Product Overview

The Epro PR6424/101-101 16mm Eddy Current Sensor is a non-contact displacement measurement device designed for monitoring the condition and operating behavior of critical rotating machinery. It belongs to the PR6424 sensor family developed for industrial machinery protection and condition monitoring applications. The sensor is commonly associated with equipment such as steam turbines, gas turbines, hydro turbines, compressors, pumps, and industrial fans.

Unlike contact-based measurement devices, an eddy current sensor measures the distance between its sensing tip and a conductive target without requiring physical contact. This makes the technology suitable for monitoring rotating shafts where continuous measurement is required but mechanical contact could introduce wear or interfere with machine operation.

The PR6424 series is designed to measure radial and axial shaft displacement, vibration, shaft position, eccentricity, and speed-related information. Its 16 mm sensor head provides a compact sensing arrangement for machinery installations where measurement accuracy and stable mechanical mounting are important.

The PR6424/101-101 is identified as a 16 mm eddy current sensor with a supplied weight of approximately 0.2 kg. Its application requires a compatible signal converter and the appropriate cable arrangement to form a complete measurement chain. The sensor probe alone does not provide the complete monitoring and protection functionality of a machinery monitoring system.

For industrial maintenance teams, this type of sensor can support condition monitoring programs by providing displacement information that helps identify abnormal shaft movement and changing mechanical conditions.

Technical Specifications

Note: The technical performance values above describe the PR6424 sensor family. Confirm the exact cable length, connector, thread, and mechanical configuration of the PR6424/101-101 against the product label and applicable documentation before installation.

Function and Working Principle

The PR6424/101-101 operates using the eddy current measurement principle. It generates an electromagnetic field at the sensing tip and detects changes caused by the distance between the probe and a conductive metallic target.

This measurement method allows the sensor to monitor shaft movement without contacting the rotating surface.

1. Electromagnetic Field Generation

An excitation signal is supplied to the sensor through a compatible signal converter. This produces an alternating electromagnetic field around the sensing tip.

When a conductive target, such as a suitable ferromagnetic steel shaft, enters this field, electrical eddy currents are induced in the target material.

The interaction between the target and the sensor’s electromagnetic field changes the electrical characteristics of the sensing circuit.

2. Distance Measurement

The electrical response changes according to the distance between the sensor tip and the target surface.

As the shaft moves closer to or farther away from the sensor, the measured response changes. The compatible converter processes this change and produces an output proportional to the displacement within the calibrated measurement range.

This arrangement allows engineers to monitor shaft position and movement continuously without installing a mechanical contact device against the rotating shaft.

3. Shaft Vibration Measurement

When a rotating shaft vibrates, its distance from the stationary sensor changes over time.

The PR6424 measurement chain detects these changes and provides displacement information that can be used to evaluate shaft vibration. Monitoring the vibration trend can help maintenance teams identify developing mechanical problems.

Typical conditions that may influence shaft vibration include imbalance, misalignment, bearing deterioration, looseness, and changes in operating conditions. The sensor provides measurement data; identifying the underlying mechanical cause requires additional analysis.

4. Static Position Measurement

The PR6424 series also supports static shaft-position measurement within its specified range.

This capability is useful when monitoring axial or radial shaft position, machine clearances, and changes in mechanical alignment.

Static measurements can help engineers observe gradual movement that may not be apparent from vibration measurements alone.

5. Signal Conversion

The sensor is normally used with a compatible EPRO signal converter. The converter supplies the required excitation and processes the probe response into a usable measurement signal.

The sensor, extension cable, and converter must be selected as a compatible measurement chain. Differences in cable length, connector configuration, and calibration can affect measurement performance.

Role in Industrial Machinery Protection Systems

The PR6424/101-101 can serve as a sensing element within an industrial machinery monitoring and protection arrangement.

In critical rotating equipment, shaft displacement measurements provide information about mechanical operating conditions. These measurements can be supplied to monitoring equipment for display, alarm processing, trend analysis, and machinery protection functions.

Turbine Monitoring

Steam, gas, and hydro turbines contain rotating shafts that operate under demanding mechanical and thermal conditions.

A non-contact displacement sensor can monitor shaft movement and provide information about radial vibration, axial position, and eccentricity when installed as part of a suitable measurement system.

This information helps operators evaluate machine behavior during startup, normal operation, load changes, and shutdown.

Compressor Protection

Industrial compressors operate under changing pressure, speed, and load conditions. Abnormal shaft movement may indicate a developing mechanical issue.

A properly installed eddy current measurement system can provide displacement data for monitoring compressor shaft behavior and supporting maintenance decisions.

Pump Condition Monitoring

Large industrial pumps may experience vibration and shaft-position changes due to bearing wear, hydraulic conditions, misalignment, or mechanical deterioration.

The PR6424 series can be used in suitable pump installations to monitor shaft displacement without direct contact.

Integration with Monitoring Equipment

The probe itself is only one part of the measurement system. A compatible converter and monitoring device are needed to process and use the sensor signal.

Depending on the plant architecture, monitoring equipment may communicate with a distributed control system, PLC, or plant-wide machinery protection platform.

The exact signal type, input requirements, and alarm configuration should be verified for the installed system.

Industrial Applications

The PR6424/101-101 is intended for industrial applications where non-contact measurement of rotating machinery displacement is required.

1. Steam Turbines

Steam turbines operate at high rotational speeds and are exposed to changing thermal and mechanical conditions.

Shaft displacement monitoring can help engineers observe radial vibration, axial movement, and changes in rotor position. These measurements support machinery condition assessment and protection strategies.

2. Gas Turbines

Gas turbines are critical assets in power generation and industrial processing facilities. Their rotating assemblies require continuous monitoring to maintain stable operation.

Eddy current probes can provide shaft displacement measurements when incorporated into a compatible machinery monitoring system.

3. Hydro Turbines

Hydro turbines operate with large rotating assemblies and may experience changes in mechanical loading and operating conditions.

Non-contact shaft monitoring helps maintenance personnel observe rotor movement and identify changes that require further inspection.

4. Industrial Compressors

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

The PR6424 measurement technology can support compressor monitoring by measuring shaft displacement and vibration-related movement.

5. Industrial Pumps

Large process pumps and high-speed rotating pumps may require continuous shaft monitoring.

A suitable eddy current measurement arrangement can provide information about shaft movement and help maintenance teams investigate abnormal operating conditions.

6. Industrial Fans

Large fans used in power plants, industrial ventilation systems, and process facilities may experience imbalance, bearing wear, or shaft movement.

Non-contact displacement monitoring can help identify changes in mechanical behavior and support preventive maintenance activities.

Installation and System Integration

Correct installation is essential for obtaining stable measurement results. The sensor must be positioned properly, connected to compatible equipment, and calibrated for the intended target material.

1. Confirm Sensor Compatibility

Before installation, verify the complete model number and mechanical configuration.

Check the sensor head diameter, mounting thread, cable length, connector arrangement, and compatibility with the selected signal converter.

Do not assume that every PR6424 probe can be connected directly to every converter. The complete measurement chain must follow the manufacturer’s compatibility requirements.

2. Prepare the Mounting Position

The sensor should be installed in a stable mounting arrangement facing the intended shaft measurement surface.

The mounting position must provide sufficient mechanical clearance and prevent the sensor from contacting the rotating component during normal operation or expected shaft movement.

Check the shaft surface condition and ensure that the target material is suitable for the sensor’s calibration.

3. Set the Initial Air Gap

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

The actual installation gap must be adjusted according to the applicable calibration procedure and converter output characteristics.

Incorrect gap adjustment may reduce the available measurement range or cause the output to operate outside its intended linear region.

4. Connect the Extension Cable and Converter

Connect the sensor to the appropriate extension cable and signal converter using the specified connector arrangement.

Cable routing should avoid excessive bending, mechanical damage, and unnecessary proximity to strong electrical interference sources.

Use the correct cable length and avoid unapproved substitutions that could affect the measurement chain.

5. Configure the Monitoring System

After installation, configure the monitoring equipment for the correct sensor type, sensitivity, measurement range, and alarm limits.

The monitoring system should be configured according to the machinery manufacturer’s requirements and the operating characteristics of the monitored equipment.

Where the measurements are connected to a DCS or PLC, verify the signal scaling and alarm logic before commissioning.

6. Verify Measurement Performance

Before placing the machinery into normal service, inspect the mounting arrangement, cable connections, and converter status.

Verify that the output responds correctly to changes in probe-to-target distance and that the measurement remains within the expected operating range.

Record the initial measurement values as a reference for future condition monitoring.

Compatible System Components

The PR6424/101-101 is generally used as part of a complete eddy current measurement system.

The components listed above are examples of a complete monitoring arrangement. They are not necessarily included with the sensor.

Alternative Models and Replacement Considerations

The PR6424 family contains different probe configurations. Although they may share the same general measurement technology and nominal sensor diameter, their cable, connector, mounting, and calibration details can differ.

Before replacing the PR6424/101-101, compare:

• Complete sensor model number.
• Sensor head diameter.
• Mounting thread and mechanical length.
• Cable length and cable construction.
• Connector type and pin arrangement.
• Compatible signal converter.
• Sensitivity and measurement range.
• Target material and shaft diameter.
• Operating temperature requirements.
• Calibration and monitoring-system configuration.

A sensor with the same 16 mm head diameter is not necessarily a direct replacement. The complete probe and converter combination must be verified.

Key Advantages

Non-Contact Measurement

The eddy current principle allows the sensor to measure shaft movement without touching the rotating surface. This avoids mechanical contact between the probe and the monitored shaft.

Continuous Shaft Monitoring

The measurement system can provide ongoing displacement information for critical rotating machinery, supporting condition monitoring and maintenance planning.

Static and Dynamic Measurement

The PR6424 family supports both static position measurement and dynamic displacement measurement within its specified ranges.

Compact 16 mm Sensor Head

The 16 mm sensing head provides a practical mounting format for suitable machinery installations.

Industrial Machinery Applications

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

Integration with Machinery Monitoring Systems

When connected to a compatible converter and monitoring platform, the sensor can supply measurement information for vibration analysis, alarm processing, and equipment condition assessment.

Durable Industrial Construction

The PR6424 series uses a stainless-steel sleeve and PTFE cable construction. These materials support its use in demanding industrial measurement environments within the specified operating limits.

Technical FAQs

1. What is the Epro PR6424/101-101?

The PR6424/101-101 is a 16 mm eddy current sensor designed for non-contact measurement of shaft displacement and vibration-related movement in rotating machinery.

2. What does the 16 mm specification mean?

The 16 mm specification refers to the nominal diameter of the sensor head. It identifies the probe size used in the PR6424 sensor family.

3. What is the measurement principle?

The sensor operates using electromagnetic eddy current technology. It detects changes in the electrical response caused by the distance between the probe tip and a conductive metallic target.

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

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

5. What is the static measurement range?

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

6. What is the dynamic measurement range?

The documented dynamic measurement range is 0–1,000 μm peak-to-peak. Actual performance depends on the complete measurement chain and installation conditions.

7. Does the sensor measure shaft vibration?

Yes. Changes in the distance between the sensor and the rotating shaft can be used to measure dynamic displacement associated with shaft vibration.

8. Does the PR6424/101-101 work without a signal converter?

The probe is normally used with a compatible EPRO signal converter. The converter provides the required excitation and processes the sensor response into a usable measurement signal.

9. What materials can be measured?

The PR6424 series is specified for conductive ferromagnetic target materials, with 42CrMo4 steel used as the standard reference material. Different target materials may require appropriate calibration.

10. What should be checked before replacing this sensor?

Confirm the full model number, probe diameter, mounting thread, cable length, connector, converter compatibility, and calibration requirements. These details are important for maintaining measurement accuracy and avoiding compatibility problems.

Procurement and Maintenance Recommendations

When purchasing the Epro PR6424/101-101, verify the full model number rather than selecting a replacement based only on the PR6424 series designation.

Check the sensor head diameter, cable arrangement, connector, mounting configuration, and compatibility with the existing signal converter. If the sensor is being purchased for an installed machinery protection system, compare its configuration with the original equipment documentation.

For spare-parts procurement, request clear product photographs and confirm the physical condition of the sensing tip, threaded sleeve, cable, and connector. Inspect the cable for cuts, crushing, excessive bending, or signs of heat damage.

During maintenance, verify the mounting position and initial air gap according to the manufacturer’s procedure. Keep the sensor and mounting area free from contamination that could affect installation or mechanical clearance.

Record the initial measurement values and calibration information after installation. These records can help maintenance personnel identify changes in sensor performance and distinguish instrumentation issues from actual machinery movement.

If the sensor is used on critical rotating equipment, replacement and commissioning should be performed by personnel familiar with the applicable machinery monitoring system and sensor calibration requirements.

Conclusion

The Epro PR6424/101-101 16mm Eddy Current Sensor is a non-contact measurement device designed for monitoring shaft displacement and vibration-related movement in critical rotating machinery. Its PR6424 family specifications include 4 V/mm sensitivity, a ±2.0 mm static measurement range, a dynamic measurement range of 0–1,000 μm, and a nominal center air gap of approximately 2.7 mm.

The sensor is suitable for integration into compatible machinery monitoring arrangements used with turbines, compressors, pumps, fans, and other rotating equipment. For reliable operation, the probe must be matched with the correct extension cable, signal converter, mounting arrangement, and monitoring equipment.

Accurate model identification and proper calibration are essential when purchasing, installing, or replacing the PR6424/101-101 in an industrial machinery protection system.