Product Overview

The Bently Nevada 330172-00-12-50-02-CN is a 3300 5 mm proximity probe used to measure relative shaft vibration and displacement in rotating machinery. It operates through eddy-current sensing, detecting changes in the distance between the probe tip and a conductive target. When connected to compatible monitoring equipment, it supplies the measurement signal used to evaluate shaft movement and machine operating conditions.

The 330172 product family uses a 1/4-28 UNF mounting thread and an armored probe cable. The specified ordering configuration includes a 0 mm unthreaded section, a 1.2-inch overall case length, and a 5-meter total probe cable length. It also uses a miniature coaxial ClickLoc connector with standard cable construction and no separate connector protector. The CN suffix identifies a country-specific approval option that must be evaluated against the intended installation requirements.

The 3300 5 mm proximity system is particularly useful where the available mounting space does not accommodate a larger sensing arrangement. Its nominal linear measurement range is 2 mm, comparable to the range of the 8 mm proximity system, while the smaller probe tip supports installations with more restrictive clearances.

In a centrifugal compressor, for example, a probe installed near a bearing measures shaft movement relative to the stationary mounting point. The connected monitoring system can use this signal to track vibration trends, observe changes in shaft position, and identify departures from established operating conditions. Similar measurement arrangements are used on turbines, generators, industrial pumps, and other rotating equipment.

The armored cable helps protect the probe lead against abrasion and mechanical contact with nearby structures. This is useful where the cable must pass through a confined machine installation, although the armor does not eliminate the need for proper routing, strain control, and connector inspection. Because this configuration does not include a connector protector, the connector end requires particular attention during installation and maintenance.

The probe is one component of a calibrated measurement chain rather than an independent monitoring instrument. Its electrical response depends on the compatible extension cable, Proximitor sensor, target material, and monitoring configuration. For this 5-meter probe, the corresponding 5-meter transducer arrangement must be used; adding an extension cable without checking the system’s total electrical length can produce an incompatible configuration.

Technical Specifications

Product Features

• 5 mm probe design: Supports non-contact shaft measurement in installations where mounting clearance is limited.
• 1/4-28 UNF mounting thread: Fits compatible inch-threaded probe holders and mounting provisions.
• Zero unthreaded-length option: Specifies the case configuration without an additional unthreaded section.
• 1.2-inch case length: Defines the probe body configuration for mounting and adjustment.
• Armored cable construction: Adds protection against abrasion and mechanical contact.
• 5-meter total cable length: Supports the corresponding 5-meter proximity transducer configuration.
• Standard cable option: Identifies the specified cable construction rather than a FluidLoc option.
• ClickLoc connector: Provides a locking coaxial connection for the transducer circuit.
• Connector without protector: Matches the selected connector configuration and requires appropriate handling during installation.
• 2 mm nominal linear range: Supports displacement measurements within the specified operating region.
• 7.87 V/mm nominal scale factor: Defines the intended measurement sensitivity of a compatible transducer system.
• Country-specific approval option: Identifies the CN ordering configuration for verification against the installation’s regulatory requirements.
• Machinery monitoring integration: Supplies displacement-related signals for compatible vibration and position monitoring equipment.

Working Principle

The 330172-00-12-50-02-CN measures the gap between its sensing tip and a conductive target using eddy-current technology. The probe interacts electromagnetically with the target surface, and changes in the distance alter the electrical response of the transducer circuit.

Rotating Shaft → 3300 5 mm Probe → Proximitor Sensor → Monitoring Channel → Machinery Data

When the shaft moves toward or away from the probe, the gap changes. The compatible Proximitor sensor converts the probe’s electrical response into an output related to displacement. The receiving monitoring channel then processes this output for relative vibration or shaft-position measurements.

The 3300 5 mm system has a nominal linear measurement range of 2 mm and a nominal scale factor of 7.87 V/mm (200 mV/mil). These values describe the intended system response when the probe, target, Proximitor sensor, and monitoring configuration are correctly matched.

During commissioning, the probe gap is adjusted to establish the operating point within the linear measurement region. A nominal gap of approximately 1.27 mm is commonly used for this system, subject to the applicable installation procedure. Incorrect adjustment can reduce the available measurement range or cause the monitoring system to report an inaccurate displacement value.

The 5-meter cable option is a system-level electrical specification. Because the probe’s integral cable already provides the specified 5-meter length, it is normally connected directly to a compatible 5-meter Proximitor sensor arrangement. An additional extension cable should not be introduced unless the complete configuration has been verified for the required total electrical length.

The armored cable provides additional mechanical protection, while the ClickLoc connector maintains the electrical connection between the probe and the associated equipment. Connector engagement, cable routing, and the condition of the insulation all influence the quality of the measurement signal.

The probe measures shaft movement relative to its mounting point. A loose holder, damaged cable, contaminated connector, or mismatched Proximitor sensor can therefore produce abnormal readings even when the shaft itself is operating normally. Troubleshooting should cover the complete measurement chain before an apparent vibration change is treated as evidence of a mechanical defect.

Role in a 3300 5 mm Machinery Monitoring System

The Bently Nevada 330172-00-12-50-02-CN supplies the local displacement signal used by a compatible 3300 5 mm monitoring arrangement. Its 5-meter cable configuration connects the sensing element to the corresponding Proximitor sensor without requiring an additional extension cable in the normal matched setup.

Shaft Surface → 330172 Probe → 5-meter Probe Cable → Compatible Proximitor Sensor → Monitoring Module → Operator Interface

Industrial Applications

Installation and Maintenance

1. Confirm the mounting provision: Verify that the machine accepts the 1/4-28 UNF thread and accommodates the specified 1.2-inch case configuration.
2. Inspect the target surface: Ensure that the shaft surface is conductive and suitable for eddy-current proximity measurement.
3. Check the installation clearance: Confirm that the mounting arrangement provides sufficient clearance to position the sensing tip at the required gap.
4. Set the initial probe gap: Adjust the probe according to the applicable 3300 5 mm installation procedure and the receiving monitoring system’s requirements.
5. Secure the mounting hardware: Tighten the probe and locking arrangement according to the applicable instructions while maintaining the required thread engagement.
6. Inspect the armored cable: Check the armor and outer jacket for crushing, abrasion, sharp bends, or other mechanical damage.
7. Route the cable correctly: Maintain the specified bend radius and avoid excessive pulling force, crushing, and contact with moving machinery.
8. Check the connector: Inspect the ClickLoc connection for contamination or damage, and handle it carefully because this configuration does not include a connector protector.
9. Match the transducer components: Verify that the Proximitor sensor is compatible with the 3300 5 mm system and the specified 5-meter probe length.
10. Verify the approval requirements: Confirm that the CN approval configuration is appropriate for the intended installation and applicable site requirements.
11. Establish baseline readings: Record the initial shaft-vibration or position measurements under known operating conditions for future comparison.
12. Investigate abnormal measurements: Check the probe gap, mounting stability, cable condition, connector engagement, Proximitor sensor, and monitoring-channel configuration before attributing unusual readings to a mechanical fault.

Related Components

Recommended Related Models

Key Advantages

• Measures shaft displacement without contacting the rotating target.
• Uses a 5 mm sensing format for installations with restricted mounting clearance.
• Provides a 1/4-28 UNF mounting thread.
• Incorporates an armored cable for additional mechanical protection.
• Supports a nominal 2 mm linear measurement range.
• Uses a 5-meter transducer configuration for compatibility with the corresponding Proximitor sensor.
• Integrates with compatible 3300 5 mm monitoring equipment.

Technical FAQs

What is the difference between the 3300 5 mm and 3300 XL 8 mm proximity systems?

The two systems use different probe designs and corresponding transducer configurations. Although their nominal linear measurement ranges can be similar, their probes, Proximitor sensors, and electrical characteristics should not be interchanged without confirming compatibility.

Does the 5-meter probe require an additional extension cable?

Normally, no. The probe already has a 5-meter total cable length and is intended for use with the corresponding 5-meter Proximitor sensor configuration. Adding an extension cable would change the total electrical length and should only be considered if the complete arrangement is explicitly supported.

Why does the armored version need careful cable routing?

The armor provides additional protection against abrasion and mechanical contact, but it does not make the cable immune to crushing, excessive bending, or damage at the connector. Proper routing and strain control remain necessary to maintain signal integrity.

What should be checked if the probe signal does not match the expected shaft movement?

Verify the initial gap, mounting security, connector condition, cable integrity, and Proximitor sensor compatibility. Also confirm that the monitoring channel is configured for the correct 3300 5 mm system. These checks help distinguish a transducer problem from genuine shaft movement.