Product Overview

The EPRO PR6424/107-030 16 mm Eddy Current Sensor is a non-contact displacement measurement probe designed for monitoring the operating condition of critical rotating machinery. Part of the EPRO PR6424 sensor family from Emerson, it is used in machinery protection and condition-monitoring systems where accurate shaft movement measurements are essential for reliable equipment operation.

Unlike contact-based measurement devices, an eddy current sensor measures the distance between its sensing tip and a conductive target without physically touching the target surface. This makes it suitable for continuous monitoring of rotating shafts in turbines, compressors, pumps, fans, and other industrial machines.

The PR6424 series is particularly suited to applications involving relatively large rotating shafts. Its 16 mm sensing head is designed to measure radial and axial shaft displacement, vibration, shaft position, eccentricity, and speed-related signals. These measurements can help maintenance engineers identify abnormal mechanical conditions before they develop into more serious equipment problems.

The sensor operates using an electromagnetic measurement principle. An alternating electromagnetic field is generated at the probe tip. When a conductive metal target approaches the sensing surface, eddy currents are induced in the target. The resulting change in the probe’s electrical characteristics is used to determine the distance between the probe and the target.

For complete measurement performance, the sensor is normally used as part of a compatible measurement chain consisting of the probe, extension cable where required, signal converter, and monitoring equipment. Correct matching of these components is essential for maintaining measurement accuracy and reliable signal transmission.

The PR6424/107-030 is identified by its complete model number, which should be retained when sourcing replacement equipment. Cable configuration, connector arrangement, converter compatibility, and installation dimensions should be confirmed against the exact unit documentation before commissioning.

Technical Specifications

Note: Measurement values are PR6424 family reference specifications. Confirm the exact PR6424/107-030 cable arrangement, connector, temperature limits, and converter compatibility using the product label and applicable technical documentation.

Function and Working Principle

The PR6424/107-030 uses eddy current technology to measure the distance between the probe tip and a conductive target. Its non-contact design allows continuous monitoring without mechanical contact between the sensor and the rotating shaft.

1. Electromagnetic Field Generation

The sensor contains a coil inside its sensing head. When the compatible measurement system supplies the required excitation signal, the coil produces an alternating electromagnetic field around the probe tip.

This field extends toward the surface of the target shaft. The strength and characteristics of the field depend on the probe design, operating frequency, and measurement arrangement.

2. Eddy Current Formation

When the electromagnetic field reaches a conductive metal target, small circulating electrical currents known as eddy currents are induced in the target material.

These currents influence the electromagnetic field produced by the sensor. As the distance between the probe and the shaft changes, the induced currents also change.

The resulting electrical response provides the basis for determining the relative distance between the probe and the target surface.

3. Displacement Measurement

The PR6424 series converts changes in the probe-target relationship into a measurable electrical response through a compatible signal converter.

Within the specified linear measurement range, the output changes in proportion to the distance variation. This allows the monitoring system to determine shaft movement and displacement.

The PR6424 series has a typical sensitivity of 4 V/mm when used with its specified reference target material and compatible measurement chain.

4. Shaft Vibration Monitoring

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

The sensor detects these changes and provides a signal representing shaft movement. Monitoring equipment can analyze the signal to determine vibration amplitude, waveform characteristics, and changes in machine operating condition.

This information is useful for identifying developing mechanical problems such as imbalance, misalignment, looseness, and bearing-related abnormalities.

5. Position and Eccentricity Monitoring

In addition to dynamic vibration measurement, the sensor can measure static shaft position within its specified operating range.

This function is useful for monitoring axial movement, shaft eccentricity, and other displacement conditions. In turbine applications, position measurements can provide important information about rotor movement and mechanical clearances.

Role in Industrial Machinery Protection Systems

The EPRO PR6424/107-030 can form part of a machinery condition-monitoring system that continuously observes the mechanical behavior of rotating equipment.

Shaft Vibration Monitoring

Shaft vibration is an important indicator of rotating machinery condition. Excessive vibration may indicate mechanical imbalance, shaft misalignment, looseness, or other developing faults.

The PR6424 sensor provides non-contact displacement information that can be processed by compatible monitoring equipment. Engineers can use this information to evaluate machine behavior under different operating conditions.

Axial Position Measurement

Axial shaft movement can be important in turbines and large rotating machinery. Excessive axial displacement may indicate changes in thrust-bearing condition, rotor positioning, or other mechanical problems.

A correctly installed eddy current measurement system can continuously monitor axial shaft position and provide information for machinery protection.

Eccentricity Measurement

Shaft eccentricity refers to the variation in the distance between the shaft surface and a fixed reference point during rotation.

By monitoring the shaft’s relative position, the sensor can help identify eccentricity and changes in rotor geometry or mechanical condition.

Speed and Keyphasor-Related Monitoring

Eddy current measurement systems can also support speed-related and rotational reference measurements when configured with suitable targets and monitoring equipment.

These signals may be used to support vibration analysis, phase measurements, and rotational behavior assessment. The exact function depends on the target arrangement and the connected monitoring system.

Industrial Applications

The PR6424/107-030 is intended for applications where non-contact shaft displacement and vibration measurement are required. Its measurement principle makes it suitable for critical rotating equipment operating continuously in industrial environments.

1. Steam Turbines

Steam turbines operate under high mechanical loads and elevated temperatures. Continuous shaft vibration and position monitoring can help operators identify changes in rotor behavior.

The PR6424 series is designed for critical turbomachinery applications and can be used in suitable steam turbine monitoring arrangements. Probe placement and temperature exposure must follow the exact sensor configuration requirements.

2. Gas Turbines

Gas turbines require reliable monitoring because mechanical abnormalities can affect operating stability and equipment availability.

Eddy current sensors can measure shaft displacement and vibration without contacting the rotating surface. The resulting signals can be integrated into a compatible turbine monitoring system.

3. Hydro Turbines

Hydroelectric generating equipment uses large rotating assemblies that require continuous condition monitoring.

The PR6424 series can support shaft vibration and position measurement in suitable hydro turbine installations. These measurements help maintenance teams evaluate rotor behavior and identify abnormal movement.

4. Industrial Compressors

Centrifugal and other large industrial compressors operate at high rotational speeds and often serve critical process functions.

Non-contact shaft displacement sensors can monitor vibration and shaft position, providing useful information for condition-based maintenance and machinery protection.

5. Industrial Pumps

Large process pumps and other critical pumping equipment may experience vibration caused by hydraulic conditions, mechanical wear, or alignment problems.

The sensor can provide shaft movement information when installed as part of a compatible monitoring system.

6. Industrial Fans

Large industrial fans used in power generation, chemical processing, and manufacturing facilities may require continuous vibration monitoring.

Eddy current measurement provides a non-contact method of observing shaft movement in applications where the target material and mechanical arrangement are suitable.

Installation and System Integration

Correct installation is essential for reliable measurement. The probe must be positioned appropriately relative to the target shaft, and the complete measurement chain must be configured according to the manufacturer’s requirements.

1. Verify Sensor Compatibility

Before installation, confirm the complete model number, cable configuration, connector arrangement, and required signal converter.

The PR6424 series contains different configurations. A probe with a similar diameter may have different cable lengths, mounting arrangements, or converter requirements.

Do not assume that all PR6424 probes are interchangeable without checking the complete ordering code.

2. Select an Appropriate Mounting Position

The probe should be installed at a suitable measurement location where the sensing tip faces the intended shaft target.

The mounting arrangement must provide sufficient mechanical stability and maintain the required probe-to-target distance.

For shaft vibration measurement, probe orientation and location should be selected according to the machinery monitoring design.

3. Set the Initial Air Gap

The distance between the sensor tip and the target surface is an important installation parameter.

The PR6424 series has a nominal center air gap of approximately 2.7 mm under its specified reference conditions. The actual setup procedure should follow the applicable sensor and converter documentation.

An incorrect initial gap may cause the system to operate outside its linear measurement range and reduce measurement accuracy.

4. Check Target Material

The PR6424 series uses ferromagnetic steel as its standard reference target material, with 42CrMo4 commonly used for calibration.

Target material affects the sensor’s electromagnetic response. If the actual shaft material differs from the specified reference material, engineers should confirm whether an alternative calibration or measurement arrangement is required.

5. Route and Protect the Cable

The sensor cable should be routed carefully to avoid excessive mechanical stress, sharp bends, vibration damage, and contact with hot surfaces beyond its permitted temperature range.

Use the correct cable configuration and connector arrangement for the installed probe. Cable extensions should be matched to the sensor and converter as specified by the manufacturer.

6. Connect the Signal Converter

The sensor should be connected to a compatible signal converter. The converter processes the probe response and provides a usable output for the machinery monitoring system.

The probe, extension cable, and converter must be treated as a coordinated measurement chain. Mixing incompatible components can affect calibration, sensitivity, and signal stability.

7. Verify the Measurement System

After installation, check the probe gap, cable connections, converter configuration, and monitoring-channel settings.

Verify that the measured output responds correctly to changes in target distance. Record the initial readings and configuration details so that future maintenance personnel can compare operating trends and identify abnormal changes.

Compatible System Components

The PR6424/107-030 should be used with compatible components designed for the PR6424 measurement system.

A complete measurement installation requires more than the probe alone. Confirm which cables, converters, mounting accessories, and monitoring modules are included in the supplied equipment.

Alternative Models and Replacement Considerations

The PR6424 series includes multiple probe configurations. When selecting a replacement, engineers should compare the complete model number and measurement-chain requirements rather than relying only on the 16 mm sensor diameter.

Before selecting an alternative, compare:

• Sensor head diameter.
• Complete probe model and suffix.
• Static and dynamic measurement ranges.
• Sensitivity and linearity.
• Probe mounting thread and dimensions.
• Cable length and cable construction.
• Connector type and arrangement.
• Signal converter compatibility.
• Target material and calibration requirements.
• Operating temperature and environmental conditions.

A replacement probe should be evaluated as part of the entire measurement chain. A sensor with a similar appearance may not provide the same output characteristics or compatibility.

Key Advantages

Non-Contact Measurement

The sensor measures shaft displacement without physically touching the rotating surface. This reduces mechanical wear at the sensing interface and supports continuous monitoring.

16 mm Sensing Head

The PR6424 series uses a 16 mm sensor head designed for measurement applications involving relatively large rotating shafts.

Vibration and Displacement Monitoring

The sensor can support both dynamic shaft vibration measurement and static displacement monitoring within its specified measurement range.

High Measurement Sensitivity

The series reference sensitivity of 4 V/mm allows small changes in probe-to-target distance to produce measurable electrical output changes.

Industrial Machinery Applications

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

Stainless Steel Construction

The PR6424 series uses a stainless steel sleeve and PTFE cable construction, supporting use in demanding industrial measurement environments within the specified operating limits.

Integration with Machinery Monitoring Systems

When combined with a compatible extension cable, signal converter, and monitoring equipment, the sensor can form part of a continuous machinery condition-monitoring system.

Technical FAQs

1. What is the EPRO PR6424/107-030?

The EPRO PR6424/107-030 is a 16 mm eddy current sensor designed for non-contact measurement of shaft displacement, vibration, position, and eccentricity in industrial rotating machinery.

2. What is the measurement principle?

It operates using electromagnetic induction. The probe generates an alternating electromagnetic field, which induces eddy currents in a conductive target. Changes in the probe-to-target distance affect the electrical response, allowing the system to measure displacement.

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 PR6424 series has a typical sensitivity of 4 V/mm when used with its specified reference target material and compatible measurement chain.

5. What is the static measurement range?

The series static measurement range is ±2.0 mm.

6. Can the sensor measure shaft vibration?

Yes. The PR6424 series is designed for dynamic shaft displacement and vibration measurement. Its dynamic measurement range is specified as 0–1,000 μm peak-to-peak under the applicable reference conditions.

7. Which materials can be used as measurement targets?

The standard reference target material is ferromagnetic steel, specifically 42CrMo4. Different target materials may affect the measurement response and should be evaluated before use.

8. Does the sensor need a signal converter?

A compatible signal converter is normally required to process the probe signal and provide the appropriate output for the machinery monitoring system. The probe, cable, and converter must be compatible.

9. Where is the PR6424 sensor commonly used?

Typical applications include steam turbines, gas turbines, hydro turbines, compressors, industrial pumps, and large fans. It is particularly relevant to machinery where continuous shaft vibration and position monitoring are required.

10. What should be checked before replacing the PR6424/107-030?

Verify the complete model number, probe dimensions, mounting thread, cable length, connector arrangement, measurement range, and signal converter compatibility. The replacement should match the existing monitoring system’s requirements.

Procurement and Maintenance Recommendations

When purchasing the EPRO PR6424/107-030, begin by checking the complete model number on the existing probe or equipment documentation. The PR6424 family includes multiple configurations, and differences in cable length, connectors, and mounting arrangements can affect installation compatibility.

For replacement projects, confirm whether the product is supplied as a probe only or as part of a complete measurement arrangement. Check the cable condition, connector integrity, sensor sleeve, threaded mounting section, and any included accessories.

During maintenance, inspect the probe for physical damage, contamination, loose mounting hardware, and cable deterioration. Ensure that the sensing tip remains correctly positioned and that the probe-to-target gap is within the required operating range.

It is also important to verify the signal converter and monitoring-channel configuration. Changes to the probe, extension cable, or converter may require calibration checks and adjustments to the monitoring system.

For critical machinery, maintain records of baseline vibration and shaft-position readings. Comparing current measurements with established operating trends can help identify developing mechanical problems and support condition-based maintenance planning.

Conclusion

The EPRO PR6424/107-030 16 mm Eddy Current Sensor is designed for non-contact measurement of shaft displacement and vibration in industrial rotating machinery. As part of the Emerson EPRO PR6424 family, it supports monitoring applications involving turbines, compressors, pumps, fans, and other critical equipment.

With a 16 mm sensing head, a typical series sensitivity of 4 V/mm, and a static measurement range of ±2.0 mm, the PR6424 family provides measurement capabilities for machinery condition-monitoring and protection systems.

For procurement and replacement, the complete model number and measurement-chain compatibility should always be checked. Correct probe installation, target material selection, cable matching, and signal converter configuration are essential for achieving reliable measurement performance.