Product Overview

The EPRO PR6424/014-100 16 mm Eddy Current Sensor is a non-contact displacement sensor designed for monitoring the operating condition of critical rotating machinery. Part of the PR6424 sensor family from EPRO, now associated with Emerson, it is used to measure shaft vibration, displacement, position, eccentricity, and other dynamic movement parameters.

Unlike contact-based measurement devices, an eddy current sensor measures the distance between its sensing tip and a conductive target without physically touching the rotating shaft. This measurement principle makes it suitable for continuous monitoring in equipment where direct mechanical contact would be impractical or undesirable.

The PR6424 series is commonly applied to large rotating machines, including steam turbines, gas turbines, hydro turbines, compressors, pumps, and industrial fans. These machines often operate under demanding mechanical and thermal conditions. Continuous shaft monitoring can help operators identify abnormal movement, assess machine stability, and support predictive maintenance programs.

The PR6424/014-100 belongs to the 16 mm sensor family. The series specification identifies a typical sensitivity of 4 V/mm, a static measuring range of ±2.0 mm, and a nominal center air gap of approximately 2.7 mm. Its non-contact measurement capability makes it useful for both static shaft-position measurements and dynamic vibration monitoring when paired with a compatible signal converter and monitoring system.

This sensor is typically used as part of a complete measurement chain. The probe detects changes in the distance between its tip and the shaft surface, while a compatible signal converter processes the sensor signal for use by machinery protection or condition-monitoring equipment.

For replacement and procurement purposes, the complete model number, cable arrangement, connector type, mounting dimensions, and converter compatibility should be checked carefully. Sensors within the PR6424 family may share a 16 mm sensing diameter while having different cable or connection configurations.

Technical Specifications

Note: The technical values above are based primarily on published PR6424 family specifications. Exact cable length, connector arrangement, and temperature limits should be confirmed against the specific PR6424/014-100 order configuration.

Function and Working Principle

The PR6424/014-100 uses eddy current technology to measure the distance between the sensor tip and a conductive metal target. This measurement method is widely used in rotating machinery monitoring because it can detect small changes in shaft position without requiring physical contact.

1. Eddy Current Measurement Principle

The sensor contains an electrical coil near its sensing tip. When the associated electronic system excites the coil, it produces an alternating electromagnetic field.

When a conductive metal target, such as a steel shaft, enters this field, electrical currents known as eddy currents are induced in the target surface. These currents affect the electromagnetic characteristics of the sensor coil.

As the distance between the sensor tip and the target changes, the coil’s electrical response also changes. A compatible signal converter processes this variation and produces a measurement signal corresponding to the gap distance.

This allows the system to monitor shaft movement while the machine is operating.

2. Shaft Displacement Measurement

Shaft displacement monitoring is important for large rotating machines. Excessive shaft movement may indicate bearing wear, mechanical looseness, rotor instability, alignment problems, or other abnormal operating conditions.

The PR6424 sensor measures the relative distance between its sensing tip and the shaft surface. When installed at an appropriate measurement position, it can provide information about shaft movement in the selected direction.

The static measurement range of the PR6424 family is specified as ±2.0 mm. Actual measurement performance depends on the sensor configuration, target material, installation gap, and signal converter.

3. Shaft Vibration Monitoring

During normal operation, rotating shafts may experience small periodic movements. These movements can be caused by rotor imbalance, misalignment, bearing conditions, or mechanical resonance.

By measuring changes in the sensor-to-shaft gap over time, the monitoring system can evaluate dynamic shaft movement.

The PR6424 family supports dynamic measurement ranges up to 1,000 μm under its specified operating conditions. The resulting data can help maintenance personnel assess vibration behavior and identify changes that may require investigation.

4. Position and Eccentricity Measurement

The sensor can also be used to monitor shaft position and eccentricity.

Eccentricity refers to a condition in which the rotating shaft or rotor does not maintain a uniform geometric relationship with its intended rotational axis. Monitoring this behavior can provide useful information during startup, shutdown, and normal operation.

For machinery that requires continuous position monitoring, the PR6424 can form part of a measurement system that provides shaft-position information to the control room or machinery protection equipment.

5. Signal Conversion

The sensor itself is only one component of the measurement chain. A compatible signal converter is required to process the sensor’s electrical response into a usable output.

The converter must match the sensor’s electrical characteristics and configuration. Incorrect combinations may produce inaccurate readings, unstable signals, or measurement errors.

When replacing a probe, engineers should verify the complete sensor and converter combination rather than selecting a replacement based only on the 16 mm head diameter.

Role in Industrial Machinery Monitoring Systems

The PR6424/014-100 is commonly used as part of a machinery condition-monitoring arrangement. It provides measurement information that can be evaluated by monitoring equipment, protection systems, or plant automation platforms.

1. Turbine Protection

Steam and gas turbines operate at high rotational speeds and require reliable monitoring of rotor movement. Shaft vibration and displacement measurements can help identify abnormal mechanical behavior.

Multiple proximity sensors may be installed at different measurement positions to monitor shaft movement in radial and axial directions. The resulting signals can be used by a machinery protection system to evaluate operating conditions and generate alarms or protective actions when configured thresholds are exceeded.

2. Compressor Condition Monitoring

Industrial compressors are important in power generation, petrochemical processing, oil and gas production, and other continuous-process industries.

Shaft vibration and position measurements can provide information about rotor behavior, bearing performance, and mechanical stability. The PR6424 sensor family can be incorporated into suitable compressor monitoring systems.

3. Integration with Machinery Protection Equipment

The sensor works with a compatible signal converter and monitoring hardware. The monitoring system can process the measurement signal and make it available to operators or plant-control equipment.

Depending on the system architecture, the resulting data may be used for:

• Shaft vibration monitoring.
• Radial displacement measurement.
• Axial position monitoring.
• Rotor eccentricity evaluation.
• Speed or key-phase measurement where the installation supports the required arrangement.
• Alarm and shutdown logic through the machinery protection system.

The exact functions available depend on sensor placement, converter configuration, and monitoring-system capabilities.

4. Predictive Maintenance

Continuous monitoring can help maintenance teams identify changes in machine behavior before a serious failure occurs.

For example, a gradual increase in shaft vibration may indicate a developing mechanical issue. Changes in shaft position may also provide information about bearing or rotor conditions.

The PR6424 sensor contributes measurement data to this process. Maintenance decisions should be based on trends, operating conditions, other machine measurements, and appropriate diagnostic procedures rather than a single sensor reading.

Industrial Applications

The EPRO PR6424/014-100 is intended for non-contact measurement in industrial rotating machinery. Its 16 mm sensing head is suitable for applications where the measurement target and installation geometry meet the sensor’s requirements.

1. Steam Turbines

Steam turbines are used in power generation and industrial steam-driven processes. Their rotating assemblies require continuous monitoring to help maintain stable operation.

The PR6424 sensor can be installed near suitable shaft measurement locations to monitor radial vibration, axial displacement, and shaft position.

These measurements can help operators identify abnormal rotor behavior and support machinery protection strategies.

2. Gas Turbines

Gas turbines operate under demanding mechanical and thermal conditions. Rotor stability is important for equipment reliability and safe operation.

Non-contact eddy current sensors can provide shaft displacement and vibration measurements that support monitoring of the rotating assembly.

The PR6424 family is designed for critical turbomachinery monitoring applications, subject to the temperature and installation limits of the exact sensor configuration.

3. Hydro Turbines

Hydroelectric generating equipment uses large rotating assemblies that require monitoring of shaft movement and mechanical condition.

The sensor can be incorporated into a suitable monitoring arrangement to measure shaft displacement and vibration.

Long-term measurement trends can help maintenance teams assess changes in rotor behavior and investigate potential mechanical problems.

4. Industrial Compressors

Centrifugal and other large industrial compressors require stable rotor operation. Excessive vibration or shaft displacement may affect machine reliability and process availability.

The PR6424 sensor can support continuous shaft monitoring when installed with compatible signal-processing equipment.

5. Pumps and Fans

Large industrial pumps and fans are widely used in manufacturing, power plants, water treatment facilities, and process industries.

Shaft vibration monitoring can help detect mechanical changes such as imbalance, misalignment, or bearing-related problems. The sensor may be used where the shaft diameter, target material, and installation conditions satisfy its requirements.

Installation and System Integration

Correct installation is essential for reliable measurement. The sensor must be mounted at the intended measurement position, with the correct air gap and a suitable conductive target.

1. Confirm the Sensor Model

Before installation, verify the complete model number, including the /014-100 suffix.

Different PR6424 variants may have different cable lengths, connector arrangements, protective features, or mounting configurations. A sensor with the same 16 mm diameter is not necessarily a direct replacement.

Check the sensor label, cable identification, connector, and original equipment documentation.

2. Select the Correct Mounting Position

The sensor should be installed at a position that provides a stable and representative measurement of shaft movement.

The mounting arrangement must maintain the specified clearance around the sensing tip. Ferromagnetic materials near the active sensing area can affect the electromagnetic field and introduce measurement errors.

The PR6424 family uses an M18 × 1.5 threaded mounting arrangement. Confirm the exact mechanical drawing and mounting hardware before modifying the machine.

3. Set the Initial Air Gap

The sensor must be positioned at an appropriate distance from the shaft surface.

The PR6424 family specifies a nominal center air gap of approximately 2.7 mm. The correct setting procedure should follow the manufacturer’s installation instructions and the requirements of the associated converter.

An incorrect air gap may reduce the available measurement range or result in inaccurate readings.

4. Connect the Sensor to a Compatible Converter

The sensor must be connected to a compatible signal converter. Verify the probe model, cable arrangement, connector type, and converter specification.

Do not assume that every PR6424 sensor can be connected to every EPRO converter without checking compatibility.

Inspect the cable and connector for damage, contamination, or loose connections. Cable routing should also follow the manufacturer’s recommendations to reduce interference and prevent mechanical damage.

5. Configure the Monitoring System

After installation, configure the associated monitoring system according to the sensor and converter specifications.

The commissioning process should include:

• Checking the sensor identification.
• Verifying the electrical connection.
• Confirming the initial air gap.
• Checking the measurement output.
• Confirming the measurement direction and polarity.
• Establishing appropriate alarm limits.
• Recording baseline operating values.

Alarm thresholds should be selected according to the machine manufacturer’s recommendations, applicable standards, and the actual operating characteristics of the equipment.

6. Perform Functional Verification

After installation, compare the sensor output with the expected shaft position or known operating condition where practical.

Check for unstable signals, abnormal offsets, excessive noise, and unexpected changes during machine startup.

The sensor should not be returned to critical machinery service until the complete measurement chain has been verified.

Compatible System Components

The PR6424/014-100 normally operates as part of a complete eddy current measurement system.

These components are examples of a typical monitoring arrangement. They are not necessarily included with the sensor.

Alternative Models and Replacement Considerations

The PR6424 family contains multiple 16 mm sensor variants. A replacement should be selected according to the complete model number and electrical configuration.

A similar sensor diameter does not guarantee interchangeability. Before selecting an alternative, compare:

• Complete model and suffix.
• Sensor head diameter and mechanical dimensions.
• Thread type and mounting arrangement.
• Cable length and construction.
• Connector type and pin configuration.
• Compatible signal converter.
• Sensitivity and measuring range.
• Target material and shaft diameter.
• Operating temperature requirements.
• Monitoring-system calibration requirements.

For critical machinery, replacing a sensor with a different variant may require changes to mounting, cable routing, converter configuration, or monitoring-system calibration.

Key Advantages

Non-Contact Measurement

The sensor measures shaft movement without physical contact, avoiding mechanical wear at the sensing interface.

High Measurement Sensitivity

The PR6424 family specifies a typical sensitivity of 4 V/mm, supporting the measurement of relatively small changes in shaft-to-probe distance.

Static and Dynamic Monitoring

The series supports static displacement and dynamic vibration measurement, allowing one sensor technology to contribute to multiple machinery-monitoring functions.

Industrial Rotating Machinery Applications

The PR6424 family is designed for use with critical rotating equipment, including turbines, compressors, pumps, and fans.

Stainless-Steel Sensor Sleeve

The stainless-steel sleeve provides a robust mechanical construction for industrial probe installation.

PTFE Cable Construction

The specified sensor family uses PTFE cable insulation, supporting applications that require suitable thermal and mechanical performance within the model’s rated limits.

Integration with Machinery Monitoring Systems

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

Technical FAQs

1. What is the EPRO PR6424/014-100?

It is a 16 mm non-contact eddy current sensor used to measure shaft displacement, vibration, and position in rotating machinery.

2. What is the sensor head diameter?

The sensor head diameter is 16 mm.

3. What is the measurement principle?

It uses eddy current technology. An alternating electromagnetic field interacts with a conductive target, and changes in the sensor response are used to determine the distance between the probe and the target.

4. What is the typical sensitivity?

The PR6424 family specifies a typical sensitivity of 4 V/mm, with linearity of ≤ ±1.5% under the stated specification conditions.

5. What is the static measurement range?

The published PR6424 family specification gives a static measurement range of ±2.0 mm.

6. What is the nominal air gap?

The nominal center air gap is approximately 2.7 mm. The final installation setting must follow the manufacturer’s instructions and the compatible converter requirements.

7. What materials can the sensor measure?

The specified target material is ferromagnetic steel. Target material and shaft characteristics should be checked because they affect sensor calibration and measurement performance.

8. Does the sensor require a signal converter?

Yes. The sensor is normally used with a compatible signal converter that processes the probe signal for the monitoring system.

9. Where is the PR6424/014-100 commonly used?

It is suitable for monitoring applications involving steam turbines, gas turbines, hydro turbines, compressors, pumps, and fans, provided the installation meets the sensor’s specifications.

10. What is the weight of the sensor?

The supplied listing weight is 0.2 kg. The PR6424 family specification gives an approximate reference weight of 200 g for the sensor with a 1 m cable and without armor.

11. Can the PR6424/014-100 replace another PR6424 sensor?

Not automatically. Check the complete model suffix, cable length, connector, mounting arrangement, converter compatibility, and monitoring-system calibration requirements before substitution.

Procurement and Maintenance Recommendations

When purchasing the EPRO PR6424/014-100, confirm the full model number and inspect the sensor’s cable and connector configuration. The suffix is important because variants within the PR6424 family may differ in mechanical or electrical details.

For replacement projects, compare the original probe with the proposed unit. Verify the 16 mm sensing diameter, M18 × 1.5 mounting thread, cable arrangement, connector, and signal-converter compatibility.

For used or surplus equipment, request clear photographs of the sensor label, sensing tip, threaded body, cable, and connector. Check for physical damage, bent mounting components, cable cuts, corrosion, or signs of previous overheating.

During routine maintenance, inspect the probe mounting and cable routing. Avoid excessive cable bending, mechanical tension, or contact with moving equipment. Follow the manufacturer’s minimum bending-radius requirements for the exact cable construction.

After replacement, verify the initial air gap and confirm the sensor output using the associated converter and monitoring system. Record the baseline measurement values and update maintenance documentation.

Conclusion

The EPRO PR6424/014-100 16 mm Eddy Current Sensor is designed for non-contact monitoring of shaft displacement, vibration, and position in critical rotating machinery. Its eddy current measurement principle allows it to detect small changes in the distance between the sensing tip and a conductive shaft without physical contact.

With a 16 mm sensor head and PR6424 family specifications including 4 V/mm sensitivity and a ±2.0 mm static measurement range, it can contribute to machinery protection and condition-monitoring systems when paired with compatible signal-processing equipment.

For maintenance and procurement applications, verifying the complete model number, cable arrangement, connector, mounting dimensions, and converter compatibility is essential to ensure reliable replacement and system operation.