Product Overview

The EPRO PR6424/013-021 16 mm Eddy Current Sensor is a non-contact displacement and vibration sensor designed for monitoring the operating condition of critical rotating machinery. It belongs to the EPRO PR6424 sensor family, which is used in machinery protection and condition-monitoring systems for equipment such as steam turbines, gas turbines, compressors, pumps, and industrial fans.

The sensor measures the movement and position of a conductive metal target without making physical contact. In typical installations, the probe is mounted close to a rotating shaft. Changes in the distance between the probe tip and the shaft surface affect the sensor’s electrical characteristics. A compatible signal converter processes these changes and produces a measurement signal for monitoring equipment.

The PR6424 series is designed for applications requiring accurate measurement of radial and axial shaft displacement, shaft vibration, position, eccentricity, and speed-related signals. These measurements help maintenance teams identify changes in machinery behavior and evaluate equipment condition.

The PR6424/013-021 has a nominal sensor head diameter of 16 mm. Its non-contact operating principle makes it suitable for continuous monitoring applications where mechanical contact with the rotating target would be impractical or undesirable.

With a supplied listing weight of approximately 0.2 kg, this sensor is a compact component within a larger measurement chain. For a complete installation, the probe must be matched with the appropriate extension cable and signal converter.

Technical Specifications

Note: PR6424 is a sensor family with different cable, connector, mounting, and configuration options. Confirm the complete /013-021 ordering details before selecting a replacement or connecting it to a converter.

Function and Working Principle

The PR6424/013-021 operates according to the eddy current measurement principle. It generates an electromagnetic field near the probe tip and detects changes caused by the presence and movement of a conductive target.

1. Non-Contact Displacement Measurement

The sensor is installed near a metallic shaft or another suitable conductive target. As the distance between the probe tip and the target changes, the electrical response of the sensing coil also changes.

A compatible converter interprets this response and converts it into a usable measurement signal. The system can then monitor shaft movement without requiring direct physical contact.

This is particularly useful for rotating machinery, where conventional contact-based measurement methods may cause wear or interfere with normal operation.

2. Eddy Current Detection

The probe contains a coil that generates a high-frequency electromagnetic field. When a conductive metal target enters this field, eddy currents are induced in the target surface.

These currents influence the impedance of the probe coil. The resulting electrical change is related to the distance between the probe and the target.

The measurement depends on the target material, surface characteristics, installation geometry, and correct calibration. For reliable results, the sensor and converter should be calibrated for the specified target material.

3. Shaft Vibration Monitoring

When installed close to a rotating shaft, the PR6424 can measure changes in the shaft-to-probe gap as the shaft moves.

The resulting dynamic measurement can be used to evaluate shaft vibration. Monitoring these signals helps maintenance personnel identify abnormal movement, changes in machine balance, or developing mechanical problems.

The sensor provides measurement information; vibration analysis and alarm decisions are handled by the connected monitoring system.

4. Shaft Position Measurement

The PR6424 series also supports static displacement measurement within its specified range. This allows the monitoring system to track shaft position relative to the probe.

Position measurements are important in machinery where axial or radial movement must remain within defined operating limits.

5. Signal Conversion

The sensor normally operates as part of a complete measurement chain. A compatible signal converter processes the probe response and provides an output suitable for machinery monitoring equipment.

The complete system may include:

• PR6424 eddy current sensor.
• Compatible extension cable.
• EPRO signal converter.
• Machinery monitoring or protection system.
• Control-room display, alarm, and diagnostic equipment.

The exact converter and cable combination must be confirmed against the sensor’s complete ordering configuration.

Role in Industrial Machinery Monitoring Systems

The PR6424/013-021 is typically installed as a field measurement component within a machinery condition-monitoring system. Its purpose is to provide information about shaft movement and position so that monitoring equipment can evaluate machinery operating conditions.

Turbine Protection

Steam, gas, and hydro turbines contain rotating assemblies that operate under demanding mechanical and thermal conditions. Shaft displacement and vibration measurements are important indicators of machine behavior.

The PR6424 series can provide non-contact measurements for suitable turbine monitoring arrangements. These measurements may be used by protection systems to identify abnormal shaft movement and generate alarms when configured limits are exceeded.

Compressor Monitoring

Industrial compressors often operate continuously and may be critical to production processes. Shaft vibration and position monitoring can help identify changes in rotating equipment behavior.

A PR6424 sensor installed at an appropriate measurement point can provide displacement information for the compressor monitoring system.

Pump Monitoring

Large industrial pumps may experience shaft movement caused by hydraulic forces, bearing conditions, alignment problems, or mechanical wear.

Non-contact displacement measurements can help maintenance teams evaluate shaft behavior and investigate changes in operating condition.

PLC and DCS Integration

The PR6424 sensor does not function as a standalone PLC or DCS communication module. Its measurement signal is normally processed by a compatible converter and machinery monitoring equipment before being incorporated into a wider control or monitoring architecture.

Depending on the installation, measurement values and alarm information may be passed to a PLC, distributed control system, or plant supervisory system.

This arrangement allows operators to view machinery condition alongside other process variables.

Industrial Applications

1. Steam Turbines

Steam turbines are widely used in power generation and industrial energy systems. Their rotating shafts require continuous monitoring to help maintain stable operation.

The PR6424 series can be used for suitable shaft displacement and vibration measurement points. Monitoring data can support the identification of abnormal shaft movement and changes in turbine operating condition.

2. Gas Turbines

Gas turbines operate at high rotational speeds and require reliable machinery monitoring. Non-contact eddy current sensors can measure shaft movement without touching the rotating assembly.

The PR6424 series is intended for critical turbomachinery applications, subject to the installation and temperature limits of the specific sensor configuration.

3. Hydro Turbines

Hydro turbines operate in power-generation environments where shaft position and vibration are important maintenance indicators.

The PR6424 sensor can be applied in appropriate monitoring arrangements to measure radial or axial shaft movement.

4. Industrial Compressors

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

Shaft displacement measurements can help operators monitor rotating components and investigate abnormal vibration or changes in mechanical condition.

5. Industrial Pumps

Large pumps in water treatment, power generation, chemical processing, and industrial utilities may require continuous shaft monitoring.

The PR6424 series can provide non-contact displacement measurements for compatible pump monitoring systems.

6. Industrial Fans

Large ventilation and process fans may experience vibration changes caused by imbalance, bearing deterioration, or mechanical looseness.

A properly installed eddy current measurement system can provide shaft movement information for condition monitoring.

Installation and System Integration

Correct installation is essential for measurement accuracy and reliable machinery monitoring.

1. Select the Correct Measurement Location

The sensor should be installed at a measurement point specified by the machinery design or monitoring-system documentation.

For shaft vibration monitoring, the probe is generally positioned close to the shaft surface with the required mechanical clearance. For axial position measurement, the installation geometry must be designed for the intended measurement direction.

The selected location should provide a stable mounting arrangement and avoid interference with moving machine components.

2. Confirm the Probe Mounting

The PR6424 series uses a threaded probe design in its standard configurations. The mounting thread, sensor length, cable routing, and available clearance should be checked against the exact /013-021 configuration.

Avoid excessive mechanical force when installing the probe. Incorrect mounting can damage the sensor or change the intended measurement position.

3. Set the Initial Air Gap

The distance between the probe tip and the target surface is an important measurement parameter.

For the PR6424 series, the nominal center air gap is approximately 2.7 mm under the documented standard measurement conditions. The actual setup should follow the manufacturer’s installation and calibration instructions.

An incorrect air gap may result in an output outside the intended linear measurement region.

4. Verify Target Material

The PR6424 series is calibrated for a specified ferromagnetic steel target, with 42CrMo4 used as the standard reference material in its technical specifications.

Different shaft materials or surface conditions may influence the sensor response. Confirm the target material and calibration requirements before commissioning.

5. Connect the Compatible Converter

The probe must be connected to a compatible signal converter using the appropriate cable and connector arrangement.

Check the complete sensor model, cable type, cable length, converter model, and connector configuration. Do not assume that all PR6424 variants can be connected to every converter without checking compatibility.

6. Route and Protect the Cable

The sensor cable should be routed away from sources of electrical interference, excessive mechanical stress, and moving equipment.

Maintain the manufacturer’s minimum bending radius and avoid sharp bends, crushing, or unnecessary cable tension. Inspect connectors and cable insulation before commissioning.

7. Calibrate and Test the Measurement Chain

After installation, verify the complete sensor, cable, and converter arrangement. Confirm the initial gap, signal response, measurement direction, and output behavior.

Where required, perform calibration using the specified target material and measurement equipment. Record the final installation and calibration information for future maintenance.

Compatible System Components

The PR6424/013-021 is generally used with supporting measurement and monitoring equipment.

The listed components are examples of a typical measurement arrangement. They are not necessarily supplied with the sensor.

Alternative Models and Replacement Considerations

The PR6424 is part of a wider EPRO eddy current sensor family. Related models may have different probe diameters, measuring ranges, temperature limits, or installation requirements.

When replacing the PR6424/013-021, check the following:

• Complete sensor part number.
• Probe diameter and mounting thread.
• Probe length and installation clearance.
• Cable length and cable construction.
• Connector type and pin configuration.
• Compatible signal converter.
• Measurement range and sensitivity.
• Target material and shaft dimensions.
• Operating temperature and environmental conditions.
• Existing machinery monitoring-system configuration.

A sensor with the same nominal diameter may still have a different cable or connector arrangement. Replacement selection should therefore be based on the complete part number and measurement-chain requirements.

Key Advantages

Non-Contact Measurement

The eddy current principle allows shaft displacement to be measured without physical contact, avoiding mechanical contact between the probe and the rotating target.

Suitable for Critical Rotating Machinery

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

Displacement and Vibration Measurement

The sensor supports both static position measurement and dynamic shaft movement measurement within its specified operating range.

Compact 16 mm Probe Design

The 16 mm sensor head provides a practical mounting format for suitable industrial machinery measurement locations.

High Measurement Sensitivity

The PR6424 series has a specified sensitivity of 4 V/mm under its standard measurement conditions, supporting detailed shaft displacement monitoring.

Integration with Machinery Protection Systems

When paired with a compatible converter and monitoring equipment, the sensor can form part of a machinery condition-monitoring and protection arrangement.

Industrial Sensor Construction

The sensor family uses a stainless steel sleeve and PTFE cable construction, supporting its intended industrial measurement applications within the specified environmental limits.

Technical FAQs

1. What is the EPRO PR6424/013-021?

The EPRO PR6424/013-021 is a 16 mm eddy current sensor designed for non-contact measurement of shaft displacement, vibration, position, and related movement in rotating machinery.

2. What is the sensor head diameter?

The nominal sensor head diameter is 16 mm.

3. What is the measuring range of the PR6424 series?

The documented static measuring range is ±2.0 mm. The dynamic measurement range is 0–1,000 μm peak-to-peak under the specified measurement conditions.

4. What is the sensitivity?

The PR6424 series has a nominal sensitivity of 4 V/mm for its standard measurement configuration.

5. What is the nominal air gap?

The nominal center air gap is approximately 2.7 mm. The correct installation gap should be established according to the manufacturer’s installation instructions.

6. What equipment can use this sensor?

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

7. Does the PR6424/013-021 require a signal converter?

Yes. The sensor is normally used with a compatible signal converter that processes its measurement response and provides an output for machinery monitoring equipment.

8. Can the sensor measure shaft vibration?

Yes. It can measure dynamic shaft movement when installed with the correct geometry and connected to a compatible measurement system.

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

The standard target material is ferromagnetic steel, with 42CrMo4 used as the reference material in the published specifications. Other materials may require specific calibration consideration.

10. What is the weight of the sensor?

The supplied listing weight is 0.2 kg. The PR6424 technical specification also gives approximately 200 grams for the sensor with a 1-meter cable and without armor.

Procurement and Maintenance Recommendations

When purchasing the EPRO PR6424/013-021, verify the complete part number rather than relying only on the PR6424 family designation. Probe length, cable configuration, connector arrangement, and converter compatibility can affect whether a replacement is suitable for an existing installation.

For used or surplus sensors, inspect the probe tip, threaded sleeve, cable insulation, connector, and identification label. Check for visible damage, corrosion, cable deformation, or signs of previous mechanical impact.

For critical machinery, functional verification should be performed using the appropriate converter and test equipment. Confirm that the measurement response is stable and that the installed sensor is calibrated for the intended target material.

During routine maintenance, inspect cable routing, mounting security, connector condition, and measurement trends. Sudden changes in sensor output should be investigated rather than corrected by changing the probe gap without first checking the machinery and measurement chain.

Maintaining accurate records of sensor part numbers, converter configurations, installation gaps, and calibration data can simplify future replacement and troubleshooting.

Conclusion

The EPRO PR6424/013-021 16 mm Eddy Current Sensor is designed for non-contact shaft displacement and vibration measurement in critical rotating machinery. Its 16 mm probe design and the PR6424 family’s 4 V/mm sensitivity and ±2.0 mm static measuring range make it suitable for appropriately configured machinery monitoring systems.

Used with a compatible extension cable, signal converter, and monitoring equipment, the sensor can provide valuable information about shaft movement and operating condition. For replacement and procurement projects, verifying the complete model number, cable configuration, converter compatibility, and calibration requirements is essential for reliable operation.