Product Overview

The EPRO PR6424/019-121 16 mm Eddy Current Sensor is a non-contact displacement sensor designed for monitoring the operating condition of rotating machinery. It belongs to the PR6424 sensor family, which is used in industrial machinery protection and condition-monitoring applications involving turbines, compressors, pumps, fans, and other critical rotating equipment.

Unlike contact-based measuring devices, an eddy current sensor measures the distance between its sensing head and a conductive target without physically touching the target surface. This measurement principle allows the sensor to monitor shaft movement continuously while avoiding mechanical contact with the rotating component.

The PR6424 series is commonly used to measure shaft vibration, radial and axial displacement, shaft position, eccentricity, and rotational speed-related signals. These measurements help maintenance and control systems identify abnormal mechanical behavior and evaluate equipment operating conditions.

The PR6424/019-121 has a 16 mm sensor head diameter and a supplied weight of approximately 0.2 kg. Its compact sensing head and non-contact measurement principle make it suitable for installation near rotating shafts when the required mounting clearance and measurement conditions are satisfied.

The sensor is typically used with a compatible signal-conditioning or monitoring system. The complete measuring chain includes the probe, extension cable where required, compatible driver or converter, and monitoring equipment. Correct matching of these components is essential for accurate measurement.

The suffix /019-121 identifies a specific product configuration. Before replacement or installation, users should verify the cable length, connector arrangement, mounting details, and electrical compatibility against the original product label and applicable documentation.

Technical Specifications

Note: Electrical and measurement values above describe the PR6424 16 mm sensor family. Confirm the exact operating temperature, cable length, connector, and mechanical configuration of the PR6424/019-121 before installation.

Function and Working Principle

The PR6424/019-121 operates using the eddy current measurement principle. It generates an electromagnetic field at the sensing head and detects changes in that field caused by the distance between the sensor and a conductive target.

When the sensor is installed near a rotating shaft, changes in the shaft-to-probe gap influence the sensor’s electrical response. The associated signal-conditioning equipment converts this response into a usable measurement signal.

1. Non-Contact Displacement Measurement

The sensor measures the distance between its sensing head and a suitable conductive target without physical contact.

This is particularly useful in rotating machinery because the shaft moves while the machine is operating. A contact-based measuring arrangement would be unsuitable for many such applications, whereas an eddy current probe can continuously observe the changing gap.

The resulting signal can be used to monitor shaft displacement and identify changes in mechanical condition.

2. Shaft Vibration Monitoring

As a rotating shaft vibrates, its position relative to the sensor changes. The PR6424 sensor detects these variations and provides a measurement signal for the connected monitoring equipment.

Vibration measurements can help identify mechanical problems such as rotor imbalance, shaft misalignment, looseness, and changes in bearing condition. The sensor itself measures displacement; diagnosing the underlying fault requires analysis of the measurement signal together with other machine data.

3. Axial and Radial Position Monitoring

Depending on the mounting arrangement, the sensor can measure radial shaft movement or axial displacement.

Radial measurements are commonly used to monitor shaft vibration relative to the machine housing. Axial measurements can help identify changes in the shaft’s position along its rotational axis.

These measurements are important in turbines and compressors, where shaft movement must remain within the equipment’s permitted operating limits.

4. Eccentricity Measurement

Shaft eccentricity describes the variation between the shaft’s geometric center and its rotational axis. An eddy current sensor can detect changes in the gap between the probe and the shaft surface.

Eccentricity information can help maintenance personnel evaluate rotor condition, especially during startup, shutdown, and low-speed operation.

5. Speed-Related Measurement

The sensor can also provide signals associated with rotating shaft movement. When correctly configured with compatible monitoring equipment, these signals may be used for rotational speed or keyphasor-related measurement.

The exact measurement function depends on sensor positioning, target geometry, signal-conditioning hardware, and monitoring-system configuration.

Role in Industrial Machinery Monitoring Systems

The PR6424/019-121 is generally used as a sensing component within a larger machinery protection or condition-monitoring system. It does not independently provide a complete machinery protection function.

Connection to Signal-Conditioning Equipment

The sensor normally works with a compatible driver or signal converter. This equipment supplies the required operating excitation and processes the probe response into a measurement signal.

The sensor, cable, and driver must be treated as a matched measuring system. Differences in cable length, connector type, or electrical characteristics can affect measurement performance.

Integration with Machinery Monitoring Systems

The conditioned signal can be connected to an appropriate monitoring module or machinery protection system. Depending on the system design, measurements may be used for vibration trends, displacement monitoring, alarm generation, and equipment shutdown logic.

The monitoring platform evaluates the signal against configured limits and operating conditions. The sensor provides the measurement input, while the monitoring system performs the corresponding analysis and protection functions.

Support for Predictive Maintenance

Continuous shaft-displacement monitoring provides useful information about rotating machinery condition. Maintenance teams can compare current measurements with historical trends to identify changes that may indicate developing mechanical problems.

This information can support condition-based maintenance, equipment inspection planning, and troubleshooting.

Industrial Applications

The PR6424 16 mm sensor family is designed for critical rotating machinery applications. Its use depends on suitable target material, installation geometry, and compatibility with the associated measuring electronics.

1. Steam Turbines

Steam turbines operate at high rotational speeds and require continuous monitoring of shaft behavior. Eddy current sensors can measure shaft vibration and displacement, helping operators identify abnormal rotor movement.

The measurements may be used as part of a turbine machinery protection system to monitor changes during startup, normal operation, and shutdown.

2. Gas Turbines

Gas turbines contain high-speed rotating assemblies that operate under demanding thermal and mechanical conditions. Shaft displacement and vibration monitoring provide important information about rotor behavior.

A correctly installed PR6424 sensor can contribute measurement signals to a compatible monitoring system used for turbine condition assessment.

3. Industrial Compressors

Large compressors are widely used in petrochemical plants, refineries, gas processing facilities, and industrial production systems.

Shaft vibration and position measurements help maintenance teams assess mechanical operating conditions and detect changes that may require inspection.

4. Pumps

Industrial pumps operate under changing flow, pressure, and load conditions. In critical pump installations, non-contact displacement sensors can be used to monitor shaft movement and support mechanical condition assessment.

The sensor’s suitability depends on shaft dimensions, target material, mounting clearance, and the required measurement range.

5. Industrial Fans

Large fans and ventilation systems may use rotating assemblies that require vibration monitoring. Eddy current sensors can provide shaft-displacement measurements for compatible machinery-monitoring systems.

These measurements can help identify abnormal mechanical movement before it develops into a more serious equipment problem.

6. Power Generation Equipment

Power generation facilities depend on reliable operation of turbines, generators, pumps, and other rotating machinery. Shaft displacement measurements can form part of an overall machinery-monitoring strategy.

The PR6424 series can be used where its measurement characteristics and installation configuration match the requirements of the monitored equipment.

Installation and System Integration

Proper installation is essential for accurate measurement. The sensor must be mounted with suitable clearance, aligned with the target surface, and connected to compatible signal-conditioning equipment.

1. Confirm the Sensor Configuration

Before installation, verify the complete PR6424/019-121 model number. Check the sensor head, cable arrangement, connector, mounting thread, and overall assembly configuration.

Do not assume that every PR6424 probe has the same cable length or connector arrangement. Different suffixes may identify different mechanical or electrical configurations.

2. Select a Suitable Mounting Position

The sensing head should be positioned so that it faces the intended conductive target. The mounting arrangement must maintain the required clearance and avoid interference from nearby metallic objects.

For shaft monitoring, the sensor should be installed at the measurement location specified by the machinery manufacturer or monitoring-system design.

3. Set the Correct Air Gap

The PR6424 family has a nominal center air gap of approximately 2.7 mm. The actual installation gap should be established according to the applicable sensor and driver documentation.

An incorrect air gap may cause the measurement signal to operate outside its intended linear region. This can reduce measurement accuracy and affect the reliability of vibration or displacement monitoring.

4. Verify Target Material

Eddy current measurement depends on the electrical and magnetic properties of the target material. The PR6424 family specifications reference ferromagnetic steel, with 42CrMo4 used as a standard target material.

If the actual shaft material differs, verify the required calibration and measurement characteristics before commissioning.

5. Check Cable Routing

The sensor cable should be routed away from sources of electrical interference, excessive heat, sharp edges, and mechanical damage.

Observe the minimum bending radius specified for the actual cable assembly. Avoid unnecessary cable extensions or substitutions unless they are approved for the measuring system.

6. Connect Compatible Signal-Conditioning Equipment

Connect the sensor to its compatible driver or signal converter. Confirm the connector type, cable length, and electrical configuration before energizing the system.

A probe should not be connected to an arbitrary monitoring input without checking compatibility. Incorrect matching can lead to unreliable measurements or equipment damage.

7. Perform Measurement Verification

After installation, verify the sensor output and air-gap setting using the applicable commissioning procedure. Confirm that the signal changes correctly when the target position changes.

Check the complete measurement channel, including the probe, cable, driver, monitoring module, and alarm configuration. Record the final installation details for future maintenance.

Compatible System Components

The PR6424/019-121 is part of a complete displacement-measurement arrangement. The following components may be required depending on the system design.

The table describes typical components in an eddy current measurement system. It does not mean that these items are included with the sensor.

Alternative Models and Replacement Considerations

The PR6424 series includes multiple 16 mm sensor configurations. Although models may share similar measurement principles and family-level specifications, they should not be treated as interchangeable without checking their complete ordering codes.

Before selecting a replacement, compare the following:

• Complete sensor model and ordering code.
• Sensor head diameter and mechanical dimensions.
• Mounting thread and installation arrangement.
• Cable length and cable construction.
• Connector type and pin configuration.
• Compatible driver or signal converter.
• Target material and required air gap.
• Measurement range and sensitivity.
• Operating temperature and environmental conditions.
• Monitoring-system input requirements.

A replacement probe should be selected as part of the complete measurement channel rather than by sensor diameter alone.

Key Advantages

Non-Contact Measurement

The eddy current principle allows shaft displacement to be measured without physical contact. This makes the sensor suitable for continuously monitoring rotating machinery.

16 mm Sensor Head

The 16 mm sensing head is designed for applications requiring this probe size and its corresponding mounting arrangement.

Continuous Shaft Monitoring

The sensor can provide displacement-related signals for compatible machinery-monitoring systems, supporting ongoing evaluation of rotating equipment.

High-Resolution Measurement Capability

The PR6424 family specifies a typical sensitivity of 4 V/mm and linearity of ≤ ±1.5%. These characteristics support precise displacement measurement when the probe is correctly installed and matched with suitable electronics.

Industrial Machinery Applications

The sensor family is used in applications involving turbines, compressors, pumps, fans, and other rotating machinery.

Integration with Condition-Monitoring Systems

The probe can be incorporated into machinery protection and condition-monitoring arrangements to provide information about shaft movement and vibration.

Support for Maintenance Planning

Measurement trends can help maintenance personnel identify changes in machine behavior and plan inspections according to equipment condition.

Technical FAQs

1. What is the EPRO PR6424/019-121?

The PR6424/019-121 is a 16 mm eddy current displacement sensor designed for non-contact monitoring of rotating machinery. It is used to measure shaft displacement and related mechanical movement when connected to compatible signal-conditioning equipment.

2. What is the sensor head diameter?

The supplied sensor head diameter is 16 mm, consistent with the PR6424 16 mm sensor family.

3. What is the measurement principle?

It uses electromagnetic eddy current technology. Changes in the distance between the sensing head and a conductive target influence the sensor response, allowing displacement to be measured without physical contact.

4. What is the typical sensitivity of the PR6424 series?

The published family specification gives a typical sensitivity of 4 V/mm. Actual performance depends on the sensor configuration, target material, installation gap, and matching electronics.

5. What is the static measurement range?

The PR6424 family specifies a static measurement range of ±2.0 mm. The applicable range should be confirmed against the complete measurement-system configuration.

6. What is the nominal center air gap?

The typical nominal center air gap is approximately 2.7 mm. The correct installation gap must follow the applicable sensor and driver documentation.

7. What materials can the sensor measure?

The PR6424 family is designed for conductive ferromagnetic targets. Its specifications reference 42CrMo4 steel as a standard target material. Other materials may require additional verification or calibration.

8. Which machines commonly use this sensor?

Typical applications include steam turbines, gas turbines, hydro turbines, compressors, pumps, fans, and other rotating machinery that requires shaft-displacement monitoring.

9. Can the PR6424/019-121 connect directly to a PLC?

It is normally used with compatible sensor electronics or a signal-conditioning unit. The conditioned output can then be connected to an appropriate monitoring module, PLC, or DCS input. Direct connection should not be assumed without checking the electrical interface.

10. What should be checked before replacing the sensor?

Verify the full model number, sensor head diameter, mounting thread, cable length, connector, driver compatibility, target material, and measurement requirements. Matching only the 16 mm probe diameter is not sufficient to establish compatibility.

Procurement and Maintenance Recommendations

When purchasing the EPRO PR6424/019-121, verify the complete ordering code and inspect the product label. The /019-121 suffix should be checked carefully because cable length, connector arrangement, and mechanical details may differ among PR6424 variants.

For replacement projects, compare the original sensor with the proposed unit and confirm that the existing driver and monitoring equipment support the replacement configuration. If the sensor is supplied with a cable or connector assembly, verify that these components match the installed system.

During maintenance, inspect the sensing head for physical damage, contamination, or signs of impact. Check the cable insulation, connector condition, mounting hardware, and cable routing. Any adjustment to the air gap should follow the manufacturer’s procedure.

For critical machinery, verify the complete measurement channel rather than testing the probe in isolation. This includes the sensor, cable, driver, monitoring input, alarm settings, and associated protection logic.

Keeping installation records, cable details, calibration information, and monitoring-system settings can make future troubleshooting and replacement work more efficient.

Conclusion

The EPRO PR6424/019-121 16 mm Eddy Current Sensor is designed for non-contact displacement measurement in industrial rotating machinery. It belongs to the PR6424 family, which is used for shaft vibration, radial and axial displacement, position, eccentricity, and related machinery-monitoring applications.

With a supplied sensor head diameter of 16 mm and weight of approximately 0.2 kg, the sensor can be used in installations designed for the PR6424 16 mm probe configuration. Its measurement performance depends on correct installation, suitable target material, proper air-gap adjustment, and compatibility with the associated driver and monitoring equipment.

For procurement and replacement, confirming the complete model suffix, cable configuration, connector, and electrical compatibility is essential to maintaining reliable machinery monitoring.