Product Overview

The Epro PR6426/010-010+CON021 combines a 32 mm eddy current sensor with a CON021 signal converter for non-contact displacement measurement in critical rotating machinery. The assembly is suitable for applications involving steam turbines, gas turbines, compressors, pumps, and industrial fans, where shaft position and movement need to be monitored without physical contact between the probe and the rotating surface.

In a turbine bearing installation, the sensor measures the relative position of the shaft against a stationary mounting point. Changes in this measurement can help engineers evaluate rotor movement during startup, thermal expansion, load changes, and abnormal operating conditions. In a large compressor, shaft-displacement measurements can be reviewed alongside vibration and operating data to investigate changes in rotor behavior.

The PR6426/010-010 performs the actual sensing, while the CON021 processes the sensor response into an electrical output for compatible monitoring equipment. This distinction matters during installation and replacement: the sensor must be positioned correctly relative to the target, and the converter must match the intended measuring range and output configuration.

For the standard PR6426 measuring configuration, the CON021 supports a nominal static measuring range of ±4.0 mm, with a nominal sensitivity of 2 V/mm and a specified linearity performance of ±1.5% maximum. The complete measuring chain depends on the target material, installation gap, and calibration, so these values should be applied to the appropriate standard configuration rather than assumed to describe every PR6426 variant.

The /010-010 designation identifies the specific sensor variant. Although other PR6426 models may share the same sensor-head diameter, their connection arrangements and ordering configurations should be checked before substitution. The complete sensor-converter combination should be matched to the installed monitoring channel.

Technical Specifications

Product Features

• Combined sensing and signal conditioning: The PR6426/010-010 detects shaft displacement, and the CON021 converts the sensor response into a usable electrical output for compatible monitoring equipment.
• Standard-range measurement: The standard PR6426 configuration supports a static measuring range of ±4.0 mm. This is appropriate where the required displacement span falls within the calibrated operating range.
• Defined sensitivity: The nominal sensitivity of 2 V/mm establishes the relationship between target movement and the conditioned output in the specified measuring configuration.
• High-frequency response: The CON021 has a specified frequency range of 0–20,000 Hz at -3 dB and a rise time below 15 µs, supporting dynamic displacement measurements within the operating limits of the complete measuring chain.
• Non-contact operation: The sensor detects relative movement without a contacting element rubbing against the rotating shaft, avoiding contact-related wear at the sensing point.
• Industrial sensor construction: The stainless-steel sleeve and PTFE cable are suited to the specified sensor operating environment.
• Configurable output range: The CON021 supports the specified negative-voltage output configurations. The selected output must correspond to the receiving monitoring input and its scaling.
• Integration with machinery monitoring: The conditioned signal can be used for displacement display, trend recording, and evaluation against configured monitoring limits.

Working Principle

The PR6426/010-010 measures displacement through electromagnetic coupling between its sensing coil and a conductive target. When the CON021 excites the sensor, an alternating electromagnetic field forms around the sensing head. This field induces eddy currents in the target, affecting the electrical response of the sensor coil.

As the shaft moves relative to the stationary probe, the distance between the sensing head and the target changes. The corresponding change in electromagnetic coupling is processed by the converter and translated into an output voltage associated with the shaft’s position.

The measurement path is:

Conductive Shaft Target → PR6426/010-010 Sensor → CON021 Signal Converter → Machinery Monitoring System

In the standard PR6426 configuration, the nominal static measuring range is ±4.0 mm, with a sensitivity of 2 V/mm. The initial gap establishes the operating point within this range. If the sensor is installed too close to or too far from the target, the available measurement travel can become uneven, and the output may no longer represent the expected displacement correctly.

The target material also affects the measurement response. The standard reference target is ferromagnetic steel, specifically 42CrMo4. A different shaft material may change the relationship between target movement and the electrical output, so the material and calibration requirements should be reviewed when installing the sensor on an existing machine.

The CON021 supplies the conditioned signal to the monitoring system. The receiving equipment interprets that signal according to its configured measurement scale and alarm limits. A sudden change in the reading may indicate actual shaft movement, but it can also result from an incorrect gap, a connection problem, or a mismatch between converter output and monitoring input.

For this reason, commissioning should verify the complete measurement channel rather than only confirming that the sensor is electrically connected.

Role in the Machinery Monitoring Architecture

The PR6426/010-010+CON021 occupies the sensing and signal-conditioning stages of a machinery monitoring channel. The sensor measures relative shaft movement, and the converter prepares the response for use by compatible monitoring electronics.

In a turbine installation, the measurement channel may be used to monitor shaft position near a bearing. In a compressor, the output can be evaluated alongside vibration, speed, and process conditions to investigate changes in rotor behavior.

The converter configuration must be preserved when replacing the assembly. A standard-range CON021 and an extended-range CON021 variant do not necessarily have the same measurement scaling. If the converter type changes, the monitoring channel may require recalibration and adjustment of its configured displacement range.

Industrial Applications

Installation and Maintenance

1. Verify both model designations: Confirm PR6426/010-010 and CON021 against the installed assembly and maintenance records. Do not identify the complete measuring chain by the sensor series alone.
2. Confirm the standard measuring configuration: Check that the application requires the standard PR6426 range rather than an extended-range converter. Verify the expected shaft movement against the nominal static range of ±4.0 mm.
3. Check the target material: Confirm that the measured shaft surface is suitable for the calibrated measuring chain. The standard reference material is ferromagnetic steel, 42CrMo4.
4. Inspect the mounting arrangement: Examine the bracket, fixing points, and mounting surface before installation. The sensor must remain stationary relative to the machine structure during operation.
5. Set the initial gap: Establish the sensor-to-target distance using the applicable installation and calibration procedure. The nominal center air gap is approximately 5.5 mm for the standard measuring configuration.
6. Check the sensing-area clearance: Inspect nearby ferrous components that could influence the electromagnetic field. Confirm that the mounting arrangement meets the clearance requirements for the installed sensor.
7. Inspect the sensor head: Check the sleeve and sensing surface for mechanical damage, deformation, or contamination. Verify that the probe is securely mounted before commissioning.
8. Examine the cable route: Look for cuts, crushing, abrasion, or excessive bending. Keep the cable away from moving machinery and heat sources that exceed its applicable operating limits.
9. Verify the converter connection: Confirm that the sensor cable and connector arrangement match the CON021 input. Check all connections before energizing the measurement channel.
10. Check the power supply and output range: Verify the converter supply voltage and selected output configuration against the receiving monitoring input. Confirm signal polarity and engineering-unit scaling.
11. Test the measurement response: Follow the approved commissioning procedure to confirm that changes in target position produce the expected output. Check that the signal remains within the calibrated range and that the monitoring system displays the correct displacement.
12. Record the final configuration: Document the sensor model, converter designation, initial gap, output range, monitoring-channel scaling, and commissioning results. These records support consistent maintenance and future replacement.

Compatible System Components

The sensor, converter, and monitoring input should be treated as one measurement channel. Replacing one component may affect calibration, output scaling, or the configured measuring range, so the complete arrangement should be checked before returning the machine to service.

Recommended Related Models

Key Advantages

• Combines the PR6426 sensor with a compatible CON021 signal converter.
• Supports standard-range shaft-displacement measurement.
• Offers a nominal sensitivity of 2 V/mm in the specified configuration.
• Provides a converter frequency range of 0–20,000 Hz at -3 dB.
• Integrates with compatible machinery monitoring channels.

Technical FAQs

What distinguishes the standard CON021 configuration from the CON021/916 extended-range versions?

The standard CON021 configuration for PR6426 supports a nominal static measuring range of ±4.0 mm. The CON021/916 variants are configured for larger extended measuring ranges, so their calibration and output scaling differ. The converter must match the required measurement span.

Does the sensor produce a displacement value without the CON021 converter?

The sensor detects displacement through its electromagnetic response, but the complete measuring chain requires compatible signal-conditioning electronics to produce the intended monitoring output. The CON021 processes the sensor response for connection to suitable monitoring equipment.

Why should the output voltage configuration be checked before connecting the assembly?

The CON021 supports specified negative-voltage output ranges. The receiving input must be compatible with the selected range and configured with the correct scaling. Otherwise, the displayed displacement may not correspond to the actual shaft position.

What should be checked if the sensor output becomes unstable after maintenance?

Inspect the initial gap, mounting rigidity, cable condition, connector security, converter supply, and monitoring-channel configuration. Also consider whether nearby metal or a change in target conditions could affect the sensor response before attributing the problem to a defective sensor.