Product Overview

The Epro PR6424/017-100 16 mm Eddy Current Sensor is a non-contact displacement sensor designed for monitoring the condition and operating performance of critical rotating machinery. Part of the EPRO PR6424 sensor family from Emerson, it is used in industrial machinery protection and condition-monitoring systems to measure shaft vibration, displacement, position, and eccentricity.

Unlike contact-based measurement devices, an eddy current sensor measures the distance between its sensing tip and a conductive target without physically touching the rotating shaft. This measurement principle allows continuous monitoring without introducing mechanical contact between the sensor and the machine component.

The PR6424 series is designed for demanding turbomachinery applications, including steam turbines, gas turbines, hydro turbines, compressors, pumps, and fans. Its measurements can help operators identify abnormal shaft movement, detect changes in machine operating conditions, and support predictive maintenance programs.

The PR6424/017-100 has a nominal sensor head diameter of 16 mm. The PR6424 family specification includes a sensitivity of 4 V/mm, a static measurement range of ±2.0 mm, and a dynamic measurement range of 0 to 1,000 μm. These characteristics make the sensor suitable for applications requiring accurate measurement of shaft movement and vibration.

The sensor operates as part of a complete measurement chain. A compatible signal converter conditions the probe signal and provides an output that can be interpreted by a machinery monitoring or protection system. Correct matching of the sensor, extension cable, converter, and target material is essential for measurement accuracy.

Technical Specifications

Note: The measurement and performance values above are PR6424 family specifications. Confirm the exact probe suffix, cable arrangement, connector, and compatible converter before using them as configuration-specific acceptance values.

Function and Working Principle

The PR6424/017-100 uses eddy current technology to measure the distance between the sensor tip and a conductive target. In a typical installation, the sensor is mounted near a rotating machine shaft with a controlled air gap.

1. Eddy Current Measurement Principle

The sensor generates an electromagnetic field at its sensing tip. When a conductive metal target, such as a ferromagnetic steel shaft, enters this field, eddy currents are induced in the target surface.

The induced currents affect the electrical characteristics of the sensor coil. Changes in the distance between the probe tip and the target therefore produce corresponding changes in the sensor signal.

A compatible signal converter processes this response and converts it into a usable measurement output. The resulting signal can represent shaft position or dynamic movement, depending on the monitoring configuration.

Because the measurement is non-contact, the probe can monitor a rotating shaft without mechanical wear caused by direct contact.

2. Shaft Vibration Measurement

Shaft vibration is an important indicator of rotating machinery condition. Changes in vibration amplitude may be associated with imbalance, misalignment, bearing problems, looseness, or other mechanical abnormalities.

The PR6424 sensor measures the changing distance between the probe tip and the shaft surface. The dynamic component of this measurement can be used by a monitoring system to evaluate shaft vibration.

Multiple probes may be installed at different positions to monitor radial shaft movement in different directions.

3. Shaft Position and Displacement Measurement

The sensor can also measure the relative position of a shaft. Static displacement measurements are useful for observing shaft movement, alignment changes, and axial or radial position variations.

In turbine and compressor applications, position measurements can contribute to machinery protection strategies by helping operators identify abnormal movement before it develops into a more serious mechanical problem.

4. Eccentricity Monitoring

Eccentricity describes the deviation of a rotating shaft from its expected geometric center. Excessive eccentricity can cause uneven movement and increased vibration.

By monitoring the distance between the sensor and the shaft surface during rotation, the PR6424 system can provide information used to assess shaft eccentricity.

5. Signal Conversion

The probe is part of a complete eddy current measurement system rather than a standalone voltage-output instrument. A compatible EPRO signal converter is required to condition the sensor signal and provide the appropriate output for monitoring equipment.

The probe, cable, and converter must be matched according to the manufacturer’s specifications. Incorrect combinations can affect sensitivity, measurement range, calibration, and overall system accuracy.

Role in Industrial Machinery Protection Systems

The PR6424/017-100 can be integrated into industrial machinery monitoring systems to provide continuous information about rotating equipment condition.

Turbine Monitoring

Steam and gas turbines operate at high rotational speeds and under demanding thermal and mechanical conditions. Shaft displacement and vibration measurements are important for evaluating rotor behavior.

Eddy current sensors can be installed near selected shaft locations to monitor radial vibration, axial movement, and other relevant parameters. The resulting measurements can be processed by machinery protection equipment to support alarms and protective actions.

Compressor Monitoring

Industrial compressors are widely used in oil and gas processing, chemical production, refrigeration, and other process industries.

Changes in shaft vibration or displacement may indicate mechanical wear, imbalance, misalignment, or operating instability. Continuous monitoring helps maintenance teams identify abnormal trends and investigate potential problems.

Pump and Fan Monitoring

Large pumps and industrial fans often operate continuously. Their bearings, shafts, and rotating assemblies are exposed to mechanical loads that can change with operating conditions.

A properly installed eddy current sensor can provide shaft movement information that supports equipment condition monitoring and maintenance planning.

Integration with Machinery Monitoring Equipment

The sensor’s conditioned output can be connected to compatible machinery monitoring equipment. Depending on the system architecture, measured values may be used for:

• Shaft vibration monitoring.
• Axial and radial displacement monitoring.
• Shaft position monitoring.
• Eccentricity evaluation.
• Alarm and trip logic.
• Historical condition trending.
• Predictive maintenance analysis.

The exact functions depend on the installed converter, monitoring rack, configuration, and system engineering.

Industrial Applications

1. Steam Turbines

Steam turbines are used in power generation and industrial energy systems. Their rotating shafts require continuous monitoring because abnormal vibration or displacement can affect mechanical reliability.

The PR6424 sensor can provide non-contact shaft measurements for turbine condition-monitoring and protection systems.

2. Gas Turbines

Gas turbines operate under high temperatures and demanding mechanical conditions. Rotor vibration and shaft displacement are important parameters for evaluating turbine performance.

A suitable PR6424 installation can provide measurement signals for monitoring the dynamic behavior of rotating components.

3. Hydro Turbines

Hydro turbines operate in power-generation facilities where continuous equipment availability is important. Shaft movement and vibration measurements can help maintenance personnel evaluate mechanical condition and identify changes in rotor behavior.

4. Centrifugal and Axial Compressors

Compressors are widely used in petrochemical plants, natural gas processing facilities, refineries, and industrial gas systems.

Shaft vibration and position monitoring can support early detection of abnormal mechanical conditions. The PR6424 sensor can be used as part of an appropriately configured compressor monitoring system.

5. Industrial Pumps

Large process pumps may operate continuously under changing flow, pressure, and load conditions. Monitoring shaft movement can provide useful information about pump mechanical condition.

6. Industrial Fans

Large fans and ventilation equipment contain rotating assemblies that may develop imbalance, misalignment, or other mechanical problems. Non-contact shaft measurement can contribute to condition-monitoring programs.

Installation and System Integration

Correct installation is essential for reliable measurement. The sensor must be mounted with the correct mechanical clearance and connected to a compatible signal converter.

1. Confirm the Sensor Model

Before installation, verify the complete PR6424/017-100 model number. Check the probe configuration, cable length, connector type, mounting thread, and other model-specific characteristics.

Different PR6424 variants may have different cable arrangements, mechanical configurations, or converter compatibility requirements.

2. Select the Correct Mounting Position

The sensor should be installed at the measurement location specified by the machinery monitoring design.

For shaft vibration monitoring, the probe is normally positioned close to the shaft surface. The mounting arrangement must maintain a stable mechanical position and prevent unwanted movement caused by vibration or thermal expansion.

Ensure that sufficient clearance is available around the probe tip and that nearby ferromagnetic materials do not interfere with the intended measurement geometry.

3. Set the Correct Air Gap

The distance between the sensor tip and the shaft is a critical installation parameter.

The PR6424 family has a nominal center air gap of approximately 2.7 mm. The actual installation gap must be established according to the applicable probe and converter instructions.

Incorrect gap adjustment may cause the signal to operate outside its intended linear range, reducing measurement accuracy or preventing the monitoring system from interpreting the signal correctly.

4. Connect the Compatible Converter

The probe must be connected to a compatible EPRO signal converter. The converter processes the probe signal and provides an output suitable for machinery monitoring equipment.

Check the probe and converter combination, cable arrangement, connector compatibility, and calibration requirements before commissioning.

5. Route and Protect the Cable

The sensor cable should be routed away from sources of mechanical damage, excessive heat, and electrical interference.

Avoid sharp bends, excessive tension, and unsupported cable sections. Maintain the manufacturer’s specified minimum bending radius and use suitable cable protection where necessary.

6. Perform Calibration and Functional Testing

After mechanical installation and electrical connection, verify the sensor’s output using the appropriate commissioning procedure.

Check the air gap, signal stability, converter configuration, and measurement response. Confirm that the monitoring system displays plausible values before returning the equipment to normal operation.

Record the final installation and calibration information for future maintenance.

Compatible System Components

The PR6424/017-100 is normally used with other components in an eddy current measurement chain.

Not every component listed above is included with the sensor. The correct converter and cable combination must be confirmed for the exact probe variant.

Alternative Models and Replacement Considerations

The PR6424 series includes multiple 16 mm probe configurations. A replacement should be selected according to the original mechanical and electrical requirements rather than the sensor diameter alone.

Before replacing the PR6424/017-100, compare:

• Complete sensor model number.
• Sensor head diameter and mechanical dimensions.
• Mounting thread and installation length.
• Cable type and overall length.
• Connector and extension cable arrangement.
• Compatible signal converter.
• Sensitivity and measurement range.
• Target shaft material.
• Required operating temperature range.
• Monitoring-system input requirements.

A probe with the same 16 mm diameter is not necessarily a direct replacement. Differences in cable configuration, calibration, or converter compatibility can affect the complete measurement chain.

Key Advantages

Non-Contact Measurement

The sensor measures shaft movement without physical contact, avoiding mechanical wear between the sensing tip and the rotating target.

Continuous Shaft Monitoring

The PR6424 family is designed for continuous monitoring applications involving rotating machinery.

High Measurement Sensitivity

The family specification provides a nominal sensitivity of 4 V/mm, supporting the measurement of small changes in shaft position.

Static and Dynamic Measurement

The sensor family supports both static displacement and dynamic vibration measurements, allowing it to serve multiple machinery-monitoring functions.

Industrial Mechanical Construction

The sensor uses a stainless-steel sleeve and PTFE cable construction designed for demanding industrial environments.

Turbomachinery 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 signal converter, the sensor can provide measurement information for machinery monitoring and protection equipment.

Technical FAQs

1. What is the Epro PR6424/017-100?

The PR6424/017-100 is a 16 mm non-contact eddy current displacement sensor used for monitoring shaft vibration, position, displacement, and eccentricity in rotating machinery.

2. What is the sensor head diameter?

The nominal sensor head diameter is 16 mm.

3. What measurement principle does the sensor use?

It uses eddy current technology. The sensor generates an electromagnetic field, and changes in the distance to a conductive target affect the sensor’s electrical response.

4. What is the sensitivity of the PR6424 series?

The PR6424 family specification gives a sensitivity of 4 V/mm, with linearity of approximately ±1.5%.

5. What is the measurement range?

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

6. Does the sensor require a signal converter?

Yes. It operates as part of a measurement chain with a compatible EPRO signal converter. The converter conditions the probe signal for use by monitoring equipment.

7. What machinery can use this sensor?

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

8. What type of target material is required?

The PR6424 family is specified for ferromagnetic steel targets, with 42CrMo4 used as the standard reference material in its performance specifications.

9. What should be checked before replacing the sensor?

Check the complete model number, sensor dimensions, mounting thread, cable arrangement, connector, converter compatibility, measurement range, and target material.

10. What is the weight of the PR6424/017-100?

The supplied product weight is 0.2 kg. The PR6424 family specification lists approximately 200 grams for the sensor with a 1-meter cable and without armor.

Procurement and Maintenance Recommendations

When purchasing the Epro PR6424/017-100, verify the complete part number and ensure that the offered sensor matches the original installation. The PR6424 family contains multiple variants, so the 16 mm sensor diameter alone is not sufficient for confirming compatibility.

For replacement projects, check the mounting thread, probe length, cable configuration, connector, and compatible signal converter. Confirm whether the quoted product includes only the probe or also includes an extension cable and other accessories.

During maintenance, inspect the probe body, sensing tip, cable insulation, connector, and mounting hardware. Check for mechanical damage, contamination, loose connections, or signs of overheating.

The installation air gap should be checked during commissioning or after probe replacement. Verify the converter configuration and confirm that the monitoring system receives a stable and plausible measurement signal.

For critical turbomachinery, replacement sensors should be checked against the original system documentation and machinery protection requirements. Incorrect sensor selection or calibration can affect vibration monitoring and equipment protection.

Conclusion

The Epro PR6424/017-100 16 mm Eddy Current Sensor is a non-contact measurement device designed for shaft vibration, displacement, position, and eccentricity monitoring in critical rotating machinery. Its PR6424 family specifications include 4 V/mm sensitivity, a ±2.0 mm static measurement range, and a dynamic range of 0 to 1,000 μm.

Designed for use with compatible signal converters, the sensor can form part of a complete machinery condition-monitoring and protection system. Accurate model identification, correct air-gap adjustment, compatible cable selection, and proper converter configuration are essential for reliable operation in industrial applications.