Product Overview

The Epro PR6424/103-021 16 mm Eddy Current Sensor is a non-contact displacement measurement device designed for monitoring the operating condition of critical rotating machinery. Manufactured under the EPRO product line associated with Emerson, the PR6424 series is widely used in machinery protection and condition monitoring applications involving turbines, compressors, pumps, fans, and other industrial rotating equipment.

Unlike contact-based measurement devices, an eddy current sensor measures the distance between its sensing tip and a conductive target without requiring physical contact. This measurement principle allows the sensor to monitor shaft movement continuously while the machine is operating.

The PR6424 series is designed for measuring radial and axial shaft displacement, vibration, shaft position, eccentricity, and speed-related signals. These measurements are important for identifying abnormal mechanical behavior, including excessive shaft movement, changes in bearing clearance, and vibration conditions that may indicate developing equipment problems.

The PR6424/103-021 belongs to the 16 mm sensor family. Its 16 mm sensing head is intended for installations where a larger probe diameter is appropriate for the required measurement range and machinery configuration.

The sensor works as part of a complete measurement system. A compatible extension cable and signal converter are normally required to transmit and condition the probe signal. The converter transforms changes in the sensor’s electromagnetic characteristics into an electrical output that can be processed by machinery monitoring equipment.

With a supplied weight of approximately 0.2 kg, the PR6424/103-021 is a compact sensing component suitable for integration into industrial machinery monitoring installations. Before replacement or installation, engineers should verify the exact probe variant, cable arrangement, connector type, and converter compatibility.

Technical Specifications

Note: Measurement values are representative PR6424 series specifications. Confirm the exact temperature range, cable length, connector, thread, and installation configuration for PR6424/103-021 before commissioning.

Function and Working Principle

The PR6424/103-021 operates using the electromagnetic eddy current principle. This technology is widely used in machinery monitoring because it allows accurate displacement measurements without direct mechanical contact.

1. Electromagnetic Field Generation

When the sensor is connected to a compatible signal converter, an alternating electrical signal energizes the sensing coil inside the probe.

This creates an electromagnetic field around the sensing tip. When a suitable conductive target, such as a ferromagnetic steel shaft, approaches the probe, the electromagnetic field interacts with the target surface.

The interaction generates eddy currents within the target material.

2. Distance Measurement

The strength of the eddy currents changes according to the distance between the sensor tip and the target surface.

As the shaft moves closer to or farther away from the probe, the electrical characteristics of the sensing circuit change. The measurement system detects these changes and converts them into a signal representing the distance between the probe and the shaft.

This makes it possible to monitor shaft displacement continuously without requiring mechanical contact.

3. Shaft Vibration Monitoring

Rotating shafts naturally experience some movement during operation. However, excessive vibration or displacement may indicate mechanical problems.

The PR6424 series can measure dynamic shaft movement within its specified measurement range. The resulting signal can be processed by machinery protection equipment to evaluate vibration behavior and identify abnormal operating conditions.

4. Position and Eccentricity Measurement

In addition to vibration, the sensor can measure static shaft position. This information is useful for evaluating shaft alignment, bearing clearances, and relative shaft movement.

Eccentricity measurements can help identify irregular shaft geometry or rotational movement that differs from the expected operating condition.

5. Signal Conversion

The probe does not normally operate as an independent industrial monitoring output device. It requires a compatible signal converter to condition the measurement signal.

The converter provides an electrical output that can be connected to a machinery monitoring system, protection rack, or other compatible monitoring equipment.

Correct matching between the sensor, extension cable, and converter is essential for maintaining measurement accuracy.

Role in Industrial Machinery Protection Systems

The Epro PR6424/103-021 plays an important role in monitoring the mechanical condition of rotating equipment. Its measurements can be used by machinery protection systems to detect changes in shaft behavior and support preventive maintenance.

Turbine Monitoring

Steam, gas, and hydro turbines operate under demanding mechanical conditions. Continuous shaft displacement and vibration monitoring help operators identify abnormal movement that may affect turbine reliability.

The PR6424 sensor can provide shaft-related measurement signals for compatible turbine monitoring systems.

Compressor Condition Monitoring

Industrial compressors are used in chemical processing, oil and gas facilities, refrigeration systems, and manufacturing plants.

Changes in shaft vibration or position may indicate developing mechanical problems. Continuous non-contact measurement helps maintenance teams evaluate operating conditions and identify changes that require further investigation.

Pump Protection

Large industrial pumps often operate continuously and are critical to production processes. Shaft displacement monitoring can support the detection of abnormal vibration and changes in mechanical operating conditions.

The sensor can be incorporated into a suitable pump monitoring arrangement when the probe installation and measurement range match the equipment design.

Fan and Blower Monitoring

Industrial fans and blowers may experience vibration caused by imbalance, misalignment, bearing deterioration, or other mechanical conditions.

Although the sensor must be selected according to the machinery configuration, non-contact measurement can provide useful information for monitoring shaft movement in appropriate installations.

Integration with Machinery Monitoring Equipment

The sensor’s conditioned signal can be connected to compatible monitoring equipment for processing, alarm generation, and machinery protection.

Depending on the system design, measurement data may also be made available to plant control systems for operational monitoring and maintenance analysis.

Industrial Applications

The PR6424/103-021 is intended for applications where reliable non-contact measurement of rotating machinery is required.

1. Steam Turbines

Steam turbines operate at high rotational speeds and require continuous monitoring of mechanical conditions. Shaft vibration and displacement measurements can help operators identify abnormal movement and evaluate turbine operating stability.

The PR6424 series provides a suitable sensing technology for compatible turbine shaft monitoring installations.

2. Gas Turbines

Gas turbines are commonly used in power generation and industrial drive systems. Their operating conditions require reliable monitoring of rotating components.

Non-contact eddy current sensors can measure shaft movement and provide information for machinery protection systems.

3. Industrial Compressors

Centrifugal and other industrial compressor systems often operate continuously in demanding environments.

Shaft displacement and vibration measurements help maintenance personnel evaluate mechanical behavior and identify potential problems before they develop into major equipment failures.

4. Industrial Pumps

Pumps used in chemical plants, power stations, water treatment facilities, and petrochemical installations may require continuous mechanical condition monitoring.

When installed in an appropriate measurement arrangement, the PR6424 sensor can monitor shaft movement without introducing mechanical contact with the rotating component.

5. Generators and Rotating Machinery

Generators and other large rotating machines require stable shaft operation to maintain reliable performance.

Non-contact displacement monitoring can provide useful information about shaft position and vibration, supporting machinery condition assessment and maintenance planning.

6. Power Generation Facilities

Power plants depend on turbines, generators, pumps, fans, and auxiliary rotating equipment. Monitoring sensors such as the PR6424 series can form part of a broader machinery protection strategy.

The measurement signals help operators understand machine behavior and respond to abnormal conditions.

Installation and System Integration

Correct installation is essential for obtaining stable measurements from the PR6424/103-021. The probe position, target material, measurement gap, cable arrangement, and converter compatibility all influence system performance.

1. Verify Sensor Compatibility

Before installation, confirm the complete model number and compare the replacement sensor with the existing probe.

Check the sensing head diameter, mechanical thread, cable length, connector arrangement, and compatible signal converter.

A sensor with the same 16 mm diameter may still have a different electrical or mechanical configuration.

2. Select the Correct Mounting Position

The probe should be installed according to the machinery manufacturer’s measurement arrangement.

The sensing tip must face a suitable conductive target surface. The mounting position should provide the required clearance and prevent interference with the rotating shaft during normal and abnormal operating conditions.

3. Set the Initial Air Gap

The PR6424 series has a nominal center air gap of approximately 2.7 mm under its specified measurement conditions.

The initial gap must be established according to the applicable sensor and converter documentation. Incorrect probe positioning may reduce measurement accuracy or cause the signal to operate outside its linear range.

4. Verify the Target Material

Eddy current sensors depend on the electrical and magnetic characteristics of the target material.

The PR6424 series uses ferromagnetic steel as its standard target reference. Differences in shaft material, surface condition, or geometry can affect measurement performance.

Verify that the actual target material matches the measurement system requirements.

5. Connect the Extension Cable and Converter

The probe should be connected using the compatible cable and signal converter specified for the measurement system.

Avoid assuming that connectors or cables from different sensor configurations are interchangeable. Incorrect combinations may cause signal errors or prevent the system from operating correctly.

6. Protect Cable Routing

The sensor cable should be routed away from sources of excessive heat, mechanical damage, and electrical interference.

Observe the specified minimum bending radius and avoid excessive tension at cable connections. Secure the cable so that vibration or movement does not damage the wiring.

7. Calibrate and Test the Measurement System

After installation, verify the probe gap, converter configuration, signal output, and measurement response.

Where required, compare the measurement output with known displacement references. Confirm that alarm and trip thresholds are configured according to the machinery protection requirements.

Document the final installation position and calibration settings for future maintenance.

Compatible System Components

The PR6424/103-021 is normally used as part of a complete eddy current measurement system.

The components listed above are examples of equipment used in PR6424 measurement systems. They should not be considered automatically included with the PR6424/103-021 sensor.

Alternative Models and Replacement Considerations

The PR6424 belongs to the EPRO 16 mm eddy current sensor family. Other variants may have different cable lengths, mounting arrangements, connector types, or other configuration details.

Before selecting an alternative, compare:

• Sensor head diameter.
• Probe mounting thread and insertion length.
• Cable length and cable construction.
• Connector type and wiring arrangement.
• Signal converter compatibility.
• Sensitivity and linear measurement range.
• Operating temperature limits.
• Target material and shaft diameter.
• Installation clearances and initial air gap.
• Machinery monitoring input requirements.

A replacement probe should not be selected by diameter alone. The complete measurement chain must be compatible to maintain reliable monitoring performance.

Key Advantages

Non-Contact Measurement

The PR6424 sensor measures shaft movement without requiring physical contact with the rotating target. This avoids mechanical contact between the probe tip and the monitored shaft 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 shaft position and displacement monitoring.

Dynamic Vibration Measurement

The sensor is designed to measure dynamic shaft movement and can be used in machinery vibration monitoring applications when connected to compatible signal-conditioning equipment.

Compact 16 mm Sensing Head

The 16 mm probe diameter supports installation in machinery monitoring arrangements designed for this sensor size.

Industrial Machinery Applications

The PR6424 family is suitable for measurement applications involving turbines, compressors, pumps, fans, and other rotating machinery.

Continuous Condition Monitoring

The sensor provides measurement information that can be processed by compatible monitoring equipment, supporting machinery condition assessment and maintenance planning.

Integration with EPRO Measurement Systems

The probe can be integrated with compatible extension cables and signal converters to form a complete eddy current measurement channel.

Technical FAQs

1. What is the Epro PR6424/103-021?

The Epro PR6424/103-021 is a 16 mm eddy current sensor designed for non-contact measurement of shaft displacement and vibration in industrial rotating machinery.

2. What is the main function of this sensor?

Its main function is to measure the distance between the probe tip and a conductive target. In machinery applications, this measurement can be used to monitor shaft vibration, radial and axial displacement, position, and eccentricity.

3. What is the sensor head diameter?

The sensor head diameter is 16 mm, consistent with the PR6424 product family.

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

The typical sensitivity is 4 V/mm, equivalent to approximately 101.6 mV/mil. The exact measurement performance depends on the complete sensor and converter configuration.

5. What is the static measurement range?

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

6. What is the dynamic measurement range?

The published PR6424 series specification gives a dynamic measurement range of 0–1,000 μm. The applicable operating range should be checked against the measurement system configuration.

7. Does the PR6424/103-021 require a signal converter?

Yes. The sensor is normally used with a compatible signal converter and the required cable arrangement. The converter conditions the probe signal for use by machinery monitoring equipment.

8. What materials can the sensor measure?

The PR6424 series uses ferromagnetic steel as its standard target material reference. Target material and surface characteristics should be checked before installation.

9. Where is the PR6424 series commonly used?

Typical applications include steam turbines, gas turbines, hydro turbines, compressors, pumps, fans, generators, and other industrial rotating machinery.

10. What should be checked before replacing the sensor?

Verify the complete model number, probe diameter, mounting dimensions, cable length, connector type, signal converter compatibility, target material, and initial air gap. A replacement must match the original measurement-system requirements.

Procurement and Maintenance Recommendations

When purchasing the Epro PR6424/103-021, begin by confirming the complete model designation on the existing sensor or equipment documentation. The PR6424 family contains multiple variants, and differences in cable length, connector configuration, and mounting details can affect compatibility.

For replacement projects, compare the original sensor with the proposed unit before installation. Check whether the required extension cable and converter are already available or need to be sourced separately.

For used or surplus sensors, inspect the sensing head, cable insulation, connector, mounting thread, and physical condition. Request clear product photographs and available inspection or test information.

During maintenance, periodically inspect the probe mounting arrangement and cable routing. Look for loose connections, damaged insulation, contamination, or signs of mechanical interference. Confirm that the probe gap and signal output remain within the measurement system’s specified operating conditions.

It is also useful to maintain records of probe locations, cable configurations, converter settings, and calibration results. These records help maintenance personnel identify the correct replacement and reduce troubleshooting time.

Conclusion

The Epro PR6424/103-021 16 mm Eddy Current Sensor is designed for non-contact shaft displacement and vibration measurement in critical industrial rotating machinery. Its measurement principle allows continuous monitoring without physical contact with the rotating target.

With a 16 mm sensing head and a supplied weight of approximately 0.2 kg, the sensor is suitable for integration into compatible EPRO machinery monitoring systems. Its typical PR6424 family specifications include 4 V/mm sensitivity, a ±2.0 mm static measurement range, and a 0–1,000 μm dynamic measurement range.

For industrial maintenance, replacement, and machinery protection projects, accurate identification of the complete sensor configuration is essential. Cable, connector, mounting, target material, and converter compatibility should all be checked before installation.