Product Overview

The EPRO PR6424/010-010+CON021 16 mm Eddy Current Sensor is a non-contact measurement system designed for monitoring the movement and operating condition of rotating machinery. It combines a PR6424 series 16 mm eddy current probe with a compatible CON021 signal converter to measure shaft displacement, vibration, position, eccentricity, and speed-related parameters.

Manufactured within the EPRO product family associated with Emerson, the PR6424 series is designed for critical rotating equipment in power generation, petrochemical processing, and other industrial applications. Typical monitored machines include steam turbines, gas turbines, hydro turbines, compressors, pumps, and fans.

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 makes it suitable for continuous monitoring of machinery where shaft movement and vibration provide important information about equipment condition.

The PR6424 probe uses an electromagnetic measurement principle. When positioned near a suitable ferromagnetic target, changes in the distance between the probe and the target affect the sensor’s electrical characteristics. The associated signal converter processes this response and produces an output suitable for monitoring and protection equipment.

The PR6424 series has a nominal sensitivity of 4 V/mm and a specified linearity of no more than ±1.5%. Its standard static measuring range is ±2.0 mm, while its dynamic measurement range is specified from 0 to 1,000 μm. These characteristics make it useful for measuring both shaft position and dynamic vibration in appropriately configured machinery-monitoring systems.

The 16 mm probe diameter is an important identification feature when selecting replacement sensors. Buyers should also verify the complete model number, cable arrangement, connector type, calibration, and converter configuration because different PR6424 variants may have different mechanical and electrical characteristics.

Technical Specifications

Note: Specifications can vary with probe suffix, cable configuration, calibration, and converter version. Confirm the complete product identification and applicable technical documentation before replacement.

Function and Working Principle

The PR6424/010-010+CON021 system operates through the eddy current measurement principle. It detects changes in the distance between the sensor tip and a conductive target and converts these changes into an electrical signal for machinery monitoring.

1. Non-Contact Displacement Measurement

The sensor probe generates an electromagnetic field near its sensing tip. When a conductive metal shaft enters this field, eddy currents are induced in the target material.

The electrical characteristics of the probe change according to the distance between the sensor and the shaft. The system uses this relationship to determine the relative position of the target.

Because measurement does not require physical contact, the probe can monitor rotating shafts without introducing mechanical friction or wear at the measurement point.

2. Shaft Vibration Monitoring

Rotating machinery naturally experiences some degree of movement during operation. Excessive vibration, however, may indicate mechanical problems such as imbalance, misalignment, looseness, or bearing-related deterioration.

The PR6424 sensor can measure dynamic shaft displacement. When installed at suitable measurement positions, it provides signals that can be used to evaluate vibration behavior and identify changes in machine condition.

The resulting measurements can support continuous monitoring and maintenance decisions, particularly for machinery where unexpected shutdowns have significant operational consequences.

3. Static Position Measurement

In addition to dynamic vibration, the sensor can measure the relative position of a shaft or other suitable target.

Static displacement information is useful when monitoring shaft position, axial movement, and changes in mechanical clearances. The standard static range is specified as ±2.0 mm, subject to the applicable calibration and installation arrangement.

4. Signal Conversion Through CON021

The CON021 is an eddy current signal converter designed for compatible EPRO sensor types, including PR6424.

It processes the electrical response from the probe and provides a usable output signal for monitoring and protection equipment. The converter’s documented frequency range is 0 to 20,000 Hz at -3 dB, with a rise time below 15 μs.

The converter must be matched to the probe type and measuring range. An incompatible converter or incorrect calibration can result in inaccurate measurements.

5. Continuous Machinery Monitoring

When connected to a suitable monitoring system, the sensor assembly can provide continuous measurement information. Engineers can use these signals to observe changes in shaft movement and evaluate whether machinery is operating within its configured limits.

The sensor is a measurement component rather than a complete machinery-protection system. Alarm thresholds, shutdown logic, signal processing, and operator displays are handled by the associated monitoring and control equipment.

Role in Industrial Machinery Protection Systems

The PR6424/010-010+CON021 is designed to provide measurement signals for machinery monitoring and protection applications.

Turbine Shaft Monitoring

Steam, gas, and hydro turbines contain high-speed rotating components that require continuous condition monitoring. Shaft vibration and displacement measurements help maintenance teams assess mechanical behavior during operation.

The PR6424 sensor can be installed at appropriate measurement locations to monitor radial shaft movement or other specified displacement parameters.

Compressor Monitoring

Industrial compressors operate under changing process loads and mechanical conditions. Monitoring shaft displacement and vibration can help identify abnormal operating behavior.

The sensor can provide measurement signals for compatible monitoring equipment, supporting condition-based maintenance strategies.

Pump Monitoring

Large industrial pumps are often critical to continuous production. Abnormal vibration or shaft movement may indicate changes in bearing condition, alignment, balance, or mechanical loading.

A properly installed eddy current sensor can provide non-contact shaft measurements for monitoring applications.

PLC and Monitoring System Integration

The CON021 signal converter provides an electrical output that can be connected to compatible monitoring equipment. Integration with a PLC or distributed control system depends on the input signal requirements and the system architecture.

For critical machinery protection, the sensor should be connected through an appropriately designed monitoring system rather than assuming that every PLC analog input can accept the converter’s output directly.

Industrial Applications

1. Steam Turbines

Steam turbines are widely used in power generation and industrial energy systems. Their rotating shafts operate under demanding mechanical and thermal conditions.

The PR6424 sensor can support radial displacement and vibration monitoring, helping operators observe shaft behavior and identify changes that may require investigation.

2. Gas Turbines

Gas turbines are used in power plants, industrial facilities, and mechanical-drive applications. Continuous monitoring is important because abnormal shaft vibration can affect reliability and operating availability.

The PR6424 series is designed for critical turbomachinery measurement applications, including gas turbines.

3. Hydro Turbines

Hydro turbines operate under varying hydraulic and mechanical loads. Shaft position and vibration measurements can help maintenance teams assess machine condition and identify changes in operating behavior.

Non-contact sensing is useful for monitoring rotating components without introducing contact-related wear.

4. Industrial Compressors

Compressors in petrochemical plants, refineries, and manufacturing facilities may operate continuously for extended periods.

Shaft displacement and vibration measurements can support condition monitoring and help identify mechanical changes before they develop into more serious operational problems.

5. Industrial Pumps

Pumps used in water treatment, chemical processing, power generation, and manufacturing may require continuous monitoring.

The sensor can provide shaft movement information for compatible monitoring systems, helping maintenance teams assess the mechanical condition of critical pump assemblies.

6. Industrial Fans

Large industrial fans and ventilation systems are often used in process plants and power stations. Shaft vibration monitoring can help identify imbalance, mechanical looseness, and other operating abnormalities.

The PR6424 system may be used where the measurement requirements and installation geometry match the sensor’s specifications.

Installation and System Integration

Correct installation is essential for measurement accuracy and reliable operation.

1. Verify the Sensor Model

Before installation, confirm the complete PR6424/010-010 model designation and the associated CON021 converter.

Check the probe diameter, thread, cable configuration, connector arrangement, measuring range, and calibration information. Different PR6424 variants should not be assumed to have identical mechanical configurations.

2. Select a Suitable Measurement Position

The probe must be positioned so that its sensing tip faces an appropriate conductive target. The installation location should provide the required mechanical clearance and avoid interference from surrounding components.

The standard PR6424 specification identifies ferromagnetic steel, such as 42CrMo4, as the target material. Target material and shaft geometry can affect measurement performance.

3. Set the Initial Air Gap

The distance between the probe tip and the shaft must be adjusted according to the applicable calibration and installation instructions.

The PR6424 specification identifies a nominal center air gap of approximately 2.7 mm. The actual setup should follow the applicable probe and converter documentation.

Incorrect air-gap adjustment can reduce the usable measurement range or produce inaccurate readings.

4. Protect and Route the Cable

Cable routing should prevent excessive bending, mechanical damage, and unnecessary exposure to heat or vibration.

The probe cable should be routed away from strong electrical interference sources where practical. Connector cleanliness and secure connections are important for maintaining signal stability.

5. Install the CON021 Converter

The CON021 converter should be mounted in a suitable electrical enclosure and connected according to its terminal and wiring specifications.

Its documented protection class is IP20, so it should not be installed where it is directly exposed to water, dust, or other unsuitable environmental conditions.

Verify the supply voltage, output wiring, grounding, and probe connection before energizing the measurement chain.

6. Verify the Measurement Signal

After installation, check the converter output and confirm that the signal changes appropriately as the shaft position changes.

Where possible, compare the installed system against the required calibration procedure and monitoring-system configuration. Confirm alarm and trip thresholds separately in the machinery-protection system.

Compatible System Components

The PR6424/010-010+CON021 is part of a measurement chain. It must be matched with suitable signal-processing and monitoring equipment.

The probe and converter form the measurement chain, while monitoring modules and control-system components are selected according to the overall machinery-protection design.

Alternative Models and Replacement Considerations

The PR6424 series includes multiple probe configurations and measuring-range options. Related models should not be treated as direct replacements without checking the full ordering code.

Before replacing the PR6424/010-010+CON021, check:

• Complete probe model and suffix.
• Sensor head diameter.
• Probe thread and mounting dimensions.
• Cable length and cable construction.
• Connector type and adapter arrangement.
• Signal converter model and measuring range.
• Sensitivity and linearity specifications.
• Initial air gap and calibration requirements.
• Monitoring-system input compatibility.
• Mechanical and environmental installation conditions.

A probe with the same 16 mm diameter may still have a different cable arrangement, calibration, or measuring range. Exact model verification is therefore important.

Key Advantages

Non-Contact Measurement

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

Suitable for Critical Rotating Machinery

The PR6424 family is designed for applications involving turbines, compressors, pumps, and fans where continuous shaft monitoring is important.

Measurement of Static and Dynamic Displacement

The system supports both static shaft-position measurement and dynamic displacement monitoring within its specified operating range.

High Sensitivity

The documented sensitivity of 4 V/mm supports the measurement of relatively small changes in the probe-to-target distance.

Compatible Signal Conversion

The CON021 converter is designed to process signals from compatible EPRO eddy current probes, including the PR6424 series.

Continuous Condition Monitoring

When integrated with suitable monitoring equipment, the sensor can provide ongoing measurement information for machinery-condition assessment.

Industrial Measurement Design

The PR6424 probe uses a stainless-steel sleeve and PTFE cable construction, supporting use in demanding industrial measurement environments within the specified operating limits.

Technical FAQs

1. What is the EPRO PR6424/010-010+CON021?

It is a 16 mm eddy current sensor configuration using a PR6424 probe and a compatible CON021 signal converter. It is designed for non-contact measurement of shaft displacement and vibration in rotating machinery.

2. What does the 16 mm specification mean?

The 16 mm specification identifies the nominal diameter of the sensor head. It is an important mechanical dimension when selecting mounting hardware or replacing an existing probe.

3. What can this sensor measure?

It can be used to measure radial and axial shaft displacement, position, eccentricity, and speed/key-related parameters when installed and configured for the appropriate measurement.

4. What is the sensitivity of the PR6424 sensor?

The documented sensitivity is 4 V/mm, equivalent to approximately 101.6 mV/mil. The specified linearity is no more than ±1.5%.

5. What is the standard measuring range?

The PR6424 standard static range is ±2.0 mm. Its dynamic measuring range is specified from 0 to 1,000 μm. The applicable range should be confirmed against the exact probe and converter configuration.

6. What is the function of the CON021 converter?

The CON021 processes the electrical response from the compatible eddy current probe and provides an output signal for machinery monitoring equipment.

7. Can the sensor be used with a PLC?

It may be integrated into a suitable automation system through compatible signal-processing equipment. The PLC input must match the converter’s output characteristics. For critical protection functions, use an appropriately designed machinery-monitoring system.

8. Where is the PR6424 series commonly used?

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

9. What should be checked before replacing the sensor?

Verify the full model number, sensor diameter, mounting thread, cable configuration, connector, converter type, measuring range, and calibration. These details are important for maintaining measurement accuracy.

10. What is the weight of the PR6424/010-010+CON021?

The supplied listing weight is 0.32 kg. The actual weight can vary according to cable length, cable armor, connector, and included accessories.

Procurement and Maintenance Recommendations

When purchasing the EPRO PR6424/010-010+CON021, verify that the complete probe and converter configuration matches the installed measurement chain. The sensor head diameter alone is not sufficient for identifying a compatible replacement.

Request clear photographs of the probe label, converter label, cable, connector, and any supplied mounting accessories. Confirm the cable length and whether the product is supplied as a complete probe-and-converter assembly or as separate components.

For maintenance, inspect the probe cable for damage, check connector condition, and verify that the mounting arrangement remains secure. Avoid changing the initial air gap without following the calibration and installation procedure.

If the monitoring system reports abnormal or unstable readings, inspect the complete measurement chain rather than replacing the probe immediately. Possible causes include cable damage, loose connections, incorrect air-gap adjustment, converter mismatch, unsuitable target material, or incorrect monitoring-system configuration.

Keep records of sensor calibration, converter settings, installation position, and baseline operating measurements. These records can help maintenance teams compare future readings and identify changes in machinery condition.

Conclusion

The EPRO PR6424/010-010+CON021 16 mm Eddy Current Sensor is a non-contact measurement configuration designed for monitoring shaft displacement and vibration in critical rotating machinery. Its PR6424 probe provides a nominal sensitivity of 4 V/mm, a linearity specification of no more than ±1.5%, and a standard static measuring range of ±2.0 mm.

Paired with the CON021 signal converter, the system can provide measurement signals for compatible machinery-monitoring equipment. Its applications include turbines, compressors, pumps, and industrial fans.

For replacement and maintenance projects, the complete model number, probe dimensions, cable arrangement, converter compatibility, and calibration should be verified before installation. Correct configuration and commissioning are essential for reliable shaft measurement and machinery-condition monitoring.