Product Overview

The Epro PR6424/102-021 16 mm Eddy Current Sensor is a non-contact displacement measurement probe designed for monitoring the operating condition of critical rotating machinery. It belongs to the PR6424 sensor family developed for industrial machinery protection and condition monitoring applications.

The sensor uses eddy current technology to measure the distance between its sensing tip and a conductive target, typically a ferromagnetic steel shaft. Changes in the probe-to-target gap affect the electrical characteristics of the sensor, allowing the measurement system to determine shaft displacement and vibration without requiring physical contact.

In industrial installations, the PR6424 series is commonly used to monitor radial shaft vibration, axial displacement, shaft position, eccentricity, and rotational speed-related signals. These measurements are particularly important for large rotating machines where changes in shaft movement can indicate mechanical wear, imbalance, misalignment, bearing deterioration, or other abnormal operating conditions.

The PR6424 sensor has a nominal sensing diameter of 16 mm. Its typical sensitivity is 4 V/mm, with a static measurement range of ±2.0 mm and a dynamic measurement range of 0–1,000 μm. The nominal center air gap is approximately 2.7 mm under the specified standard measuring conditions.

The PR6424/102-021 is intended to operate as part of a compatible eddy current measurement chain. A suitable signal converter conditions the probe signal and provides an output that can be used by machinery monitoring equipment or an industrial control system.

Because the exact suffix configuration determines physical and connection details, buyers should verify the probe’s cable arrangement, connector, mounting dimensions, and compatible converter before installation or replacement.

Technical Specifications

Note: The measurement values above describe the PR6424 family under its specified standard conditions. Confirm the exact PR6424/102-021 ordering configuration and matching converter before using these values for a critical measurement installation.

Function and Working Principle

The PR6424/102-021 operates using the eddy current principle. It measures the relative distance between the sensor tip and a conductive target without making physical contact.

1. Eddy Current Measurement

The sensor generates a high-frequency electromagnetic field around its sensing tip. When a conductive metallic target enters this field, electrical currents known as eddy currents are induced on the target surface.

These currents influence the electromagnetic characteristics of the sensor. As the distance between the probe and target changes, the electrical response also changes.

The measurement electronics use this relationship to determine the gap between the probe and the target. With a suitable signal converter, the measurement can be converted into a proportional electrical output for monitoring and control equipment.

2. Shaft Displacement Measurement

One important application of the PR6424 series is measuring shaft displacement in rotating machinery.

The probe is installed near the shaft surface with a specified initial gap. As the shaft moves relative to the probe, the gap changes. The measurement system detects these changes and provides displacement information.

This measurement can help identify abnormal shaft movement and support the assessment of machine mechanical condition.

3. Shaft Vibration Monitoring

During normal operation, rotating shafts experience movement caused by mechanical forces, bearing characteristics, and operating conditions.

The PR6424 sensor can detect dynamic changes in shaft position. When installed as part of an appropriate monitoring system, these measurements can be used to evaluate shaft vibration.

Vibration information is valuable for identifying changes associated with imbalance, misalignment, looseness, bearing problems, and other mechanical conditions.

4. Axial Position and Eccentricity Measurement

The PR6424 can also be used in suitable arrangements to measure axial displacement and shaft eccentricity.

Axial position monitoring is important for machinery where shaft movement along its rotational axis must remain within defined limits. Eccentricity measurements help identify uneven shaft geometry or changes in shaft movement during rotation.

These measurements support machinery condition assessment and protection strategies.

5. Signal Conversion

The sensor probe is not normally used as a standalone industrial measurement output device. It operates with a compatible signal converter that supplies the required excitation and processes the probe response.

The converter produces a conditioned signal suitable for monitoring equipment. The converter model and measurement range must match the probe configuration.

For example, the CON021 converter family supports PR6424 sensors in its specified standard and extended measurement configurations. The exact converter ordering code must be selected according to the required range and probe setup.

Role in Industrial Machinery Monitoring Systems

The PR6424/102-021 can be installed as part of a machinery protection and condition monitoring system. It provides displacement information that helps engineers evaluate the mechanical condition of rotating equipment.

Turbine Monitoring

Steam, gas, and hydro turbines operate under demanding mechanical and thermal conditions. Shaft displacement and vibration measurements help operators monitor machine behavior during startup, normal operation, and shutdown.

A suitable PR6424 measurement chain can provide information about shaft movement that supports machinery protection and maintenance decisions.

Compressor Condition Monitoring

Industrial compressors operate with rotating shafts, bearings, and other mechanical components that require continuous monitoring in critical installations.

The sensor can measure shaft vibration and displacement, helping maintenance teams identify abnormal mechanical movement before it develops into a more serious equipment problem.

Pump Monitoring

Large industrial pumps are used in power generation, water treatment, petrochemical processing, and manufacturing. Shaft vibration and position measurements can help assess pump operating conditions.

The PR6424 can be incorporated into suitable pump monitoring arrangements where its measurement range and mechanical installation requirements are appropriate.

Fan and Blower Monitoring

Industrial fans and blowers may experience vibration changes caused by imbalance, bearing wear, or mechanical looseness.

Non-contact shaft monitoring provides information about actual shaft movement and can support preventive maintenance programs.

Integration with Machinery Protection Equipment

The conditioned sensor signal can be connected to compatible machinery monitoring equipment. Depending on the monitoring architecture, measured values may be used for display, alarm generation, trend analysis, and protective shutdown logic.

The probe itself does not independently perform machine shutdown or protection logic. These functions are handled by the associated monitoring and control equipment.

Industrial Applications

1. Steam Turbine Shaft Monitoring

Steam turbines are widely used in power generation and industrial energy systems. Their rotating assemblies operate at high speeds and require reliable mechanical condition monitoring.

The PR6424 series can measure shaft displacement and vibration in suitable turbine installations. Monitoring these parameters helps operators identify changes in shaft behavior and evaluate the condition of rotating components.

2. Gas Turbine Monitoring

Gas turbines are used in power generation, mechanical drive applications, and industrial energy systems.

Shaft vibration and displacement measurements provide important information about rotor behavior. A correctly installed eddy current measurement system can support continuous monitoring of critical turbine components.

3. Industrial Compressor Protection

Compressors are essential in petrochemical plants, gas processing facilities, refineries, and manufacturing operations.

The PR6424 can be used in suitable compressor installations to monitor shaft vibration and position. These measurements help maintenance personnel investigate abnormal vibration trends and potential mechanical deterioration.

4. Centrifugal Pump Monitoring

Large centrifugal pumps are often installed in continuous-process applications. Changes in shaft movement may be associated with bearing problems, rotor imbalance, misalignment, or mechanical wear.

A non-contact eddy current sensor can provide shaft displacement information for compatible pump monitoring systems.

5. Generator and Rotating Equipment Monitoring

Generators and other large rotating machines require stable shaft operation. Monitoring shaft displacement and vibration helps engineers assess mechanical behavior and identify abnormal conditions.

The PR6424 measurement principle is suitable for applications where non-contact measurement of a conductive shaft surface is required.

6. Industrial Fan and Blower Systems

Large fans and blowers are used in ventilation, combustion air systems, cooling installations, and industrial process equipment.

Shaft vibration monitoring can help identify mechanical changes and support maintenance planning. The sensor must be installed with appropriate mechanical clearance and target-surface characteristics.

Installation and System Integration

Correct installation is essential for accurate measurements and reliable operation. The sensor must be matched with the target material, mounting arrangement, cable configuration, and signal converter.

1. Verify the Sensor Configuration

Before installation, confirm the complete model number PR6424/102-021 and check the physical configuration.

Important details include:

• Sensor head diameter.
• Probe body and mounting thread.
• Cable length and cable construction.
• Connector type.
• Compatible signal converter.
• Required measurement range.
• Environmental and temperature limitations.

Do not assume that all PR6424 probes have identical cable lengths or connector arrangements.

2. Select the Correct Target Material

The PR6424 series is calibrated for a specified ferromagnetic steel target, with 42CrMo4 used as the standard reference material.

Different target materials can affect sensor response and measurement accuracy. If the actual shaft material differs from the specified reference material, verify whether the measurement chain requires material-specific calibration or compensation.

The shaft surface should also be suitable for reliable non-contact measurement.

3. Set the Initial Air Gap

The nominal center air gap for the PR6424 standard measuring configuration is approximately 2.7 mm.

The actual installation gap must be established according to the applicable sensor and converter documentation. Incorrect probe positioning may reduce the available measurement range or result in an unsuitable output signal.

Avoid setting the probe too close to the shaft, as excessive proximity can cause the measurement to operate outside its specified range.

4. Install the Probe Securely

The sensor should be mounted in a mechanically stable position. Excessive movement of the probe body can introduce measurement errors that may be mistaken for actual shaft displacement.

Use the specified mounting hardware and follow the manufacturer’s installation requirements. Ensure that the probe does not contact the rotating shaft under any expected operating condition.

5. Connect the Compatible Signal Converter

The PR6424 must be connected to a compatible signal converter. The converter supplies the required operating conditions and processes the probe signal.

The EPRO CON021 family supports PR6424 sensors in defined measuring configurations. The selected converter must match the required measurement range and sensor arrangement.

Confirm the connector, cable, converter ordering code, and wiring before energizing the system.

6. Route and Protect the Cable

Sensor cables should be routed carefully to reduce the risk of mechanical damage and electrical interference.

Avoid routing sensitive measurement cables alongside high-current motor cables or other sources of strong electromagnetic interference unless the installation design provides appropriate separation and shielding.

Protect cables from excessive bending, abrasion, heat, vibration, and contact with moving machinery.

7. Verify the Measurement Signal

After installation, check the sensor gap and verify that the converter produces a stable output.

Compare the measured signal with the expected shaft position and operating conditions. If the signal is unstable or outside the expected range, inspect the probe mounting, cable connections, target material, air gap, converter configuration, and grounding arrangement.

Compatible System Components

The PR6424/102-021 operates as part of a complete displacement measurement chain. The following components may be required depending on the system design.

The components listed above are system elements and are not necessarily included with the sensor. The exact bill of materials should be checked before ordering.

Alternative Models and Replacement Considerations

The PR6424 belongs to the EPRO PR642x eddy current sensor family. Other models in this family have different sensing diameters, measuring ranges, and application characteristics.

A replacement should not be selected based only on the PR6424 family name or the 16 mm probe diameter. The following details should be compared:

• Complete sensor catalog number.
• Probe diameter and mounting dimensions.
• Cable length and connector arrangement.
• Target material and calibration requirements.
• Static and dynamic measurement ranges.
• Sensitivity and linearity.
• Operating temperature.
• Signal converter model.
• Monitoring-system input requirements.

Using an incompatible probe or converter may result in incorrect measurement scaling or unreliable monitoring signals.

Key Advantages

Non-Contact Measurement

The PR6424 measures the distance to a conductive target without physical contact. This makes it suitable for monitoring rotating shafts where mechanical contact would be impractical.

Shaft Vibration Monitoring

The sensor can detect dynamic changes in shaft position and provide measurement information for machinery condition monitoring.

Displacement and Position Measurement

The PR6424 series supports static displacement measurement, allowing engineers to monitor shaft position and movement within the specified measurement range.

Compact 16 mm Probe Design

The 16 mm sensing diameter supports installation in suitable machinery monitoring arrangements where a larger probe is required than smaller-diameter eddy current sensors.

Integration with Signal Conversion Equipment

The sensor can be combined with a compatible EPRO signal converter to provide conditioned measurement signals for industrial monitoring systems.

Industrial Machinery Applications

The PR6424 family is designed for critical rotating equipment, including turbines, compressors, pumps, and fans.

Support for Condition-Based Maintenance

Continuous shaft measurement can help maintenance teams identify changes in machine behavior and investigate possible mechanical deterioration.

Technical FAQs

1. What is the Epro PR6424/102-021?

The Epro PR6424/102-021 is a 16 mm eddy current sensor designed for non-contact measurement of shaft displacement and vibration in rotating machinery.

2. What is the sensing diameter?

The sensor head diameter is 16 mm, as specified for the PR6424 family and in the supplied product description.

3. What is the measurement principle?

It uses eddy current technology. The probe generates an electromagnetic field, and changes in the distance to a conductive target affect the sensor response. A compatible converter processes this response into a usable measurement signal.

4. What is the typical sensitivity of the PR6424?

The typical sensitivity is 4 V/mm when calibrated for the specified standard target material and used with the appropriate measurement converter.

5. What is the static measurement range?

The PR6424 family has a typical static measurement range of ±2.0 mm under its standard measuring configuration.

6. What is the dynamic measurement range?

The typical dynamic measurement range is 0–1,000 μm. The actual usable range depends on the measurement chain and operating conditions.

7. Which signal converter can be used?

The EPRO CON021 converter family supports PR6424 sensors in defined standard and extended measuring configurations. The exact converter version must be selected according to the required range and sensor configuration.

8. What target material is used for standard calibration?

The standard reference target material is ferromagnetic steel, typically 42CrMo4. Different target materials may affect measurement characteristics and should be checked against the calibration requirements.

9. Where is the PR6424 sensor commonly used?

Typical applications include steam turbines, gas turbines, hydro turbines, compressors, pumps, fans, generators, and other critical rotating machinery.

10. What should be checked when replacing an existing PR6424 sensor?

Confirm the complete model number, probe dimensions, mounting thread, cable length, connector, target material, converter compatibility, and measurement range. A replacement should match the original measurement chain rather than simply having the same nominal probe diameter.

Procurement and Maintenance Recommendations

When purchasing the Epro PR6424/102-021, verify the complete catalog number and physical configuration. The suffix is important because probe versions may differ in cable length, connector arrangement, mounting details, and other ordering characteristics.

For replacement projects, compare the new sensor with the installed probe. Check the probe body, cable, connector, mounting thread, and compatible signal converter. If the original sensor is part of a machinery protection system, verify the complete measurement chain before returning the machine to service.

For used or surplus units, request clear photographs of the model label, probe body, cable, and connector. Confirm the condition of the sensing tip, cable insulation, and mechanical sleeve. Where possible, request a functional test using a compatible converter.

During routine maintenance, inspect the cable for cuts, abrasion, heat damage, and loose connections. Check that the probe mounting remains secure and that the sensing gap has not changed because of mechanical movement.

If the measurement becomes unstable, investigate the probe-to-shaft gap, target surface, cable condition, connector, converter configuration, and electrical interference. Avoid changing the calibration or measurement range without confirming the original system settings.

Keeping the sensor model, converter configuration, cable details, and installation measurements in the maintenance records can make future troubleshooting and replacement more efficient.

Conclusion

The Epro PR6424/102-021 16 mm Eddy Current Sensor is designed for non-contact measurement of shaft displacement and vibration in critical rotating machinery. Its PR6424 family specifications include 4 V/mm sensitivity, a static measurement range of ±2.0 mm, a dynamic measurement range of 0–1,000 μm, and a nominal center air gap of approximately 2.7 mm.

The sensor can be integrated into suitable machinery monitoring systems through a compatible signal converter. It is relevant to turbine, compressor, pump, fan, and other rotating-equipment applications where reliable shaft movement measurement is required.

For procurement and replacement, the complete model suffix and matching converter configuration should be verified. Correct mechanical installation, target-material compatibility, cable protection, and measurement-chain calibration are essential for reliable operation.