Product Overview

The Epro PR6424/010-000 16 mm Eddy Current Sensor is a non-contact displacement sensor designed for monitoring the operating condition of critical rotating machinery. Manufactured under the EPRO product line associated with Emerson, the PR6424 series is used in machinery protection and condition-monitoring systems for applications such as steam turbines, gas turbines, compressors, pumps, and industrial fans.

The sensor measures the distance between its probe tip and a conductive target, typically a ferromagnetic steel shaft. Unlike contact-based measurement devices, it does not need to touch the rotating surface. This allows it to monitor shaft movement without introducing mechanical contact between the sensor and the machine.

The PR6424/010-000 belongs to the 16 mm sensor family. Its measurement capabilities support the monitoring of radial and axial shaft displacement, dynamic vibration, shaft position, eccentricity, and speed-related information when used with a compatible signal converter and monitoring system.

The PR6424 series uses eddy current technology. A high-frequency electromagnetic field is generated at the sensor tip. When a suitable conductive target enters this field, eddy currents are induced in the target. Changes in the electromagnetic response are related to the distance between the probe and the target surface. A compatible converter processes this response and produces a usable measurement signal.

This measurement principle is particularly valuable in rotating machinery because small changes in shaft position can indicate changes in bearing condition, rotor behavior, alignment, or operating stability.

Technical Specifications

Note: PR6424 suffixes identify different probe and cable configurations. Confirm the exact ordering code, cable length, connector arrangement, armor, and temperature limits before purchasing. The 0.2 kg figure corresponds to the manufacturer’s approximate weight for a sensor with a 1 m cable and no armor.

Function and Working Principle

The PR6424/010-000 uses eddy current measurement technology to monitor the distance between the sensor tip and a conductive target. Its operation depends on the electromagnetic interaction between the probe coil and the target material.

1. Electromagnetic Field Generation

An alternating electrical signal supplied through the compatible measurement system energizes the sensor coil. This produces a high-frequency electromagnetic field around the probe tip.

The sensor is installed near the rotating shaft or another suitable conductive target. The gap between the sensor tip and the target affects the electromagnetic response of the probe.

2. Eddy Current Induction

When the electromagnetic field reaches a conductive shaft surface, small circulating electrical currents known as eddy currents are induced in the target material.

These currents influence the electrical characteristics of the sensor coil. As the distance between the probe and the shaft changes, the electromagnetic coupling also changes.

The measurement system uses this relationship to determine shaft displacement.

3. Displacement Measurement

The PR6424 series is designed to measure both static and dynamic displacement.

Static measurement is useful for identifying the relative position of a shaft. Dynamic measurement is used to monitor movement that changes over time, including vibration and shaft oscillation.

The manufacturer’s specification sheet lists a static range of ±2.0 mm and a dynamic range of 0 to 1,000 μm. The specified sensitivity is 4 V/mm, with linearity of no more than ±1.5%.

These characteristics allow the sensor to provide information about small changes in shaft position when the probe, target, converter, and monitoring system are correctly matched.

4. Signal Conversion

The sensor probe is part of a measurement chain rather than a standalone industrial transmitter with a universal output.

A compatible EPRO signal converter, such as an appropriate CON-series unit, processes the probe’s electrical response and generates a measurement signal for the connected monitoring equipment.

The converter configuration determines the available output and interface. The probe and converter must therefore be selected as a compatible combination.

5. Machinery Condition Monitoring

The displacement information can be used by a machinery protection or condition-monitoring system to identify changes in rotating equipment behavior.

For example, increasing shaft vibration, an unexpected change in shaft position, or abnormal displacement during startup may indicate a developing mechanical issue.

The sensor provides measurement data; diagnosis and protective action are handled by the connected monitoring and control system.

Role in Industrial Control and Machinery Protection Systems

The Epro PR6424/010-000 is commonly considered for machinery monitoring installations where reliable shaft displacement measurement is required.

Turbine Monitoring

Steam and gas turbines operate at high rotational speeds and require continuous monitoring of important mechanical parameters. Shaft displacement measurements help operators understand rotor movement and identify abnormal operating conditions.

A properly installed PR6424 probe can provide measurement information for radial or axial shaft movement, depending on the installation arrangement.

Compressor Monitoring

Industrial compressors operate under varying pressure, speed, and load conditions. Changes in shaft movement may indicate bearing wear, alignment problems, or other mechanical conditions.

A non-contact eddy current sensor can monitor shaft behavior without physically contacting the rotating surface.

Pump Monitoring

Large industrial pumps are used in power generation, chemical processing, water treatment, and manufacturing facilities. Shaft displacement monitoring can contribute to machinery protection and maintenance planning.

The sensor must be installed with the correct target material, mounting arrangement, and measurement gap.

Integration with Monitoring Equipment

The PR6424 probe is normally used with a compatible signal converter and machinery monitoring system. The converter processes the probe signal and provides the measurement output required by the monitoring equipment.

Before integration, engineers should verify:

• Probe and converter compatibility.
• Cable type and total cable length.
• Connector arrangement.
• Sensor supply and converter requirements.
• Measurement range and sensitivity.
• Monitoring system input requirements.
• Alarm and trip configuration.

A sensor probe should not be treated as directly interchangeable with a complete monitoring transmitter or a different sensor system.

Industrial Applications

1. Steam Turbines

Steam turbines are used in power plants and industrial energy systems. Continuous shaft monitoring is important because rotor displacement and vibration can affect operating stability.

The PR6424 sensor can be installed at suitable measurement locations to monitor shaft movement. Its non-contact measurement principle is appropriate for applications where the rotating surface must remain free from mechanical contact.

2. Gas Turbines

Gas turbines operate under demanding mechanical and thermal conditions. Machinery monitoring systems use displacement and vibration measurements to assess rotor behavior.

A suitable PR6424 configuration can provide shaft-position information when installed with the correct probe mounting, cable, converter, and monitoring equipment.

3. Industrial Compressors

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

Monitoring shaft displacement can help maintenance teams identify changes in rotor behavior. This information may be evaluated alongside vibration, temperature, pressure, and other operating measurements.

4. Centrifugal Pumps

Large centrifugal pumps often operate continuously and may be critical to production or utility services.

Non-contact shaft measurement can help monitor mechanical conditions in suitable pump installations. Correct sensor positioning and target material are essential for reliable readings.

5. Industrial Fans and Blowers

Large fans and blowers are used in ventilation, combustion-air systems, cooling installations, and industrial process equipment.

Shaft displacement monitoring can provide useful information about rotating assembly behavior, particularly in installations where unexpected vibration or movement may affect equipment availability.

6. Power Generation Equipment

Power generation facilities use machinery protection systems to monitor turbines, generators, compressors, and auxiliary rotating equipment.

The PR6424 series can form part of a wider monitoring arrangement when its measurement characteristics and installation requirements match the equipment being monitored.

Installation and System Integration

Correct installation is essential for obtaining stable and repeatable displacement measurements.

1. Verify the Target Material

The PR6424 series is designed for use with conductive ferromagnetic targets. The manufacturer’s standard target material is 42CrMo4 steel.

The actual shaft material and surface condition should be checked before installation. Different target materials can affect the sensor’s measurement response.

2. Select the Correct Mounting Location

The probe must be installed at the measurement location specified by the machinery monitoring design.

For radial vibration monitoring, the sensor is generally positioned toward the shaft surface. For axial displacement monitoring, the probe is arranged to measure movement along the shaft axis.

The mounting position should provide a stable mechanical reference and sufficient clearance from surrounding components.

3. Set the Initial Air Gap

The sensor-to-target gap is an important installation parameter. The PR6424 specification identifies an approximate nominal center air gap of 2.7 mm.

The final gap should be set according to the manufacturer’s installation procedure and the compatible converter configuration.

Incorrect probe positioning may cause measurement errors, reduced usable range, or unstable output.

4. Check Cable and Connector Configuration

The sensor uses a cable construction based on PTFE insulation. Cable length, armor, connector type, and termination arrangement depend on the exact ordering configuration.

Avoid sharp bends, excessive pulling force, and routing alongside high-interference power conductors where this could affect the measurement system.

The supplied sensor should be checked against the required extension cable and converter connection before installation.

5. Connect the Compatible Signal Converter

The PR6424 probe requires a compatible signal-conditioning arrangement. An appropriate EPRO converter processes the probe response and provides the output expected by the monitoring system.

Confirm the exact converter model and its compatibility with the PR6424/010-000 configuration. Do not assume that every CON-series converter or cable arrangement is interchangeable.

6. Verify the Measurement Signal

After installation, verify the initial gap, signal stability, and measurement response. Compare the output with the expected shaft position and the monitoring system’s configuration.

Where possible, record baseline readings during normal operation. These measurements can provide a reference for future condition assessment.

7. Maintain Mechanical Stability

The probe mounting must remain secure during machine operation. Loose brackets, damaged threads, cable movement, or changes in the probe position can affect measurement accuracy.

During maintenance, inspect the probe, cable, connector, mounting hardware, and surrounding installation area.

Compatible System Components

A complete PR6424 measurement arrangement normally includes the probe, suitable cable connections, a compatible signal converter, and a monitoring system.

The components above describe typical parts of an EPRO displacement measurement arrangement. They are not necessarily included with the PR6424/010-000 sensor.

Alternative Models and Replacement Considerations

The PR6424 family includes multiple 16 mm probe configurations. Some models may have similar measurement characteristics but differ in cable length, sensor length, connector, armor, or installation arrangement.

A replacement should not be selected based only on the 16 mm sensor diameter. Before substitution, compare:

• Complete probe model number.
• Sensor head diameter and mechanical dimensions.
• Thread type and probe length.
• Cable length and cable construction.
• Connector type and termination.
• Target material and shaft geometry.
• Sensitivity and measurement range.
• Compatible signal converter.
• Monitoring system input and scaling.

A different probe may require a different converter, extension cable, mounting arrangement, or monitoring configuration.

Key Advantages

Non-Contact Measurement

The sensor measures shaft movement without physical contact with the rotating target. This avoids direct mechanical wear between the probe and the shaft during normal operation.

Suitable for Critical Rotating Machinery

The PR6424 series is designed for machinery monitoring applications involving turbines, compressors, pumps, and fans.

Static and Dynamic Measurement

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

Defined Sensitivity

The manufacturer’s specification lists a sensitivity of 4 V/mm and linearity of ≤ ±1.5%, providing defined measurement characteristics for compatible system configurations.

Compact 16 mm Sensor Head

The 16 mm probe format supports installation in suitable machinery measurement locations where the mounting arrangement accommodates the sensor dimensions.

Industrial Cable Construction

The sensor uses a stainless-steel sleeve and PTFE cable construction, with the exact cable and mechanical configuration determined by the ordering code.

Integration with Machinery Monitoring Systems

When paired with a compatible converter, the probe can provide measurement information to machinery protection and condition-monitoring equipment.

Technical FAQs

1. What is the Epro PR6424/010-000?

The PR6424/010-000 is a 16 mm non-contact eddy current sensor designed for measuring shaft displacement and position in rotating machinery.

2. What does an eddy current sensor measure?

An eddy current sensor measures the distance between its probe tip and a conductive target. In rotating machinery, this measurement can be used to monitor shaft displacement, vibration, position, and eccentricity.

3. What is the sensor head diameter?

The sensor head diameter is 16 mm.

4. What is the sensitivity of the PR6424 series?

The manufacturer’s specification lists a sensitivity of 4 V/mm, with linearity of ≤ ±1.5%.

5. What is the static measurement range?

The specified static measurement range is ±2.0 mm.

6. What is the nominal air gap?

The manufacturer’s specification lists an approximate nominal center air gap of 2.7 mm. The actual installation gap should be established using the applicable installation procedure and compatible converter.

7. Does the PR6424/010-000 require a signal converter?

Yes. The probe operates as part of an eddy current measurement system. A compatible signal converter is required to process the probe response and provide the appropriate measurement output.

8. What equipment can use this sensor?

Typical applications include steam turbines, gas turbines, compressors, pumps, fans, and other critical rotating machinery.

9. What is the weight of the sensor?

The supplied listing weight is 0.2 kg. The manufacturer’s specification gives an approximate weight of 200 g for the sensor with a 1 m cable and without armor.

10. Can another PR6424 model replace the PR6424/010-000?

Not automatically. Different suffixes may identify different cable lengths, probe dimensions, connectors, and mechanical configurations. Confirm the complete ordering code and converter compatibility before replacement.

Procurement and Maintenance Recommendations

When purchasing the Epro PR6424/010-000, verify the complete model number and compare it with the probe installed in the machinery. The suffix is important because it identifies the specific mechanical and cable configuration.

For replacement projects, confirm the sensor head diameter, thread, probe length, cable length, connector arrangement, and compatibility with the existing converter. A probe that belongs to the same PR6424 family may still require a different cable or installation arrangement.

For used or refurbished equipment, inspect the probe tip, sleeve, cable insulation, connector, and mounting threads. Check for signs of physical damage, contamination, corrosion, or cable deterioration. Where the sensor is used in a critical machinery protection system, suitable functional testing should be considered before installation.

During routine maintenance, inspect the probe mounting and cable routing. Avoid changing the sensor position without recording the original measurement gap. After maintenance or replacement, verify the signal response and confirm that the monitoring system uses the correct sensitivity and scaling.

Maintaining accurate spare-part records can also help reduce replacement errors. Store the complete catalog number, cable configuration, converter model, and installation details together with the machinery maintenance documentation.

Conclusion

The Epro PR6424/010-000 16 mm Eddy Current Sensor is designed for non-contact measurement of shaft displacement and position in critical rotating machinery. Its eddy current measurement principle supports static and dynamic monitoring without requiring physical contact with the rotating shaft.

With a 16 mm sensor head, 4 V/mm sensitivity, a specified static range of ±2.0 mm, and an approximate weight of 0.2 kg, the PR6424/010-000 can be used in suitable turbine, compressor, pump, and fan monitoring arrangements.

For reliable operation, the sensor must be matched with the correct cable, compatible signal converter, target material, and machinery monitoring system. Verifying the complete ordering code and installation configuration is essential when purchasing or replacing this industrial sensor.