Product Overview

The EPRO PR6424/009-100 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 developed for machinery protection and condition-monitoring applications in industrial environments.

The sensor measures the distance between its probe tip and a conductive metallic target without making physical contact. When installed near a rotating shaft, it can detect changes in the gap between the probe and the shaft surface. These changes can be used to monitor shaft vibration, radial and axial displacement, shaft position, eccentricity, and rotational speed-related signals.

The PR6424 series is commonly used in critical rotating equipment, including steam turbines, gas turbines, hydro turbines, compressors, pumps, and industrial fans. These machines often operate under continuous mechanical and thermal loads. Monitoring shaft movement provides useful information for identifying abnormal vibration, changes in bearing conditions, and potential mechanical problems.

The PR6424/009-100 has a nominal sensor head diameter of 16 mm. Its compact sensing head supports installation in machinery-monitoring arrangements where accurate probe positioning is important. The supplied product information lists a weight of approximately 0.2 kg.

A complete eddy current measurement system generally requires more than the sensor itself. Depending on the selected configuration, an extension cable and compatible signal converter are used to connect the probe to monitoring equipment. The converter conditions the sensor signal and provides an output suitable for vibration monitoring, machinery protection, or control-system integration.

When selecting this model, the complete part number should be checked carefully. Cable length, connector type, armored or unarmored construction, and converter compatibility can differ among PR6424 configurations.

Technical Specifications

Note: The performance values above are published PR6424 series specifications. Confirm the exact temperature limits, cable construction, cable length, and connector arrangement for the PR6424/009-100 configuration before installation.

Function and Working Principle

The PR6424/009-100 uses the eddy current principle to measure the distance between the sensor and a conductive metallic target. Unlike contact-based measurement devices, it does not need to touch the rotating shaft. This makes it suitable for continuous monitoring of high-speed machinery.

1. Eddy Current Measurement Principle

The sensor generates a high-frequency electromagnetic field at its probe tip. When a conductive metallic target approaches the sensing surface, eddy currents are induced in the target material.

These currents influence the electromagnetic characteristics of the probe. Changes in the distance between the probe and the target therefore produce corresponding changes in the sensor’s electrical response.

A compatible signal converter processes this response and produces a measurement signal related to the probe-to-target gap.

The measurement depends on the target material, probe installation, cable configuration, and correct calibration. For reliable results, the sensor should be used with the target material and measurement electronics specified for the system.

2. Shaft Vibration Measurement

When a probe is installed close to a rotating shaft, changes in the measured gap can indicate shaft movement.

As the shaft rotates, mechanical vibration may cause the distance between the shaft surface and the sensor to vary. The resulting dynamic signal can be used to evaluate shaft vibration.

This information is particularly important for turbines, compressors, and other large rotating machines, where excessive vibration can contribute to bearing wear, mechanical damage, or unplanned shutdowns.

3. Shaft Position Measurement

The sensor can also provide information about the relative position of a shaft.

Static displacement measurements help monitoring systems identify changes in shaft position, including movement associated with bearing clearance, thermal expansion, or mechanical loading.

The PR6424 series has a published static measurement range of approximately ±2.0 mm. Actual measurement accuracy depends on calibration, installation geometry, and the characteristics of the target surface.

4. Eccentricity and Speed-Related Monitoring

Eccentricity describes the variation between the rotational centerline and the geometric center of a rotating component. An eddy current sensor can detect changes in the probe-to-shaft gap as the shaft rotates.

The resulting signal can help machinery-monitoring systems assess shaft eccentricity and rotational behavior. Depending on the monitoring arrangement, the sensor can also provide speed or keyphasor-related information.

For these functions, probe placement and signal interpretation must follow the requirements of the machinery-monitoring system.

5. Signal Conditioning

The sensor is normally used with compatible signal-conditioning electronics. The converter supplies the necessary excitation and processes the probe response into a usable output.

The resulting signal can be connected to a machinery protection system, vibration monitor, or other compatible monitoring equipment.

A PR6424 probe should not be treated as a complete standalone monitoring system. The probe, cable, converter, and receiving equipment must be selected as a compatible measurement chain.

Role in Industrial Machinery Monitoring Systems

The PR6424/009-100 can serve as a sensing component in an industrial machinery protection and condition-monitoring system.

In critical rotating equipment, mechanical conditions can change gradually before a major failure occurs. Continuous measurement of shaft movement helps maintenance teams observe operating trends and identify abnormal conditions.

Turbine Monitoring

Steam, gas, and hydro turbines contain high-speed rotating assemblies. Shaft vibration and position are important parameters for evaluating their mechanical condition.

The PR6424 sensor can be installed at selected measurement locations to monitor radial or axial shaft movement. Monitoring equipment processes the sensor signal and compares operating values with configured alarm and trip limits.

Compressor Monitoring

Industrial compressors operate under varying mechanical and process loads. Shaft vibration can provide information about rotor balance, bearing performance, and other mechanical conditions.

A correctly installed PR6424 measurement channel can support continuous monitoring of compressor shaft movement.

Pump Monitoring

Large industrial pumps may operate continuously in water treatment, power generation, petrochemical, and manufacturing facilities.

Monitoring shaft displacement can help maintenance teams identify changes in rotating behavior and investigate possible mechanical problems.

PLC and DCS Integration

A machinery protection system may exchange alarm, status, or measurement information with a PLC or distributed control system.

The PR6424 probe itself does not directly function as a PLC communication module. Its signal must first be processed by compatible measurement electronics. The resulting output can then be integrated into a suitable control or monitoring architecture.

Industrial Applications

1. Steam Turbines

Steam turbines are used in power generation and industrial energy systems. Their rotating shafts operate under demanding mechanical and thermal conditions.

The PR6424 series can be used to monitor shaft vibration and displacement. Continuous measurements help operators assess machinery behavior and respond to abnormal operating trends.

2. Gas Turbines

Gas turbines are used in power plants, industrial facilities, and mechanical-drive applications. Their high rotational speeds make shaft monitoring an important part of equipment protection.

A properly installed eddy current sensor can provide non-contact measurements of shaft movement for the turbine monitoring system.

3. Hydro Turbines

Hydro turbines operate in power-generation environments where bearing conditions, shaft alignment, and rotor movement are important maintenance considerations.

Shaft displacement monitoring can help identify changes in the mechanical condition of the rotating assembly.

4. Industrial Compressors

Compressors are widely used in chemical processing, petrochemical facilities, gas transportation, and manufacturing.

The PR6424 sensor can support compressor monitoring by measuring shaft vibration and relative displacement. These measurements can be used alongside other machinery-monitoring parameters.

5. Industrial Pumps

Large pumps are commonly installed in power stations, water treatment facilities, and process plants. Continuous shaft monitoring can help maintenance teams identify abnormal vibration and investigate possible bearing or alignment issues.

6. Industrial Fans

Large fans and blowers are used in ventilation systems, boilers, cooling systems, and industrial process equipment.

Where shaft displacement monitoring is required, an eddy current sensor can provide non-contact measurement without introducing mechanical contact with the rotating component.

Installation and System Integration

Correct installation is essential for achieving stable measurement performance. Probe positioning, target material, cable routing, and signal-converter compatibility all influence the final measurement.

1. Confirm the Complete Model Number

Before installation, verify the full part number PR6424/009-100.

Different PR6424 configurations may have different cable lengths, cable protection, connector arrangements, and installation characteristics. Confirm the supplied hardware against the equipment documentation.

2. Select the Correct Mounting Location

The probe should be installed at a measurement location defined by the machinery-monitoring design.

For shaft vibration monitoring, the sensor is typically positioned close to the shaft surface with a controlled measurement gap. The mounting structure must remain stable during machinery operation.

Avoid mounting arrangements that introduce excessive movement, vibration, or mechanical looseness into the sensor assembly.

3. Check the Target Surface

The PR6424 series is designed for measurement against a suitable ferromagnetic steel target.

The shaft surface should meet the required material and surface-condition specifications. Target material differences, surface irregularities, and mechanical runout can influence the measurement signal.

The recommended shaft diameter for the published series specification is at least 80 mm.

4. Set the Correct Air Gap

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

The actual installation gap should be established using the manufacturer’s calibration and setup procedure. Incorrect probe positioning may reduce the usable measurement range or produce inaccurate readings.

Do not use the nominal air gap as a substitute for the installation procedure specified for the complete sensor and converter combination.

5. Connect the Signal Converter

The sensor must be paired with compatible signal-conditioning electronics.

Check the converter model, connector type, cable arrangement, and calibration requirements. An incompatible converter or incorrect cable configuration can cause measurement errors or prevent the system from operating correctly.

6. Route and Protect the Cable

Route the sensor cable according to the manufacturer’s recommendations. Avoid sharp bends, excessive mechanical tension, and locations where the cable may be exposed to heat, abrasion, or moving machinery.

Where required, use appropriate cable protection and maintain the specified bending radius.

7. Verify the Measurement Signal

After installation, confirm the sensor gap, signal output, calibration, and measurement stability.

Compare the readings with the machinery-monitoring system’s expected values. Check for abnormal noise, unstable signals, or unexpected changes during startup and normal operation.

Record the installation details and calibration information for future maintenance.

Compatible System Components

A complete PR6424 measurement channel generally consists of a probe, compatible cable arrangement, signal converter, and monitoring equipment.

The converter examples above are part of the wider PR6424 measurement-system family. Confirm compatibility with the exact PR6424/009-100 configuration before ordering.

Alternative Models and Replacement Considerations

The PR6424 series includes multiple 16 mm sensor configurations. Related models may share general measurement characteristics but can differ in cable length, connector, mounting arrangement, and other ordering details.

When replacing an existing sensor, compare the following details:

• Complete sensor model number.
• Probe diameter and mechanical dimensions.
• Thread type and mounting arrangement.
• Cable length and cable construction.
• Connector type and termination.
• Sensor-to-converter compatibility.
• Measurement sensitivity and calibration.
• Operating temperature requirements.
• Target material and shaft diameter.
• Monitoring-system input requirements.

A sensor from the same series is not automatically a direct replacement. Differences in cable configuration or signal-conditioning requirements may affect the installation.

Key Advantages

Non-Contact Measurement

The eddy current principle allows the sensor to measure shaft movement without physical contact. This is useful for continuous monitoring of rotating machinery.

16 mm Sensor Head

The 16 mm sensing head provides a defined installation format for machinery-monitoring arrangements designed around the PR6424 series.

Shaft Vibration Monitoring

The sensor can measure dynamic changes in the probe-to-shaft gap, supporting radial and axial vibration monitoring when installed in the appropriate arrangement.

Static Displacement Measurement

The published PR6424 series specification includes a static measurement range of ±2.0 mm, supporting shaft-position monitoring.

High Measurement Sensitivity

The series has a nominal sensitivity of 4 V/mm and linearity of up to ±1.5%, subject to the specified measurement conditions and correct system calibration.

Industrial Rotating Machinery Applications

The PR6424 series is designed for demanding machinery-monitoring applications involving turbines, compressors, pumps, and fans.

Integration with Machinery Protection Systems

When paired with compatible signal-conditioning electronics, the sensor can provide measurement signals for machinery protection and condition-monitoring equipment.

Technical FAQs

1. What is the EPRO PR6424/009-100?

The EPRO PR6424/009-100 is a 16 mm eddy current sensor designed for non-contact measurement of shaft displacement and vibration in rotating machinery.

2. What does the sensor measure?

Depending on the installation and monitoring arrangement, it can measure radial and axial shaft displacement, shaft position, eccentricity, and speed-related signals.

3. What is the sensor head diameter?

The sensor head diameter is 16 mm.

4. What is the measurement principle?

It uses the eddy current principle. An electromagnetic field at the probe tip interacts with the conductive target, and changes in the probe-to-target gap influence the sensor’s electrical response.

5. What is the sensitivity of the PR6424 series?

The published series sensitivity is 4 V/mm, with linearity specified at up to ±1.5% under the applicable measurement conditions.

6. What is the static measurement range?

The published static measurement range is approximately ±2.0 mm.

7. What is the dynamic measurement range?

The published dynamic measurement range is 0–1,000 μm.

8. Does the sensor need a signal converter?

A complete measurement channel generally requires compatible signal-conditioning electronics. The converter processes the probe response and provides a suitable output for monitoring equipment.

9. Can the PR6424/009-100 be used with a PLC?

It can form part of a PLC-based monitoring arrangement, but the probe itself is not a direct PLC communication device. A compatible converter or machinery-monitoring system must provide the appropriate signal interface.

10. What is the weight of the sensor?

The supplied product information lists the weight as approximately 0.2 kg. Actual weight can depend on cable length, cable protection, and included accessories.

11. What target material is suitable?

The PR6424 series is specified for measurement against ferromagnetic steel, with 42CrMo4 commonly used as the standard reference material.

12. What should be checked before replacing the sensor?

Verify the complete model number, probe dimensions, cable length, connector, mounting thread, converter compatibility, and calibration requirements. These details are important for maintaining measurement accuracy and system compatibility.

Procurement and Maintenance Recommendations

When purchasing the EPRO PR6424/009-100, confirm the full model number and inspect the product label. Verify whether the supplied unit includes an integrated cable, connector, protective sleeve, or additional accessories.

For replacement projects, compare the new sensor with the installed unit. Similar-looking probes may have different cable lengths, connector arrangements, and mechanical configurations.

Before installation, inspect the probe tip, sensor body, cable insulation, and connector. Damaged cable insulation or a loose connector can affect measurement stability. The probe should also be checked for contamination or mechanical damage.

During operation, review the monitoring system’s vibration and displacement trends. Sudden changes in readings should be investigated alongside bearing temperature, operating speed, load, and other available machinery parameters.

Keep records of the sensor model, installation location, converter type, calibration information, and cable arrangement. These records can simplify future maintenance and help prevent compatibility errors when spare parts are ordered.

For critical rotating equipment, sensor replacement should follow the machinery protection system’s maintenance procedures. Verify the measurement channel after replacement before returning the equipment to normal operation.

Conclusion

The EPRO PR6424/009-100 16 mm Eddy Current Sensor is designed for non-contact monitoring of shaft vibration, displacement, position, and related operating conditions in rotating machinery. Its 16 mm sensing head and the PR6424 series measurement characteristics make it suitable for properly configured monitoring systems used with turbines, compressors, pumps, and industrial fans.

With a published sensitivity of 4 V/mm, static measurement range of ±2.0 mm, and dynamic range of 0–1,000 μm, the PR6424 series supports machinery condition monitoring when installed and calibrated correctly.

For industrial maintenance and procurement, verifying the complete model number, cable configuration, connector, and signal-converter compatibility is essential. Correct component matching helps maintain reliable measurements and supports the long-term operation of machinery protection systems.