Product Overview

The Epro PR6424/015-000 16 mm Eddy Current Sensor is a non-contact displacement sensor designed for monitoring the condition and operating behavior of rotating machinery. Developed for demanding industrial environments, this sensor belongs to the Emerson EPRO PR6424 series and is used in machinery protection and condition-monitoring systems.

The sensor measures the distance between its probe tip and a conductive target, typically a ferromagnetic steel shaft. By detecting changes in this distance, the monitoring system can evaluate shaft displacement, vibration, axial position, eccentricity, and other mechanical conditions.

Unlike contact-based measurement devices, an eddy current sensor does not need to touch the rotating shaft. This non-contact measurement method is particularly useful for high-speed machinery, where continuous physical contact would introduce wear and measurement limitations.

The PR6424 series uses a 16 mm sensor head and is designed for critical rotating equipment such as steam turbines, gas turbines, hydro turbines, compressors, pumps, and fans. It provides a typical sensitivity of 4 V/mm and a static measurement range of ±2.0 mm when used with a compatible signal converter and correctly calibrated target material.

The PR6424/015-000 is suitable for applications where reliable shaft displacement and vibration information is required for machinery monitoring. Its performance depends on the complete measurement chain, including the sensor, extension cable where applicable, signal converter, monitoring system, and installation arrangement.

Technical Specifications

Note: The specifications above describe the PR6424 series and the supplied product information. Confirm the exact cable, connector, mounting, temperature, and converter configuration for PR6424/015-000 before installation.

Function and Working Principle

The PR6424/015-000 uses eddy current technology to measure the distance between the sensor tip and a conductive metallic target. It converts changes in the electromagnetic interaction between the probe and the target into an electrical signal that can be processed by a compatible converter.

1. Eddy Current Measurement Principle

An eddy current sensor contains a coil inside its sensing head. When the sensor is connected to a compatible signal converter, the coil generates a high-frequency electromagnetic field around the probe tip.

When a conductive metal target, such as a rotating steel shaft, enters this field, circulating electrical currents known as eddy currents are induced in the target surface.

These currents influence the electromagnetic characteristics of the sensor coil. As the distance between the probe and the shaft changes, the coil’s electrical response changes as well.

The signal converter processes this response and produces an output related to the distance between the sensor and the target.

This allows the sensor to measure shaft movement without making physical contact with the rotating component.

2. Shaft Displacement Measurement

The PR6424 series can measure changes in the distance between the probe and a shaft surface. This information is useful for detecting shaft movement relative to the sensor mounting position.

Static displacement measurement can help identify changes in shaft position, while dynamic measurement can be used to evaluate shaft movement during operation.

In turbine and compressor installations, displacement information can support the assessment of bearing conditions, shaft alignment, and mechanical stability.

3. Shaft Vibration Monitoring

When a rotating shaft moves repeatedly during operation, the distance between the shaft surface and the stationary sensor changes.

The sensor detects these variations and produces an electrical signal representing the shaft’s relative movement. A compatible monitoring instrument can process this signal to calculate vibration amplitude and other relevant parameters.

The PR6424 series has a dynamic measurement range of 0–1,000 μm under its specified operating conditions. Actual measurement performance depends on installation geometry, target material, calibration, and the connected monitoring equipment.

4. Axial Position and Eccentricity Monitoring

The sensor can also be used in suitable measurement arrangements to monitor axial shaft position and eccentricity.

Axial position monitoring helps identify movement along the shaft axis, which can be important in turbine and compressor protection. Eccentricity measurement can provide information about shaft geometry and movement during startup or operation.

The measurement arrangement must be designed according to the machinery configuration and the monitoring system’s requirements.

Role in Industrial Machinery Protection Systems

The Epro PR6424/015-000 is a sensing component rather than a complete machinery protection system. It supplies measurement information to compatible signal-conditioning and monitoring equipment.

A typical measurement chain includes the following components:

1. PR6424 eddy current sensor.
2. Compatible extension cable, if required by the installation.
3. EPRO signal converter.
4. Machinery monitoring or protection equipment.
5. Plant control, alarm, or supervisory system.

Each component must be compatible with the others. Sensor calibration, cable configuration, connector type, and converter selection are important factors in achieving reliable measurement results.

Turbine Monitoring

Steam and gas turbines contain rotating shafts that operate at high speeds and under demanding mechanical conditions. Shaft vibration and displacement measurements help operators evaluate machinery behavior.

The PR6424 series can be installed at suitable measurement locations to monitor radial or axial shaft movement. Its output can be processed by a compatible turbine monitoring system to support alarm and protection functions.

Compressor Condition Monitoring

Industrial compressors are used in gas processing, chemical production, refining, and other continuous-process industries.

Shaft vibration and position measurements can provide information about rotor behavior, bearing conditions, and mechanical stability. Non-contact sensing is particularly useful because the rotating shaft does not need to physically touch the probe.

Pump Monitoring

Large industrial pumps may operate continuously in power plants, water-treatment facilities, refineries, and chemical plants.

A suitable displacement sensor installation can provide shaft movement information that supports maintenance decisions and equipment-condition assessment.

Generator Monitoring

Generators contain rotating assemblies whose mechanical condition is important for reliable operation.

When integrated into an appropriate monitoring arrangement, eddy current sensors can provide shaft displacement and vibration information for maintenance and machinery protection purposes.

Industrial Applications

The PR6424/015-000 is designed for applications requiring non-contact measurement of rotating machinery. Typical applications include:

1. Steam Turbines

Steam turbines operate at high rotational speeds and are exposed to thermal and mechanical loads. Monitoring shaft vibration and displacement helps maintenance teams evaluate rotor behavior and identify abnormal operating conditions.

The PR6424 series can be used at suitable measurement points to provide shaft movement information to a compatible turbine monitoring system.

2. Gas Turbines

Gas turbines are important in power generation and industrial energy systems. Their rotating components require continuous condition monitoring to support reliable operation.

Eddy current sensors can measure shaft movement without contacting the rotating surface, providing information that can be used for vibration analysis and machinery protection.

3. Industrial Compressors

Centrifugal and other large industrial compressors rely on accurately controlled rotating assemblies. Shaft vibration monitoring can help identify changes in mechanical behavior.

The PR6424 sensor can be used in an appropriate measurement arrangement to monitor shaft displacement and vibration.

4. Hydro Turbines

Hydro turbines operate under varying hydraulic and mechanical conditions. Shaft movement and vibration information can help operators assess the condition of rotating equipment.

A suitable PR6424 installation can contribute to the monitoring of radial or axial shaft movement.

5. Industrial Pumps

Large pumps used in water treatment, chemical processing, and power generation may require continuous mechanical-condition monitoring.

Non-contact displacement measurement can provide useful information about shaft movement and vibration, especially in installations where conventional contact measurement is unsuitable.

6. Industrial Fans

Large fans and ventilation equipment can experience imbalance, shaft movement, and vibration during operation.

Where the shaft dimensions and installation requirements are suitable, an eddy current sensor can provide information for condition-monitoring systems.

Installation and System Integration

Correct installation is essential for accurate measurement. The sensor must be positioned and calibrated according to the manufacturer’s requirements and the characteristics of the target shaft.

1. Verify the Sensor Model

Before installation, check the complete model number, PR6424/015-000, and confirm the sensor’s cable and connector configuration.

Do not assume that all PR6424 probes have identical mechanical dimensions, cable arrangements, or converter compatibility. Different suffixes may identify different cable, mounting, or configuration options.

2. Confirm the Mounting Arrangement

The sensor must be mounted securely so that it maintains a stable position relative to the shaft.

The mounting location should provide sufficient mechanical clearance and allow the sensor to measure the intended target surface. The sensor head must not contact the rotating shaft during normal operation or expected shaft movement.

The specified 16 mm sensor head diameter should be considered when designing the mounting bracket, probe holder, and installation clearance.

3. Set the Correct Measurement Gap

The distance between the sensor tip and the target shaft is important for accurate measurement.

The PR6424 series has a nominal center air gap of approximately 2.7 mm in its specified measurement configuration. The final installation gap must follow the applicable sensor and converter instructions.

An incorrect gap may result in an output outside the calibrated measurement range, reducing accuracy or causing an invalid signal.

4. Check Target Material

The PR6424 series is designed for measurement against ferromagnetic steel targets. The standard calibration material is 42CrMo4 steel.

If the actual shaft material differs from the standard calibration material, the measurement characteristics may change. Verify material compatibility and calibration requirements before commissioning.

5. Connect the Signal Converter

The sensor must be connected to a compatible signal converter and measurement system.

Confirm the correct converter type, cable length, connector arrangement, and electrical connections. Avoid assuming that a sensor can be connected directly to a PLC analog input without the required signal-conditioning equipment.

6. Route and Protect the Cable

The sensor cable should be routed away from sources of electrical interference, high temperatures beyond its rating, sharp edges, and moving machinery.

Observe the specified cable bending radius and protect the cable from mechanical damage. Cable shielding and grounding should follow the manufacturer’s installation instructions.

7. Perform Calibration and Functional Testing

After installation, verify the measurement gap and confirm that the sensor and converter are correctly matched.

Check the output signal at the specified operating position and compare it with the expected measurement range. Test the monitoring channel and verify that alarm and protection settings correspond to the machinery requirements.

Record the final installation position, calibration information, cable configuration, and monitoring-channel settings for future maintenance.

Compatible System Components

A complete PR6424 measurement arrangement may include several components. The exact selection depends on the installed monitoring platform and the required cable configuration.

The components listed are examples of equipment used in compatible measurement arrangements. They are not necessarily included with the PR6424/015-000 sensor.

Alternative Models and Replacement Considerations

The PR6424 family includes multiple configurations. A replacement should be selected according to the measurement range, probe dimensions, cable arrangement, mounting thread, converter compatibility, and target material.

When replacing an existing probe, compare the complete model number rather than selecting a sensor based only on the 16 mm diameter.

Important replacement factors include:

• Sensor head diameter and mechanical dimensions.
• Probe mounting thread and installation length.
• Static and dynamic measurement range.
• Sensitivity and linearity.
• Cable type and overall length.
• Connector and extension cable configuration.
• Signal converter compatibility.
• Target material and calibration requirements.
• Operating temperature and environmental conditions.

A replacement sensor that has the same nominal diameter may still produce an incompatible signal if its electrical or mechanical configuration differs.

Key Advantages

Non-Contact Measurement

The PR6424 sensor measures shaft displacement without touching the rotating surface. This avoids direct mechanical contact between the sensing element and the moving target.

Suitable for Critical Rotating Machinery

The PR6424 series is designed for machinery such as turbines, compressors, pumps, and fans, where shaft movement and vibration information can be important for condition monitoring.

16 mm Sensor Head

The 16 mm sensing head provides a defined installation size for suitable machinery-monitoring arrangements.

High Measurement Sensitivity

The series provides a typical sensitivity of 4 V/mm, supporting the conversion of small distance changes into measurable electrical signals.

Static and Dynamic Measurement

The sensor supports both static displacement measurement and dynamic shaft movement measurement within the specified operating range.

Industrial Construction

The stainless-steel sleeve and PTFE cable construction are intended for industrial sensing applications. Actual environmental suitability depends on the exact configuration and installation conditions.

Integration with Monitoring Systems

When connected to a compatible signal converter, the sensor can provide measurement information to machinery monitoring and protection equipment.

Technical FAQs

1. What is the Epro PR6424/015-000?

The PR6424/015-000 is a 16 mm eddy current sensor designed for non-contact measurement of shaft displacement and vibration in rotating machinery.

2. What is the sensor head diameter?

The sensor head diameter is 16 mm, as identified by the PR6424 series designation and supplied product information.

3. What is the measurement principle?

It uses the eddy current principle. An electromagnetic field generated by the probe interacts with a conductive target, and changes in this interaction are used to determine the distance between the sensor and the target.

4. What is the typical sensitivity?

The PR6424 series has a typical sensitivity of 4 V/mm when used with the specified converter and standard calibration target.

5. What is the static measurement range?

The typical static measurement range is ±2.0 mm.

6. Can the PR6424/015-000 measure shaft vibration?

Yes. The sensor can measure dynamic changes in the distance between the probe and a rotating shaft. A compatible converter and monitoring system process the signal to evaluate shaft vibration.

7. Which target material is recommended?

The PR6424 series is specified for ferromagnetic steel, with 42CrMo4 used as the standard calibration material.

8. Does the sensor need to contact the shaft?

No. It is a non-contact sensor. It measures the gap between the probe tip and the shaft surface without physical contact.

9. Does the sensor connect directly to a PLC?

A compatible signal converter is normally required to condition the sensor signal. The resulting output can then be connected to an appropriate monitoring or control-system input.

10. What should be checked before replacing this sensor?

Verify the complete model number, sensor diameter, mounting dimensions, cable length, connector, converter compatibility, measurement range, and target material. These details are necessary to avoid measurement errors or integration problems.

Procurement and Maintenance Recommendations

When purchasing the Epro PR6424/015-000, verify the complete model number and confirm that the supplied probe matches the existing machinery-monitoring installation.

The sensor’s cable configuration and connector arrangement should be checked carefully. Different PR6424 suffixes can represent different product configurations, so a similar-looking sensor should not automatically be treated as a direct replacement.

For maintenance and spare-parts management, keep records of the probe model, installation location, converter type, cable length, measurement gap, and calibration information. These records help technicians identify the correct replacement and reduce commissioning time.

During routine inspections, check the probe mounting, cable condition, connector, and sensor clearance. Look for loose mounting hardware, damaged insulation, excessive cable bending, or signs of mechanical contact with the shaft.

If the monitoring signal becomes unstable, inspect the entire measurement chain rather than replacing the sensor immediately. Potential causes include incorrect sensor gap, cable damage, connector problems, converter faults, grounding issues, and changes in the target surface.

For critical rotating equipment, replacement and calibration should follow the machinery manufacturer’s and monitoring-system supplier’s procedures.

Conclusion

The Epro PR6424/015-000 16 mm Eddy Current Sensor is designed for non-contact shaft displacement and vibration measurement in critical rotating machinery. Its measurement principle allows it to monitor shaft movement without physical contact, making it suitable for applications involving turbines, compressors, pumps, fans, and generators.

With a typical sensitivity of 4 V/mm and a static measurement range of ±2.0 mm, the PR6424 series can provide useful measurement information when paired with a compatible signal converter and correctly installed monitoring system.

For maintenance and replacement projects, the complete model number, cable configuration, mounting arrangement, target material, and converter compatibility should be verified before ordering. Correct installation and calibration are essential for dependable machinery-condition monitoring.