Product Overview

The EPRO PR6424/107-021 16 mm Eddy Current Sensor is a non-contact displacement measurement device designed for monitoring the operating condition of critical rotating machinery. Manufactured under the EPRO product line of Emerson, the PR6424 series is widely associated with machinery protection and condition monitoring applications involving turbines, compressors, pumps, fans, and other industrial rotating equipment.

Unlike conventional contact sensors, an eddy current sensor measures the movement of a conductive target without requiring physical contact. This makes it particularly useful for monitoring rotating shafts, where continuous measurement is needed without introducing mechanical friction or additional wear.

The PR6424/107-021 belongs to the 16 mm sensor family. It is designed to detect changes in the distance between the sensor tip and a conductive metallic target. These changes can be converted into electrical signals by a compatible signal converter and subsequently used by machinery monitoring equipment.

In industrial applications, the sensor can support measurements of radial shaft vibration, axial shaft displacement, shaft position, eccentricity, and rotational speed-related signals. Such measurements are important for identifying abnormal machine behavior before it develops into a serious mechanical failure.

The PR6424 series uses an eddy current measurement principle and provides a typical sensitivity of 4 V/mm with linearity of approximately ±1.5%. Its static measurement range is ±2.0 mm, while its dynamic measurement range extends to 1,000 μm.

For maintenance engineers, the PR6424/107-021 is relevant to machinery monitoring installations where accurate shaft displacement information is required. When selecting a replacement, the complete model number, cable arrangement, connector configuration, and signal converter compatibility should be checked carefully.

Technical Specifications

Note: The performance values above describe the PR6424 16 mm sensor family. Confirm the exact PR6424/107-021 cable length, connector, mounting thread, and environmental limits against the product-specific documentation.

Function and Working Principle

The PR6424/107-021 operates using the eddy current measurement principle. It generates an electromagnetic field around the sensor tip and detects changes in that field when a conductive metallic target moves relative to the probe.

The resulting electrical response can be processed by a compatible signal converter to produce a measurement signal representing the distance between the sensor and the target.

1. Non-Contact Displacement Measurement

The sensor measures the distance between its sensing tip and a conductive target, typically a ferromagnetic steel shaft.

When the shaft moves closer to or farther away from the sensor, the electromagnetic characteristics at the sensing tip change. The sensor detects this variation and provides a corresponding measurement response.

Because the measurement does not require physical contact, the sensor can continuously monitor rotating machinery without mechanically touching the shaft.

2. Eddy Current Measurement Technology

An alternating electrical signal generates an electromagnetic field at the sensor tip. When a conductive target enters this field, eddy currents are induced in the target material.

These currents influence the electromagnetic behavior of the sensor. The resulting change is related to the distance between the sensor and the target.

A compatible signal converter processes this response and converts it into a usable electrical output.

For reliable measurements, the probe, extension cable, converter, and monitoring equipment must be treated as a matched measurement system.

3. Shaft Vibration Monitoring

One important application of the PR6424 series is measuring dynamic shaft displacement.

As rotating equipment operates, its shaft may move because of mechanical imbalance, misalignment, bearing deterioration, or changing operating loads. The sensor detects these movements and provides information that can be used to evaluate vibration behavior.

The resulting measurements help maintenance personnel identify abnormal shaft movement and investigate potential mechanical problems.

4. Shaft Position and Axial Displacement

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

In turbines and other large rotating machines, changes in axial shaft position may indicate mechanical movement or developing equipment problems. Continuous position monitoring helps operators observe these conditions during normal operation.

The sensor’s measurement range and installation position must be selected according to the mechanical design and monitoring requirements.

5. Signal Conversion and Monitoring

The PR6424/107-021 is a sensing component rather than a complete standalone machinery protection system.

Its measurement response must be processed by a compatible signal converter. The converted signal can then be supplied to monitoring equipment, protection systems, or industrial control interfaces.

Correct matching of the probe, cable, converter, and monitoring channel is essential for accurate measurement performance.

Role in Industrial Machinery Protection Systems

The PR6424/107-021 can serve as part of a machinery condition monitoring architecture. It provides shaft displacement information that helps operators and maintenance engineers evaluate the mechanical condition of rotating equipment.

Turbine Monitoring

Steam turbines, gas turbines, and hydro turbines contain rotating shafts operating under demanding mechanical and thermal conditions.

Shaft vibration and displacement measurements help identify changes in rotor behavior. The PR6424 series is designed for non-contact monitoring applications involving these types of critical machines.

Compressor Protection

Industrial compressors are often used in continuous-process facilities where unexpected shutdowns can affect production.

Shaft displacement monitoring can provide useful information about rotor movement and mechanical stability. When integrated with a suitable monitoring system, these measurements support equipment condition assessment and maintenance planning.

Pump Monitoring

Large industrial pumps may operate continuously under varying flow and pressure conditions.

Monitoring shaft movement can help maintenance teams investigate mechanical imbalance, alignment problems, and other conditions that may affect pump reliability.

Fan and Blower Monitoring

Industrial fans and blowers are commonly used in ventilation, cooling, combustion-air supply, and process systems.

A non-contact displacement sensor can monitor shaft movement and provide data for evaluating the operating condition of rotating assemblies.

Industrial Applications

The EPRO PR6424/107-021 is intended for industrial machinery monitoring applications where non-contact displacement measurement is required.

1. Steam Turbines

Steam turbines operate at high rotational speeds and require continuous monitoring of mechanical movement.

The sensor can be installed near an appropriate shaft measurement location to detect radial vibration or axial displacement. The resulting data can support machinery protection and condition monitoring strategies.

2. Gas Turbines

Gas turbines are used in power generation and industrial mechanical-drive applications.

Shaft displacement measurements help operators monitor rotor behavior during startup, normal operation, and changing load conditions.

The PR6424 series is designed for critical turbomachinery monitoring applications where reliable non-contact measurements are important.

3. Industrial Compressors

Centrifugal compressors and other rotating compressor systems often operate continuously in demanding environments.

Shaft vibration monitoring can help identify changes in rotor behavior, allowing maintenance teams to investigate possible imbalance, bearing problems, or mechanical deterioration.

4. Industrial Pumps

Large pumps used in chemical processing, water treatment, and energy facilities may require continuous mechanical condition monitoring.

The sensor can provide displacement information that contributes to a broader pump monitoring system.

5. Industrial Fans and Blowers

Fans and blowers are essential components in many manufacturing and process facilities.

Monitoring shaft movement can help identify abnormal vibration and support preventive maintenance activities.

6. Power Generation Equipment

Power generation facilities depend on reliable rotating machinery.

Non-contact shaft displacement measurements can form part of a monitoring strategy designed to improve equipment availability and help identify developing mechanical problems.

Installation and System Integration

Proper installation is essential for obtaining reliable measurements from the PR6424/107-021.

The sensor must be mounted in a suitable position relative to the shaft, and the installation must follow the manufacturer’s mechanical and electrical requirements.

1. Verify the Sensor Configuration

Before installation, confirm the complete model number, PR6424/107-021.

Check the sensor cable length, connector arrangement, mounting structure, and compatibility with the existing signal converter.

Different PR6424 variants may have different cable and mechanical configurations. A sensor from the same product family should not automatically be considered a direct replacement.

2. Prepare the Mounting Location

The sensor should be installed at the designated measurement location with suitable mechanical support.

The mounting arrangement must maintain the required clearance between the sensor tip and the shaft surface.

For PR6424 installations, the manufacturer’s guidance concerning sensor alignment, shaft diameter, and surrounding metallic materials should be followed.

3. Set the Measurement Gap

The nominal center air gap for the PR6424 series is approximately 2.7 mm.

The actual installation gap must be established according to the applicable calibration and installation procedure.

An incorrect gap can reduce measurement accuracy or move the sensor outside its intended linear operating range.

4. Connect the Sensor Cable

The cable connects the probe to its compatible signal converter.

Cable routing should minimize unnecessary mechanical stress, sharp bends, and exposure to unsuitable environmental conditions.

The exact cable length and connector arrangement should be verified for the /107-021 configuration. Avoid mixing extension cables or connectors from incompatible sensor assemblies.

5. Connect to the Signal Converter

The sensor must be connected to a compatible EPRO signal converter.

The converter processes the probe response and produces an output suitable for the machinery monitoring system.

Incorrect cable or converter combinations may affect measurement sensitivity, calibration, and signal stability.

6. Verify the Monitoring Channel

After installation, verify the sensor output and monitoring channel configuration.

Check the measurement gap, signal stability, channel scaling, and alarm settings. Compare the measured values with the machine’s operating conditions and the monitoring system’s commissioning requirements.

Compatible System Components

The PR6424/107-021 normally operates as part of a complete displacement measurement chain.

The components listed above describe a typical monitoring arrangement. They are not necessarily included with the PR6424/107-021 sensor.

Alternative Models and Replacement Considerations

The PR6424 series includes different sensor configurations and ordering variants. When replacing the PR6424/107-021, the complete model number must be checked rather than relying only on the 16 mm sensor diameter.

Before choosing a replacement, compare:

• Sensor head diameter.
• Complete model and ordering suffix.
• Mounting thread and mechanical dimensions.
• Cable length and cable protection.
• Connector and adaptor arrangement.
• Measurement sensitivity and linearity.
• Static and dynamic measurement ranges.
• Compatible signal converter.
• Operating temperature limits.
• Target material and shaft dimensions.

A replacement sensor should be approved only after the complete measurement chain has been checked.

Key Advantages

Non-Contact Measurement

The sensor measures shaft displacement without physical contact, avoiding mechanical wear caused by conventional contact measurement methods.

16 mm Sensor Design

The 16 mm sensing head is intended for machinery applications requiring the measurement characteristics of the PR6424 series.

High Measurement Sensitivity

The series provides a typical sensitivity of 4 V/mm, supporting the measurement of relatively small changes in shaft position.

Static and Dynamic Measurement

The PR6424 series supports both static position measurement and dynamic displacement monitoring.

Machinery Protection Applications

The sensor is designed for critical rotating equipment, including turbines, compressors, pumps, and fans.

Industrial Environmental Design

The stainless-steel sensor sleeve and PTFE cable are intended for demanding industrial measurement environments, subject to the limits of the specific configuration.

Integration with Monitoring Systems

When connected to a compatible converter and monitoring system, the sensor can provide useful information for machinery condition assessment and protection.

Technical FAQs

1. What is the EPRO PR6424/107-021?

The PR6424/107-021 is a 16 mm non-contact eddy current sensor from the EPRO PR6424 product family. It is designed for measuring shaft displacement and vibration in industrial rotating machinery.

2. What is the sensor head diameter?

The sensor head diameter is 16 mm.

3. What measurement principle does the PR6424/107-021 use?

It uses the eddy current principle. An electromagnetic field generated by the sensor interacts with a conductive target, and changes in the sensor response are used to determine the target’s displacement.

4. What is the typical sensitivity of the PR6424 series?

The published series specification gives a typical sensitivity of 4 V/mm, with linearity of approximately ±1.5%.

5. What is its static measurement range?

The PR6424 series has a static measurement range of ±2.0 mm.

6. What is the dynamic measurement range?

The published dynamic measurement range is 0 to 1,000 μm. The applicable measurement setup should be checked against the complete system documentation.

7. What is the nominal center air gap?

The nominal center air gap is approximately 2.7 mm. The final installation gap should follow the manufacturer’s calibration and mounting procedure.

8. Does the sensor require a signal converter?

Yes. The PR6424 sensor operates as part of a measurement system and requires a compatible signal converter to process its response into a usable measurement signal.

9. What equipment can the PR6424 series monitor?

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

10. What is the weight of the PR6424/107-021?

The supplied product weight is 0.2 kg. The PR6424 series specification also lists approximately 200 grams for the sensor with a 1-meter cable without armor. Actual weight can vary with cable length and configuration.

Procurement and Maintenance Recommendations

When purchasing the EPRO PR6424/107-021, verify the complete model number and inspect the sensor’s physical condition. Particular attention should be given to the sensing tip, mounting sleeve, cable, connector, and identification label.

For replacement projects, confirm that the sensor matches the existing converter and extension cable arrangement. A sensor with the same 16 mm diameter may still have a different cable configuration or mechanical installation requirement.

During maintenance, inspect the sensor mounting position and cable condition. Check for loose connections, damaged insulation, excessive cable bending, and contamination around the sensing area.

It is also important to verify the measurement gap and converter calibration after sensor replacement. Incorrect installation or mismatched system components can cause unstable readings or inaccurate displacement measurements.

For critical machinery, sensor measurements should be evaluated together with other operating parameters, including vibration, temperature, speed, and load. This provides a more complete picture of equipment condition.

Conclusion

The EPRO PR6424/107-021 16 mm Eddy Current Sensor is designed for non-contact shaft displacement and vibration measurement in critical industrial rotating machinery. Its PR6424 series characteristics include 4 V/mm typical sensitivity, approximately ±1.5% linearity, a ±2.0 mm static measurement range, and a 16 mm sensing head.

By working with a compatible signal converter and machinery monitoring system, the sensor can support shaft position monitoring, vibration analysis, and industrial equipment protection.

For maintenance and replacement applications, confirming the exact model suffix, cable configuration, mounting requirements, and converter compatibility is essential for reliable measurement performance.