Product Overview

The EPRO PR6424/010-140 16 mm Eddy Current Sensor is a non-contact displacement and vibration sensor designed for monitoring the condition of large rotating machinery. It belongs to the PR6424 sensor family developed for critical industrial equipment, including steam turbines, gas turbines, hydro turbines, compressors, pumps, and fans.

Manufactured under the EPRO product line associated with Emerson, the PR6424 series is used in machinery protection and condition-monitoring systems. Its primary function is to measure the relative movement between a sensor probe and a conductive shaft surface without requiring physical contact. This measurement method allows the sensor to monitor shaft vibration, axial displacement, position, eccentricity, and rotational speed-related parameters.

The PR6424/010-140 has a nominal sensor head diameter of 16 mm. Eddy current technology makes it suitable for applications where continuous measurement of shaft movement is important for machinery protection and operational monitoring.

In a typical installation, the sensor is mounted near a rotating shaft. Changes in the distance between the probe tip and the shaft surface alter the sensor’s electrical characteristics. A compatible signal converter processes this change and produces a measurement signal for a machinery monitoring system.

The PR6424 sensor is particularly relevant to installations where early identification of abnormal shaft movement can help maintenance teams investigate bearing problems, mechanical imbalance, shaft misalignment, and other developing equipment conditions.

Technical Specifications

Note: The measurement figures above describe the PR6424 16 mm sensor family. Cable length, connector, mounting arrangement, and environmental limits should be confirmed for the exact PR6424/010-140 configuration.

Function and Working Principle

The PR6424/010-140 uses the eddy current principle to measure the distance between the sensor tip and a conductive target. Unlike contact-based measurement devices, the probe does not need to touch the rotating shaft.

1. Eddy Current Measurement

The sensor generates an electromagnetic field at its probe tip. When a conductive metal surface approaches this field, electrical currents known as eddy currents are induced in the target material.

The induced currents affect the electromagnetic characteristics of the sensor. 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 converts it into a measurement signal. The resulting output can represent shaft displacement or vibration, depending on the monitoring configuration.

2. Shaft Vibration Measurement

During normal operation, rotating machinery experiences some degree of shaft movement. Excessive or changing movement may indicate mechanical conditions that require investigation.

The PR6424 sensor measures relative shaft movement by continuously monitoring the gap between the probe tip and the shaft surface.

When installed as part of a suitable monitoring system, the measurement can help identify changes in vibration amplitude and support machinery condition assessment.

3. Axial Displacement Measurement

Axial displacement refers to movement of a shaft along its rotational axis. Excessive axial movement can be associated with thrust-bearing problems, mechanical wear, or changes in operating conditions.

A correctly installed PR6424 probe can measure this movement without physical contact. The resulting signal can be used by a compatible machinery protection system to monitor shaft position and identify abnormal displacement.

4. Position and Eccentricity Monitoring

The sensor can also be used to monitor shaft position and eccentricity.

Eccentricity describes the degree to which a rotating shaft or component is offset from its intended rotational center. Changes in eccentricity may be associated with mechanical deformation, thermal effects, installation problems, or other equipment conditions.

Continuous position measurements provide useful information for machinery monitoring and maintenance analysis.

5. Signal Conversion and Monitoring

The sensor probe is normally part of a complete measurement chain rather than an independent monitoring instrument.

A typical arrangement consists of:

• PR6424 eddy current probe.
• Compatible extension cable, where required by the selected configuration.
• Compatible signal converter or preamplifier.
• Machinery monitoring module or protection system.
• Control-room monitoring and alarm interface.

The exact converter, cable, and monitoring hardware must be selected according to the sensor configuration and system requirements.

Role in Industrial Machinery Protection Systems

The PR6424/010-140 can provide important measurement information within a turbine or rotating-equipment protection system.

Turbine Monitoring

Steam and gas turbines contain high-speed rotating components that require continuous monitoring. Shaft vibration and axial displacement are important parameters because abnormal movement can affect mechanical clearances, bearings, and other critical components.

The PR6424 sensor can be installed at suitable measurement locations to provide non-contact shaft movement information to a compatible monitoring system.

Compressor Condition Monitoring

Industrial compressors operate under changing mechanical and process conditions. Abnormal shaft vibration may be associated with imbalance, misalignment, bearing deterioration, or other mechanical issues.

By continuously measuring shaft movement, the sensor supports condition-monitoring strategies that help maintenance teams identify changes in equipment behavior.

Pump Monitoring

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

Where shaft vibration or axial position monitoring is required, an eddy current sensor can provide measurement information for a suitable protection system.

PLC and DCS Integration

The PR6424 probe normally connects to a compatible signal-conditioning and monitoring arrangement. A PLC or DCS may receive processed measurement values or alarm information through the monitoring system.

Engineers should verify the available signal outputs and interface requirements before designing the control-system connection. The sensor should not be treated as a direct PLC input without the appropriate signal-conditioning equipment.

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 sensor can be used to monitor shaft vibration and axial displacement, providing information that supports turbine protection and maintenance activities.

2. Gas Turbines

Gas turbines require reliable monitoring of rotating components. Shaft movement measurements can help maintenance teams evaluate mechanical behavior and identify abnormal operating conditions.

A properly installed eddy current sensor provides continuous non-contact measurement for compatible machinery protection systems.

3. Hydro Turbines

Hydroelectric generating equipment contains large rotating assemblies. Shaft movement and vibration monitoring are important for evaluating mechanical stability and identifying changes in equipment condition.

The PR6424 16 mm sensor family is designed for critical rotating machinery applications, including hydro turbines.

4. Industrial Compressors

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

Monitoring shaft vibration and displacement can support preventive maintenance programs and help identify developing mechanical problems.

5. Industrial Pumps and Fans

Large pumps and fans may operate for extended periods under changing load conditions. Eddy current sensors can be used in suitable installations to monitor shaft movement and provide data for machinery condition assessment.

Installation and System Integration

Correct installation is essential for obtaining reliable measurement results from the PR6424/010-140.

1. Verify the Sensor Configuration

Before installation, check the complete model number, probe dimensions, cable configuration, connector type, and required signal converter.

The /010-140 suffix should be verified against the actual sensor label and the corresponding manufacturer documentation. Do not assume that every PR6424 probe uses the same cable length or connector arrangement.

2. Select the Correct Mounting Position

The sensor should be installed at the designated measurement point on the bearing housing or machinery structure.

The probe must be positioned so that its sensing face is directed toward the intended conductive shaft surface. Mounting stability is important because movement of the sensor body can affect measurement accuracy.

3. Set the Initial Air Gap

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

Incorrect gap settings can result in inaccurate measurements, insufficient operating range, or signal-conditioning problems.

4. Check Shaft and Target Material

The PR6424 sensor is designed for measurement against suitable ferromagnetic steel targets. The shaft material and surface condition should be checked before installation.

The manufacturer’s specifications identify a reference shaft diameter of at least 80 mm for the PR6424 measurement application. Installation geometry should also follow the manufacturer’s clearance and target-area requirements.

5. Connect the Signal Converter

Connect the probe to its compatible signal converter or preamplifier using the specified cable and connector arrangement.

Check cable continuity, connector condition, grounding, and cable routing. Avoid unnecessary bending, crushing, or mechanical damage to the sensor cable.

6. Calibrate and Commission

After mechanical installation, verify the measurement gap and calibrate the complete measurement chain according to the manufacturer’s procedure.

Commissioning should include:

• Checking the probe and converter compatibility.
• Verifying the initial gap voltage.
• Confirming the measurement response.
• Checking the signal output and polarity.
• Comparing readings with the monitoring-system configuration.
• Verifying alarm and trip settings where applicable.

The measurement chain should be tested as a complete system rather than evaluating the probe in isolation.

Compatible System Components

A PR6424 installation normally requires compatible signal-conditioning and monitoring equipment.

Not every component listed above is automatically compatible with every PR6424/010-140 configuration. Confirm the complete measurement-chain requirements before ordering replacement parts.

Alternative Models and Replacement Considerations

The PR6424 series includes multiple 16 mm sensor configurations. Although they may share a similar measurement principle, their cable arrangements, connector options, mounting designs, and electrical compatibility can differ.

Before selecting a replacement, compare:

• Sensor head diameter.
• Full catalog number and suffix.
• Probe length and thread specification.
• Integrated cable length and construction.
• Connector type.
• Sensitivity and linearity.
• Measurement range.
• Required converter or preamplifier.
• Target material and shaft diameter.
• Operating temperature and environmental requirements.

A sensor with the same 16 mm head diameter is not necessarily a direct replacement. The complete measurement chain must be checked to ensure that the replacement produces the required signal and measurement characteristics.

Key Advantages

Non-Contact Measurement

The eddy current principle allows the sensor to measure shaft movement without physical contact, avoiding mechanical contact between the probe tip and the rotating target.

Continuous Shaft Monitoring

The sensor can provide measurement information for continuous monitoring of shaft vibration, position, and displacement.

Suitable for Critical Rotating Machinery

The PR6424 family is designed for applications involving turbines, compressors, pumps, and fans.

High Measurement Sensitivity

The series specification identifies a sensitivity of 4 V/mm and linearity of up to ±1.5%, supporting accurate measurement within the specified operating range.

Compact 16 mm Sensor Head

The 16 mm probe head allows installation in suitable machinery locations where a larger sensor may not fit.

Integration with Machinery Protection Systems

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

Industrial Monitoring Capability

The sensor supports measurement strategies intended to help maintenance teams identify changes in rotating-equipment behavior.

Technical FAQs

1. What is the EPRO PR6424/010-140?

It is a 16 mm non-contact eddy current sensor designed for measuring shaft vibration, axial displacement, position, and related parameters in rotating machinery.

2. What is the diameter of the sensor head?

The nominal sensor head diameter is 16 mm.

3. What is the operating principle?

The sensor generates an electromagnetic field at its probe tip. A conductive shaft surface changes the electrical characteristics of this field, allowing the system to determine the distance between the probe and the target.

4. What is the sensitivity of the PR6424 series?

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

5. What is the static measurement range?

The PR6424 16 mm sensor family has a specified static measurement range of ±2.0 mm.

6. What is the nominal center air gap?

The nominal center air gap is approximately 2.7 mm. The actual installation gap must be established according to the manufacturer’s calibration procedure.

7. Can the PR6424/010-140 measure shaft vibration?

Yes. It can be used in a compatible measurement chain to monitor radial shaft vibration and other shaft movement parameters.

8. Does the sensor require a signal converter?

A compatible signal-conditioning device is normally required to convert the probe response into a usable monitoring signal. Confirm the correct converter for the exact sensor configuration.

9. Where is the PR6424 series commonly used?

Typical applications include steam turbines, gas turbines, hydro turbines, compressors, pumps, and industrial fans.

10. What should be checked before purchasing a replacement?

Verify the complete model number, sensor diameter, cable length, connector type, mounting arrangement, sensitivity, measurement range, and compatibility with the installed signal converter.

Procurement and Maintenance Recommendations

When purchasing the EPRO PR6424/010-140, confirm the full catalog number and inspect the product label. The suffix is important because different PR6424 configurations may have different cable lengths, connectors, and mounting arrangements.

For replacement applications, verify that the new probe is compatible with the existing signal converter and monitoring module. A mechanically similar sensor may not provide the correct electrical characteristics for the installed measurement chain.

For maintenance, inspect the probe tip, threaded sleeve, cable, and connector for mechanical damage or contamination. Check that the sensor mounting remains secure and that the cable is protected from excessive bending, vibration, heat, and abrasion.

If the monitoring system reports abnormal readings, check the complete measurement chain. Possible causes include an incorrect initial gap, cable damage, connector problems, an incompatible converter, or changes in the shaft target surface.

Keep the original installation records, calibration information, and sensor configuration details. These records can help maintenance teams identify suitable replacement components and reduce commissioning time.

Conclusion

The EPRO PR6424/010-140 16 mm Eddy Current Sensor is a non-contact measurement device designed for monitoring shaft vibration, displacement, position, and eccentricity in critical rotating machinery.

With a 16 mm sensor head, 4 V/mm sensitivity, and a specified static measurement range of ±2.0 mm, the PR6424 family supports machinery monitoring applications involving turbines, compressors, pumps, and fans.

For reliable operation, the sensor must be installed with the correct measurement gap and used with compatible signal-conditioning and monitoring equipment. When sourcing a replacement, verifying the complete model number, cable configuration, connector, and measurement-chain compatibility is essential.