Product Overview

The Epro PR6424/008-100 16 mm Eddy Current Sensor is a non-contact displacement sensor designed for monitoring the condition and operating behavior of critical rotating machinery. Part of the PR6424 sensor family from EPRO, associated with Emerson’s machinery health monitoring portfolio, this probe is used to measure shaft vibration, radial and axial displacement, shaft position, eccentricity, and rotational speed-related signals.

Unlike contact-based measurement devices, an eddy current sensor does not need to touch the rotating shaft. It operates by generating an electromagnetic field near a conductive target. Changes in the distance between the probe tip and the target surface affect the sensor’s electrical characteristics. When connected to a compatible signal converter, these changes can be processed into measurement signals for machinery monitoring and protection systems.

The PR6424 series features a nominal sensor head diameter of 16 mm. Its non-contact measuring principle makes it suitable for applications where continuous observation of shaft movement is required without introducing mechanical contact between the sensor and the rotating component.

The PR6424/008-100 is relevant to industrial facilities that operate turbines, compressors, pumps, fans, and other large rotating machines. In these applications, shaft vibration and displacement measurements can help operators identify abnormal mechanical behavior and evaluate equipment condition.

The sensor is designed to work as part of a complete measurement chain. A typical installation includes the eddy current probe, an appropriate extension cable where required, a compatible signal converter, and a machinery monitoring or protection system. Correct matching of these components is essential for obtaining reliable measurement results.

Technical Specifications

Note: The technical values above describe the PR6424 sensor family. Verify the exact cable length, connector, probe construction, and installation configuration of the PR6424/008-100 before ordering. The 0.2 kg weight is consistent with the manufacturer’s approximate weight for a sensor with 1 m cable and no armor.

Function and Working Principle

The PR6424/008-100 uses eddy current technology to measure the distance between the sensor tip and a conductive target. This method is particularly useful for monitoring rotating shafts because it can detect small changes in shaft position without physical contact.

1. Electromagnetic Field Generation

The sensor contains an electrical coil near its sensing tip. When supplied through a compatible measurement system, the coil generates an alternating electromagnetic field.

When a conductive metal surface enters this field, electrical currents known as eddy currents are induced in the target. These currents affect the electromagnetic characteristics of the sensor coil.

The resulting change is related to the distance between the probe and the target surface.

2. Displacement Measurement

As a rotating shaft moves closer to or farther away from the probe, the electromagnetic interaction changes. The measurement system detects these changes and converts them into a signal representing the shaft-to-probe gap.

This allows the PR6424 sensor to monitor shaft movement without touching the rotating surface.

In a properly installed system, the measurement can be used to observe shaft position, radial movement, axial displacement, and other mechanical conditions.

3. Static Position Measurement

Static measurement is used to determine the relative position of a shaft or conductive target. The PR6424 family has a published static measurement range of ±2.0 mm.

This function is relevant to applications where operators need to monitor shaft position, axial movement, or changes in the mechanical clearance between rotating and stationary components.

4. Dynamic Vibration Measurement

Dynamic measurement focuses on rapid changes in shaft displacement. As a rotating shaft vibrates, its distance from the sensor changes continuously.

The PR6424 family supports dynamic measurement from 0 to 1,000 μm. The resulting signal can be evaluated by machinery monitoring equipment to assess vibration behavior and identify abnormal operating patterns.

5. Signal Conversion

The probe is normally used with a compatible EPRO signal converter. The converter processes the probe’s electrical response and provides a usable output for a monitoring system.

The probe, extension cable, and converter must be selected as a compatible combination. Differences in cable length, connector type, and probe configuration can affect measurement performance.

Role in Industrial Machinery Monitoring Systems

The PR6424/008-100 is generally used as a measurement component within a larger machinery condition monitoring or protection system. Its function is to provide shaft-related measurement information that can be evaluated by monitoring equipment.

Turbine Shaft Monitoring

Steam, gas, and hydro turbines operate under demanding mechanical conditions. Shaft displacement and vibration measurements help operators monitor rotor behavior during startup, normal operation, load changes, and shutdown.

An eddy current probe can provide continuous information about the movement of the shaft relative to the stationary machine structure.

Compressor Condition Monitoring

Large compressors are important assets in petrochemical plants, refineries, gas processing facilities, and industrial utilities.

The PR6424 series can be used to monitor shaft vibration and position in compatible compressor installations. Measurement data can support condition assessment and help maintenance teams investigate abnormal mechanical behavior.

Pump and Fan Monitoring

Industrial pumps and fans may experience vibration changes due to imbalance, misalignment, bearing deterioration, or other mechanical conditions.

When installed in an appropriate measurement arrangement, an eddy current sensor can provide shaft displacement information for machinery monitoring systems.

Machinery Protection Integration

The sensor’s output can be processed by compatible monitoring equipment. Depending on the system architecture, measurement values may be used for alarm generation, shutdown logic, historical trend analysis, and maintenance planning.

The sensor itself is not a complete machinery protection system. Protection functions depend on the compatible converter, monitoring hardware, configuration, and plant control strategy.

Industrial Applications

1. Steam Turbines

Steam turbines are commonly used in power generation and industrial energy systems. Continuous shaft vibration and position monitoring is important because changes in rotor behavior may indicate developing mechanical problems.

The PR6424 series can be installed at appropriate measurement locations to monitor shaft displacement and vibration in compatible turbine monitoring systems.

2. Gas Turbines

Gas turbines operate at high rotational speeds and under demanding thermal and mechanical conditions. Shaft monitoring is an important part of equipment condition assessment.

Non-contact displacement sensors can provide information about rotor movement without requiring physical contact with the rotating shaft.

3. Hydro Turbines

Hydro turbine installations may require continuous observation of shaft movement and vibration under changing hydraulic and mechanical loads.

A suitable PR6424 installation can contribute to the measurement system used to monitor shaft behavior and equipment condition.

4. Industrial Compressors

Compressors used in gas transportation, refining, petrochemical processing, and manufacturing may operate continuously for extended periods.

Shaft displacement monitoring can help maintenance teams identify changes in vibration behavior and investigate possible mechanical faults.

5. Centrifugal Pumps

Large centrifugal pumps are used in water treatment, chemical processing, power plants, and industrial fluid systems.

Where shaft displacement measurement is required, an eddy current sensor can be integrated into a suitable monitoring arrangement.

6. Industrial Fans

Large fans used in ventilation, combustion air supply, and process exhaust systems may require continuous vibration monitoring.

The PR6424 series can support shaft movement measurement when the sensor, target material, installation clearance, and monitoring equipment are correctly matched.

Installation and System Integration

Correct installation is essential for accurate measurement. The sensor’s position, target material, cable routing, and signal converter configuration all influence measurement quality.

1. Verify the Sensor Configuration

Before installation, confirm the complete model number and the actual probe configuration. The /008-100 suffix should be checked against the product label and applicable documentation.

Confirm the cable arrangement, connector type, probe construction, and any required extension cable. Do not assume that every PR6424 model uses the same cable length or connector configuration.

2. Check the Mounting Position

The probe must be mounted at the specified measurement location with the correct clearance from the shaft or target surface.

The PR6424 family has a nominal center air gap of approximately 2.7 mm. The actual installation gap should be established using the manufacturer’s calibration and installation procedures.

An incorrect gap can cause inaccurate readings or place the sensor outside its specified linear measuring range.

3. Confirm Target Material

Eddy current measurement depends on the electrical and magnetic properties of the target material.

The PR6424 specification identifies ferromagnetic steel, with 42CrMo4 as the standard reference material. If the actual shaft material differs, verify whether the measurement system requires a different calibration or correction.

4. Install the Probe Securely

The sensor should be mounted in a mechanically stable position. Excessive movement of the mounting bracket or probe support can introduce measurement errors.

The installation should also provide suitable clearance from surrounding metallic components. Nearby conductive materials can affect the electromagnetic field and should be considered during mechanical design.

5. Protect the Cable

Route the probe cable away from high-temperature surfaces, moving machinery, sharp edges, and sources of electrical interference.

Avoid excessive bending, pulling, or twisting. The cable’s insulation and mechanical protection should remain intact throughout installation and operation.

Where cable armor or protective tubing is required, confirm that it matches the actual sensor configuration.

6. Connect the Compatible Signal Converter

The probe must be connected to an appropriate EPRO signal converter. The converter should match the sensor model, cable arrangement, connector, and measurement requirements.

Incorrect combinations can lead to measurement errors, unstable signals, or an inability to obtain the expected output.

7. Commission the Measurement System

After installation, verify the sensor gap, cable connections, converter configuration, and output signal.

Check that the measurement changes in the expected direction when the target distance changes. Confirm that the monitoring system receives a stable signal and that alarm limits are configured according to the machinery manufacturer’s requirements and the plant’s protection philosophy.

Compatible System Components

The PR6424/008-100 is normally part of a complete measurement chain rather than a standalone monitoring system.

The components listed above are examples of equipment used in a complete measurement installation. They are not necessarily included with the sensor.

Alternative Models and Replacement Considerations

The PR6424 family includes different probe configurations. Although models may share the same 16 mm sensor head diameter, they should not be treated as automatically interchangeable.

Before selecting a replacement, compare the following:

• Complete sensor model and suffix.
• Sensor head diameter and mechanical dimensions.
• Probe mounting thread and installation arrangement.
• Cable length and cable construction.
• Connector type and pin configuration.
• Signal converter compatibility.
• Sensitivity and measurement range.
• Target material and required air gap.
• Temperature and environmental requirements.
• Monitoring system input and calibration requirements.

A probe with the same 16 mm head diameter may still have a different cable, connector, or electrical configuration. Replacing a sensor without checking these details can result in incorrect readings or an incompatible measurement chain.

Key Advantages

Non-Contact Measurement

The PR6424 sensor measures shaft displacement without physical contact with the rotating component. This avoids the mechanical wear associated with contact-based measurement methods.

16 mm Sensor Head

The 16 mm sensing head is designed for industrial machinery monitoring installations where a defined probe diameter is required.

Shaft Vibration and Position Monitoring

The PR6424 family supports both static and dynamic measurement, allowing a suitable system to monitor shaft position and vibration-related movement.

High Measurement Sensitivity

The published sensitivity of 4 V/mm supports the detection of small changes in the distance between the sensor and the target.

Industrial Machinery Applications

The sensor family is intended for critical rotating machinery, including turbines, compressors, pumps, and fans.

Integration with Machinery Monitoring Systems

When paired with a compatible converter and monitoring equipment, the probe can provide measurement data for machinery condition assessment and protection strategies.

Established EPRO Measurement Technology

The PR6424 family is associated with industrial machinery health monitoring applications where continuous shaft displacement measurement is required.

Technical FAQs

1. What is the Epro PR6424/008-100?

The PR6424/008-100 is a 16 mm eddy current sensor designed for non-contact measurement of shaft displacement and vibration in rotating machinery.

2. What does an eddy current sensor measure?

It measures changes in the distance between the sensor tip and a conductive target. In rotating machinery applications, this can be used to monitor shaft vibration, position, radial and axial displacement, and eccentricity.

3. What is the sensor head diameter?

The sensor head diameter is 16 mm, consistent with the PR6424 series designation.

4. What is the measurement range?

The PR6424 family specifies a static measurement range of ±2.0 mm and a dynamic measurement range of 0 to 1,000 μm.

5. What is the sensitivity of the PR6424 sensor?

The published family sensitivity is 4 V/mm, equivalent to approximately 101.6 mV/mil, with linearity of no more than ±1.5%.

6. Does the sensor need to touch the shaft?

No. It uses an electromagnetic field to detect changes in the distance between the probe and the conductive target. The sensor can therefore measure shaft movement without physical contact.

7. Which target materials can be measured?

The PR6424 specification identifies ferromagnetic steel, with 42CrMo4 as the standard reference material. The target material should be verified before installation because material properties affect calibration and measurement performance.

8. Does the sensor work independently?

No. A complete measurement system normally requires a compatible signal converter and appropriate monitoring equipment. Depending on the installation, an extension cable may also be required.

9. What is the approximate weight?

The supplied product weight is 0.2 kg. The manufacturer’s family specification gives an approximate weight of 200 grams for the sensor with 1 m cable and no armor.

10. Which industries use the PR6424 series?

Typical applications include power generation, oil and gas, petrochemical processing, industrial utilities, and manufacturing facilities operating turbines, compressors, pumps, and fans.

11. Can the PR6424/008-100 replace another PR6424 probe?

Not automatically. The complete model suffix, cable configuration, connector, mounting arrangement, and signal converter compatibility should be checked before replacement.

Procurement and Maintenance Recommendations

When purchasing the Epro PR6424/008-100, verify the complete model number and confirm that the supplied sensor matches the configuration required by the existing machinery monitoring system.

For replacement projects, request clear photographs of the probe label, sensor head, cable, and connector. Confirm whether the unit is supplied with the required cable length and whether additional extension cables or connectors are needed.

The 16 mm sensor head diameter and 0.2 kg weight are useful product identification details, but they do not fully define electrical compatibility. The sensor’s cable and converter arrangement must also match the existing installation.

During maintenance, inspect the sensor mounting, cable insulation, connector condition, and mechanical protection. Check that the probe remains securely positioned and that the measurement gap is within the manufacturer’s recommended range.

If the monitoring system reports an abnormal signal, investigate the entire measurement chain rather than replacing the probe immediately. Potential causes include incorrect air gap, damaged cables, loose connections, incompatible converters, target-surface conditions, and configuration errors.

For critical machinery, sensor replacement should be followed by calibration verification and functional testing. Record the final configuration and measurement values to support future maintenance and troubleshooting.

Conclusion

The Epro PR6424/008-100 16 mm Eddy Current Sensor is designed for non-contact monitoring of shaft displacement and vibration in critical rotating machinery. With a 16 mm sensor head, a typical family sensitivity of 4 V/mm, and a static measurement range of ±2.0 mm, the PR6424 series supports machinery monitoring applications involving turbines, compressors, pumps, and fans.

The sensor operates as part of a complete measurement chain that includes compatible cabling, signal conversion, and monitoring equipment. Correct model identification, installation clearance, target material, and converter compatibility are essential for reliable operation.

For industrial maintenance and spare-parts procurement, verifying the complete PR6424/008-100 configuration helps ensure that the replacement sensor is suitable for the intended machinery monitoring system.