Product Overview

The Epro PR6424/106-030 16 mm Eddy Current Sensor is a non-contact displacement probe designed for monitoring the condition and operating behavior of industrial rotating machinery. Part of the PR6424 sensor family from EPRO, now associated with Emerson, this probe is used in machinery protection and condition-monitoring systems where accurate shaft movement measurements are essential.

Unlike contact-based measurement devices, an eddy current sensor measures the distance between its sensing tip and a conductive metallic target without physically touching the rotating surface. This makes it suitable for continuous monitoring of machinery operating at high speeds, including turbines, compressors, pumps, and industrial fans.

The PR6424 series is designed to measure radial and axial shaft displacement, shaft position, eccentricity, and vibration. These measurements help maintenance teams identify changes in machine behavior that may indicate bearing wear, shaft movement, rotor imbalance, or other developing mechanical problems.

The PR6424/106-030 has a 16 mm sensor head diameter. Its compact sensing head and threaded mounting arrangement support installation in suitable machinery-monitoring locations. The supplied product information lists a weight of approximately 0.2 kg.

The sensor is normally used as part of a complete measurement chain. A compatible EPRO signal converter or monitoring channel provides the necessary signal conditioning and measurement processing. The probe, extension cable, connector, converter, and monitoring system must be selected as a compatible combination.

For industrial users, the PR6424/106-030 is relevant to applications where continuous shaft displacement and vibration measurements contribute to equipment protection, maintenance planning, and operational reliability.

Technical Specifications

Note: Performance values are PR6424 family reference specifications. Confirm the exact cable length, connector arrangement, mounting dimensions, and environmental limits against the complete PR6424/106-030 configuration documentation.

Function and Working Principle

The PR6424/106-030 operates using the eddy current measurement principle. It generates an electromagnetic field at the sensing tip and detects changes in that field when a conductive metallic target moves relative to the probe.

This allows the sensor to measure shaft displacement without direct mechanical contact.

1. Electromagnetic Field Generation

An excitation signal is supplied to the probe through a compatible signal converter. The sensing coil inside the probe produces an electromagnetic field around the sensor tip.

When a conductive target, such as a suitable steel shaft, approaches the sensing area, electrical currents known as eddy currents are induced in the target surface.

The strength and characteristics of these currents depend on the distance between the sensor and the target.

2. Displacement Measurement

As the shaft moves closer to or farther away from the sensor, the electromagnetic interaction changes. The associated signal variation is processed by the compatible converter.

Within the specified linear measurement range, the resulting output can represent the relative distance between the probe tip and the target surface.

This principle allows the sensor to detect small changes in shaft position that may be difficult to identify through visual inspection or conventional contact measurement.

3. Shaft Vibration Monitoring

When a rotating shaft vibrates, its position relative to the stationary sensor changes continuously.

The probe detects these variations and provides measurement information that can be used to evaluate shaft vibration. Depending on the monitoring arrangement, measurements can help identify abnormal vibration amplitude, changes in rotor behavior, and developing mechanical faults.

For meaningful vibration analysis, probe positioning, target material, installation rigidity, and measurement-system configuration must all be considered.

4. Static Position Measurement

The PR6424 series also supports static displacement measurement within its specified range.

This capability is useful for monitoring shaft position, axial movement, and eccentricity. In rotating machinery, changes in static position may indicate mechanical clearance changes, bearing-related movement, or thermal effects.

5. Signal Conditioning

The probe is normally connected to a compatible EPRO converter or monitoring channel. The converter supplies the required excitation and processes the probe signal into a usable measurement output.

The sensor should not be treated as a standalone industrial transmitter. Correct operation depends on the compatibility of the probe, cable, converter, and monitoring equipment.

Role in Industrial Machinery Monitoring Systems

The PR6424/106-030 can form part of a continuous machinery-monitoring system. Its measurements provide information about the mechanical condition of rotating equipment and can be used by monitoring instruments, protection systems, and plant maintenance personnel.

Shaft Displacement Monitoring

Shaft displacement measurements help determine how far a rotating shaft moves relative to a fixed reference point.

In turbines and compressors, abnormal shaft movement may indicate changes in bearing clearance, rotor position, or mechanical alignment. Continuous monitoring helps operators identify changes before they develop into more serious equipment problems.

Vibration Monitoring

The probe can be installed to measure shaft vibration in an appropriate monitoring arrangement. Vibration information can be evaluated alongside other machine measurements, including bearing temperature, speed, and process conditions.

Using multiple measurement points can provide a more complete understanding of rotor behavior.

Equipment Protection

Machinery protection systems use sensor measurements to monitor whether equipment remains within defined operating limits.

When connected to a compatible monitoring system, the PR6424 sensor can contribute to alarm and trip strategies. Actual alarm thresholds, trip logic, and protective actions are determined by the monitoring system configuration.

Integration with Plant Automation

Machinery-monitoring equipment can exchange status and alarm information with a plant control system. This allows operators to view equipment conditions alongside process information.

The sensor itself performs the displacement measurement; the converter and monitoring equipment handle signal processing, evaluation, and system-level communication.

Industrial Applications

The PR6424/106-030 is intended for industrial rotating-machinery monitoring. Its non-contact measurement principle makes it useful in applications where shaft movement must be measured continuously without introducing mechanical contact.

1. Steam Turbines

Steam turbines operate under demanding mechanical and thermal conditions. Monitoring shaft vibration and displacement helps operators assess rotor behavior during startup, normal operation, and shutdown.

The PR6424 series can be used in suitable turbine monitoring arrangements to measure radial or axial shaft movement.

2. Gas Turbines

Gas turbines operate at high rotational speeds and require reliable machinery protection systems.

Non-contact displacement probes can provide information about rotor movement and vibration. These measurements help maintenance teams identify abnormal mechanical behavior and investigate changes in operating conditions.

3. Hydro Turbines

Hydro turbine installations require monitoring of rotating components and shaft movement. Depending on the machine design, displacement measurements can help evaluate rotor position, vibration, and mechanical stability.

The sensor can be considered for suitable monitoring points where the shaft material and installation geometry meet the probe requirements.

4. Industrial Compressors

Centrifugal and other rotating compressors may experience changes in shaft vibration due to imbalance, bearing wear, alignment issues, or operating-condition changes.

The PR6424 sensor can provide non-contact shaft displacement measurements for compatible compressor monitoring systems.

5. Industrial Pumps

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

Displacement measurements can help maintenance teams evaluate shaft movement and identify potential mechanical problems during operation.

6. Industrial Fans

Large fans and blower systems may operate continuously in manufacturing plants and process facilities. Shaft vibration monitoring can help detect developing imbalance or mechanical deterioration.

The probe can be used where the installation meets the sensor’s target-material and measurement requirements.

Installation and System Integration

Correct installation is essential for obtaining stable and meaningful measurement results. The sensor must be mounted securely and positioned according to the mechanical and electrical requirements of the complete EPRO measurement system.

1. Verify the Complete Model Number

Before installation, confirm that the probe is identified as PR6424/106-030.

Different PR6424 variants may have different cable lengths, connector arrangements, mounting details, or other configuration characteristics. A probe from the same product family should not automatically be considered interchangeable.

2. Confirm the Target Material

The eddy current measurement principle depends on the electrical and magnetic characteristics of the target material.

PR6424 family specifications reference ferromagnetic steel, with 42CrMo4 commonly used as the standard target material. If the shaft uses a different material or surface treatment, confirm the measurement-system compatibility before commissioning.

3. Prepare the Mounting Position

The sensor should be mounted securely with the correct alignment and mechanical clearance.

The probe tip must face the intended measurement surface without contacting the rotating shaft. Ensure that nearby metallic structures do not interfere with the sensing field.

For the PR6424 family, the sensor body uses an M18 × 1.5 mounting arrangement in documented configurations. Confirm the exact mounting dimensions for the supplied variant before machining or modifying a mounting bracket.

4. Set the Initial Air Gap

The distance between the sensor tip and the target surface is important for measurement accuracy.

The PR6424 family reference specification gives a nominal center air gap of approximately 2.7 mm. The actual installation gap should be established according to the applicable sensor and converter documentation.

An incorrect gap can reduce the available linear measurement range or cause inaccurate readings.

5. Connect the Compatible Converter

Connect the probe through the specified cable and connector arrangement to a compatible EPRO signal converter.

Check the complete measurement chain before energizing the system. Incorrect cable or converter combinations may cause unstable output or incorrect measurement values.

6. Route and Protect the Cable

The sensor cable should be routed away from high-power conductors and sources of electrical interference where practical.

Avoid excessive bending, twisting, crushing, or mechanical tension. Maintain the cable bending radius specified for the actual cable construction.

Where the installation is exposed to heat, vibration, or mechanical damage, use suitable cable protection and routing methods.

7. Perform Commissioning Checks

After installation, verify the probe gap, mounting stability, cable connection, and converter compatibility.

Check the measurement output under stationary conditions and compare it with the expected initial gap. During machine operation, verify that the measurement remains within the expected operating range.

Document the final installation position and converter settings to support future inspection and replacement work.

Compatible System Components

The PR6424/106-030 is generally used as part of a complete machinery-monitoring measurement chain.

These components are not necessarily included with the sensor. Confirm the complete bill of materials and compatibility requirements before ordering.

Alternative Models and Replacement Considerations

The PR6424 series includes different probe variants and configurations. Replacement selection should consider more than the 16 mm sensor head diameter.

Before selecting a replacement, compare:

• Complete probe model and suffix.
• Sensor head diameter.
• Mounting thread and mechanical dimensions.
• Cable length and cable construction.
• Connector type and pin arrangement.
• Compatible signal converter.
• Measurement sensitivity and linearity.
• Static and dynamic measurement ranges.
• Target material and shaft diameter.
• Operating temperature and environmental requirements.

A probe with the same nominal diameter may still be electrically or mechanically incompatible with the original installation.

Key Advantages

Non-Contact Measurement

The sensor measures shaft displacement without physical contact with the rotating surface. This avoids mechanical contact between the probe and shaft during normal operation.

High-Resolution Displacement Monitoring

The PR6424 family provides a reference sensitivity of 4 V/mm and a linearity specification of up to ±1.5%, supporting detailed shaft displacement measurement when correctly installed.

Vibration Measurement Capability

The sensor can be used in suitable monitoring arrangements to measure dynamic shaft movement and provide information for machinery condition assessment.

Compact 16 mm Sensor Head

The 16 mm sensing head supports installation in suitable machinery-monitoring locations where mounting space and probe access must be considered.

Continuous Machinery Monitoring

When integrated with a compatible converter and monitoring system, the sensor can provide continuous measurement information for critical rotating equipment.

Industrial Rotating Machinery Applications

The PR6424 family is designed for applications involving turbines, compressors, pumps, and fans, supporting machinery monitoring in demanding industrial environments.

Integration with Protection Systems

The probe can form part of a machinery protection measurement chain, allowing displacement information to be evaluated alongside other operating parameters.

Technical FAQs

1. What is the Epro PR6424/106-030?

The PR6424/106-030 is a 16 mm non-contact eddy current sensor designed for measuring shaft displacement and position in industrial rotating machinery.

2. What is the sensor head diameter?

The sensor head diameter is 16 mm, as specified in the supplied product description.

3. What does an eddy current sensor measure?

An eddy current sensor measures the distance between its sensing tip and a conductive target. In rotating machinery, this principle can be used to monitor shaft displacement, vibration, position, and eccentricity.

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

The PR6424 family reference specification gives a sensitivity of 4 V/mm, with linearity up to ±1.5%. Confirm the applicable specification for the complete sensor configuration.

5. What is the static measurement range?

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

6. What is the dynamic measurement range?

The documented PR6424 family dynamic measurement range is 0–1,000 μm. The usable range depends on the sensor, converter, target, and installation conditions.

7. Does the PR6424/106-030 require a signal converter?

Yes. The probe is normally used with a compatible EPRO signal converter or monitoring channel. The converter provides the excitation and signal-conditioning functions required for measurement.

8. What materials can be used as the measurement target?

The PR6424 family reference specification identifies ferromagnetic steel, with 42CrMo4 as a standard target material. Confirm compatibility when the shaft uses a different material or surface treatment.

9. Where is the PR6424/106-030 commonly used?

Typical applications include steam turbines, gas turbines, hydro turbines, compressors, industrial pumps, and fans. It is used where non-contact shaft displacement or vibration monitoring is required.

10. What should be checked before replacing this sensor?

Verify the complete model number, sensor diameter, mounting thread, cable length, connector, converter compatibility, measurement range, and target material. Matching only the PR6424 series name is not sufficient for confirming interchangeability.

Procurement and Maintenance Recommendations

When purchasing the Epro PR6424/106-030, verify the complete model number and inspect the physical condition of the sensing head, mounting thread, cable, and connector. The product suffix should be checked carefully because different PR6424 variants may have different cable and mechanical configurations.

For critical machinery applications, confirm that the replacement probe is compatible with the installed signal converter and monitoring channel. A probe with a matching diameter may not provide the correct electrical characteristics or connection arrangement.

For used or surplus equipment, request clear photographs of the product label, sensing head, cable, and connector. Confirm the cable length, physical condition, and any available test information before installation.

During routine maintenance, inspect the probe mounting, cable routing, connector condition, and measurement stability. Check for loose mounting hardware, damaged cable insulation, contamination around the sensing tip, and changes in the initial probe gap.

It is also useful to maintain records of the original probe position, air gap, converter configuration, and normal operating measurements. These records can help maintenance personnel identify changes and simplify future sensor replacement.

Conclusion

The Epro PR6424/106-030 16 mm Eddy Current Sensor is a non-contact measurement probe designed for shaft displacement, position, and vibration monitoring in industrial rotating machinery. Its 16 mm sensing head and eddy current measurement principle make it suitable for integration into compatible machinery-monitoring and protection systems.

With a PR6424 family reference sensitivity of 4 V/mm, a static measurement range of ±2.0 mm, and a dynamic range of 0–1,000 μm, the sensor can provide useful measurement information for turbines, compressors, pumps, and fans.

For reliable operation, the probe must be matched with the correct extension cable, signal converter, target material, and mounting arrangement. Verifying the complete model number and system compatibility is essential when purchasing or replacing the PR6424/106-030.