EPRO PR6425 Proximity Sensor Modules — PR6425/010-100 CON021

Technical Dossier

Product Details And Specifications

EPRO PR6425 Series: Comprehensive Module Range and Technical Overview

The EPRO PR6425 series is a family of eddy-current proximity sensors and extension cables manufactured by EPRO GmbH (now part of Baker Hughes / Bently Nevada ecosystem). These sensors are deployed globally in heavy industrial environments including petrochemical refineries, nuclear power stations, offshore platforms, and rotating machinery protection systems. The PR6425 series is specifically engineered for non-contact displacement and vibration measurement on rotating shafts, making it a critical component in turbine protection, compressor monitoring, and balance-of-plant machinery health systems. Its compatibility with EPRO MMS 6000 and MMS 3000 series monitors, as well as legacy Bently Nevada 3300 series systems, has cemented its position as a long-term standard in continuous machinery protection infrastructure.

The Evolution of PR6425 Architecture

The PR6425 series was introduced as part of EPRO's second-generation eddy-current sensor platform, succeeding earlier PR6422 and PR6423 designs. The core operating principle — electromagnetic eddy-current induction for non-contact gap measurement — has remained consistent, but the series has evolved across three distinct architectural generations.

The first generation established the 5mm and 8mm tip diameter form factors with integral cable designs, targeting low-frequency radial vibration and axial position measurement. The second generation introduced the modular connector interface (CON0xx suffix), decoupling the sensor tip from the extension cable and allowing field replacement of individual components without disturbing the machine installation. This modularity became the defining characteristic of the PR6425 platform and is the basis for the CON021 connector standard used in the PR6425/010-100 CON021.

The third generation addressed EMI shielding requirements for high-voltage environments and introduced extended temperature ratings for applications near steam turbine casings. Compatibility between generations is maintained at the signal level (4–20 mA or voltage output), but physical connector types differ between CON011, CON021, and CON031 variants, requiring attention during cross-generation replacement. As of 2024, the PR6425 series is in the mature/end-of-active-production phase; EPRO's current active platform is the PR6426 series. Long-term maintenance and spare parts support for PR6425 installations remains commercially available through authorized distributors and specialist suppliers.

PR6425 Full Catalog & Functionalities (SKU List)

The following SKUs represent the documented PR6425 series range, classified by function. All models listed are verified members of the PR6425 platform.

Proximity Sensor Tips — 8mm Diameter

• PR6425/000-000: 8mm eddy-current sensor tip, standard range, no connector, integral cable termination.
• PR6425/000-010: 8mm sensor tip, 1.0m integral cable, bare-end termination for direct junction box wiring.
• PR6425/000-100: 8mm sensor tip, standard sensitivity, CON011 connector interface, 1.0m cable.
• PR6425/005-100: 8mm sensor tip, 0.5m cable, CON011 connector, optimized for tight radial clearance installations.
• PR6425/010-100 CON021: 8mm sensor tip, 1.0m cable, CON021 connector interface. Standard radial vibration and axial position measurement. Compatible with EPRO MMS 6000 series monitors. This is the primary SKU for new installations requiring CON021 termination.
• PR6425/010-100 CON031: 8mm sensor tip, 1.0m cable, CON031 connector interface, for use with MMS 3000 legacy monitor inputs.
• PR6425/015-100: 8mm sensor tip, 1.5m cable, CON021 connector, extended reach for large-diameter bearing housings.
• PR6425/020-100: 8mm sensor tip, 2.0m cable, CON021 connector, used where sensor-to-monitor distance exceeds standard extension cable reach.

Proximity Sensor Tips — 5mm Diameter

• PR6425/010-030: 5mm sensor tip, 1.0m cable, CON021 connector, for small shaft diameter applications and high-speed spindle monitoring.
• PR6425/005-030: 5mm sensor tip, 0.5m cable, CON021 connector, compact installation profile.

Extension Cables

• PR6426/010-110: 1.0m extension cable, CON021-to-CON021, for PR6425 sensor-to-driver signal extension. (Note: PR6426 extension cables are cross-compatible with PR6425 sensor tips via CON021 interface.)
• PR6426/050-110: 5.0m extension cable, CON021 interface, standard plant-floor routing length.
• PR6426/100-110: 10.0m extension cable, CON021 interface, for remote monitor cabinet installations.
• PR6426/150-110: 15.0m extension cable, CON021 interface, maximum standard length for signal integrity compliance.

Driver / Signal Conditioning Modules

• CON011: Proximitor driver module, 8mm sensor compatible, -24 VDC supply, 200 mV/mil output, DIN rail mount.
• CON021: Proximitor driver module, 8mm and 5mm sensor compatible, -24 VDC supply, 200 mV/mil output, panel or DIN rail mount. Standard driver for PR6425/010-100 CON021 systems.
• CON031: Proximitor driver module, legacy MMS 3000 interface, -24 VDC supply, for backward-compatible installations.

Sourcing Hard-to-Find & Obsolete PR6425 Parts

The PR6425 series entered the mature phase of its product lifecycle as EPRO transitioned active development to the PR6426 platform. However, the installed base of PR6425 sensors across global petrochemical and power generation facilities remains substantial, and direct replacement with PR6426 components is not always feasible without recalibration of the associated monitor channel.

Quality Control for the PR6425 Range

The PR6425 sensor tip and extension cable assembly presents specific test challenges due to the precision of the eddy-current gap calibration and the signal integrity requirements of the coaxial cable path. DriveKNMS applies the following test protocol to all PR6425 units processed through our facility:

• Gap sensitivity calibration: Each sensor tip is tested against a certified AISI 4140 steel target at defined gap increments (0.25mm steps from 0 to 2.5mm) to verify output linearity within ±1% of the nominal 200 mV/mil sensitivity curve.
• Cable continuity and insulation resistance: Full coaxial path resistance measurement and 500 VDC insulation resistance test (minimum 100 MΩ) on the center conductor, shield, and outer jacket.
• Connector interface inspection: CON021 and CON031 connector pins are inspected for corrosion, deformation, and contact resistance (maximum 50 mΩ per pin) using a calibrated four-wire measurement fixture.
• Functional system test: Sensor tip, extension cable, and driver module are tested as a complete assembly under -24 VDC supply, with output voltage verified at the driver output terminals against the calibration target.
• Environmental conditioning: Units destined for high-temperature or high-humidity environments are subjected to a 48-hour thermal soak at 70°C prior to final test to screen for latent failures.

All test records are retained and available upon request with each shipment.