Product Overview

The Epro PR6424/008-101 16 mm Eddy Current Sensor is a non-contact displacement and vibration sensor designed for monitoring the operating condition of large rotating machinery. It belongs to the PR6424 series developed for critical equipment such as steam turbines, gas turbines, hydro turbines, compressors, pumps, and industrial fans.

As part of an online machinery monitoring system, the sensor measures changes in the distance between its probe tip and a conductive metallic target, typically a rotating steel shaft. These changes can be used to monitor shaft vibration, radial and axial displacement, shaft position, eccentricity, and rotational speed-related characteristics.

Unlike contact-based measurement devices, the PR6424 sensor does not need to physically touch the rotating shaft. Its non-contact operating principle allows it to monitor moving components without introducing mechanical friction between the probe and the target surface.

The PR6424/008-101 has a nominal sensor head diameter of 16 mm. This probe size is intended for applications where a larger measurement target and an appropriate mounting arrangement are available. Its measurement performance makes it suitable for machinery condition monitoring and protection systems where continuous information about shaft movement is important.

The PR6424 series uses eddy current technology and is normally integrated with a compatible signal converter. The converter processes the probe signal and provides an output that can be connected to machinery monitoring equipment or a suitable control system.

For industrial maintenance teams, the PR6424/008-101 can serve as a replacement sensor in existing EPRO monitoring installations, provided that its mechanical dimensions, cable configuration, connector arrangement, and converter compatibility match the original system.

Technical Specifications

Note: The measurement and environmental figures above describe the PR6424 family. Confirm the exact temperature rating, cable arrangement, connector, and mechanical configuration for the individual PR6424/008-101 unit before installation.

Function and Working Principle

The PR6424/008-101 operates using the eddy current measurement principle. It generates an electromagnetic field at the sensor tip and detects changes in that field when a conductive metallic target moves relative to the probe.

This method allows the sensor to measure small changes in the distance between the probe and a rotating shaft.

1. Non-Contact Displacement Measurement

The sensor is installed close to the surface of a rotating shaft without making physical contact. As the shaft moves, the distance between the shaft surface and probe tip changes.

The sensor responds to these variations and produces an electrical signal related to the measured gap. When connected to a compatible converter, the signal can be processed into a measurement output for monitoring equipment.

This arrangement is useful in machinery where continuous shaft movement must be monitored without interrupting normal operation.

2. Eddy Current Detection

An alternating electromagnetic field is generated by the probe coil. When a conductive metallic target enters this field, eddy currents are induced in the target surface.

These currents influence the electromagnetic characteristics of the probe. Changes in the distance between the probe and target therefore produce corresponding changes in the sensor’s electrical response.

The signal converter processes this response and provides a usable measurement signal.

3. Shaft Vibration Monitoring

A rotating shaft may move slightly during operation because of imbalance, misalignment, bearing wear, mechanical looseness, or other operating conditions.

The PR6424 sensor can detect changes in shaft-to-probe distance. These measurements can be used to determine shaft vibration and identify changes in the mechanical condition of rotating equipment.

Continuous vibration monitoring can help maintenance teams identify developing problems before they result in serious equipment damage.

4. Shaft Position and Displacement Monitoring

The sensor can also measure static shaft position and changes in shaft displacement.

This is important in large turbines and compressors, where axial or radial movement may affect clearances, bearing conditions, and overall machine reliability.

The PR6424 series provides a static measurement range of approximately ±2.0 mm under its specified measurement conditions.

5. Signal Conversion and Monitoring

The sensor is generally used with a compatible EPRO signal converter. The converter supplies the required excitation and processes the probe response into an output suitable for monitoring equipment.

The complete measurement chain normally includes the probe, the appropriate extension or connection arrangement where required, and the signal converter.

Correct matching of these components is essential for measurement accuracy and stable operation.

Role in Industrial Machinery Protection Systems

The PR6424/008-101 can form part of an online monitoring system that collects mechanical condition data from critical rotating equipment.

Turbine Monitoring

Steam and gas turbines operate at high rotational speeds and under demanding mechanical and thermal conditions. Shaft vibration and displacement measurements help operators assess rotor behavior and identify abnormal operating trends.

A properly installed PR6424 sensor can provide measurement information for turbine monitoring and protection equipment.

Compressor Condition Monitoring

Large compressors are widely used in power generation, chemical processing, oil and gas production, and industrial manufacturing.

Monitoring shaft vibration and position can help detect changes associated with imbalance, misalignment, bearing deterioration, or other mechanical conditions.

Pump and Motor Monitoring

Industrial pumps and motors may operate continuously for long periods. Changes in shaft movement can indicate developing mechanical problems.

Non-contact displacement measurement provides information that can be used alongside bearing vibration, temperature, and process measurements.

Integration with DCS and Monitoring Systems

The sensor itself is not a DCS communication module. It provides a measurement signal through its compatible signal-conditioning equipment.

The processed output can then be connected to suitable machinery protection systems, monitoring equipment, or control-system interfaces.

This arrangement allows operators to view machinery condition information alongside process variables such as pressure, temperature, flow, and motor operating status.

Industrial Applications

1. Steam Turbines

Steam turbines require continuous monitoring because rotor vibration and displacement can affect mechanical clearances and operating stability.

The PR6424 series can be used to monitor shaft movement and support condition assessment in turbine installations.

2. Gas Turbines

Gas turbines operate under high-speed and high-temperature conditions. Shaft displacement and vibration measurements are important for monitoring rotor behavior.

A suitable PR6424 installation can provide non-contact measurement information for a compatible turbine monitoring system.

3. Hydro Turbines

Hydro turbines operate with large rotating assemblies and may experience changes in shaft position and vibration under varying operating loads.

Non-contact sensors can monitor shaft movement and provide information for maintenance planning.

4. Industrial Compressors

Centrifugal and other large compressors require reliable shaft monitoring to help maintain stable operation.

The PR6424 sensor can measure shaft displacement and vibration when installed with the correct mounting and signal-conversion equipment.

5. Industrial Pumps

Large process pumps are often critical to production continuity. Shaft movement measurements can help maintenance teams assess mechanical conditions and identify abnormal vibration trends.

6. Industrial Fans

Large fans used in industrial ventilation and process systems may experience vibration due to imbalance, bearing wear, or mechanical looseness.

A properly configured monitoring arrangement can provide useful information about shaft movement and equipment condition.

Installation and System Integration

Correct installation is essential for achieving reliable measurements from an eddy current sensor.

1. Verify Probe Compatibility

Before installation, confirm the complete model number and mechanical configuration of the PR6424/008-101.

Check the sensor head diameter, mounting thread, probe length, cable length, connector type, and any additional connection components. Do not assume that all PR6424 probes have identical mechanical or electrical configurations.

2. Prepare the Mounting Position

The probe should be installed in a stable mounting location with the correct orientation toward the measurement target.

The mounting structure must minimize unwanted movement. Loose mounting hardware or vibration of the sensor support can introduce measurement errors.

Ensure that the probe tip has adequate clearance from surrounding metallic structures and that the target surface meets the sensor’s material requirements.

3. Set the Initial Air Gap

The distance between the probe tip and shaft surface must be adjusted according to the manufacturer’s installation instructions.

The PR6424 family specifies a nominal center air gap of approximately 2.7 mm. This is a reference value for the specified measurement configuration, not a substitute for the correct installation procedure.

An incorrect initial gap can reduce the available measurement range or cause an inaccurate output.

4. Connect the Signal Converter

Use a compatible EPRO converter and the correct cable arrangement. The converter must match the probe’s electrical configuration and connector requirements.

Cable routing should avoid unnecessary interference from high-voltage conductors, switching equipment, and other sources of electromagnetic noise.

5. Verify Signal Output

After installation, check the measurement signal under the appropriate commissioning procedure.

Confirm that the output responds correctly to changes in shaft-to-probe distance and that the converter and monitoring system interpret the signal correctly.

Where possible, compare the sensor reading with other available machinery measurements to establish a reliable baseline.

6. Document the Installation

Record the probe model, mounting location, initial gap, cable arrangement, converter model, and monitoring channel assignment.

These details help maintenance personnel identify the correct replacement sensor and reduce commissioning time during future maintenance work.

Compatible System Components

The PR6424/008-101 is generally part of a complete displacement measurement chain rather than an independent monitoring system.

The exact components required depend on the installed monitoring architecture and the probe’s ordering configuration.

Alternative Models and Replacement Considerations

The PR6424 family includes different probe configurations. A replacement should be selected according to the original installation rather than the 16 mm head diameter alone.

Before purchasing a replacement, compare:

• Complete sensor model and ordering code.
• Sensor head diameter.
• Mounting thread and probe length.
• Cable length and cable construction.
• Armored or non-armored cable configuration.
• Connector type and cable termination.
• Signal converter compatibility.
• Measurement range and sensitivity.
• Operating temperature requirements.
• Monitoring-system input configuration.

A probe with the same 16 mm diameter is not necessarily an electrically or mechanically interchangeable replacement.

Key Advantages

Non-Contact Measurement

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

Suitable for Critical Rotating Machinery

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

Displacement and Vibration Measurement

The sensor supports measurement of static shaft position and dynamic movement, allowing the monitoring system to evaluate different aspects of rotating machinery behavior.

Compact 16 mm Sensor Head

The 16 mm head diameter supports installation in suitable monitoring locations where the required mounting clearance is available.

Industrial Measurement Performance

The PR6424 family provides a nominal sensitivity of 4 V/mm and a static measurement range of approximately ±2.0 mm under specified conditions.

Integration with EPRO Monitoring Equipment

When matched with the correct signal converter, the sensor can be integrated into an established machinery monitoring arrangement.

Lightweight Construction

The supplied weight is 0.2 kg, consistent with the published approximate weight of a PR6424 sensor with a 1-meter cable and no armor.

Technical FAQs

1. What is the Epro PR6424/008-101?

It is a 16 mm eddy current sensor designed for non-contact measurement of shaft displacement, vibration, 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 eddy current technology. The probe generates an electromagnetic field, and changes in the distance to a conductive metallic target alter the probe’s electrical response.

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

The published typical sensitivity is 4 V/mm, with linearity of no greater than ±1.5% under specified conditions.

5. What is the static measurement range?

The PR6424 family specifies a static measurement range of approximately ±2.0 mm.

6. Does the sensor measure shaft vibration?

Yes. It detects dynamic changes in the distance between the probe and shaft surface. The processed signal can be used by compatible monitoring equipment to evaluate shaft vibration.

7. Can the sensor operate without a signal converter?

The sensor is normally used with a compatible signal converter. The converter provides the required signal conditioning and measurement output for the monitoring system.

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 PR6424/008-101?

The supplied product weight is 0.2 kg. The published PR6424 family specification lists approximately 200 grams for the sensor with a 1-meter cable and without armor.

10. Can another PR6424 model replace the /008-101?

Not automatically. The complete suffix identifies configuration details that may affect mechanical installation and electrical compatibility. Check the mounting dimensions, cable, connector, and converter requirements before substitution.

Procurement and Maintenance Recommendations

When purchasing the Epro PR6424/008-101, verify the full ordering code and compare it with the label on the installed sensor. The 16 mm sensor head diameter alone is not sufficient to establish compatibility.

For replacement projects, confirm the probe’s mounting thread, overall length, cable construction, connector arrangement, and compatibility with the installed signal converter. If the sensor is part of a machinery protection system, also verify the monitoring channel configuration and required measurement range.

For used or refurbished sensors, inspect the probe tip, threaded sleeve, cable insulation, connector, and any signs of mechanical damage. Request clear photographs and available test information before purchasing.

During routine maintenance, inspect the mounting hardware and cable routing. Avoid pulling or sharply bending the cable, and ensure that the probe remains securely positioned. Changes to the mounting position or initial air gap should be followed by the appropriate calibration and verification procedure.

Maintaining a record of sensor locations, converter models, cable lengths, and baseline measurements can make future replacement and troubleshooting more efficient.

Conclusion

The Epro PR6424/008-101 16 mm Eddy Current Sensor is designed for non-contact shaft displacement and vibration measurement in critical rotating machinery. With a 16 mm sensor head and a supplied weight of 0.2 kg, it can be used in suitable turbine, compressor, pump, and fan monitoring installations.

The PR6424 family offers a typical sensitivity of 4 V/mm, a static measurement range of approximately ±2.0 mm, and a nominal center air gap of approximately 2.7 mm. For reliable operation, the probe must be matched with the correct signal converter, cable arrangement, mounting hardware, and monitoring-system input.

Accurate model verification is particularly important when replacing an existing sensor. Confirming the complete /008-101 configuration helps ensure mechanical fit, electrical compatibility, and dependable machinery monitoring.