Product Overview

The Epro PR6424/102-030 16 mm Eddy Current Sensor is a non-contact displacement and vibration measurement probe designed for monitoring critical rotating machinery. Part of the Emerson EPRO PR6424 sensor family, it is used in machinery condition monitoring systems where accurate measurement of shaft movement, position, and vibration is important for equipment protection and operational reliability.

Unlike contact-type measuring devices, an eddy current sensor measures the distance between its sensing tip and a conductive target without physically touching the target surface. This makes it suitable for continuous monitoring of rotating shafts in equipment such as steam turbines, gas turbines, compressors, pumps, and industrial fans.

The PR6424 series uses a 16 mm sensing head and is designed for applications involving relatively large rotating shafts. Its measurement capabilities include radial and axial shaft displacement, shaft position, eccentricity, and dynamic vibration. The sensor can also be used for speed-related measurements when incorporated into an appropriately configured monitoring system.

The sensor operates as part of a measurement chain. A compatible extension cable and signal converter are required to condition the probe signal and provide an output suitable for a machinery monitoring or protection system. Compatibility between the probe, cable, and converter must be confirmed before installation.

With a sensor head diameter of 16 mm and a supplied listing weight of 0.2 kg, the PR6424/102-030 is a compact sensing component for industrial machinery monitoring applications.

Technical Specifications

Note: Measurement values are PR6424 family reference specifications. Exact cable length, connector arrangement, mounting dimensions, temperature limits, and electrical compatibility should be checked against the complete PR6424/102-030 ordering code.

Function and Working Principle

The PR6424/102-030 uses the eddy current measurement principle to detect changes in the distance between the sensor head and a conductive metal target. This technology is widely used in rotating machinery monitoring because it provides continuous, non-contact measurement.

1. Eddy Current Measurement

An alternating electrical signal inside the sensor generates an electromagnetic field around the probe tip. When a conductive metal surface approaches the sensing area, eddy currents are induced in the target material.

These currents influence the electrical characteristics of the sensor coil. The resulting change is related to the distance between the sensor and the target.

A compatible signal converter processes this change and produces a measurement signal that can be interpreted by a machinery monitoring system.

2. Shaft Displacement Measurement

The sensor can measure the position of a rotating shaft relative to its mounting reference. This is important in large rotating machines where shaft movement may indicate changes in bearing condition, mechanical alignment, or operating loads.

The PR6424 family provides a typical static measurement range of ±2.0 mm. The actual usable range depends on the initial gap, target material, installation geometry, and converter configuration.

3. Shaft Vibration Monitoring

As a shaft rotates, it may move slightly in response to imbalance, misalignment, bearing wear, or changing mechanical forces.

The sensor detects changes in the gap between the probe tip and the shaft surface. These variations can be processed into vibration measurements by the associated monitoring system.

The PR6424 series has a reference dynamic measurement range of 0–1,000 μm. This makes it suitable for applications where shaft vibration trends are important for machinery condition assessment.

4. Position and Eccentricity Monitoring

In addition to dynamic vibration, the sensor can measure relatively slow changes in shaft position. This information can help operators and maintenance engineers evaluate shaft movement during different operating conditions.

Eccentricity measurements can also provide useful information about the relationship between the shaft centerline and the surrounding mechanical structure.

5. Signal Conversion

The sensor probe is not a standalone standard 4–20 mA transmitter. It requires a compatible signal converter to process the probe’s electrical characteristics and provide a usable output.

The complete measurement arrangement generally includes:

• PR6424 eddy current probe.
• Compatible extension cable.
• Compatible signal converter.
• Machinery monitoring or protection system.

All components must be matched according to the manufacturer’s specifications. Using an incompatible cable or converter may result in incorrect measurements or an unstable signal.

Role in Industrial Machinery Monitoring Systems

The PR6424/102-030 is intended for use in machinery monitoring installations where continuous information about shaft movement is required.

Turbine Protection

Steam, gas, and hydro turbines operate with high-speed rotating shafts and precision bearing arrangements. Changes in shaft vibration or position may indicate developing mechanical problems.

A correctly installed eddy current sensor can provide measurement information to a turbine monitoring system, helping operators identify abnormal trends and investigate potential problems.

Compressor Condition Monitoring

Industrial compressors often operate continuously in demanding process environments. Shaft vibration and displacement measurements can support condition monitoring and maintenance planning.

Multiple probes may be installed at different measurement locations to observe shaft behavior and provide a more complete picture of machine condition.

Pump Monitoring

Large industrial pumps may experience vibration changes caused by hydraulic conditions, bearing deterioration, misalignment, or mechanical imbalance.

Non-contact shaft monitoring provides information that can help maintenance teams distinguish between normal operating movement and potentially abnormal conditions.

PLC and Monitoring-System Integration

The sensor normally works through a compatible signal converter or monitoring module. The conditioned signal can then be used by a machinery protection system, monitoring platform, or suitable automation architecture.

The probe itself should not be treated as a direct PLC input device unless the complete signal-conditioning arrangement has been designed for that purpose.

Industrial Applications

1. Steam Turbines

Steam turbines require continuous monitoring of shaft vibration and displacement to support reliable operation. The PR6424 sensor family is designed for critical turbomachinery applications, including steam turbine installations.

The probe can be installed near an appropriate shaft measurement location to observe changes in shaft movement during operation.

2. Gas Turbines

Gas turbines operate at high rotational speeds and under demanding thermal and mechanical conditions. Monitoring shaft vibration and position is an important part of machinery condition assessment.

The exact sensor configuration and installation location must be selected according to the turbine design and environmental requirements.

3. Hydro Turbines and Generators

Hydro turbine installations may require long-term monitoring of shaft movement and bearing-related vibration. Eddy current probes can provide non-contact measurements that support operational monitoring and maintenance analysis.

4. Industrial Compressors

Centrifugal compressors and other large rotating machines often use shaft displacement probes as part of their protection and monitoring systems.

The PR6424 series can support radial and axial shaft measurement when installed with the appropriate converter and mounting arrangement.

5. Large Industrial Pumps

Large pumps used in power generation, petrochemical processing, and water treatment may require continuous monitoring of rotating components.

Shaft vibration and position data can help maintenance teams investigate mechanical changes before they develop into more serious equipment problems.

6. Industrial Fans

Large fans and ventilation equipment may operate continuously in industrial facilities. Monitoring shaft movement can help identify developing mechanical imbalance, bearing problems, or changes in machine condition.

Installation and System Integration

Correct installation is essential for obtaining reliable measurement results from the PR6424/102-030.

1. Verify the Complete Model Number

Before installation, confirm the full ordering code printed on the sensor label. The PR6424 family includes multiple probe configurations that may differ in cable length, cable construction, connector arrangement, and mechanical dimensions.

Do not assume that two probes with the same 16 mm sensing-head diameter have identical electrical or mechanical configurations.

2. Select the Correct Mounting Position

The sensor must be installed at a suitable measurement location with an appropriate view of the shaft surface.

The mounting arrangement should provide sufficient mechanical stability and prevent the probe from moving independently of the machine structure.

The surrounding installation must also maintain the required clearance from nearby ferrous materials, according to the manufacturer’s mounting instructions.

3. Set the Initial Air Gap

The initial distance between the sensor tip and the shaft surface is important for accurate measurement.

The PR6424 family specifies a typical nominal center air gap of approximately 2.7 mm. The actual installation gap must be set according to the applicable sensor and converter documentation.

An incorrect initial gap may cause the measurement to operate outside the intended linear range.

4. Check the Shaft Surface

The measurement target should meet the specified material and surface requirements. The PR6424 family references ferromagnetic steel, with 42CrMo4 identified as a standard target material.

Surface condition, material composition, shaft geometry, and nearby metal structures can influence measurement performance. These factors should be considered during installation and calibration.

5. Connect the Extension Cable and Converter

Connect the probe to the compatible extension cable and signal converter using the specified connector arrangement.

Avoid unnecessary cable stress, sharp bends, and mechanical damage. Follow the cable manufacturer’s minimum bending-radius requirements and protect the connection from vibration and environmental contamination.

6. Commission the Measurement System

After mechanical installation and electrical connection, verify the initial gap and signal response.

The commissioning procedure should include:

• Confirming the probe and converter model compatibility.
• Checking cable continuity and connector condition.
• Verifying the initial air gap.
• Confirming the converter’s calibration settings.
• Checking the output signal under stationary conditions.
• Comparing measurements with expected machine conditions.
• Recording the final installation parameters.

A properly commissioned measurement chain provides a reliable basis for subsequent machinery condition monitoring.

Compatible System Components

The PR6424/102-030 operates as part of a complete eddy current measurement system. The following components represent the main equipment categories involved in a typical installation.

The converter models listed are examples of the wider PR6424 system family. They should not be considered automatically interchangeable with the PR6424/102-030. Always confirm the approved probe, cable, and converter combination.

Alternative Models and Replacement Considerations

The PR6424 series contains multiple 16 mm eddy current probe configurations. A replacement should be selected according to the original installation requirements rather than sensor diameter alone.

Before selecting a replacement, check:

• Sensor head diameter.
• Complete ordering code.
• Thread type and mounting dimensions.
• Cable length and construction.
• Connector type.
• Compatible signal converter.
• Initial air-gap requirements.
• Target shaft material and diameter.
• Operating temperature range.
• Required measurement range and sensitivity.

A replacement probe with a similar physical appearance may not provide the same electrical response or converter compatibility.

Key Advantages

Non-Contact Measurement

The sensor measures shaft movement without direct mechanical contact. This avoids the wear associated with contact-based measurement methods.

Continuous Shaft Monitoring

When connected to a suitable monitoring system, the probe can provide continuous measurement information about shaft displacement and vibration.

High Measurement Sensitivity

The PR6424 family has a typical sensitivity of 4 V/mm, supporting accurate measurement of small changes in the distance between the probe and the target.

Static and Dynamic Measurement

The sensor family supports both static position measurement and dynamic displacement measurement, allowing multiple types of shaft movement to be monitored.

Industrial Turbomachinery Applications

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

Compact Sensing Head

The 16 mm sensing head supports installation in appropriately designed machinery monitoring arrangements where probe mounting space is limited.

Integration with Machinery Monitoring Systems

With a compatible cable and signal converter, the sensor can form part of an industrial machinery monitoring and protection installation.

Technical FAQs

1. What is the Epro PR6424/102-030?

The Epro PR6424/102-030 is a 16 mm eddy current sensor from the Emerson EPRO PR6424 family. It is designed for non-contact measurement of shaft displacement, position, 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 the eddy current principle. An electromagnetic field generated at the probe tip interacts with a conductive target, and the resulting electrical changes are used to determine the distance between the sensor and the target.

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

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 published PR6424 family static measurement range is ±2.0 mm. The usable range depends on the initial air gap and the complete measurement configuration.

6. What is the dynamic measurement range?

The PR6424 family specifies a dynamic measurement range of 0–1,000 μm. This supports shaft vibration measurement when used with compatible signal-conditioning equipment.

7. Does the sensor require a signal converter?

Yes. The probe requires a compatible signal converter to condition its measurement signal for use by a machinery monitoring or protection system.

8. What equipment can use this sensor?

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

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

Verify the complete ordering code, sensor diameter, mounting thread, cable length, connector type, target material, and signal converter compatibility. These details can differ between PR6424 variants.

10. What is the weight of the PR6424/102-030?

The supplied product listing weight is 0.2 kg. The PR6424 family specification sheet also gives an approximate weight of 200 grams for the sensor with a 1-meter cable and without armor. Actual weight may vary with cable and configuration.

Procurement and Maintenance Recommendations

When purchasing the Epro PR6424/102-030, confirm the complete model number and compare it with the sensor installed on the machine. This is particularly important for replacement projects involving critical turbines, compressors, and other continuously operating rotating equipment.

The probe should be supplied with a clearly identifiable model label and the correct cable and connector configuration. Buyers should also confirm whether the required extension cable and signal converter are included or must be ordered separately.

For used or surplus sensors, inspect the sensing tip, threaded sleeve, cable insulation, connector, and identification label. Mechanical damage, cable deterioration, or an incorrect connector configuration may affect installation and measurement reliability.

During routine maintenance, inspect the probe mounting, cable routing, connector condition, and signal stability. Avoid unnecessary movement of the sensor after calibration. If the measured signal changes unexpectedly, investigate the initial gap, cable connection, converter configuration, target surface, and machine condition before replacing the probe.

For critical machinery, keep records of the original installation position, calibration settings, and measurement trends. This information helps maintenance personnel compare current operating conditions with historical data and identify changes that may require further inspection.

Conclusion

The Epro PR6424/102-030 16 mm Eddy Current Sensor is designed for non-contact monitoring of shaft displacement, position, and vibration in industrial rotating machinery. As part of the Emerson EPRO PR6424 family, it is suitable for measurement systems used with turbines, compressors, pumps, fans, and other critical equipment.

With a 16 mm sensing head, typical sensitivity of 4 V/mm, and a family-level static measurement range of ±2.0 mm, the PR6424 series supports detailed machinery condition monitoring when paired with the correct extension cable and signal converter.

For procurement and replacement, confirming the complete ordering code and the compatibility of the entire measurement chain is essential. Correct installation, air-gap adjustment, calibration, and routine inspection help maintain reliable measurement performance.