Product Overview

The Epro PR6424/104-100 16 mm Eddy Current Sensor is a non-contact displacement sensor designed for monitoring the condition and operating behavior of rotating machinery. It belongs to the EPRO PR6424 sensor family, which is widely associated with machinery protection and condition-monitoring applications in power generation, petrochemical processing, and industrial manufacturing.

The sensor uses the eddy-current measurement principle to detect changes in the distance between its sensing tip and a conductive metallic target. When installed near a rotating shaft, it can measure shaft vibration, radial and axial displacement, shaft position, eccentricity, and other movement-related parameters. Because the measurement takes place without direct mechanical contact, the probe can continuously monitor shaft movement without physically touching the rotating surface.

The PR6424 series is designed for applications involving relatively large rotating shafts, including steam turbines, gas turbines, hydro turbines, compressors, pumps, and fans. Its 16 mm sensing head provides a measurement arrangement suitable for machinery where reliable shaft-position and vibration information is important for equipment protection and maintenance.

The PR6424 family has a typical sensitivity of 4 V/mm, a static measurement range of ±2.0 mm, and a dynamic measurement range of 0 to 1,000 μm peak-to-peak. Its nominal center air gap is approximately 2.7 mm. These characteristics allow the sensor to detect both relatively slow changes in shaft position and faster vibration movements.

The PR6424/104-100 is intended to operate as part of a compatible measurement chain. A complete installation generally includes the sensor probe, an appropriate extension cable where required, and a compatible signal converter. The converter processes the probe signal and provides an output suitable for machinery monitoring or protection equipment.

The supplied product information identifies a 16 mm sensor head diameter and a weight of approximately 0.2 kg. Cable length, connector arrangement, mounting thread, and other configuration details should be checked against the exact product label before replacement or installation.

Technical Specifications

Note: Measurement values describe the PR6424 sensor family. Exact cable, connector, mounting, temperature, and certification details should be confirmed against the PR6424/104-100 configuration.

Function and Working Principle

The PR6424/104-100 operates using electromagnetic induction, commonly known as the eddy-current principle. This technology enables accurate distance measurement between the probe tip and a conductive metallic target without requiring physical contact.

1. Electromagnetic Field Generation

The sensor contains a coil near its sensing tip. When connected to a compatible signal converter, the coil generates a high-frequency electromagnetic field around the probe head.

When a conductive metallic target, such as a rotating steel shaft, enters this field, electrical currents known as eddy currents are induced on the target surface.

2. Distance Measurement

The strength of the eddy currents changes according to the distance between the probe tip and the target. As the shaft moves closer to or farther away from the sensor, the electrical characteristics of the sensing coil change.

The signal converter evaluates these changes and converts them into an electrical output corresponding to the measured gap.

This makes it possible to detect small changes in shaft position and movement without direct mechanical contact.

3. Shaft Vibration Monitoring

When a machine rotates, its shaft may move slightly because of imbalance, misalignment, bearing wear, mechanical looseness, or other operating conditions.

A stationary PR6424 probe positioned near the shaft can detect these movements. The resulting measurement signal can be used to evaluate vibration amplitude and identify changes in machine behavior.

Continuous vibration monitoring can help maintenance teams identify developing mechanical problems before they lead to severe equipment damage.

4. Axial and Radial Displacement Measurement

The sensor can be installed in different orientations according to the measurement objective.

• Radial measurement: Detects shaft movement perpendicular to the shaft centerline.
• Axial measurement: Detects movement along the shaft axis.
• Position measurement: Monitors the distance between the probe and the shaft or another suitable target.
• Eccentricity measurement: Helps identify variations in shaft position during rotation.

The installation direction, probe position, target material, and mechanical mounting arrangement must be selected according to the monitoring system design.

5. Signal Conversion and Monitoring

The PR6424 probe is part of a measurement chain rather than a standalone digital monitoring device. It requires a compatible signal converter to condition the sensor signal.

The converter produces an output that can be connected to suitable machinery monitoring equipment. Depending on the system architecture, the resulting measurements may be used for vibration displays, alarm generation, trend analysis, and machine protection.

Role in Industrial Machinery Monitoring Systems

The PR6424/104-100 can serve as a sensing element in machinery condition-monitoring and protection systems. It provides displacement information that helps operators and maintenance engineers understand the mechanical condition of critical rotating equipment.

Turbine Shaft Monitoring

Steam, gas, and hydro turbines contain rotating assemblies that operate under demanding mechanical and thermal conditions. Shaft movement must be monitored to help identify abnormal vibration, changes in position, and mechanical instability.

A properly installed PR6424 sensor can provide continuous displacement measurements for compatible turbine monitoring systems.

Compressor Protection

Industrial compressors are often used in applications where unexpected equipment failure can interrupt production or affect process safety.

The sensor can be used to monitor shaft movement and vibration when installed as part of a suitable monitoring arrangement. Changes in measured vibration can provide useful information for maintenance investigation.

Bearing Condition Assessment

Shaft displacement measurements can help engineers evaluate the mechanical behavior of rotating assemblies. Changes in vibration patterns may be associated with bearing wear, looseness, misalignment, or other mechanical conditions.

The sensor does not independently identify every fault type. Its measurements should be interpreted alongside other vibration, temperature, process, and maintenance information.

Integration with Machinery Protection Equipment

The sensor’s conditioned signal can be connected to compatible machinery monitoring equipment. This allows measured displacement to be used in alarm and protection strategies.

Correct converter selection, signal scaling, alarm limits, and system configuration are necessary for reliable operation.

Industrial Applications

The Epro PR6424/104-100 is intended for applications where non-contact shaft displacement and vibration measurement are required.

1. Steam Turbines

Steam turbines operate at high rotational speeds and require continuous monitoring of mechanical movement. Shaft vibration and axial displacement are important parameters in evaluating turbine condition.

A correctly installed PR6424 sensor can provide measurement information for compatible turbine monitoring systems. Multiple probes may be installed at different positions to monitor radial vibration and axial movement.

2. Gas Turbines

Gas turbines operate under demanding thermal and mechanical conditions. Monitoring rotor movement can help maintenance teams assess operating stability and identify changes that may require inspection.

The PR6424 series is designed for rotating machinery applications that include gas turbines. Exact sensor temperature limits and installation requirements must be checked for the selected configuration.

3. Hydro Turbines

Hydro turbine installations contain large rotating assemblies that may experience changes in shaft alignment, vibration, and mechanical loading.

Non-contact displacement measurement can help monitor shaft behavior and support long-term condition assessment.

4. Industrial Compressors

Centrifugal and other industrial compressors are used in chemical plants, refineries, gas processing facilities, and manufacturing systems.

Shaft vibration monitoring is important for identifying changes in rotor behavior. The PR6424 can provide displacement measurements when paired with a compatible converter and monitoring system.

5. Industrial Pumps

Large pumps used in water treatment, power generation, and process industries may require continuous monitoring of rotating components.

The sensor can help detect changes in shaft movement that may be associated with mechanical wear, misalignment, or abnormal operating conditions.

6. Industrial Fans and Blowers

Large fans and blowers are used in ventilation, combustion-air supply, cooling, and process-gas handling systems.

A non-contact sensor can monitor shaft vibration and help maintenance personnel assess changes in mechanical condition during operation.

Installation and System Integration

Correct installation is essential for measurement accuracy and reliable operation. The sensor must be installed with suitable mechanical clearance, compatible target material, and an appropriate signal-conversion arrangement.

1. Confirm the Exact Sensor Configuration

Before installation, verify that the sensor model is PR6424/104-100. Check the product label and compare the cable, connector, mounting thread, and probe dimensions with the existing installation.

Different PR6424 variants may have different cable lengths, mounting arrangements, and electrical configurations. A sensor from the same family should not automatically be treated as a direct replacement.

2. Select a Suitable Mounting Position

Install the probe at the measurement location specified by the machinery monitoring design.

The probe should be securely mounted and positioned so that its sensing tip faces the intended metallic target. The mounting structure must resist vibration and prevent unintended movement during operation.

Avoid mounting arrangements that allow the probe to loosen or shift during machine operation.

3. Set the Correct Air Gap

The PR6424 family has a nominal center air gap of approximately 2.7 mm. The actual setup procedure should follow the sensor and converter documentation.

Correct probe positioning is important because an incorrect air gap can reduce measurement accuracy or cause the output to operate outside its intended linear range.

The target material and surface condition should also be considered during calibration.

4. Use a Compatible Signal Converter

The PR6424 probe must be paired with a compatible signal converter. The converter should match the probe’s electrical characteristics and calibration requirements.

Common EPRO CON-series converter families are used in PR6424 measurement systems, but compatibility must be confirmed for the exact probe variant and converter model.

Do not assume that every converter in the same product family is interchangeable.

5. Route and Protect the Cable

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

Avoid sharp bends, crushing, excessive tension, and contact with hot surfaces beyond the cable’s specified temperature limits.

Where the installation requires additional cable protection, select accessories that are compatible with the original sensor configuration.

6. Calibrate and Verify the Measurement Chain

After installation, verify the complete measurement chain, including the probe, cable, converter, and monitoring equipment.

Check the output response across the required measurement range and confirm that the displayed values correspond to the actual mechanical gap.

Record the initial readings and configuration parameters. These records provide a useful reference for future maintenance and condition comparisons.

Compatible System Components

The PR6424/104-100 is normally used with additional measurement and monitoring equipment. The following components illustrate the typical system arrangement.

The components listed above are examples of equipment used in a complete measurement installation. They are not necessarily included with the sensor.

Alternative Models and Replacement Considerations

The PR6424 belongs to a wider family of EPRO eddy-current sensors. Other models may provide similar measurement functions, but their sensing diameters, measuring ranges, cable arrangements, and temperature capabilities can differ.

Before selecting an alternative, compare the following:

• Sensor head diameter.
• Static and dynamic measurement ranges.
• Sensitivity and linearity.
• Nominal air gap.
• Probe thread and mounting dimensions.
• Cable length and connector type.
• Operating temperature range.
• Compatible signal converter.
• Target material and shaft diameter.
• Monitoring system input requirements.

A sensor with the same nominal diameter may still have a different electrical or mechanical configuration. Always verify the full part number before replacing an installed probe.

Key Advantages

Non-Contact Measurement

The sensor measures the distance to a conductive target without direct physical contact. This makes it suitable for continuous monitoring of rotating shafts.

High Measurement Sensitivity

The PR6424 family provides a typical sensitivity of 4 V/mm, supporting the detection of relatively small displacement changes.

Shaft Vibration Monitoring

The sensor can provide measurement information for radial and axial shaft movement when installed in an appropriate monitoring arrangement.

Static and Dynamic Measurement

Its measurement characteristics support both shaft-position monitoring and dynamic vibration measurement.

Industrial Rotating Machinery Applications

The PR6424 family is designed for applications involving turbines, compressors, pumps, fans, and other critical rotating equipment.

Stainless Steel Sensor Construction

The series uses a stainless steel sensor sleeve, providing a durable mechanical construction for industrial installation.

Integration with Machinery Monitoring Systems

When paired with a compatible converter, the sensor can supply conditioned measurement signals to machinery monitoring and protection equipment.

Technical FAQs

1. What is the Epro PR6424/104-100?

The Epro PR6424/104-100 is a 16 mm eddy-current sensor designed for non-contact measurement of shaft displacement and vibration in rotating machinery.

2. What is the sensor head diameter?

The supplied product specification identifies a sensor head diameter of 16 mm.

3. What measurement principle does the PR6424 use?

It uses the eddy-current principle. An electromagnetic field generated by the sensor interacts with a conductive metallic target, and changes in the distance between the probe and target affect the electrical characteristics of the sensing coil.

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

The typical sensitivity is 4 V/mm, with a specified linearity of approximately ±1.5% under the applicable reference conditions.

5. What is the static measurement range?

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

6. What is the dynamic measurement range?

The typical dynamic measurement range is 0 to 1,000 μm peak-to-peak. Actual application performance depends on the installation and measurement-chain configuration.

7. What type of target material is required?

The standard reference target is ferromagnetic steel, with 42CrMo4 used as the reference material in the series specifications. Target material differences can affect calibration and measurement accuracy.

8. Does the PR6424/104-100 work without a signal converter?

The sensor is intended to operate as part of a compatible measurement chain. A suitable signal converter is required to condition the probe signal for monitoring equipment.

9. Where is this sensor commonly used?

Typical applications include steam turbines, gas turbines, hydro turbines, industrial compressors, pumps, fans, and other rotating machinery requiring shaft vibration or displacement monitoring.

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

Verify the complete model number, sensor diameter, cable length, connector, mounting thread, measurement characteristics, converter compatibility, and temperature requirements. Matching only the PR6424 family name is not sufficient to establish interchangeability.

Procurement and Maintenance Recommendations

When purchasing the Epro PR6424/104-100, verify the complete model number on the sensor label. The PR6424 family contains multiple configurations, and differences in cable length, connector arrangement, mounting dimensions, and electrical compatibility can affect replacement suitability.

For spare-parts procurement, request clear photographs of the sensing head, mounting section, cable, and connector. Confirm whether the sensor is supplied with an extension cable or other accessories, and establish whether the listed weight refers to the sensor alone or a complete assembly.

During installation, protect the sensing tip from impact and contamination. Handle the cable carefully and avoid excessive bending or tension. Confirm the mounting position and air gap before commissioning.

For ongoing maintenance, compare sensor readings with the baseline measurements recorded during commissioning. Unexpected changes in vibration or shaft position should be investigated together with other machinery operating data. Inspect the mounting arrangement, cable condition, converter connections, and monitoring-system configuration when measurement abnormalities occur.

For critical rotating machinery, keep a correctly identified spare sensor available where practical. Confirming compatibility before an emergency replacement can reduce troubleshooting time and help restore the monitoring system more efficiently.

Conclusion

The Epro PR6424/104-100 16 mm Eddy Current Sensor is designed for non-contact measurement of shaft displacement and vibration in critical rotating machinery. Its 16 mm sensing head, typical 4 V/mm sensitivity, ±2.0 mm static range, and 0–1,000 μm dynamic range make it suitable for a variety of turbine, compressor, pump, and fan monitoring applications.

As part of a compatible probe, cable, converter, and monitoring arrangement, the sensor provides useful information about shaft movement and machinery operating conditions. Correct model identification, air-gap adjustment, converter compatibility, and cable installation are essential for reliable measurement performance.