in both directions around the operating point. An incorrect gap can reduce the available measurement range or produce readings that do not accurately represent shaft movement.

The integral cable forms part of the electrical measurement circuit rather than serving only as a physical connection. A compatible extension cable and Proximitor sensor are required to complete the system. The probe and associated components must maintain the specified total electrical configuration for the expected output characteristics.

Role in a 3300 XL Machinery Monitoring System

The Bently Nevada 3300703-000-050-10-02-00 provides the local shaft-displacement measurement used by a compatible machinery monitoring channel. It is installed near a conductive target surface, commonly at a designated bearing measurement point, and supplies a signal to the associated transducer and monitoring equipment.

Shaft Surface → Proximity Probe → Extension Cable → Proximitor Sensor → Monitoring Channel → Operator Interface

Industrial Applications

Installation and Maintenance

1. Confirm the mounting arrangement: Verify that the installation uses the specified M14 × 1.5 thread and accommodates the 50 mm probe case configuration.
2. Inspect the target surface: Ensure that the shaft surface is conductive and suitable for the intended eddy-current measurement.
3. Check the mounting location: Position the probe at the designated measurement point with the correct orientation relative to the shaft.
4. Set the initial probe gap: Establish the operating gap according to the 3300 XL 11 mm installation procedure and the receiving monitoring system’s requirements.
5. Secure the probe: Tighten the mounting and locking hardware according to the applicable installation instructions to prevent unwanted probe movement.
6. Inspect the integral cable: Check the cable jacket and connection for damage, crushing, excessive bending, or mechanical strain.
7. Connect the compatible extension cable: Use the specified 3300 XL 11 mm extension cable to maintain the intended transducer configuration.
8. Install the Proximitor sensor: Connect the probe circuit to a compatible 3300 XL 11 mm Proximitor sensor and follow the specified terminal arrangement.
9. Route the cable correctly: Keep the cable protected from mechanical damage and avoid routing practices that can introduce electrical interference.
10. Verify the measurement response: Confirm that the transducer output corresponds to the established probe gap and the configured monitoring-channel settings.
11. Establish a baseline: Record the initial shaft-position or vibration measurement under a known operating condition.
12. Review measurements during maintenance: Inspect the probe mounting, cable connections, signal stability, and measurement trends when abnormal readings occur.

Related Components

Recommended Related Models

Key Advantages

• Supports non-contact shaft-displacement measurement in rotating machinery.
• Provides a nominal 4 mm linear measurement range.
• Uses the 3300 XL 11 mm proximity transducer architecture.
• Features an M14 × 1.5 mounting thread for compatible metric installations.
• Supplies displacement-related signals for vibration and position monitoring.
• Integrates with compatible extension cables, Proximitor sensors, and monitoring equipment.

Technical FAQs

Why use an 11 mm proximity probe instead of the 3300 XL 8 mm version?

The 3300 XL 11 mm system provides a longer linear measurement range than the standard 8 mm system. This can be beneficial for applications requiring a wider displacement range, including certain axial-position and differential-expansion measurements.

What does the 3.94 V/mm scale factor represent?

The scale factor describes the nominal relationship between probe-system output voltage and displacement within the specified linear range. It allows compatible monitoring equipment to convert electrical signal changes into shaft-movement measurements.

Why must the extension cable and Proximitor sensor match the probe system?

The probe, extension cable, and Proximitor sensor form a calibrated electrical circuit. Using compatible components with the specified total electrical configuration helps maintain the intended sensitivity and measurement response.

What can cause unstable readings even when the shaft is operating normally?

Unstable readings can result from a loose probe mount, incorrect probe gap, damaged cable, poor connections, electrical interference, or a mismatch in the transducer circuit. Checking the complete measurement chain helps distinguish instrumentation problems from actual shaft movement.