Product Overview

The Epro PR6424/012-100 16 mm Eddy Current Sensor is a non-contact displacement measurement probe designed for monitoring the operating condition of critical rotating machinery. As part of the EPRO PR6424 sensor family, it is used in industrial machinery protection and condition monitoring systems to measure shaft vibration, radial and axial displacement, shaft position, eccentricity, and rotational speed-related signals.

The PR6424 series is commonly applied to large rotating machines where continuous monitoring of shaft movement is important for operational reliability. Typical equipment includes steam turbines, gas turbines, hydro turbines, compressors, industrial pumps, and fans. These machines often operate under demanding mechanical and thermal conditions, making accurate shaft monitoring an important part of preventive maintenance and equipment protection.

Unlike contact-based measurement devices, an eddy current sensor measures the distance between its probe tip and a conductive target without requiring physical contact. The probe generates an electromagnetic field. When a conductive shaft surface enters this field, eddy currents are induced in the target, changing the electrical characteristics of the sensor. A compatible signal converter processes this change and produces an output corresponding to the measured gap.

The PR6424 family uses a nominal 16 mm sensor tip and is designed for applications requiring measurement of shaft movement over a relatively large displacement range. Its typical sensitivity is 4 V/mm, with a static measurement range of ±2.0 mm and a recommended dynamic measurement range of 0 to 1,000 μm peak-to-peak.

The PR6424/012-100 is identified by its complete model number, which should be retained when sourcing replacement parts. Cable length, connector arrangement, mounting thread, and compatibility with the associated signal converter should be checked against the original equipment configuration before installation.

Technical Specifications

Note: The technical values above describe the PR6424 sensor family. Confirm the exact PR6424/012-100 cable, connector, mounting, and temperature configuration using the product nameplate and matching documentation.

Function and Working Principle

The PR6424/012-100 uses eddy current technology to detect changes in the distance between the sensor tip and a conductive target. This measurement principle allows the sensor to monitor shaft movement without mechanical contact.

1. Electromagnetic Field Generation

The sensor contains a coil near its measuring tip. When supplied by a compatible signal converter, the coil generates a high-frequency electromagnetic field.

This field extends into the area in front of the probe. When a conductive metallic target approaches the sensing surface, the electromagnetic interaction changes according to the distance between the target and the sensor.

2. Eddy Current Formation

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 impedance of the sensor coil. The amount of influence changes as the gap between the sensor and shaft changes.

The system uses this relationship to determine shaft displacement. Because the measurement does not require physical contact, the probe can monitor rotating machinery continuously without touching the moving shaft.

3. Displacement Signal Conversion

The sensor probe normally operates as part of a complete measurement chain. A compatible signal converter supplies the probe and processes its electrical response.

The converter transforms the probe signal into a usable output proportional to the measured gap. Depending on the monitoring system, this output can be used by machinery protection equipment, monitoring modules, or other compatible measurement devices.

Correct probe and converter matching is essential. A probe should not be assumed compatible with every signal converter simply because both belong to the same general sensor family.

4. Shaft Vibration Measurement

During normal operation, a rotating shaft moves slightly due to mechanical forces, bearing conditions, imbalance, and other operating influences.

By continuously measuring the distance between the probe and the shaft, the system can identify changes in shaft position over time. Dynamic measurements provide information about shaft vibration and mechanical movement.

This information can help maintenance personnel identify abnormal operating conditions before they develop into more serious equipment problems.

5. Static Position Measurement

The PR6424 family also supports static displacement measurement within its specified measuring range. This capability can be used to monitor shaft position, axial movement, and eccentricity.

For large turbines and compressors, changes in shaft position may provide useful information about bearing conditions, thermal expansion, rotor movement, and mechanical alignment.

Role in Industrial Machinery Monitoring Systems

The Epro PR6424/012-100 is a sensing component rather than a complete machinery protection system. It normally works with a compatible signal converter and monitoring equipment to provide useful operating information.

Shaft Vibration Monitoring

Shaft vibration is an important indicator of rotating machinery condition. Excessive vibration can be associated with rotor imbalance, misalignment, bearing problems, looseness, or other mechanical abnormalities.

A properly installed PR6424 probe measures shaft movement without contact. The resulting signal can be evaluated by the monitoring system to identify changes in vibration behavior.

Axial Displacement Monitoring

Axial displacement describes movement of a rotor along its shaft axis. In turbines and compressors, excessive axial movement may affect clearances and mechanical operating conditions.

An appropriately positioned sensor can monitor this movement and provide information to the machinery protection system.

Eccentricity Monitoring

Shaft eccentricity describes the difference between the shaft’s geometric center and its rotational center. Changes in eccentricity may be relevant during startup, shutdown, and normal operation.

The PR6424 series can be used in suitable measurement arrangements to monitor this condition.

Rotational Speed and Key-Related Signals

Depending on the monitoring arrangement and target geometry, an eddy current measurement system may also be used to detect rotational speed or key-related events.

The specific signal processing and measurement configuration must be selected according to the monitoring system design.

Integration with Machinery Protection Equipment

The probe’s output is processed by a compatible signal converter and can then be connected to a suitable machinery monitoring or protection system.

The complete measurement chain includes the sensor, extension cable where required, signal converter, monitoring equipment, and associated wiring. Each component must be compatible with the others to achieve reliable measurement performance.

Industrial Applications

The PR6424 series is intended for critical rotating machinery where non-contact shaft measurement is required.

1. Steam Turbines

Steam turbines operate at high rotational speeds and under demanding thermal conditions. Shaft vibration and axial displacement are important parameters for monitoring rotor behavior.

The PR6424 series can be installed at suitable measurement positions to provide information about shaft movement. This information can help operators evaluate mechanical condition and identify abnormal trends.

2. Gas Turbines

Gas turbines are used in power generation and industrial mechanical-drive applications. Their rotating assemblies require continuous monitoring to support reliable operation.

Eddy current probes can be used to measure shaft displacement and vibration at selected monitoring points. The resulting signals can support machinery protection and maintenance activities.

3. Hydro Turbines

Hydro turbines operate under changing hydraulic and mechanical loads. Monitoring shaft movement helps maintenance teams understand rotor behavior and identify potential mechanical abnormalities.

A suitable PR6424 measurement arrangement can provide non-contact shaft displacement information for condition monitoring.

4. Industrial Compressors

Centrifugal and other large compressors often operate continuously in industrial facilities. Rotor vibration and shaft position are important parameters in assessing compressor condition.

The PR6424 probe can be used in compatible compressor monitoring systems to measure shaft movement and provide data for machinery diagnostics.

5. Industrial Pumps

Large process pumps are used in power plants, petrochemical facilities, water treatment systems, and manufacturing plants. Shaft movement can provide useful information about bearing and rotor conditions.

The sensor can be installed at appropriate monitoring locations where non-contact displacement measurement is required.

6. Industrial Fans

Large fans and blowers are common in ventilation, combustion-air, and process-gas systems. Abnormal shaft movement may indicate imbalance, misalignment, or mechanical wear.

A compatible eddy current monitoring arrangement can help detect changes in shaft vibration behavior.

Installation and System Integration

Correct installation is essential for obtaining stable measurements from the PR6424/012-100. Probe positioning, target material, cable routing, and converter compatibility all affect measurement performance.

1. Verify the Exact Sensor Configuration

Before installation, check the complete model number and confirm the probe’s cable arrangement, connector type, mounting thread, and length.

The PR6424 family contains multiple configurations. Components that look similar may have different cable lengths, armor arrangements, connector interfaces, or converter compatibility.

For replacement work, compare the new probe with the original installed unit and its equipment documentation.

2. Select a Suitable Measurement Location

The sensor should be positioned so that its tip faces the intended shaft measurement surface. The mounting arrangement must maintain the required clearance and avoid contact between the probe and the rotating shaft.

The target surface should be suitable for eddy current measurement. The PR6424 family uses ferromagnetic steel as its standard reference target material.

The shaft surface should be clean and free from conditions that could interfere with the measurement, such as excessive deposits or unsuitable surface geometry.

3. Set the Initial Air Gap

The initial air gap is a critical installation parameter. The PR6424 family has a nominal center air gap of approximately 2.7 mm.

The final setting must follow the applicable sensor and converter documentation. An incorrect gap may cause the output to operate outside its intended linear measurement region.

Use the specified adjustment procedure and appropriate measurement tools during installation.

4. Check Cable Routing

The sensor cable should be routed carefully to avoid mechanical damage, excessive bending, and interference from high-power electrical conductors.

Where the installation uses an extension cable, confirm that its type and length are compatible with the probe and converter.

Avoid unnecessary cable joints or unapproved connectors because they may affect signal quality.

5. Match the Signal Converter

The PR6424 probe must be paired with a compatible signal converter. The converter supplies the probe and processes the measurement signal.

Before commissioning, verify the probe model, converter model, cable configuration, calibration data, and system requirements.

Do not assume that a converter used with another PR6424 suffix will automatically be suitable for the PR6424/012-100.

6. Perform Calibration and Functional Checks

After installation, check the initial gap, output response, and measurement stability. Verify that the signal changes consistently as the target distance changes.

The monitoring system should be checked for correct engineering units, measurement direction, alarm settings, and signal scaling.

Record the installation gap and relevant calibration information for future maintenance.

Compatible System Components

A complete PR6424 measurement arrangement normally includes several components that work together to produce usable machinery condition data.

These components are not necessarily supplied together with the sensor. Confirm the actual contents of the order and the requirements of the installed monitoring system.

Alternative Models and Replacement Considerations

The PR6424 is one member of the EPRO PR642x eddy current sensor family. Other models may have different tip diameters, measurement ranges, sensitivities, or temperature capabilities.

A related model should not be treated as a direct replacement without engineering review. The sensor tip diameter, measuring range, sensitivity, target material, mounting arrangement, cable configuration, and converter calibration all affect compatibility.

For an existing installation, retaining the original model number is generally the most reliable starting point for replacement procurement.

Key Advantages

Non-Contact Measurement

The PR6424 uses eddy current technology to measure shaft displacement without physical contact. This makes it suitable for monitoring rotating machinery where contact-based measurement would be impractical.

Suitable for Critical Rotating Machinery

The sensor family is designed for machinery such as turbines, compressors, pumps, and fans, where shaft movement is an important condition-monitoring parameter.

Static and Dynamic Measurement

The PR6424 family supports both static displacement and dynamic shaft movement measurement within its specified operating range.

High Sensitivity

The typical sensitivity of 4 V/mm allows the measurement system to detect relatively small changes in the probe-to-target distance.

Industrial Construction

The stainless steel sensor sleeve and PTFE cable used in applicable configurations support industrial installation requirements. Exact materials and environmental limits should be confirmed for the specific suffix.

Integration with Machinery Monitoring Systems

When paired with a compatible converter, the sensor can provide measurement signals for machinery monitoring and protection equipment.

Support for Condition-Based Maintenance

Continuous shaft measurement provides information that maintenance teams can use to evaluate operating trends and investigate abnormal mechanical behavior.

Technical FAQs

1. What is the Epro PR6424/012-100?

The Epro PR6424/012-100 is a 16 mm eddy current sensor used for non-contact measurement of shaft displacement and vibration in rotating machinery.

2. What does the sensor measure?

Depending on the installation and signal-processing arrangement, it can be used to measure radial and axial shaft displacement, vibration, position, eccentricity, and speed/key-related signals.

3. What is the sensor head diameter?

The sensor head diameter is 16 mm.

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

The typical sensitivity is 4 V/mm when used with the specified reference target material and a compatible signal converter.

5. What is its measurement range?

The PR6424 family has a static measurement range of ±2.0 mm and a recommended dynamic measurement range of 0 to 1,000 μm peak-to-peak.

6. Does the sensor require physical contact with the shaft?

No. It uses an electromagnetic eddy current principle and measures the gap between the probe and a conductive target without touching the rotating shaft.

7. Which machines commonly use this sensor?

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

8. Does the PR6424/012-100 work without a signal converter?

The probe normally operates as part of a measurement chain with a compatible signal converter. The converter supplies and conditions the probe signal for use by monitoring equipment.

9. Can another PR6424 model replace the PR6424/012-100?

Not automatically. Different suffixes can identify different cable, connector, mounting, or electrical configurations. Verify the complete model number and converter compatibility before replacement.

10. What is the listed weight of the sensor?

The supplied listing weight is 0.2 kg. The actual weight may vary with cable length, armor, connector, and included accessories.

Procurement and Maintenance Recommendations

When purchasing the Epro PR6424/012-100, confirm the complete model number and inspect the product label. Because the PR6424 family includes multiple configurations, checking only the 16 mm sensor diameter is not sufficient to establish compatibility.

For replacement procurement, compare the existing probe’s cable length, cable armor, connector, mounting thread, and signal converter. Confirm whether the required extension cable or other accessories are included in the order.

For used or surplus equipment, request clear photographs of the sensor body, identification label, cable, and connector. Check the condition of the probe tip, cable insulation, threaded section, and connector contacts. Where possible, request functional test information or calibration details.

During routine maintenance, inspect the cable route and mounting arrangement for signs of abrasion, loosening, or mechanical damage. Keep the probe tip and target measurement area in suitable condition. Check the signal converter and monitoring system for stable output and correct scaling.

If abnormal readings occur, do not immediately assume that the probe has failed. Check the initial gap, target surface, cable integrity, converter compatibility, grounding, and monitoring-system configuration before replacing components.

Conclusion

The Epro PR6424/012-100 16 mm Eddy Current Sensor is designed for non-contact shaft displacement and vibration monitoring in critical rotating machinery. Its measurement principle allows it to detect changes in the distance between the probe tip and a conductive shaft surface without physical contact.

With a typical PR6424 family sensitivity of 4 V/mm, a static measuring range of ±2.0 mm, and a dynamic range of 0 to 1,000 μm peak-to-peak, the sensor can support machinery monitoring applications involving turbines, compressors, pumps, and fans.

For reliable operation, the probe must be installed with the correct air gap and paired with a compatible signal converter and cable arrangement. When sourcing a replacement, verify the complete PR6424/012-100 configuration rather than relying on the sensor diameter alone.