Product Overview

The Epro PR6424/017-000 16 mm Eddy Current Sensor is a non-contact displacement probe designed for monitoring the mechanical condition of rotating machinery. Part of the EPRO PR6424 sensor family from Emerson, it is used in machinery protection and condition-monitoring systems to measure shaft vibration, radial and axial displacement, position, eccentricity, and rotational behavior.

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 non-contact measurement principle makes it suitable for continuous monitoring applications where mechanical contact could cause wear, affect measurement accuracy, or interfere with machine operation.

The PR6424 series is designed for critical rotating equipment, including steam turbines, gas turbines, hydro turbines, compressors, pumps, and fans. These machines often operate at high speeds and under demanding mechanical conditions. Monitoring shaft movement provides useful information for identifying abnormal vibration, changes in shaft position, and developing mechanical problems.

The PR6424/017-000 uses a 16 mm sensing head and is intended to operate as part of a compatible eddy current measurement system. The probe works with an appropriate signal converter and monitoring equipment to transform changes in the sensor-to-shaft gap into electrical signals that can be evaluated by machinery protection systems.

Its key family specifications include a nominal sensitivity of 4 V/mm, a static measurement range of ±2.0 mm, and a dynamic measurement range of 0 to 1,000 μm. The supplied product weight is approximately 0.2 kg, consistent with the manufacturer’s stated weight for a sensor with a 1-meter cable and no armor.

For maintenance teams, the PR6424/017-000 provides a measurement component for machinery monitoring installations where reliable shaft-displacement information is important for equipment protection and predictive maintenance.

Technical Specifications

Note: The supplied weight is retained as the product listing value. Cable length, connector arrangement, armor, thread configuration, and other options should be checked against the exact delivered assembly.

Function and Working Principle

The PR6424/017-000 operates using the eddy current measurement principle. It generates an electromagnetic field near the sensor tip and measures changes caused by the distance between the probe and a conductive target.

This technology is widely used in rotating machinery monitoring because it can measure shaft movement without requiring physical contact.

1. Eddy Current Measurement Principle

An electronic circuit supplies the probe coil with a high-frequency excitation signal. This produces an electromagnetic field around the sensing tip.

When a conductive metal target, such as a ferromagnetic steel shaft, is positioned within the field, eddy currents are induced in the target surface. These currents affect the electrical characteristics of the probe coil.

As the distance between the probe and the shaft changes, the impedance of the probe circuit changes accordingly. A compatible signal converter processes this variation and produces an electrical output related to the measured gap.

The resulting signal can be used by a machinery monitoring system to determine shaft displacement and vibration.

2. Shaft Vibration Measurement

During normal operation, rotating shafts may experience small movements caused by mechanical imbalance, bearing conditions, alignment errors, or changing operating loads.

The PR6424 sensor can measure these movements dynamically. When installed at an appropriate position near the shaft, it provides a signal representing changes in the probe-to-shaft distance.

Two or more measurement directions may be used in a monitoring arrangement to evaluate shaft vibration behavior. The exact number and orientation of probes depend on the machine design and monitoring requirements.

3. Shaft Position Measurement

In addition to dynamic vibration, the PR6424 family supports static displacement measurement.

Static measurements can be used to monitor changes in shaft position, including axial movement or other relative displacement, when the probe is installed in a suitable arrangement.

This information can help operators identify changes in machine condition and investigate abnormal mechanical behavior.

4. Eccentricity and Speed-Related Monitoring

Eccentricity describes the variation in the distance between the shaft surface and a fixed measurement reference as the shaft rotates.

A properly installed eddy current probe can detect this variation. Depending on the monitoring system and measurement configuration, the resulting signal can also support speed-related or key-phase monitoring functions.

The sensor must be installed with the correct target geometry and connected to compatible signal-processing equipment.

5. Signal Conversion

The PR6424/017-000 is a probe rather than a complete machinery monitoring system. It normally operates with a compatible extension cable and signal converter.

The converter conditions the probe signal and provides an output suitable for monitoring equipment. The final system may then display measurements, generate alarms, and initiate protective actions according to configured limits.

Correct matching of the probe, cable, converter, and monitoring input is essential for accurate measurement.

Role in Industrial Machinery Monitoring Systems

The PR6424/017-000 can be used as a sensing component in machinery condition-monitoring and protection installations. Its purpose is to provide displacement-related information that helps operators evaluate the operating condition of critical rotating equipment.

Turbine Monitoring

Steam, gas, and hydro turbines contain rotating shafts and bearing assemblies that must operate within defined mechanical limits.

Eddy current probes can monitor shaft vibration and displacement at selected measurement locations. The resulting signals help monitoring systems identify changes that may indicate imbalance, misalignment, bearing problems, or other mechanical abnormalities.

Compressor Protection

Industrial compressors are used in power generation, chemical processing, oil and gas facilities, and manufacturing plants.

Shaft vibration and position measurements can provide information about compressor operating conditions. Continuous monitoring is particularly important for machines that operate for long periods or support critical production processes.

Pump and Fan Monitoring

Large industrial pumps and fans may experience vibration changes caused by bearing wear, imbalance, mechanical looseness, or operating conditions.

A non-contact displacement sensor can provide shaft-related measurements that complement other monitoring devices, such as bearing temperature sensors and accelerometers.

Machinery Protection Systems

A complete machinery protection system combines sensors, signal converters, monitoring modules, alarm logic, and operator interfaces.

The PR6424/017-000 provides the probe-level measurement. The monitoring system evaluates the resulting signal and compares it with configured operating limits.

Depending on the system design, abnormal measurements may generate warnings or initiate protective actions to help prevent further machinery damage.

Industrial Applications

1. Steam Turbines

Steam turbines operate under high-speed and high-temperature conditions. Shaft vibration and displacement monitoring are important for evaluating rotor behavior and identifying mechanical changes.

The PR6424 sensor family is designed for critical turbomachinery applications and can be installed at appropriate shaft-monitoring locations.

2. Gas Turbines

Gas turbines are used in power generation and industrial mechanical-drive applications. Their rotating assemblies require continuous condition monitoring.

Eddy current probes can provide shaft vibration and position measurements for machinery protection and diagnostic systems.

3. Hydro Turbines

Hydro turbines operate in power-generation facilities where long-term equipment availability is important.

Shaft displacement measurements can help operators monitor rotor movement and investigate changes in mechanical condition.

4. Centrifugal Compressors

Centrifugal compressors are common in petrochemical plants, gas processing facilities, and industrial utilities.

Shaft vibration and displacement monitoring can help detect developing mechanical issues and support maintenance planning.

5. Industrial Pumps

Large process pumps may operate continuously in water treatment, chemical production, and energy facilities.

When used in an appropriate monitoring arrangement, eddy current sensors can provide information about shaft movement and vibration.

6. Industrial Fans

Large fans used in power plants, ventilation systems, and industrial processing facilities may require continuous mechanical monitoring.

Non-contact probes can contribute to a wider condition-monitoring arrangement when the shaft geometry and measurement requirements are suitable.

Installation and System Integration

Correct installation is essential for reliable measurements. The probe must be positioned correctly, connected to compatible electronics, and configured for the target material and measurement range.

1. Confirm the Probe Configuration

Before installation, verify the complete model number and the supplied assembly.

Check the sensor head diameter, mounting thread, cable arrangement, connector type, cable length, and whether the cable is armored. These details can differ between PR6424 variants.

Do not assume that every PR6424 probe has an identical mechanical configuration.

2. Prepare the Mounting Location

The probe should be installed at a location that provides a stable measurement reference and suitable clearance from surrounding metal components.

Metallic materials near the sensing area can influence the electromagnetic field and affect measurement performance. Follow the manufacturer’s clearance and mounting recommendations.

The shaft surface should also be appropriate for eddy current measurement. The manufacturer’s standard target material is ferromagnetic steel, with 42CrMo4 identified as the reference material.

3. Set the Initial Air Gap

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

The initial gap should be established using the applicable installation procedure and compatible signal converter. Incorrect probe positioning may result in an output outside the intended linear measurement region.

Always follow the relevant calibration and setup instructions rather than relying only on visual positioning.

4. Connect the Extension Cable and Converter

The probe must be connected to compatible system components. Depending on the assembly, this may include an extension cable, connector, and signal converter.

Check the electrical and mechanical compatibility of all components. Cable length and configuration can affect the measurement system and must match the approved combination.

5. Route and Protect the Cable

Route the sensor cable away from high-power conductors, sources of excessive heat, sharp edges, and moving machinery.

Observe the specified minimum bending radius. Avoid excessive pulling force, twisting, or mechanical damage to the cable insulation.

Where the installation requires additional cable protection, use the correct armored configuration and approved accessories.

6. Calibrate and Verify the Measurement

After installation, verify the initial gap and check the sensor output through the compatible converter or monitoring system.

Confirm that the measurement changes in the expected direction as the shaft-to-probe distance changes. Check signal stability and compare the result with the system’s configured measurement range.

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

Compatible System Components

The PR6424/017-000 should be treated as one part of a complete eddy current measurement system.

The table describes typical system components. They are not necessarily supplied with the PR6424/017-000 sensor.

Alternative Models and Replacement Considerations

The PR6424 series includes different probe variants. Although they share the 16 mm sensor-family design, their cable arrangements, mounting details, connector configurations, and other options may differ.

A similar sensor diameter does not guarantee direct replacement compatibility. Before ordering an alternative, compare the complete part number, cable length, connector, mounting thread, sensitivity, target material, and converter requirements.

Key Advantages

Non-Contact Measurement

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

16 mm Sensing Head

The 16 mm sensing head is designed for machinery-monitoring applications where this probe size and its associated measurement characteristics are required.

Static and Dynamic Measurement

The PR6424 family supports both static displacement and dynamic shaft vibration measurements, allowing it to contribute to different machinery-monitoring functions.

High Measurement Sensitivity

The specified sensitivity of 4 V/mm and linearity of up to ±1.5% support displacement measurement when the probe is correctly installed and used with compatible electronics.

Industrial Machinery Applications

The sensor family is designed for use with turbines, compressors, pumps, fans, and other critical rotating machinery.

Compact Sensor Assembly

The supplied sensor weight of approximately 0.2 kg makes the probe assembly practical for installations where sensor mounting space and cable routing must be considered.

Integration with Machinery Monitoring Systems

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

Technical FAQs

1. What is the Epro PR6424/017-000?

The PR6424/017-000 is a 16 mm non-contact eddy current displacement sensor designed for monitoring shaft vibration, displacement, position, and eccentricity 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 electromagnetic induction. The probe generates an electromagnetic field, and changes in the distance to a conductive shaft affect the probe’s electrical characteristics. A compatible converter processes these changes into a usable measurement signal.

4. What is the sensitivity of the PR6424 series?

The specified sensitivity is 4 V/mm, with linearity of up to ±1.5%.

5. What is the static measurement range?

The static measurement range is ±2.0 mm.

6. What is the dynamic measurement range?

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

7. What material should be used as the measurement target?

The standard target material is ferromagnetic steel. The manufacturer’s reference material is 42CrMo4 steel.

8. What is the nominal air gap?

The nominal center air gap is approximately 2.7 mm. The final installation gap must be established using the applicable calibration procedure.

9. Can the PR6424/017-000 connect directly to a PLC?

It is a sensor probe and normally requires a compatible signal converter and monitoring interface. PLC integration depends on the output and architecture of the connected monitoring system.

10. What is the weight of the sensor?

The supplied product weight is approximately 0.2 kg. The manufacturer’s specification identifies approximately 200 grams for the sensor with a 1-meter cable and without armor.

11. Can another PR6424 model replace this sensor?

Not automatically. Related models may have different cable lengths, connectors, mounting details, and other configuration options. Check the full part number and system compatibility before substitution.

Procurement and Maintenance Recommendations

When purchasing the Epro PR6424/017-000, verify the complete model number and confirm that the delivered sensor matches the installed machinery monitoring system.

Check the sensor head diameter, mounting thread, cable length, connector, cable armor, and compatible signal converter. These details are important because a probe with the same 16 mm sensing diameter may still have a different installation or electrical configuration.

For used or refurbished units, request clear photographs of the sensor head, cable, connector, and identification label. Check for damaged insulation, bent mounting sections, corrosion, or other signs of mechanical damage. Where possible, request a functional test using compatible measurement equipment.

During maintenance, inspect the probe mounting, cable routing, connector condition, and surrounding installation environment. Keep the sensing area clear of unintended metallic obstructions and verify that the initial air gap remains within the specified operating range.

For critical rotating machinery, sensor replacement should be followed by calibration and a functional check of the complete measurement chain. This includes the probe, extension cable, converter, monitoring module, and alarm configuration.

Conclusion

The Epro PR6424/017-000 16 mm Eddy Current Sensor is a non-contact displacement probe designed for monitoring critical rotating machinery. Its measurement capabilities support shaft vibration, displacement, position, and eccentricity monitoring in applications such as turbines, compressors, pumps, and industrial fans.

With a specified sensitivity of 4 V/mm, a static measurement range of ±2.0 mm, and a dynamic range of 0 to 1,000 μm, the PR6424 sensor family provides measurement information for machinery protection and condition-monitoring systems.

For replacement and procurement projects, verifying the complete sensor configuration is essential. The probe must be matched with the correct cable, signal converter, mounting arrangement, and monitoring equipment to support reliable measurement performance.