Product Overview

The Epro PR6424/104-030 16 mm Eddy Current Sensor is a non-contact displacement and vibration probe designed for monitoring the operating condition of critical rotating machinery. It belongs to the PR6424 sensor family developed for industrial machinery protection and condition-monitoring applications. The product is associated with Emerson’s EPRO machinery health monitoring portfolio.

Unlike contact-based measuring devices, an eddy current sensor measures the distance between its sensing tip and a conductive metallic target without physically touching the target surface. This makes it suitable for continuous monitoring of rotating shafts, where direct mechanical contact would be impractical or could introduce additional wear.

The PR6424 series is used in applications involving steam turbines, gas turbines, hydro turbines, compressors, pumps, and fans. It can measure radial and axial shaft displacement, shaft position, eccentricity, and other dynamic movement. These measurements provide information that maintenance and control systems can use to evaluate machine condition and identify abnormal operating behavior.

The PR6424/104-030 has a 16 mm sensor head diameter. Its compact sensing head supports installation in machinery-monitoring arrangements where the probe must be positioned close to a rotating shaft. The supplied listing weight is approximately 0.2 kg.

The PR6424 series reference specifications include a nominal sensitivity of 4 V/mm, a static measurement range of ±2.0 mm, and a dynamic measurement range of 0–1,000 μm. These characteristics make the sensor suitable for applications requiring continuous shaft-motion measurement.

The sensor normally operates as part of a complete measurement chain. A compatible extension cable and signal converter are selected according to the system design. The converter conditions the probe signal and provides an output suitable for connection to a machinery monitoring or protection system.

When selecting a replacement, users should verify the complete model number, cable arrangement, connector type, probe thread, and converter compatibility. Different PR6424 variants may share the same sensing-head diameter while having different mechanical or electrical configurations.

Technical Specifications

Note: The technical performance values are PR6424 family reference specifications. Confirm the exact PR6424/104-030 cable, connector, mounting, temperature, and converter requirements against the product label and applicable documentation.

Function and Working Principle

The PR6424/104-030 uses the eddy current measurement principle to detect the distance between its sensing tip and a metallic target. The method is widely used in rotating machinery because it provides continuous, non-contact measurement of shaft movement.

1. Eddy Current Measurement Principle

The sensor generates an alternating electromagnetic field around its sensing tip. When a conductive metallic surface approaches the probe, eddy currents are induced in the target material.

These currents affect the electromagnetic characteristics of the probe. The resulting change in the sensor circuit is related to the distance between the probe tip and the target surface.

A compatible signal converter processes this change and produces a measurable output corresponding to the target displacement.

The measurement principle allows the sensor to monitor shaft movement without physical contact. This is particularly useful for machinery operating at high speed or under continuous industrial duty.

2. Shaft Displacement Measurement

Shaft displacement refers to the movement of a rotating shaft relative to a fixed reference point. The PR6424 series can be used to measure static shaft position and dynamic movement.

Static measurements are useful for identifying shaft position and changes in operating clearance. Dynamic measurements help reveal vibration and other periodic shaft movements.

In practical installations, the probe is mounted at a defined position near the shaft surface. The sensor gap must be adjusted according to the manufacturer’s installation requirements to ensure that the target remains within the measurement range.

3. Vibration Monitoring

The sensor can provide information about radial and axial shaft vibration. By measuring changes in the distance between the probe and the rotating shaft, the monitoring system can identify dynamic movement.

Vibration information is important for evaluating rotating machinery. Changes in vibration behavior may be associated with imbalance, misalignment, looseness, bearing-related problems, or changes in operating conditions.

The sensor itself measures displacement at its installation point. Additional monitoring equipment and engineering analysis are needed to interpret the measurement and determine the cause of abnormal behavior.

4. Position and Eccentricity Monitoring

The PR6424 series can also be used for shaft position and eccentricity measurements.

Shaft eccentricity describes the difference between the geometric center of a shaft and its actual rotational behavior. Monitoring eccentricity can help identify mechanical conditions that affect rotating equipment.

Axial position measurement is useful in machinery where shaft movement along its rotational axis must remain within specified limits. This is particularly important for large turbines and compressors.

5. Signal Conversion

The probe is generally used with a compatible EPRO signal converter. The converter supplies the required excitation and conditions the sensor response into an output that can be interpreted by machinery monitoring equipment.

The complete measurement chain may include:

• PR6424 eddy current probe.
• Compatible extension cable.
• Signal converter.
• Machinery protection or condition-monitoring system.

All components must be electrically and mechanically compatible. A sensor with the correct diameter is not necessarily interchangeable with another model if the cable, connector, or converter requirements differ.

Role in Industrial Machinery Monitoring Systems

The PR6424/104-030 can serve as a measurement component in a continuous machinery-monitoring arrangement. It provides shaft-related measurement information that can be used by monitoring equipment, protection systems, and plant maintenance personnel.

Turbine Protection

Turbines contain high-speed rotating assemblies that operate under demanding mechanical and thermal conditions. Continuous shaft monitoring helps operators understand the machine’s movement during startup, normal operation, and shutdown.

The PR6424 series can be used for radial and axial displacement measurements in suitable turbine-monitoring installations. These measurements can support the evaluation of shaft vibration and position.

Compressor Condition Monitoring

Industrial compressors depend on stable rotor operation. Excessive shaft movement may affect clearances, mechanical efficiency, and equipment reliability.

A correctly installed eddy current sensor can provide continuous shaft-displacement information for the compressor monitoring system. Engineers can use the resulting data to compare operating behavior over time.

Pump and Fan Monitoring

Large pumps and industrial fans often operate continuously. Shaft vibration and displacement measurements can help maintenance teams identify changes in machine behavior before they develop into more serious operational problems.

The sensor can be incorporated into a monitoring arrangement where measurements are collected and evaluated by a suitable monitoring system.

Integration with Machinery Protection Equipment

The sensor does not normally operate as a standalone machinery protection controller. Its measurement signal must be processed by a compatible converter and monitoring device.

The monitoring system can then display measurement values, generate alarms, and provide protection functions according to the configured application.

The exact alarm thresholds and protection responses must be established through machinery engineering and the equipment manufacturer’s recommendations.

Industrial Applications

The PR6424/104-030 is intended for applications where non-contact shaft measurement is required. Its 16 mm sensing head and PR6424 series measurement characteristics make it relevant to several types of rotating equipment.

1. Steam Turbines

Steam turbines operate at high rotational speeds and require continuous monitoring of mechanical condition. Shaft vibration and displacement measurements help operators evaluate rotor behavior and identify changes during operation.

The PR6424 series can be used in suitable turbine protection systems to monitor radial and axial shaft movement.

2. Gas Turbines

Gas turbines are used in power generation and industrial mechanical-drive applications. Their rotating assemblies require reliable condition monitoring because abnormal shaft movement can affect operating stability.

A properly installed eddy current sensor can provide shaft-displacement information for the turbine monitoring system.

3. Hydro Turbines

Hydro turbines operate under changing hydraulic and mechanical conditions. Shaft position and vibration monitoring can help maintenance teams evaluate the condition of rotating components.

The sensor can be considered for installations where the shaft material, diameter, mounting arrangement, and measurement requirements meet the PR6424 series specifications.

4. Industrial Compressors

Centrifugal and other large industrial compressors rely on accurate rotor alignment and stable shaft movement. Continuous displacement monitoring can support maintenance planning and machinery protection.

The PR6424 series is suitable for applications where the measurement target is compatible with the sensor’s eddy current operating principle.

5. Pumps

Large process pumps and power-station pumps may require continuous shaft monitoring. Measurements can help identify changes in vibration and shaft position that may be associated with mechanical wear or abnormal operating conditions.

6. Industrial Fans

Large fans used in industrial ventilation, combustion-air systems, and process plants can benefit from continuous vibration monitoring.

The sensor can be installed as part of a suitable machinery-monitoring arrangement to provide shaft movement information.

Installation and System Integration

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

1. Verify the Complete Model Number

Before installation, confirm that the sensor is identified as PR6424/104-030. Check the label and compare the complete ordering code with the existing system documentation.

Do not assume that every PR6424 probe has identical cable length, connector arrangement, mounting dimensions, or converter compatibility.

2. Confirm the Target Material

Eddy current sensors require a suitable conductive target. The PR6424 series reference specification identifies ferromagnetic steel as the standard target material.

The target material should be considered during sensor selection and calibration. Using a material different from the specified reference can affect measurement characteristics.

3. Position the Sensor Correctly

The sensor must be mounted at the appropriate distance from the shaft surface. The nominal center air gap for the PR6424 series is approximately 2.7 mm.

The final gap must be established according to the applicable installation procedure. Incorrect positioning may place the target outside the linear measuring range and cause inaccurate readings.

The probe should be securely mounted to prevent movement caused by vibration or mechanical loosening.

4. Check Probe Alignment

The probe should be aligned with the intended measurement direction. For radial vibration measurement, the probe is positioned to detect shaft movement across the selected radial axis.

For axial position measurement, the installation geometry must allow the probe to measure movement along the shaft axis.

The number and arrangement of probes depend on the monitoring requirements and the machinery design.

5. Verify Cable and Connector Compatibility

The sensor cable connects the probe to the compatible extension cable or signal converter, depending on the system arrangement.

Check the connector type, cable length, shielding, and electrical compatibility before connecting the sensor. Avoid sharp bends, excessive pulling force, and routing near sources of strong electrical interference.

The cable should be protected from mechanical damage, high temperatures beyond its rating, and contact with moving equipment.

6. Connect the Signal Converter

A compatible converter is required to condition the probe signal for use by the monitoring system.

The exact converter model must be confirmed from the sensor configuration and system documentation. Do not select a converter based only on the fact that it supports the PR6424 family.

7. Establish the Measurement Gap

After mounting the probe, establish the correct initial gap according to the manufacturer’s procedure.

The gap should be checked before the machinery is returned to service. An incorrect gap can reduce measurement accuracy or cause the output to operate outside the intended linear range.

8. Test the Measurement System

After installation, verify the sensor connection, converter operation, measurement output, and monitoring-system response.

Where possible, compare the sensor readings with the expected machine condition and commissioning records. Confirm that alarms and monitoring functions are configured correctly before placing the equipment into normal operation.

Compatible System Components

The PR6424/104-030 normally forms part of a complete machinery-monitoring measurement chain.

The components listed above describe a typical measurement arrangement. They are not necessarily included with the sensor.

Alternative Models and Replacement Considerations

The PR6424 series includes different probe configurations. Although several models share a 16 mm sensing head, their cable and mechanical arrangements may differ.

When selecting a replacement, verify:

• Complete probe model and ordering code.
• Sensor head diameter.
• Thread and mounting dimensions.
• Cable length and connector arrangement.
• Signal converter compatibility.
• Sensitivity and linear measurement range.
• Target material and shaft diameter.
• Operating temperature and environmental requirements.
• Monitoring-system input requirements.

A similar sensor diameter does not guarantee direct interchangeability. The probe, cable, converter, and monitoring channel must be evaluated as one measurement system.

Key Advantages

Non-Contact Measurement

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

Continuous Shaft Monitoring

The sensor can provide displacement information for machinery monitoring systems, supporting the evaluation of shaft vibration and position.

16 mm Sensing Head

The 16 mm sensor head provides a compact sensing format for installations designed around the PR6424 series.

High Measurement Sensitivity

The PR6424 series reference sensitivity of 4 V/mm supports measurement of relatively small changes in the probe-to-target distance.

Static and Dynamic Measurement

The series supports static position measurement and dynamic displacement measurement, allowing the monitoring system to evaluate different aspects of shaft behavior.

Industrial Machinery Applications

The PR6424 series is designed for critical rotating machinery such as turbines, compressors, pumps, and fans.

Integration with Monitoring Systems

When paired with the correct cable and signal converter, the sensor can form part of a continuous machinery-monitoring arrangement.

Technical FAQs

1. What is the Epro PR6424/104-030?

The Epro PR6424/104-030 is a 16 mm eddy current sensor designed for non-contact measurement of shaft displacement and vibration in industrial rotating machinery.

2. What is the sensor head diameter?

The sensor head diameter is 16 mm, as indicated by the supplied product description and the PR6424 series specification.

3. What is the measurement principle?

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

4. What is the sensitivity of the PR6424 series?

The PR6424 series reference sensitivity is 4 V/mm, with a specified linearity of up to ±1.5%. Confirm the applicable specification for the exact probe configuration.

5. What is the static measurement range?

The PR6424 series reference static measurement range is ±2.0 mm.

6. What is the dynamic measurement range?

The PR6424 series reference dynamic measurement range is 0–1,000 μm. The actual usable range depends on the measurement configuration and application.

7. Which machines can use this sensor?

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

8. Does the sensor require a signal converter?

A compatible signal converter is normally required to condition the probe signal for the machinery monitoring system. The correct converter must be selected according to the complete probe configuration.

9. What target material is specified for the PR6424 series?

The standard reference target is ferromagnetic steel, with 42CrMo4 identified in the series documentation. The actual shaft material should be checked during system design.

10. What should be checked before replacing an existing PR6424 sensor?

Verify the full model number, probe diameter, thread, cable length, connector, converter compatibility, measurement range, and installation gap. These details determine whether the replacement can operate correctly in the existing monitoring system.

Procurement and Maintenance Recommendations

When purchasing the Epro PR6424/104-030, begin by checking the complete product code on the installed probe or equipment documentation. This is important because different PR6424 variants may have similar physical dimensions but different cable, connector, or mounting arrangements.

For replacement projects, compare the existing sensor with the proposed unit and confirm compatibility with the extension cable, signal converter, and machinery monitoring system. If the probe is part of a protection system, verify the complete measurement channel before returning the equipment to operation.

For used or refurbished sensors, request clear photographs of the probe body, connector, cable, and identification label. Inspect the sensing tip, threaded section, cable insulation, and connector for visible damage. Confirm whether the product has been tested and whether any accessories are included.

During routine maintenance, inspect the probe mounting arrangement and cable routing. Check for loose mounting nuts, damaged insulation, contamination, and signs of mechanical contact. Review measurement trends and compare current readings with commissioning data and historical operating conditions.

If the signal becomes unstable, investigate the probe gap, cable connections, converter compatibility, target surface, grounding, and monitoring-system configuration. Replacing the sensor without checking the complete measurement chain may not resolve the underlying problem.

Conclusion

The Epro PR6424/104-030 16 mm Eddy Current Sensor is a non-contact measurement probe designed for monitoring shaft displacement, vibration, position, and eccentricity in critical rotating machinery. Its PR6424 series reference specifications include 4 V/mm sensitivity, a ±2.0 mm static measurement range, and a dynamic measurement range of 0–1,000 μm.

With its 16 mm sensing head and approximately 0.2 kg supplied listing weight, the sensor is intended for integration into machinery-monitoring systems used in turbines, compressors, pumps, and fans.

For maintenance and replacement applications, the complete model number and measurement-chain compatibility are essential. Confirm the probe’s cable and connector configuration, mounting requirements, target material, and signal converter before installation to help ensure reliable monitoring performance.