Product Overview

The Epro PR6424/016-000 16 mm Eddy Current Sensor is a non-contact displacement sensor designed for monitoring the operating condition of rotating machinery. It belongs to the PR6424 sensor family, developed for applications that require accurate measurement of shaft vibration, radial and axial displacement, position, eccentricity, and rotational speed-related parameters.

The PR6424 series is associated with EPRO machinery protection and condition-monitoring products, now part of Emerson’s machinery health portfolio. Its eddy current measurement technology allows the sensor to detect the distance between the probe tip and a suitable conductive target without physical contact. This makes it particularly useful for machinery where continuous shaft monitoring is required during operation.

The sensor has a nominal 16 mm sensing head and is designed for critical rotating equipment such as steam turbines, gas turbines, hydro turbines, compressors, pumps, and industrial fans. When installed with a compatible signal converter and monitoring system, it can provide measurement information for machinery protection, condition assessment, and predictive maintenance.

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 to 1,000 μm. These characteristics make it suitable for applications that require both shaft-position monitoring and dynamic vibration measurement.

The PR6424/016-000 model is identified as a 16 mm eddy current sensor. Its exact cable arrangement, connector configuration, probe length, and installation accessories should be verified against the complete product label and supplied documentation before ordering.

Technical Specifications

Note: The technical values above describe the PR6424 family. Confirm the exact electrical, mechanical, cable, and connector configuration of the PR6424/016-000 before installation or replacement.

Function and Working Principle

The PR6424/016-000 uses eddy current technology to measure the distance between the sensor tip and a conductive metal target. Unlike contact-based measurement devices, the probe does not need to touch the rotating shaft. This allows it to monitor shaft movement continuously without introducing mechanical contact between the sensor and the target surface.

1. Eddy Current Measurement

The sensor generates an electromagnetic field around its probe tip. When a suitable conductive target, such as a ferromagnetic steel shaft, enters this field, eddy currents are induced in the target material.

These currents affect the electromagnetic characteristics of the sensor. Changes in the distance between the probe and the target therefore produce corresponding changes in the sensor’s electrical response.

A compatible signal converter processes this response and provides a usable measurement signal for monitoring equipment.

2. Shaft Displacement Measurement

Shaft displacement monitoring helps identify changes in the position of a rotating shaft relative to the sensor mounting point.

The PR6424 family provides a typical static measurement range of ±2.0 mm. This capability can be used to monitor shaft position and detect movement that may be associated with bearing conditions, mechanical wear, thermal expansion, or changes in machine alignment.

The sensor’s actual measurement performance depends on correct installation, target material, probe gap, converter compatibility, and calibration.

3. Shaft Vibration Measurement

Rotating machinery can experience radial and axial movement during operation. Excessive shaft vibration may indicate mechanical problems such as imbalance, misalignment, looseness, or bearing-related deterioration.

The PR6424 series supports dynamic measurement from 0 to 1,000 μm. When connected to a compatible monitoring system, the sensor can provide vibration-related signals for machinery condition assessment.

4. Position and Eccentricity Monitoring

The sensor can also be used to monitor shaft position and eccentricity. Eccentricity describes the degree to which a rotating shaft or rotor deviates from its intended geometric center.

Changes in eccentricity can be relevant to machinery condition evaluation, particularly in turbines and other large rotating equipment.

Continuous position monitoring helps maintenance teams identify abnormal changes and investigate possible mechanical causes.

5. Signal Conversion

The sensor is normally used as part of a measurement system rather than as a standalone industrial output device.

A compatible EPRO signal converter, such as an appropriate CON-series unit, conditions the probe signal and provides an output suitable for machinery monitoring equipment.

The converter must match the probe’s electrical characteristics and configuration. Using an incompatible converter may result in incorrect measurements or unstable operation.

Role in Industrial Machinery Monitoring Systems

The PR6424/016-000 can be incorporated into machinery protection and condition-monitoring systems where continuous measurement of shaft movement is required.

Turbine Protection

Steam, gas, and hydro turbines contain high-speed rotating components that require continuous monitoring. Shaft vibration and displacement measurements can help identify abnormal operating conditions before they develop into more serious mechanical problems.

The PR6424 sensor family is designed for this type of critical turbomachinery application.

Compressor Condition Monitoring

Industrial compressors operate under changing load and process conditions. Shaft vibration and position measurements provide useful information about the mechanical condition of rotating assemblies.

When connected to a suitable monitoring system, the sensor can support condition-based maintenance and help maintenance personnel investigate abnormal vibration trends.

Pump Monitoring

Large industrial pumps are widely used in power generation, petrochemical processing, water treatment, and manufacturing. Continuous shaft monitoring can help identify changes associated with alignment, bearing condition, and mechanical stability.

The PR6424 sensor can be used where its measurement range and installation configuration are suitable for the pump design.

PLC and DCS Integration

A machinery monitoring system may exchange measurement values, alarm states, or diagnostic information with a PLC or distributed control system.

The PR6424 probe itself should not be treated as a conventional PLC analog transmitter. Its signal must first be processed by a compatible converter or monitoring interface. The available output type and system connection depend on the selected converter and monitoring hardware.

Industrial Applications

1. Steam Turbines

Steam turbines require reliable monitoring of shaft movement and vibration. Abnormal shaft behavior may be associated with rotor imbalance, bearing deterioration, thermal effects, or alignment problems.

The PR6424 sensor family provides non-contact measurement for monitoring radial and axial shaft displacement in suitable turbine installations.

2. Gas Turbines

Gas turbines operate at high speeds and under demanding thermal and mechanical conditions. Monitoring shaft position and vibration is important for evaluating rotor behavior and identifying abnormal operating trends.

The sensor’s non-contact design allows measurement without direct mechanical contact with the rotating shaft.

3. Hydro Turbines

Hydro turbines are used in power generation facilities where rotating equipment must operate reliably over extended periods. Shaft displacement and vibration monitoring can help maintenance teams evaluate mechanical stability and identify developing problems.

The PR6424 series can be used in suitable hydro-turbine monitoring arrangements.

4. Industrial Compressors

Centrifugal and other industrial compressors require stable rotor operation. Excessive vibration or changes in shaft position may indicate developing mechanical problems.

The sensor can provide measurement information for compressor protection and condition-monitoring systems when installed with compatible signal-processing equipment.

5. Industrial Pumps

Large process pumps may operate continuously in demanding environments. Shaft monitoring can provide useful information about mechanical behavior and support maintenance planning.

The sensor is suitable for applications where the probe’s dimensions, temperature range, measurement characteristics, and mounting arrangement meet the equipment requirements.

6. Industrial Fans

Large industrial fans are used in power plants, manufacturing facilities, and process industries. Monitoring shaft movement can help maintenance teams assess mechanical stability and detect abnormal vibration.

The PR6424 can be considered for suitable fan installations that require non-contact shaft measurement.

Installation and System Integration

Correct installation is essential for accurate measurement and reliable long-term operation.

1. Confirm Probe Compatibility

Before installation, verify the complete PR6424/016-000 model number and the associated cable and connector configuration.

Check that the probe is compatible with the selected signal converter. Do not assume that all PR6424 probes and CON-series converters can be freely interchanged without checking the manufacturer’s compatibility documentation.

2. Select the Correct Mounting Position

The probe must be mounted at the correct location relative to the shaft or target surface. The mounting arrangement should provide adequate mechanical stability and prevent unintended movement during machine operation.

The sensor tip must have sufficient clearance from surrounding metallic structures. Nearby conductive materials can affect the electromagnetic field and influence measurement accuracy.

3. Set the Initial Air Gap

The PR6424 family has a nominal center air gap of approximately 2.7 mm.

The actual installation gap must be established according to the applicable sensor and converter documentation. Incorrect probe positioning can cause inaccurate readings or move the measurement outside the intended linear operating range.

4. Verify the Target Material

The specified reference target material is ferromagnetic steel, with 42CrMo4 commonly used as the standard reference material.

Different target materials and surface conditions may influence the sensor’s measurement response. Confirm that the actual shaft material is suitable for the selected sensor system.

5. Protect the Cable and Connections

The sensor cable should be routed away from high-power conductors and sources of electrical interference where required. Avoid sharp bends, excessive pulling force, and mechanical damage.

Follow the manufacturer’s minimum bending-radius and connection requirements for the exact cable configuration. Ensure that connectors are clean, secure, and correctly installed.

6. Configure the Signal Converter

The compatible converter must be configured for the correct probe type and measurement arrangement. Verify sensitivity, output scaling, measurement direction, and the required monitoring parameters.

After installation, perform a calibration or functional verification according to the manufacturer’s instructions.

7. Test the Complete Monitoring Channel

A complete measurement channel includes the probe, cable, converter, and monitoring equipment. Testing only the sensor does not confirm that the entire measurement system is operating correctly.

Check the probe gap, cable continuity, converter status, signal stability, and monitoring-system response before placing the equipment into normal service.

Compatible System Components

The PR6424/016-000 is typically used with compatible signal-conditioning and machinery-monitoring equipment.

The components listed above describe a typical measurement arrangement. They are not necessarily supplied with the sensor.

Alternative Models and Replacement Considerations

The PR6424 belongs to the EPRO 16 mm eddy current sensor family. Other PR6424 configurations may have different cable lengths, probe dimensions, connectors, and installation characteristics.

When selecting a replacement, compare:

• Complete sensor model number and suffix.
• Sensor head diameter and probe length.
• Thread size and mounting arrangement.
• Cable length and cable construction.
• Connector type and pin configuration.
• Compatible signal converter.
• Sensitivity and measurement range.
• Target material and shaft dimensions.
• Operating temperature and environmental conditions.
• Required monitoring-system input characteristics.

A sensor with the same nominal 16 mm head diameter may still have a different electrical or mechanical configuration. Exact model matching is recommended for critical machinery protection channels.

Key Advantages

Non-Contact Measurement

The eddy current principle allows the sensor to monitor shaft movement without physical contact with the rotating target.

16 mm Sensor Head

The 16 mm sensing head is designed for suitable industrial machinery installations where a larger probe may not be appropriate.

Displacement and Vibration Monitoring

The PR6424 family supports both static position measurement and dynamic shaft vibration measurement.

High Measurement Sensitivity

The typical sensitivity of 4 V/mm supports accurate measurement of changes in the probe-to-target gap when used with the correct converter and calibration.

Industrial Turbomachinery Applications

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

Integration with Machinery Monitoring Systems

When paired with compatible signal-conditioning equipment, the sensor can provide measurement information for machinery protection and condition-monitoring systems.

Stainless Steel Construction

The sensor sleeve uses stainless steel, while the cable uses PTFE insulation. These materials are intended for demanding industrial measurement environments within the specified operating limits.

Technical FAQs

1. What is the Epro PR6424/016-000?

The PR6424/016-000 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 sensor head diameter is 16 mm.

3. What is the measurement principle?

It uses eddy current technology. The probe generates an electromagnetic field, and changes in the distance between the probe and a conductive target affect the sensor’s electrical response.

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

The typical sensitivity is 4 V/mm, with a specified linearity of up to ±1.5% under the stated measurement conditions.

5. What is the static measurement range?

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

6. What is the dynamic measurement range?

The documented dynamic measurement range is 0 to 1,000 μm.

7. Which machines can use this sensor?

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

8. Does the sensor connect directly to a PLC?

It is normally connected to a compatible signal converter or machinery monitoring system first. The processed output can then be integrated into a PLC or DCS, depending on the selected interface.

9. What material should the target shaft use?

The standard reference target is ferromagnetic steel, commonly specified as 42CrMo4. Confirm the actual target material against the sensor documentation.

10. What is the weight of the sensor?

The supplied product weight is 0.2 kg. The Emerson family specification sheet lists approximately 200 grams for the sensor with a 1-meter cable and without armor.

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

Verify the complete model number, probe dimensions, cable length, connector, signal converter compatibility, and measurement settings. Matching only the 16 mm diameter is not sufficient.

Procurement and Maintenance Recommendations

When purchasing the Epro PR6424/016-000, verify the complete catalog number and confirm that the supplied probe matches the configuration required by the existing machinery monitoring system.

Request clear photographs of the product label, probe body, cable, and connector. For replacement projects, compare the new sensor with the installed unit before removing the original probe. This is particularly important in turbine and compressor protection systems, where an incorrect probe or converter combination can compromise the measurement channel.

For routine maintenance, inspect the sensor cable for damage, check the connector condition, and confirm that the probe remains securely mounted. Review the measured gap and signal stability during scheduled machinery inspections.

If the monitoring signal becomes unstable, investigate the probe mounting, cable condition, connector contacts, converter compatibility, target material, and electrical interference. Do not assume that every abnormal reading indicates a defective sensor; problems elsewhere in the measurement channel can produce similar symptoms.

For critical machinery, maintain accurate records of sensor model numbers, installation positions, converter configurations, calibration information, and replacement history. These records help reduce troubleshooting time and improve maintenance consistency.

Conclusion

The Epro PR6424/016-000 16 mm Eddy Current Sensor is designed for non-contact measurement of shaft displacement, vibration, position, and eccentricity in industrial rotating machinery. Its 16 mm sensing head and the PR6424 family’s typical 4 V/mm sensitivity make it suitable for integration into appropriately configured machinery protection and condition-monitoring systems.

With a static measurement range of ±2.0 mm and a dynamic range of 0 to 1,000 μm, the PR6424 family supports monitoring applications involving turbines, compressors, pumps, and fans. For reliable operation, the sensor must be matched with the correct cable, signal converter, target material, and monitoring equipment.

When sourcing this model for maintenance or replacement, verify the complete catalog number and connection configuration to ensure compatibility with the installed measurement channel.