EPRO PR6423 Modules: PR6423/010-000 CON021

Technical Dossier

Product Details And Specifications

EPRO PR6423 Series: Comprehensive Module Range and Technical Overview

The EPRO PR6423 series is a family of eddy current proximity sensors and associated signal conditioning systems engineered for continuous, non-contact displacement and vibration measurement in heavy industrial environments. Deployed across petrochemical refineries, nuclear power stations, offshore platforms, and large-scale rotating machinery installations, the PR6423 series forms a critical layer of machinery protection infrastructure. 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 — a change that is converted into a calibrated DC voltage output by the paired signal conditioner.

In rotating machinery protection systems — turbines, compressors, pumps, and gearboxes — the PR6423 series is used to measure shaft radial vibration, axial position (thrust), differential expansion, and eccentricity. Its output signals are directly compatible with EPRO MMS 6000, Bently Nevada 3500, and other industry-standard machinery protection systems. The series is manufactured to IEC 61511 functional safety standards and is widely specified in SIL-rated protection loops.

The Evolution of PR6423 Architecture

The PR6423 series was developed by EPRO GmbH (later acquired by Emerson as part of the Machinery Health Management portfolio) as a standardized eddy current sensor platform to replace earlier discrete probe-and-driver assemblies that lacked interchangeability and calibration traceability.

First Generation (PR6423/0xx-000 baseline): Introduced standardized M8 and M12 threaded probe bodies with fixed cable lengths. Signal conditioning was handled externally by dedicated driver units such as the CON011 and CON021 series. Calibration was performed against a steel target (AISI 4140) with a defined sensitivity of 8 mV/µm or 200 mV/mil.

Second Generation (CON021 / CON031 conditioners): The introduction of the CON021 and CON031 signal conditioners brought improved EMI rejection, extended temperature range operation (−40°C to +85°C), and compatibility with longer cable extensions up to 9 m total system length. The PR6423/010-000 CON021 combination — the subject of this page — represents the most widely deployed configuration in this generation, covering a 0–2 mm linear measurement range.

Modern Alternatives: Emerson's current portfolio positions the PR6424 and PR9268 series as forward-compatible replacements for the PR6423 in new installations. However, the PR6423 remains the specified sensor in the majority of installed base machinery protection systems built between 1990 and 2015. Retrofit replacement requires recalibration of the full probe-driver-extension cable system and is not a drop-in substitution. As a result, the PR6423 series remains in active demand for maintenance, repair, and overhaul (MRO) procurement globally.

PR6423 Full Catalog & Functionalities (SKU List)

The following SKUs represent the verified, commonly deployed configurations within the EPRO PR6423 eddy current sensor system. Each entry reflects a distinct probe body geometry, cable length, or conditioner pairing.

PR6423/000-000: Standard eddy current probe, M8 thread, 1 m integral cable, no conditioner, 0–1 mm range.
PR6423/001-000: Standard eddy current probe, M8 thread, 3 m integral cable, 0–1 mm range.
PR6423/002-000: Standard eddy current probe, M8 thread, 5 m integral cable, 0–1 mm range.
PR6423/003-000: Standard eddy current probe, M8 thread, 9 m integral cable, 0–1 mm range.
PR6423/010-000: Standard eddy current probe, M12 thread, 1 m integral cable, 0–2 mm range — core probe body for CON021 pairing.
PR6423/010-000 CON021: Complete system — M12 probe + CON021 signal conditioner, 0–2 mm, 8 mV/µm sensitivity, −40°C to +85°C.
PR6423/011-000: M12 probe, 3 m integral cable, 0–2 mm range.
PR6423/012-000: M12 probe, 5 m integral cable, 0–2 mm range.
PR6423/013-000: M12 probe, 9 m integral cable, 0–2 mm range.
PR6423/020-000: High-temperature probe variant, M12 thread, 1 m cable, rated to +180°C probe tip.
PR6423/021-000: High-temperature probe, M12 thread, 3 m cable, +180°C rated.
PR6423/022-000: High-temperature probe, M12 thread, 5 m cable, +180°C rated.
PR6423/030-000 CON031: Extended range system, 0–4 mm, paired with CON031 conditioner, for large shaft applications.
PR6423/031-000 CON031: Extended range, 3 m cable, CON031 conditioner, 0–4 mm.
PR6423/032-000 CON031: Extended range, 5 m cable, CON031 conditioner, 0–4 mm.
PR6423/040-000: Flush-mount probe variant for tight installation clearances, M12 thread, 1 m cable.
PR6423/050-000 CON021: Armored cable variant for high-vibration environments, M12 probe, CON021 conditioner.
PR6423/060-000: ATEX/IECEx certified variant for Zone 1 hazardous area installation, M12 thread.

Sourcing Hard-to-Find & Obsolete PR6423 Parts

The PR6423 series has entered the mature-to-declining phase of its product lifecycle. Emerson/EPRO has progressively reduced factory stock of legacy configurations, and lead times for new manufacture — where still available — can exceed 20 weeks. For plant operators running machinery protection systems built around the PR6423, unplanned sensor failure creates a direct risk to machinery availability and safety system integrity.

DriveKNMS maintains a dedicated inventory of PR6423 series probes, conditioners, and extension cables sourced from decommissioned plant equipment, authorized distributor overstock, and controlled factory surplus channels. Our procurement team actively tracks global availability of discontinued configurations including the CON021 and CON031 conditioner variants. We provide:

• Same-day quotation for in-stock PR6423 configurations
• Cross-reference verification against original plant documentation and calibration records
• Emergency shipment capability for critical machinery protection applications
• Long-term supply agreements for operators managing multi-unit fleets

Quality Control for the PR6423 Range

Eddy current sensor systems require system-level validation — probe, extension cable, and conditioner must be tested as a matched set, not as individual components. DriveKNMS applies the following verification protocol to all PR6423 units prior to dispatch:

• Impedance verification: Probe tip impedance is measured at 1 MHz using a calibrated LCR meter and compared against EPRO factory specification bands for the specific probe model.
• Static calibration check: Each probe-conditioner pair is calibrated against an AISI 4140 steel target at defined gap increments (0.25 mm steps) across the full linear range. Output voltage linearity must fall within ±1% of the nominal sensitivity curve.
• Cable continuity and insulation resistance: All integral and extension cables are tested for conductor continuity and insulation resistance (minimum 100 MΩ at 500 VDC) to detect micro-fractures in armored or aged cable assemblies.
• Conditioner output verification: CON021 and CON031 units are powered at nominal supply voltage (−24 VDC) and output voltage, current consumption, and oscillator frequency are verified against datasheet limits.
• Environmental inspection: Probe bodies are inspected for thread damage, tip contamination, and cable jacket integrity. Units with physical damage to the sensing face are rejected regardless of electrical performance.