Product Overview

The EPRO PR6424/012-030 16 mm Eddy Current Sensor is a non-contact displacement measurement probe designed for monitoring the condition and operating behavior of critical rotating machinery. It belongs to the PR6424 sensor family, developed for applications that require accurate measurement of shaft vibration, radial and axial displacement, shaft position, eccentricity, and rotational speed.

Manufactured under the EPRO product line associated with Emerson, the PR6424 series is used in machinery protection and condition-monitoring systems. Typical applications include steam turbines, gas turbines, hydro turbines, compressors, pumps, fans, and other rotating equipment where shaft movement can provide important information about machine condition.

Unlike contact-based measurement devices, an eddy current sensor measures the distance between its probe tip and a conductive target without physically touching the rotating shaft. This non-contact operating principle allows the sensor to monitor dynamic shaft movement while avoiding mechanical contact with the measurement surface.

The PR6424 series uses a 16 mm sensor head and is designed for machinery with relatively large shaft diameters. Its measurement performance makes it suitable for monitoring applications where small changes in shaft position and vibration need to be detected and transmitted to a machinery protection or monitoring system.

The PR6424/012-030 should be identified by its complete catalog number when ordering replacement equipment. Different PR6424 variants may have different cable lengths, connector arrangements, mounting configurations, and signal-converter compatibility. These details should be verified before selecting accessories or integrating the sensor into an existing monitoring system.

Technical Specifications

Note: The table combines the supplied listing data with published PR6424 family specifications. Confirm the exact temperature rating, cable configuration, and converter compatibility for PR6424/012-030 before installation.

Function and Working Principle

The PR6424/012-030 uses the eddy current measurement principle to detect changes in the distance between the sensor tip and a conductive metal target. The probe generates an electromagnetic field, and the presence of a nearby conductive surface changes the electrical characteristics of the sensor circuit.

These changes are processed by a compatible signal converter to produce a measurement signal representing the distance between the probe and the target.

1. Non-Contact Displacement Measurement

The sensor is installed near the rotating shaft with a carefully adjusted measurement gap. As the shaft moves, the distance between its surface and the probe tip changes.

The sensor detects these variations without making physical contact with the shaft. This makes it suitable for continuous monitoring of rotating machinery where contact-based measurement could cause wear or interfere with machine operation.

2. Eddy Current Detection

An alternating electrical signal in the probe coil produces an electromagnetic field around the sensor tip. When a conductive target approaches the probe, eddy currents are generated in the target surface.

These currents influence the probe’s electrical impedance. The measurement electronics use this change to determine the distance between the probe and the target.

The measurement depends on the electrical and magnetic characteristics of the target material. For this reason, the sensor must be calibrated and configured for the specified target material and measurement system.

3. Shaft Vibration Monitoring

When a rotating shaft vibrates, its position relative to the stationary sensor changes. The PR6424 detects these movements and provides a signal that can be used to evaluate shaft vibration.

In machinery monitoring systems, vibration measurements can help identify abnormal operating conditions such as imbalance, misalignment, looseness, and changes in bearing behavior.

The sensor itself measures displacement. Detailed fault diagnosis requires the monitoring system to analyze the measurement together with operating speed, machine configuration, and other available data.

4. Shaft Position and Eccentricity Measurement

The PR6424 can also be used for static shaft-position measurements. These measurements help operators and maintenance engineers observe changes in shaft position relative to the machine housing.

Eccentricity monitoring is particularly relevant during startup, shutdown, and low-speed operation, when the shaft’s position may change due to thermal effects or mechanical conditions.

5. Signal Conversion

The probe is normally part of a complete measurement chain consisting of a sensor, the appropriate extension cable, and a compatible signal converter.

The converter processes the probe signal and provides an output suitable for the connected machinery monitoring or protection system. The exact output range and electrical interface depend on the converter model.

A sensor should not be treated as a standalone standard 4–20 mA transmitter unless the complete measurement system specifically provides that output.

Role in Industrial Machinery Protection Systems

The PR6424/012-030 can serve as a sensing element in machinery condition-monitoring and protection systems. Its measurements help monitoring equipment evaluate shaft movement and identify deviations from established operating conditions.

Turbine Monitoring

Steam and gas turbines operate at high rotational speeds and require continuous monitoring of important mechanical parameters. Shaft vibration and displacement measurements help operators assess the mechanical condition of the rotor and related components.

The PR6424 series is designed for this type of critical rotating machinery application.

Compressor Protection

Industrial compressors are used in oil and gas facilities, chemical plants, power stations, and manufacturing operations. Changes in shaft vibration or position may indicate developing mechanical problems.

A suitable eddy current measurement system can provide continuous displacement information for compressor monitoring and protection.

Pump Monitoring

Large industrial pumps may experience changes in shaft position and vibration due to bearing wear, hydraulic conditions, alignment problems, or mechanical damage.

Non-contact displacement measurement can provide useful information for maintenance teams responsible for pump reliability.

Integration with Monitoring Systems

The sensor’s output is processed by a compatible signal converter and then connected to the appropriate machinery monitoring or protection equipment.

The final system may provide measurement values, alarm thresholds, and protective shutdown functions. The sensor alone does not perform the complete machinery protection function; that depends on the connected monitoring hardware and its configuration.

Industrial Applications

The PR6424/012-030 is intended for industrial applications where continuous, non-contact measurement of shaft movement is required.

1. Steam Turbines

Steam turbines are used in thermal power plants, industrial power-generation facilities, and large process installations. Their rotating shafts require reliable monitoring to help detect abnormal vibration and displacement.

The PR6424 sensor can be used as part of a monitoring arrangement for observing radial and axial shaft movement.

2. Gas Turbines

Gas turbines operate under demanding mechanical and thermal conditions. Continuous monitoring of shaft vibration and position is important for evaluating machine behavior and supporting maintenance decisions.

An appropriately installed PR6424 measurement system can provide displacement data for turbine condition monitoring.

3. Hydro Turbines

Hydroelectric generating equipment uses large rotating assemblies that require monitoring during normal operation and changing load conditions.

Non-contact displacement sensors can help monitor shaft movement and provide information for machinery maintenance and protection systems.

4. Industrial Compressors

Compressors used in chemical processing, petrochemical production, and gas transportation often operate continuously. Shaft displacement and vibration measurements can help identify changes in mechanical condition.

The PR6424 series is designed for critical rotating equipment applications of this type.

5. Industrial Pumps

Large pumps are widely used in water treatment, power generation, oil and gas, and chemical processing. Monitoring shaft movement can help maintenance personnel evaluate the condition of bearings, couplings, and rotating assemblies.

6. Industrial Fans

Large ventilation and process fans may operate continuously in power plants, steel mills, cement factories, and manufacturing facilities.

A suitable displacement monitoring system can provide additional information about shaft movement and mechanical stability.

Installation and System Integration

Correct installation is essential for obtaining reliable measurement results. The sensor’s mounting position, air gap, target material, and cable arrangement all influence measurement performance.

1. Confirm the Sensor Configuration

Before installation, verify the complete PR6424/012-030 model number and compare it with the existing sensor specification.

Check the cable length, connector type, mounting thread, sensor length, and compatible signal converter. A sensor from the same PR6424 family may not automatically have the same cable or converter configuration.

2. Select the Correct Mounting Position

Install the probe in the specified mounting location so that its sensing tip faces the intended shaft measurement surface.

The mounting arrangement should provide sufficient mechanical stability and prevent the probe from moving during machine operation. Follow the manufacturer’s installation guidance for the required clearances and shaft geometry.

3. Set the Measurement Gap

The nominal center air gap for the published PR6424 series specification is approximately 2.7 mm.

The actual installation gap should be adjusted according to the applicable sensor and converter documentation. Incorrect positioning can reduce measurement accuracy or cause the system to operate outside its linear range.

4. Verify the Target Material

The PR6424 specification identifies ferromagnetic steel as the standard target material, with 42CrMo4 as a reference material.

Different target materials may produce different measurement characteristics. Confirm that the shaft material is compatible with the sensor calibration and measurement system.

5. Connect the Cable and Signal Converter

The sensor must be connected to the appropriate extension cable and signal converter according to the system design.

Check the connector condition, cable continuity, insulation, and routing. Avoid routing sensitive sensor cables alongside high-voltage motor supply cables where electromagnetic interference could affect the measurement signal.

6. Calibrate and Test the Measurement System

After installation, confirm the initial air gap and verify the output signal across the intended measurement range.

Compare the readings with known shaft positions or approved calibration references where applicable. Record the initial operating values to support future condition comparisons.

7. Connect to the Machinery Monitoring System

Connect the converter output to the designated monitoring input. Configure measurement scaling, alarm thresholds, and any required protective functions according to the machinery protection system documentation.

Before returning the machine to service, verify that the displayed values, alarm responses, and signal behavior are consistent with the expected operating conditions.

Compatible System Components

A complete PR6424 measurement installation generally requires more than the sensor probe alone. The following components may be used depending on the monitoring-system design.

The components above are examples of equipment used in PR6424 measurement systems. They are not automatically included with the PR6424/012-030 sensor. Confirm the exact converter and cable combination before ordering.

Alternative Models and Replacement Considerations

The PR6424 family includes multiple probe configurations. Replacement selection should consider the complete model number rather than the 16 mm sensor diameter alone.

Before selecting a replacement, compare:

• Complete sensor catalog number.
• Probe head diameter and physical length.
• Mounting thread and installation arrangement.
• Integrated cable length and cable type.
• Connector type and termination.
• Compatible signal converter.
• Measurement range and sensitivity.
• Target material and shaft diameter.
• Operating temperature and environmental limits.
• Existing monitoring-system input configuration.

A sensor with the same nominal diameter may still have a different electrical or mechanical configuration. Replacement work should be based on the original system documentation and verified compatibility.

Key Advantages

Non-Contact Measurement

The eddy current operating principle allows the sensor to measure shaft movement without physically touching the rotating surface. This is suitable for continuous monitoring applications.

Shaft Vibration Monitoring

The PR6424 series can measure dynamic shaft displacement and provide information for rotating machinery condition monitoring.

Static Position Measurement

The sensor can also measure changes in shaft position, supporting monitoring of axial and radial displacement.

Industrial Machinery Applications

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

High Measurement Sensitivity

The published series specification gives a sensitivity of 4 V/mm with linearity of up to ±1.5%, subject to the specified measurement system and installation conditions.

Integration with Machinery Monitoring Systems

When paired with a compatible extension cable and signal converter, the sensor can provide measurement information to industrial machinery monitoring and protection equipment.

Compact 16 mm Sensor Head

The 16 mm sensing head supports installation in suitable machinery locations where non-contact shaft measurement is required.

Technical FAQs

1. What is the EPRO PR6424/012-030?

The PR6424/012-030 is a 16 mm eddy current sensor designed for non-contact measurement of shaft displacement and vibration in rotating machinery.

2. What is the main function of this sensor?

Its main function is to measure the distance between the sensor tip and a conductive shaft surface. The resulting measurement can be used to monitor shaft vibration, position, eccentricity, and 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 published PR6424 series specification gives a sensitivity of 4 V/mm, with linearity of up to ±1.5%.

5. What is the measurement range?

The published series specification gives a static measurement range of ±2.0 mm and a dynamic measurement range of 0 to 1,000 μm.

6. Does the PR6424/012-030 operate without a signal converter?

The probe is normally used with a compatible signal converter. The converter processes the sensor signal and provides an output suitable for the connected monitoring system.

7. Which machines can use the PR6424 sensor?

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

8. What material should the sensor measure?

The published PR6424 specification identifies ferromagnetic steel as the standard target material, with 42CrMo4 as a reference material. The actual shaft material should be checked against the sensor calibration requirements.

9. What should be checked when replacing an existing PR6424 sensor?

Verify the complete model number, probe dimensions, cable length, connector arrangement, mounting thread, target material, and signal-converter compatibility.

10. What is the weight of the PR6424/012-030?

The supplied product listing weight is 0.2 kg. Actual shipping weight may vary depending on cable length, accessories, and packaging.

Procurement and Maintenance Recommendations

When purchasing the EPRO PR6424/012-030, verify the complete catalog number and compare it with the identification label on the existing probe. Confirm the sensor head diameter, cable arrangement, connector type, and required signal converter.

For replacement projects, it is important to identify whether the existing installation uses an extension cable and which converter model is installed. Replacing only the probe without checking these components can result in an incompatible measurement chain.

For used or surplus equipment, request clear photographs of the sensor body, cable, connector, and model identification. Check the condition of the sensing tip, cable insulation, mounting thread, and connector contacts. Where possible, request electrical testing or functional verification with a compatible converter.

During maintenance, inspect the sensor mounting arrangement and cable routing. Look for loose connections, damaged insulation, excessive bending, and signs of mechanical impact. Record baseline measurement values and compare them with subsequent readings to help identify changes in machine behavior.

The sensor should be installed and calibrated according to the manufacturer’s technical documentation. Incorrect air-gap adjustment, incompatible target material, or an unsuitable converter can affect measurement accuracy.

Conclusion

The EPRO PR6424/012-030 16 mm Eddy Current Sensor is designed for non-contact monitoring of shaft displacement, vibration, position, and eccentricity in critical rotating machinery. Its 16 mm sensor head and the PR6424 family’s published measurement characteristics make it suitable for applications involving turbines, compressors, pumps, and industrial fans.

For reliable operation, the sensor must be matched with the correct cable, signal converter, target material, and monitoring-system input. Accurate model identification and proper installation are especially important when replacing sensors in existing machinery protection systems.