Product Overview

The EPRO PR6424/01 16 mm Eddy Current Sensor is a non-contact displacement sensor designed for monitoring the operating condition of critical rotating machinery. Part of the EPRO PR6424 sensor family, it is used in industrial machinery protection and condition-monitoring systems to measure shaft vibration, displacement, position, eccentricity, and related dynamic movement.

The sensor operates using the eddy current measurement principle. It is installed close to a conductive target, typically a ferromagnetic steel shaft. As the distance between the sensor tip and the target changes, the electrical characteristics of the sensor coil change accordingly. When connected to a compatible signal converter, these changes can be converted into an electrical output representing the distance between the probe and the measured surface.

The PR6424 series is designed for applications involving large rotating shafts, including steam turbines, gas turbines, hydro turbines, compressors, pumps, and industrial fans. Continuous monitoring of shaft movement can help operators identify abnormal vibration, changes in shaft position, and developing mechanical problems.

The PR6424 family features a 16 mm sensor tip, a typical sensitivity of 4 V/mm, and a static measurement range of ±2.0 mm. Its dynamic measurement capability supports vibration monitoring in machinery where accurate shaft movement measurements are important for operational reliability.

The supplied listing identifies this product as PR6424/01, with a sensor head diameter of 16 mm and a weight of 0.2 kg. Because the PR6424 family includes different cable, connector, and mechanical configurations, the complete ordering code should be checked when purchasing a replacement.

Technical Specifications

Note: These specifications describe the PR6424 family. Exact cable length, connector type, mechanical dimensions, temperature limits, and other configuration details should be confirmed against the complete probe ordering code.

Function and Working Principle

The PR6424/01 uses eddy current technology to measure the distance between the sensor tip and a conductive target without making physical contact. This makes it suitable for rotating machinery where direct mechanical contact with the shaft would be impractical or could interfere with operation.

1. Non-Contact Displacement Measurement

The sensor generates an electromagnetic field around its sensing tip. When a conductive target approaches the probe, eddy currents are induced in the target surface.

The resulting change in the sensor’s electrical characteristics is related to the distance between the probe and the target. A compatible signal converter processes this response and produces an electrical output that can be used by a machinery monitoring system.

Because the measurement does not require physical contact, the sensor can continuously monitor shaft movement while the machine is operating.

2. Shaft Vibration Monitoring

Shaft vibration is an important indicator of rotating machinery condition. Changes in vibration may be associated with imbalance, misalignment, bearing problems, looseness, or other mechanical conditions.

The PR6424 series measures dynamic shaft displacement and can provide signals for machinery vibration monitoring. Monitoring personnel can use these measurements to identify changes in machine behavior and investigate abnormal operating conditions.

The sensor is intended to measure shaft movement relative to its mounting position. Correct installation and a stable mechanical mounting arrangement are therefore essential.

3. Static Position Measurement

In addition to dynamic vibration, the PR6424 series can measure static shaft position within its specified measurement range.

This capability is useful for monitoring axial movement, shaft position, and other displacement conditions in rotating equipment. In turbine applications, for example, changes in axial shaft position may be important for machinery protection and maintenance decisions.

The static measurement range of the PR6424 family is specified as ±2.0 mm.

4. Eccentricity Measurement

Shaft eccentricity describes the deviation of a shaft’s centerline or surface position from its expected rotational geometry.

By monitoring changes in the probe-to-shaft gap, an eddy current measurement system can provide information about shaft eccentricity. This can help maintenance personnel assess mechanical conditions during startup, operation, and other defined operating states.

5. Speed and Key-Related Monitoring

The PR6424 family can also be used in suitable measurement arrangements for speed and key-related signals. The exact functionality depends on the monitoring system, probe arrangement, target geometry, and signal-processing configuration.

The probe should always be matched with the appropriate converter and monitoring equipment for the intended measurement.

Role in Industrial Machinery Monitoring Systems

The PR6424/01 is a sensing component rather than a complete standalone machinery protection system. It normally works with a compatible signal converter and monitoring equipment.

Signal Converter Integration

The sensor’s raw electrical response must be conditioned before it can be used by a monitoring or control system. Compatible EPRO signal converters provide the required excitation and signal conditioning.

The converter transforms the probe response into a usable output proportional to the measured gap. The selected converter must match the probe’s electrical and mechanical configuration.

Machinery Protection Systems

A properly configured measurement chain can provide shaft displacement and vibration information to machinery protection equipment.

The monitoring system evaluates the incoming signals against configured alarm and trip limits. When measurements exceed defined thresholds, the system can notify operators or initiate protective actions according to the plant’s safety and control philosophy.

The PR6424/01 itself does not independently decide when a machine should trip. Alarm logic and protective actions are handled by the connected monitoring system.

DCS and PLC Integration

Condition-monitoring information may be made available to a distributed control system or programmable logic controller through the appropriate monitoring equipment.

This allows operators to view machinery measurements alongside process variables such as temperature, pressure, flow, and operating speed.

The exact integration method depends on the installed converter, monitoring rack, communication interfaces, and plant control architecture.

Industrial Applications

The EPRO PR6424 series is designed for critical rotating machinery where shaft displacement and vibration measurements are important.

1. Steam Turbines

Steam turbines operate under high mechanical and thermal loads. Continuous shaft monitoring can help operators identify changes in vibration, axial position, and eccentricity.

A suitable PR6424 measurement system can provide shaft displacement signals for turbine monitoring and protection applications.

2. Gas Turbines

Gas turbines are used in power generation and industrial process facilities. Their rotating assemblies require reliable condition monitoring to support stable operation.

The PR6424 series can be used in suitable turbine monitoring arrangements to measure shaft movement and vibration.

3. Hydro Turbines

Hydro turbine installations require monitoring of rotating shafts and associated mechanical components. Shaft displacement measurements can help identify changes in operating behavior and support maintenance assessments.

4. Industrial Compressors

Large compressors are commonly used in petrochemical plants, refineries, gas processing facilities, and other process industries.

Shaft vibration and displacement monitoring can provide information about compressor mechanical condition. The PR6424 series is suitable for applications where its measurement range and installation requirements match the machinery.

5. Industrial Pumps

Large process pumps may operate continuously under changing pressure and flow conditions. Monitoring shaft movement can help maintenance personnel investigate abnormal vibration and mechanical changes.

The sensor can be incorporated into an appropriate pump condition-monitoring arrangement.

6. Industrial Fans

Large fans and blower systems are widely used in power plants, cement plants, steel production, and industrial ventilation systems.

Where shaft displacement measurement is required, the PR6424 series can provide non-contact monitoring of suitable rotating components.

Installation and System Integration

Correct installation is essential for obtaining reliable measurement results. The probe must be installed with the appropriate mechanical clearance, target material, cable arrangement, and converter configuration.

1. Confirm the Target Material

The PR6424 series is designed for use with conductive ferromagnetic targets. The standard target material specified in the product documentation is 42CrMo4 steel.

Different target materials can produce different sensor responses. The target material should therefore be compatible with the sensor’s calibration and measurement system.

2. Maintain the Correct Probe Gap

The nominal center air gap for the PR6424 family is approximately 2.7 mm.

During installation, the probe-to-target gap should be adjusted according to the manufacturer’s setup procedure. The correct initial gap is important for maintaining the intended measurement range and signal linearity.

3. Secure the Sensor Mechanically

The probe should be mounted securely to prevent unwanted movement caused by vibration or mechanical looseness.

The mounting location must also provide sufficient clearance from nearby metallic objects. Unintended conductive materials close to the sensing tip may affect the measurement.

4. Use a Compatible Signal Converter

The PR6424 probe must be connected to a compatible signal converter. The converter should match the sensor’s electrical characteristics and connector configuration.

Do not assume that every converter in the EPRO range is interchangeable. Verify the complete sensor and converter part numbers before connecting the measurement chain.

5. Route and Protect the Cable

The sensor cable should be routed away from high-power conductors and other potential sources of electrical interference where required.

Avoid excessive bending, pulling, crushing, or abrasion. Cable protection and routing should follow the manufacturer’s installation requirements, particularly in environments with high temperatures or mechanical vibration.

6. Verify the Measurement Signal

After installation, check the sensor gap, converter output, signal stability, and monitoring-system scaling.

Compare the measured values with the expected operating conditions. Confirm that alarm and trip thresholds are configured according to the machinery manufacturer’s recommendations and the plant’s protection strategy.

Compatible System Components

The PR6424/01 is generally used as part of a complete machinery measurement chain.

The table describes typical components in a measurement system. They are not necessarily included with the PR6424/01 sensor.

Alternative Models and Replacement Considerations

The PR6424 belongs to a family of 16 mm eddy current sensors. Other configurations in the same family may have different cable lengths, probe lengths, armor, connector arrangements, or converter compatibility.

Before replacing a PR6424/01, check:

• Complete sensor ordering code.
• Sensor head diameter.
• Probe body length and mounting thread.
• Cable length and cable construction.
• Connector type.
• Armored or non-armored cable configuration.
• Target material and shaft diameter.
• Operating temperature.
• Measurement range and sensitivity.
• Signal converter compatibility.
• Monitoring-system input requirements.

A replacement probe should not be selected based on its 16 mm diameter alone. Differences in cable and converter configuration can affect the performance and compatibility of the complete measurement chain.

Key Advantages

Non-Contact Measurement

The eddy current principle allows shaft displacement to be measured without mechanical contact between the probe and the target.

Suitable for Critical Rotating Machinery

The PR6424 family is designed for machinery such as turbines, compressors, pumps, and fans, where shaft condition monitoring is important.

Displacement and Vibration Monitoring

The sensor supports static and dynamic shaft measurements, allowing a compatible monitoring system to evaluate different aspects of machine movement.

High Measurement Sensitivity

The typical sensitivity of 4 V/mm supports accurate displacement measurement when the probe, converter, target, and installation are correctly matched.

Industrial Mechanical Construction

The stainless steel sensor sleeve and PTFE cable construction are intended for demanding industrial measurement environments, subject to the limits of the exact configuration.

Integration with Machinery Monitoring Equipment

The probe can be incorporated into a complete measurement chain and connected to suitable machinery monitoring and plant control systems.

Technical FAQs

1. What is the EPRO PR6424/01?

The PR6424/01 is identified as a 16 mm EPRO eddy current sensor used 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. Changes in the distance between the probe and a conductive target affect the sensor’s electrical response, which is processed by a compatible signal converter.

4. What is the typical sensitivity?

The PR6424 family has a typical sensitivity of 4 V/mm, equivalent to approximately 101.6 mV/mil.

5. What is the static measurement range?

The specified static measurement range is ±2.0 mm.

6. What is the dynamic measurement range?

The PR6424 family specifies a dynamic range of 0 to 1,000 μm.

7. Does the sensor work without a signal converter?

The PR6424 probe is intended to operate as part of a measurement chain with a compatible signal converter. The converter provides the required excitation and signal conditioning.

8. What machinery can use this sensor?

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

9. What is the weight of the PR6424/01?

The supplied listing weight is 0.2 kg. This is consistent with the manufacturer’s approximate 200 g figure for the sensor with a 1 m cable and without armor. Actual weight can vary with cable and configuration.

10. Can another PR6424 model replace the PR6424/01?

A different PR6424 configuration may be suitable, but the complete ordering code must be checked. Cable length, connector type, probe dimensions, armor, and converter compatibility can differ.

Procurement and Maintenance Recommendations

When purchasing the EPRO PR6424/01, verify the complete ordering code and the physical configuration of the sensor. The 16 mm head diameter alone is not sufficient to identify every cable and connector option.

For replacement projects, compare the existing probe with the proposed replacement. Check the cable length, connector, mounting thread, probe body length, target material, and compatible converter. If the original sensor is part of a critical machinery protection system, confirm compatibility with the installed monitoring hardware before placing the order.

During maintenance, inspect the sensor body, cable insulation, connector contacts, and mounting arrangement. Look for signs of mechanical damage, cable abrasion, corrosion, or loose mounting hardware.

The probe gap should be checked according to the manufacturer’s installation procedure. After replacement, verify the converter output and monitoring-system scaling before returning the machinery to normal operation.

Keep a record of the complete sensor ordering code, converter model, cable configuration, installation gap, and commissioning measurements. This information can simplify future maintenance and reduce the risk of selecting an incompatible replacement.

Conclusion

The EPRO PR6424/01 16 mm Eddy Current Sensor is designed for non-contact monitoring of shaft displacement and vibration in critical rotating machinery. Its measurement principle allows a compatible monitoring system to detect changes in the distance between the probe and a conductive shaft surface.

With a 16 mm sensor head, a typical sensitivity of 4 V/mm, and a PR6424 family static measurement range of ±2.0 mm, the sensor is suitable for appropriately configured turbine, compressor, pump, and fan monitoring applications.

For industrial procurement and maintenance, the most important consideration is matching the complete probe configuration with the extension cable, signal converter, and monitoring system. Verifying the full ordering code helps ensure reliable measurement performance and compatibility with existing machinery protection installations.