Product Overview

The Epro PR6424/106-100 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 PR6424 sensor family developed for industrial machinery protection and condition-monitoring applications.

The sensor uses eddy current technology to measure the distance between its sensing tip and a conductive metallic target. Changes in this distance produce corresponding changes in the sensor’s electrical characteristics. When connected to a compatible signal converter, these changes can be processed into measurement signals representing shaft displacement, vibration, and position.

The PR6424 series is commonly used in equipment such as steam turbines, gas turbines, hydro turbines, compressors, pumps, and industrial fans. These machines often operate under demanding mechanical and thermal conditions. Continuous monitoring of shaft movement can help maintenance teams identify abnormal operating behavior and assess equipment condition before a mechanical problem develops into a major failure.

The PR6424/106-100 has a nominal sensor head diameter of 16 mm. The PR6424 family offers a typical sensitivity of 4 V/mm, a static measurement range of ±2.0 mm, and a dynamic measurement range of 0–1,000 μm peak-to-peak. These characteristics make the sensor suitable for applications requiring non-contact monitoring of shaft movement and vibration.

The sensor is intended to operate as part of a complete measurement chain. Depending on the installation, this chain may include the probe, extension cable, signal converter, and machinery monitoring system. Correct matching of these components is essential for measurement accuracy and reliable operation.

For maintenance and replacement projects, the complete model designation should be checked carefully. Cable configuration, connector type, thread arrangement, and converter compatibility can vary among PR6424 variants.

Technical Specifications

Note: Electrical and environmental values are typical PR6424 family specifications. Confirm the exact PR6424/106-100 configuration, including cable, connector, mounting thread, and temperature rating, before installation or replacement.

Function and Working Principle

The PR6424/106-100 uses electromagnetic induction to detect changes in the distance between the sensor tip and a metallic target. Unlike contact-based measurement devices, it does not need to touch the rotating shaft.

1. Eddy Current Measurement Principle

The sensor generates an alternating electromagnetic field at its sensing tip. When a conductive metallic surface enters this field, eddy currents are induced in the target material.

The strength of these currents changes according to the distance between the sensor and the target. This influences the electrical impedance of the sensor coil.

A compatible signal converter processes the resulting electrical changes and produces an output corresponding to the measured gap. This allows the system to monitor shaft movement without physical contact.

2. Shaft Vibration Measurement

During normal operation, rotating machinery may experience small movements caused by mechanical vibration, imbalance, bearing conditions, or other operating factors.

The PR6424 sensor measures the changing distance between its tip and the shaft surface. The resulting signal can be used by a monitoring system to evaluate dynamic shaft displacement.

Continuous vibration measurements help operators identify changes in machinery behavior and investigate abnormal operating conditions.

3. Shaft Position Monitoring

The sensor can also measure static shaft displacement within its specified measurement range.

This function is useful for monitoring shaft position in turbines and other rotating machinery. Changes in axial or radial position may provide important information about mechanical clearances, bearing conditions, and equipment operating states.

4. Eccentricity and Speed-Related Monitoring

The PR6424 sensor family supports measurements associated with shaft eccentricity and speed/key applications when configured with suitable system components.

Eccentricity measurements can help identify uneven shaft geometry or movement during rotation. Speed-related measurements can support machinery monitoring and operating-condition analysis.

The exact measurement function depends on the sensor installation, target geometry, signal-processing configuration, and connected monitoring equipment.

5. Signal Conversion and Processing

The sensor probe is not a complete standalone monitoring system. Its electrical response must be processed by a compatible signal converter.

The converter establishes the appropriate operating conditions and translates the probe signal into a usable output. This output can then be connected to machinery protection equipment, condition-monitoring systems, or other compatible monitoring devices.

Correct probe, extension cable, and converter matching is essential to maintaining the specified sensitivity and measurement performance.

Role in Industrial Machinery Protection Systems

The PR6424/106-100 can serve as a measurement element in machinery protection and condition-monitoring installations. Its primary role is to provide information about shaft movement so that monitoring equipment can evaluate the mechanical condition of rotating machinery.

Turbine Monitoring

Steam, gas, and hydro turbines contain rotating assemblies that operate under substantial mechanical and thermal loads. Monitoring shaft vibration and position can help identify changes in rotor behavior.

A properly installed PR6424 measurement chain can provide signals for evaluating shaft displacement and vibration during normal operation and changing load conditions.

Compressor Monitoring

Industrial compressors are important components in chemical processing, petrochemical facilities, gas transportation, and manufacturing plants.

Monitoring shaft vibration and position helps maintenance teams observe changes in rotating assembly behavior. The sensor can be incorporated into a suitable monitoring arrangement to provide non-contact measurement data.

Pump Monitoring

Large industrial pumps may operate continuously in demanding process environments. Shaft vibration and displacement measurements can help identify abnormal mechanical behavior.

The sensor can support condition-monitoring strategies designed to reduce unexpected equipment interruptions.

Integration with Monitoring Systems

The sensor’s output is processed through a compatible converter before being connected to a monitoring or protection system.

Depending on the installation, measurement information may be used for:

• Continuous shaft vibration monitoring.
• Axial and radial displacement monitoring.
• Shaft position analysis.
• Eccentricity measurement.
• Machinery alarm and protection functions.
• Historical condition analysis and maintenance planning.

The final alarm thresholds and protection logic must be established according to the machinery manufacturer’s recommendations and the plant’s engineering standards.

Industrial Applications

1. Steam Turbines

Steam turbines operate at high rotational speeds and under demanding thermal conditions. Monitoring shaft vibration and displacement is important for evaluating rotor stability and mechanical behavior.

The PR6424 sensor can be installed near an appropriate shaft target to provide non-contact measurement signals for a compatible turbine monitoring system.

2. Gas Turbines

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

The sensor can support shaft vibration and position measurement when its environmental and mechanical ratings are appropriate for the installation.

3. Hydro Turbines

Hydro turbines operate in power-generation environments where shaft alignment, vibration, and mechanical movement are important maintenance considerations.

A suitable eddy current measurement system can provide information about rotor movement and help engineers assess changes in equipment condition.

4. Industrial Compressors

Large compressors are used in refineries, chemical plants, gas-processing facilities, and other continuous-process industries.

The PR6424 sensor can be used to monitor shaft movement in compatible compressor installations. Measurement trends can help maintenance teams investigate changes in vibration behavior.

5. Centrifugal Pumps

Large centrifugal pumps may operate continuously in water treatment, power generation, petrochemical, and manufacturing applications.

Non-contact shaft monitoring can provide useful information about vibration and displacement, supporting condition-based maintenance.

6. Industrial Fans

Large fans and blower systems are used in ventilation, combustion-air supply, cooling, and process exhaust applications.

Where the shaft geometry and installation requirements are suitable, the PR6424 measurement chain can contribute to machinery condition monitoring.

Installation and System Integration

Proper installation is essential for accurate measurement. The sensor must be positioned and configured according to the mechanical characteristics of the target shaft and the requirements of the complete measurement chain.

1. Verify the Sensor Model

Before installation, confirm the full model number PR6424/106-100. Do not assume that all PR6424 probes have identical cable arrangements, connectors, mounting dimensions, or converter compatibility.

Check the product label and applicable documentation to identify the correct configuration.

2. Inspect the Mounting Location

Select a mounting position that provides a stable relationship between the sensor tip and the shaft surface.

The installation should account for:

• Available mounting space.
• Shaft diameter and target material.
• Sensor clearance.
• Mechanical vibration at the mounting point.
• Temperature near the sensor.
• Cable routing and protection.

The PR6424 family is designed for reference measurements on ferromagnetic steel targets. Target material and surface condition can influence measurement performance.

3. Set the Initial Air Gap

The distance between the sensing tip and the shaft must be adjusted according to the applicable sensor and converter specifications.

The nominal center air gap for the PR6424 family is approximately 2.7 mm. The correct operating gap should be established using the manufacturer’s installation procedure and the compatible converter’s electrical output characteristics.

Incorrect positioning can reduce the available measurement range or result in inaccurate signals.

4. Connect the Extension Cable and Converter

The probe must be connected to a compatible extension cable and signal converter when required by the measurement configuration.

Verify the cable length, connector type, and electrical compatibility. Do not substitute an extension cable or converter based only on physical connector similarity.

The complete measurement chain should be treated as a calibrated system.

5. Protect and Route the Cable

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

Observe the specified minimum bending radius for the actual cable construction. Avoid pulling directly on the sensor connection during installation.

Where the installation is exposed to mechanical damage or harsh environmental conditions, use suitable cable protection.

6. Verify the Measurement Signal

After installation, check the sensor and converter output across the intended operating gap.

Confirm that the output changes consistently as the target position changes. Inspect the signal for abnormal noise, instability, or unexpected offsets.

Before returning machinery to service, verify the monitoring channel, alarm settings, and protection-system response according to the plant’s commissioning procedure.

Compatible System Components

A complete PR6424 measurement arrangement may include several components. Their exact selection depends on the sensor configuration and the requirements of the machinery monitoring system.

The components listed above are examples of a typical measurement chain. They are not necessarily supplied with the PR6424/106-100 sensor.

Alternative Models and Replacement Considerations

The PR6424 belongs to a broader family of Epro eddy current sensors. Other sensor models may have different measurement ranges, sensing diameters, and installation characteristics.

A replacement should not be selected solely because it belongs to the same sensor family. Before ordering, compare:

• Complete sensor model number.
• Sensor head diameter.
• Cable length and construction.
• Connector type.
• Mounting thread and mechanical dimensions.
• Sensitivity and linearity.
• Static and dynamic measurement ranges.
• Operating temperature.
• Target material and shaft diameter.
• Signal converter compatibility.
• Certification requirements for the installation area.

For critical turbine and compressor applications, replacing a probe with a different configuration may require recalibration and verification of the complete measurement channel.

Key Advantages

Non-Contact Measurement

The PR6424 sensor measures shaft movement without physical contact. This avoids mechanical contact between the probe tip and the rotating target during normal operation.

High-Resolution Displacement Monitoring

The PR6424 family provides a typical sensitivity of 4 V/mm and a static measurement range of ±2.0 mm, supporting precise shaft displacement measurements within the specified operating range.

Dynamic Vibration Measurement

The sensor can provide dynamic measurement signals for monitoring shaft vibration in compatible machinery protection systems.

Compact 16 mm Sensor Head

The 16 mm sensing head supports installation in machinery where mounting space and probe positioning are important considerations.

Industrial Machinery Applications

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

Temperature-Resistant Construction

The PR6424 family uses a stainless-steel sleeve and PTFE cable construction. The permitted operating temperature must be confirmed for the exact sensor variant.

Integration with Monitoring Systems

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

Technical FAQs

1. What is the Epro PR6424/106-100?

The Epro PR6424/106-100 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 nominal sensor head diameter is 16 mm. This dimension is important when checking mounting clearance and replacement compatibility.

3. What is the measurement principle?

The sensor uses electromagnetic induction. It generates an alternating electromagnetic field, and the presence of a conductive target changes the sensor coil’s electrical characteristics. A compatible converter processes this change into a measurement signal.

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

The PR6424 family has a typical sensitivity of 4 V/mm, equivalent to approximately 101.6 mV/mil, with linearity specified at approximately ±1.5%.

5. What is its static measurement range?

The typical static measurement range is ±2.0 mm. The actual usable range depends on the sensor-converter combination and the correct initial gap.

6. Can the PR6424/106-100 measure shaft vibration?

Yes. The PR6424 family is designed for dynamic shaft displacement and vibration measurements. The sensor must be installed with a compatible signal converter and monitoring channel.

7. Which types of machinery use this sensor?

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

8. Does the sensor work independently without a converter?

The probe is part of a measurement chain and normally requires a compatible signal converter to process its electrical response into a usable monitoring signal.

9. What is the weight of the PR6424/106-100?

The supplied product weight is 0.2 kg. This is consistent with the PR6424 family reference weight of approximately 200 grams for a sensor with a 1-meter cable and no armor. The exact supplied cable configuration may affect the final weight.

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

Confirm the complete model number, sensor diameter, cable length, connector, mounting thread, measurement range, sensitivity, converter compatibility, and environmental ratings. The complete measurement chain should be verified before commissioning.

Procurement and Maintenance Recommendations

When purchasing the Epro PR6424/106-100, verify the complete catalog number and inspect the product label. The PR6424 family contains multiple configurations, and differences in cable length, connector arrangement, and mechanical construction can affect compatibility.

For replacement projects, compare the existing sensor with the proposed unit before installation. Confirm that the signal converter supports the selected probe and that the measurement chain can maintain the required calibration.

For used or surplus sensors, inspect the sensing tip, threaded sleeve, cable insulation, connector, and visible mechanical condition. Request clear product photographs and available inspection or test information where possible.

During routine maintenance, check that the sensor mounting remains secure and that the probe-to-shaft gap has not changed. Inspect the cable for damage, excessive bending, or loose connections. Unusual signal fluctuations should be investigated by checking the probe, cable, converter, grounding, and target surface.

For critical rotating machinery, maintain records of probe locations, channel settings, calibration information, and replacement history. Consistent documentation makes it easier to compare measurement trends and diagnose changes in machine behavior.

Conclusion

The Epro PR6424/106-100 16 mm Eddy Current Sensor is designed for non-contact measurement of shaft displacement and vibration in critical rotating machinery. Its compact 16 mm sensing head and the PR6424 family’s typical 4 V/mm sensitivity and ±2.0 mm static measurement range make it suitable for a range of industrial machinery-monitoring applications.

When integrated with a compatible extension cable, signal converter, and monitoring system, the sensor can provide useful information about shaft position, vibration, and mechanical operating conditions. Accurate model verification, correct installation, and proper measurement-chain compatibility are essential for reliable performance in turbine, compressor, pump, and fan applications.