EPRO PR6424 Modules — PR6424/000-000 CON21

Technical Dossier

Product Details And Specifications

EPRO PR6424 Series: Comprehensive Module Range and Technical Overview

The EPRO PR6424 series is a family of eddy current proximity sensors engineered for continuous, non-contact displacement and vibration measurement in rotating machinery. Deployed across global heavy industry — including petrochemical refineries, nuclear power stations, offshore platforms, and large-scale turbomachinery installations — the PR6424 series forms a core sensing layer within Bently Nevada-compatible monitoring architectures. These sensors operate on the eddy current principle: a high-frequency oscillating magnetic field is generated at the probe tip, and any conductive target entering the field induces eddy currents that alter the probe's impedance. This impedance change is converted by a paired driver/oscillator into a linear DC voltage output proportional to the gap distance between probe tip and target surface.

The PR6424 series is fully compatible with EPRO CON021, CON041, and CON081 driver/oscillator modules, and integrates directly into Bently Nevada 3300, 3500, and EPRO MMS 6000/6350 monitoring systems. Its installation base spans decades of continuous operation in environments where sensor replacement requires planned outages — making long-term spare parts availability a critical operational requirement.

The Evolution of PR6424 Architecture

The PR6424 series was developed by EPRO GmbH (Germany) as part of a broader eddy current sensor platform designed to interface with the MMS (Machinery Monitoring System) product line. Early-generation PR6424 probes were paired exclusively with CON021 oscillator/driver units and used a fixed cable assembly with a standardized 5-meter or 9-meter extension cable. The system's architecture separates the probe, extension cable, and driver into discrete, field-replaceable components — a design philosophy that remains unchanged across all generations.

As industrial monitoring standards evolved, EPRO expanded the PR6424 range to accommodate varying gap ranges (from 0–1 mm to 0–5 mm), different thread sizes (M8, M10, M14), and extended temperature ratings for high-heat environments such as gas turbine bearing housings. Later variants introduced improved EMI shielding and ATEX/IECEx certification for use in explosive atmospheres. The series entered its mature phase with the widespread adoption of Bently Nevada 3500 systems, which accept PR6424-compatible signals natively. Current procurement activity for PR6424 is driven almost entirely by maintenance, repair, and overhaul (MRO) requirements rather than new installations.

PR6424 Full Catalog & Functionalities (SKU List)

The following SKUs represent the verified PR6424 series range, classified by function and configuration. Each model is a discrete, field-replaceable component within the EPRO eddy current measurement chain.

Eddy Current Probes — Standard Range

• PR6424/000-000 CON21: Standard M8 eddy current probe, 5mm gap range, paired with CON021 driver, general-purpose radial/axial displacement measurement.
• PR6424/000-010 CON21: M8 probe, 5mm gap range, extended 10m integral cable, CON021 compatible, for installations with increased probe-to-driver distance.
• PR6424/002-000 CON21: M8 probe, 2mm gap range, high-resolution variant for tight-clearance bearing monitoring applications.
• PR6424/010-000 CON21: M10 thread body, 5mm gap range, CON021 driver, used in medium-shaft turbomachinery radial position sensing.
• PR6424/010-010 CON21: M10 probe, 5mm gap, 10m cable, CON021 compatible, standard turbine bearing housing installation.
• PR6424/014-000 CON21: M14 thread body, 5mm gap range, heavy-duty probe for large-bore bearing housings in compressors and steam turbines.
• PR6424/014-010 CON21: M14 probe, 5mm gap, 10m cable, CON021 driver, extended-reach variant for large turbine pedestals.

Eddy Current Probes — High-Temperature / ATEX Variants

• PR6424/000-000 CON21 (ATEX): M8 probe, ATEX Zone 1 certified, for use in explosive gas atmospheres, petrochemical and offshore applications.
• PR6424/010-000 CON21 (ATEX): M10 ATEX-rated probe, 5mm gap, compatible with intrinsically safe CON021 driver configurations.
• PR6424/014-000 CON21 (HT): M14 high-temperature variant, rated to 180°C continuous, gas turbine exhaust-side bearing monitoring.

Extension Cables — PR6424 Compatible

• PR9376/010-000: 1m extension cable, standard impedance, PR6424 probe to CON021 driver interconnect.
• PR9376/050-000: 5m extension cable, standard impedance, the most common field configuration for PR6424 installations.
• PR9376/090-000: 9m extension cable, used where probe-to-driver distance exceeds standard 5m reach.

Driver / Oscillator Modules — PR6424 Compatible

• CON021/916-120: Standard oscillator/driver for PR6424 series, 200mV/mil output, rack-mount or field-mount housing, 24VDC supply.
• CON041/916-120: Dual-channel driver module, supports two PR6424 probes per unit, used in X-Y radial vibration measurement configurations.
• CON081/916-120: Eight-channel driver module, high-density installations, compatible with MMS 6350 monitoring racks.

Sourcing Hard-to-Find & Obsolete PR6424 Parts

The PR6424 series is in the mature-to-end-of-life phase of its product lifecycle. EPRO GmbH (now part of Baker Hughes / Bently Nevada) has progressively reduced factory stock of legacy PR6424 configurations. Lead times from OEM channels for non-standard variants (ATEX, high-temperature, non-standard cable lengths) can exceed 16–26 weeks, and certain M8 sub-variants have been formally discontinued.

DriveKNMS maintains a dedicated inventory of PR6424 probes, extension cables, and CON021/CON041/CON081 driver modules sourced through authorized distribution and verified surplus channels. All units are subject to pre-shipment functional verification. For plants operating Bently Nevada 3300/3500 or EPRO MMS 6000/6350 systems with PR6424 installed, DriveKNMS provides lifecycle extension support including cross-reference to compatible replacement probes where direct equivalents are no longer available.

Quality Control for the PR6424 Range

Eddy current sensor systems require end-to-end system verification — probe, extension cable, and driver must be tested as a matched set, not as individual components. DriveKNMS applies the following test protocol to all PR6424 system components:

• Gap-vs-Output Linearity Test: Each PR6424 probe is mounted in a calibration fixture with a precision micrometer stage. Output voltage from the paired CON021 driver is recorded at 0.25mm increments across the full gap range. Linearity deviation must remain within ±1% of full-scale output.
• Impedance Matching Verification: Extension cable impedance is measured and confirmed to match the probe's specified system resistance. Mismatched cables cause scale factor errors that are not detectable by visual inspection.
• Driver Output Stability Test: CON021/CON041/CON081 drivers are powered at nominal 24VDC and load-tested for output voltage stability over a 30-minute thermal soak period. Drift exceeding 0.5% triggers rejection.
• ATEX Variant Inspection: ATEX-certified units are inspected for enclosure integrity, cable gland condition, and certification label legibility prior to shipment. No field repair is performed on ATEX-certified assemblies.
• Functional System Test: Where possible, probe and driver are tested as a matched pair against a known-good reference target to confirm system sensitivity (mV/mm) matches the published specification for that probe/driver combination.