Product Overview

The Epro PR6424/105-100 16 mm Eddy Current Sensor is a non-contact displacement and vibration measurement probe from the Emerson EPRO PR6424 sensor family. It is designed for machinery condition monitoring applications where accurate measurement of rotating shaft movement is essential for equipment protection and operational reliability.

The PR6424 series is commonly used with large rotating machines, including steam turbines, gas turbines, hydro turbines, compressors, pumps, and industrial fans. These machines often operate under demanding mechanical and thermal conditions. Continuous monitoring of shaft movement can help maintenance teams identify abnormal vibration, changes in shaft position, and developing mechanical problems before they result in serious equipment damage.

Unlike a contact-type measurement device, an eddy current sensor measures the distance between its sensing tip and a conductive metallic target without physically touching the target surface. This makes it suitable for monitoring rotating shafts where direct mechanical contact would introduce wear or interfere with machine operation.

The PR6424 series uses a 16 mm sensor head and is designed to measure both static shaft position and dynamic displacement. Its typical sensitivity is 4 V/mm, with a static measuring range of ±2.0 mm and a dynamic measurement range of 0 to 1,000 μm peak-to-peak under the specified measurement conditions.

The PR6424/105-100 is intended for integration into an appropriate machinery monitoring system. A complete measurement chain normally includes the sensor, a compatible extension cable where required, and a signal converter. The converter processes the sensor signal and provides an output suitable for monitoring equipment.

The exact cable length, connector arrangement, mounting details, and calibration configuration should be checked against the product label and the documentation for the /105-100 variant before installation or replacement.

Technical Specifications

Note: Performance values describe the PR6424 sensor family. Confirm the precise cable, connector, thread, temperature range, and calibration configuration of PR6424/105-100 before installation.

Function and Working Principle

The PR6424/105-100 uses the eddy current measurement principle to detect the distance between its sensing tip and a metallic target. The measurement is based on electromagnetic interaction rather than physical contact.

1. Electromagnetic Field Generation

The sensor contains a coil that generates a high-frequency electromagnetic field around the sensing tip. When the sensor is positioned near a conductive metallic target, such as a rotating steel shaft, this field interacts with the target material.

The interaction produces small circulating electrical currents known as eddy currents within the metallic surface.

2. Detection of Distance Changes

The strength of the eddy currents changes according to the distance between the sensor tip and the target surface. As the gap changes, the electrical characteristics of the sensor coil also change.

The sensor system detects these changes and converts them into an electrical measurement signal.

Because the measurement is non-contact, the sensor can monitor shaft movement continuously without mechanical contact with the rotating component.

3. Displacement Measurement

The PR6424 series is designed to measure static displacement within a nominal range of ±2.0 mm.

Static displacement measurements can help identify changes in shaft position relative to the sensor mounting point. These changes may be associated with machine movement, thermal expansion, bearing conditions, or other mechanical factors.

The measurement result must be interpreted in relation to the machine’s operating condition and the monitoring system’s configuration.

4. Shaft Vibration Measurement

When a rotating shaft moves because of vibration, the distance between the shaft surface and the sensor changes continuously.

The PR6424 sensor detects these changes and provides a signal that can be processed to determine dynamic shaft displacement.

The series has a typical dynamic measurement range of 0 to 1,000 μm peak-to-peak. This capability makes it suitable for machinery vibration monitoring when used with a compatible converter and monitoring system.

5. Signal Conversion

The sensor is part of a measurement chain rather than a standalone display device. A compatible signal converter is required to condition the probe signal and provide an output suitable for machinery monitoring equipment.

The converter and sensor must be correctly matched. Their calibration, cable configuration, target material, and electrical characteristics all affect measurement accuracy.

Role in Industrial Machinery Monitoring Systems

The PR6424/105-100 can be integrated into machinery protection and condition-monitoring systems to provide information about shaft movement and mechanical behavior.

Shaft Vibration Monitoring

Shaft vibration is an important indicator of rotating machinery condition. Changes in vibration amplitude, frequency, or operating pattern may indicate developing mechanical problems.

The PR6424 sensor provides non-contact displacement measurements that can be used by a compatible monitoring system to evaluate shaft vibration.

Axial and Radial Displacement Measurement

Rotating machinery can experience movement in different directions.

• Radial displacement describes movement perpendicular to the shaft centerline.
• Axial displacement describes movement along the shaft centerline.

Appropriately positioned sensors can measure these movements and provide information about shaft behavior during operation.

The sensor installation arrangement must be designed according to the machine geometry and the monitoring objectives.

Shaft Position Monitoring

The sensor can also be used for static position measurements. Monitoring shaft position can help maintenance teams identify changes in the mechanical relationship between the shaft and its surrounding components.

Position information is particularly useful in large rotating machinery, where thermal expansion and changes in operating conditions may affect mechanical clearances.

Integration with Machinery Protection Equipment

The PR6424 measurement chain can be connected to compatible signal converters and machinery monitoring systems.

Depending on the system design, the resulting measurements may be used for:

• Continuous vibration monitoring.
• Shaft displacement measurement.
• Position monitoring.
• Alarm generation.
• Equipment protection logic.
• Maintenance trend analysis.

The exact system interface depends on the converter and monitoring equipment selected for the installation.

Industrial Applications

The PR6424 16 mm sensor family is designed for critical rotating machinery applications. Its non-contact measurement principle makes it particularly relevant to equipment where shaft displacement and vibration are important operating parameters.

1. Steam Turbines

Steam turbines operate at high rotational speeds and require continuous monitoring of mechanical condition.

The sensor can be installed near suitable shaft measurement locations to monitor radial or axial displacement. Changes in shaft movement may help maintenance teams investigate abnormal vibration, alignment changes, and other mechanical conditions.

2. Gas Turbines

Gas turbines operate under demanding thermal and mechanical conditions. Monitoring shaft movement is an important part of maintaining equipment reliability.

A correctly installed PR6424 measurement chain can provide displacement information for compatible turbine monitoring systems.

Sensor placement and temperature limits must be checked against the specific turbine installation and the exact sensor configuration.

3. Hydro Turbines

Hydro turbines are used in power generation systems and often operate continuously for extended periods.

Non-contact shaft displacement measurement can help monitor mechanical movement and identify changes in operating behavior.

The PR6424 series is designed for large-shaft applications, making it relevant to suitable hydro turbine monitoring arrangements.

4. Industrial Compressors

Large compressors are used in chemical processing, petrochemical facilities, natural gas systems, and other industrial processes.

Shaft vibration and position monitoring can provide information about the mechanical condition of compressor assemblies.

The sensor may be used with compatible monitoring equipment to measure shaft displacement and support condition-based maintenance.

5. Industrial Pumps

Large process pumps often operate continuously and may be exposed to changing flow, pressure, and load conditions.

Monitoring shaft displacement can help identify mechanical changes that require further inspection. The sensor should be installed at an appropriate measurement location and calibrated for the actual shaft material.

6. Industrial Fans

Large fans are used in power generation, ventilation, and industrial process systems. Shaft vibration monitoring can help detect changes in rotating equipment behavior.

The PR6424 series can be considered for compatible fan applications where its measuring range and mechanical installation requirements are suitable.

Installation and System Integration

Correct installation is essential for obtaining reliable measurement results. The sensor must be positioned properly, matched with the correct converter, and configured according to the monitoring system requirements.

1. Confirm the Sensor Model

Before installation, verify the complete model number, including the /105-100 suffix.

Different PR6424 variants may have different cable lengths, connectors, mounting configurations, or other mechanical details. These differences can affect installation and system compatibility.

Do not assume that all PR6424 probes are interchangeable solely because they share the same sensor head diameter.

2. Select the Correct Mounting Position

The sensor should be installed at a suitable location where it can measure the intended shaft movement.

The mounting arrangement must provide mechanical stability and maintain the required clearance between the sensor tip and the target surface.

Avoid positions where the sensor may contact the shaft during normal operation or under expected mechanical movement.

3. Check the Target Material

The PR6424 series uses ferromagnetic steel as its standard reference target material, with 42CrMo4 used for the specified calibration reference.

Different shaft materials can affect sensor characteristics and calibration. Confirm that the actual target material is compatible with the measurement system.

4. Set the Initial Air Gap

The PR6424 series has a nominal center air gap of approximately 2.7 mm.

The final installation gap must be established according to the applicable sensor and converter documentation. Incorrect positioning can reduce measurement accuracy or cause the sensor to operate outside its intended linear range.

5. Connect the Compatible Signal Converter

The probe must be paired with a compatible signal converter. The converter processes the sensor signal and provides the output required by the machinery monitoring system.

Check connector type, cable configuration, calibration compatibility, and converter specifications before connecting the sensor.

A converter intended for another probe family or an incompatible configuration may produce incorrect measurements.

6. Route and Protect the Cable

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

Avoid sharp bends, excessive tension, and contact with moving machinery. The minimum bending radius and maximum cable temperature should follow the documentation for the exact cable configuration.

Where the installation environment requires additional protection, use suitable cable routing and mechanical protection accessories.

7. Verify the Measurement Signal

After installation, check the sensor output and confirm that the measurement changes in the expected direction as the target distance changes.

Verify the initial gap, converter configuration, signal polarity, and monitoring channel settings.

Record the commissioning values and establish baseline measurements for future condition monitoring.

Compatible System Components

The PR6424/105-100 is normally used as part of a complete eddy current measurement chain.

The components listed above are examples of elements used in PR6424 measurement systems. They are not necessarily included with the sensor. Confirm the exact system configuration before ordering replacement parts.

Alternative Models and Replacement Considerations

The PR6424 belongs to a wider family of EPRO eddy current sensors. Other sensor models may provide different measurement ranges, sensitivity values, or temperature capabilities.

Before selecting an alternative, compare:

• Sensor head diameter.
• Measurement range.
• Sensitivity and linearity.
• Nominal air gap.
• Target material.
• Sensor thread and mounting dimensions.
• Cable length and connector type.
• Operating temperature.
• Signal converter compatibility.
• Calibration and monitoring-system requirements.

A sensor with the same nominal diameter is not automatically a suitable replacement. The complete measurement chain must be evaluated to maintain reliable monitoring performance.

Key Advantages

Non-Contact Measurement

The eddy current principle allows the sensor to monitor shaft movement without touching the rotating surface. This avoids mechanical contact between the probe and the target during normal measurement.

16 mm Sensor Head

The 16 mm sensing head is designed for large rotating machinery applications where shaft displacement measurement is required.

Static and Dynamic Measurement

The PR6424 series supports both static position measurement and dynamic displacement measurement, allowing it to serve different machinery monitoring purposes.

High Measurement Sensitivity

The typical sensitivity of 4 V/mm and linearity of ≤ ±1.5% support precise displacement measurement when the sensor is correctly installed and calibrated.

Suitable for Critical Rotating Equipment

The series is designed for applications involving turbines, compressors, pumps, and fans, where continuous monitoring can support equipment reliability.

Industrial Sensor Construction

The stainless steel sleeve and PTFE cable material provide a construction intended for industrial measurement environments, subject to the specific model’s operating limits.

Integration with Monitoring Systems

When paired with a compatible converter, the sensor can provide measurement signals for machinery monitoring and protection equipment.

Technical FAQs

1. What is the Epro PR6424/105-100?

The Epro PR6424/105-100 is a 16 mm eddy current sensor from the Emerson EPRO PR6424 family. It is designed for non-contact measurement of shaft displacement and vibration in rotating machinery.

2. What is the sensor head diameter?

The nominal sensor head diameter is 16 mm.

3. What is the measurement principle?

It uses the eddy current principle. The sensor generates an electromagnetic field, and changes in the distance between the probe and a conductive metallic target affect the electrical characteristics of the sensor.

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

The typical sensitivity is 4 V/mm, with specified linearity of ≤ ±1.5% under the applicable reference conditions.

5. What is the static measurement range?

The PR6424 series has a nominal static measurement range of ±2.0 mm.

6. What is the dynamic measurement range?

The typical dynamic measurement range is 0 to 1,000 μm peak-to-peak. The actual operating range must be evaluated according to the application and measurement-system configuration.

7. What material should the sensor measure?

The standard reference target is ferromagnetic steel, with 42CrMo4 used as the reference material in the series specifications. Other materials may require specific calibration or compatibility verification.

8. Does the sensor work independently?

No. The PR6424 sensor is normally used with a compatible signal converter. An appropriate converter is required to process the sensor signal and provide an output for the monitoring system.

9. What equipment commonly uses this sensor?

Typical applications include steam turbines, gas turbines, hydro turbines, compressors, pumps, and industrial fans. It is used where non-contact shaft displacement or vibration measurement is required.

10. What should be checked before replacing the PR6424/105-100?

Confirm the complete model number, sensor head dimensions, mounting thread, cable length, connector type, converter compatibility, calibration requirements, and target material. These details are important for maintaining measurement accuracy after replacement.

Procurement and Maintenance Recommendations

When purchasing the Epro PR6424/105-100, verify the complete model number and inspect the sensor label carefully. The PR6424 family contains multiple variants, and differences in cable length, connector configuration, mounting arrangement, and calibration can affect compatibility.

For replacement projects, compare the existing probe with the proposed replacement before installation. Confirm the sensor’s mechanical dimensions, cable arrangement, compatible signal converter, and monitoring-system requirements.

For used or surplus sensors, request clear photographs of the sensing tip, threaded sleeve, cable, connector, and model label. Check for visible damage, cable cuts, deformation, corrosion, or signs of improper handling.

During maintenance, inspect the probe mounting arrangement and cable routing. Keep the sensor tip free from contamination and ensure that the probe cannot contact the rotating shaft under expected operating conditions.

If measurement values become unstable or differ significantly from established baselines, inspect the complete measurement chain. Possible causes include an incorrect air gap, damaged cable, loose connector, incompatible converter, incorrect calibration, or changes in the target surface.

Maintaining accurate records of sensor installation details and baseline readings can help simplify troubleshooting and future replacement work.

Conclusion

The Epro PR6424/105-100 is a 16 mm eddy current sensor designed for non-contact shaft displacement and vibration measurement in industrial rotating machinery. As part of the Emerson EPRO PR6424 family, it supports static and dynamic measurement and is suitable for appropriately configured machinery monitoring systems.

The series provides a typical sensitivity of 4 V/mm, a static measurement range of ±2.0 mm, and a dynamic measurement range of 0 to 1,000 μm peak-to-peak. It is commonly associated with turbine, compressor, pump, and fan monitoring applications.

For reliable operation, the sensor must be matched with a compatible signal converter and installed with the correct air gap, target material, mounting arrangement, and cable configuration. Before purchasing or replacing the PR6424/105-100, verify the complete model suffix and all connection details to ensure compatibility with the existing machinery monitoring system.