Bently Nevada PR6423 Proximity Transducer System Modules: PR6423/010-110 CON021 & Full Series

Technical Dossier

Product Details And Specifications

Bently Nevada PR6423 Series: Comprehensive Module Range and Technical Overview

The Bently Nevada PR6423 series is a family of eddy-current proximity transducers engineered for continuous, non-contact measurement of shaft radial vibration, axial position, and differential expansion in rotating machinery. Deployed across global heavy industry — including petrochemical complexes, nuclear power stations, offshore platforms, and crude oil refineries — the PR6423 system forms a critical sensing layer within machinery protection architectures compliant with API 670. Its 8 mm probe diameter and standardized Bently Nevada connector interface make it a direct-fit replacement across legacy 3300 and 3500 series monitoring racks. The series operates on the eddy-current principle: a high-frequency oscillator drives the probe tip, and any conductive target within range induces eddy currents that alter the oscillator's impedance, producing a DC voltage output proportional to gap distance. This output is conditioned by a dedicated extension cable and proximitor/driver module before being fed to the monitoring system.

The Evolution of PR6423 Architecture

The PR6423 series traces its lineage to Bently Nevada's foundational eddy-current transducer work in the 1970s, when the company standardized the 8 mm probe format for turbomachinery OEM integration. Early variants used discrete oscillator-demodulator (ODIM) circuitry housed in separate proximitor enclosures, requiring careful cable length matching between probe, extension cable, and driver. The introduction of the CON0xx driver/proximitor sub-series consolidated signal conditioning into a single field-mountable enclosure, reducing installation complexity and improving EMI immunity in high-noise plant environments.

By the 1990s, the PR6423 architecture was fully integrated into the Bently Nevada 3300 XL monitoring system, with standardized 5 m, 9 m, and 15 m cable assemblies covering the majority of turbine pedestal geometries. The transition to the 3500 platform in the 2000s maintained backward compatibility at the transducer level: PR6423 probes and extension cables remain electrically compatible with 3500/40M and 3500/42M monitor cards, provided the proximitor output range (−18 VDC nominal) is within the monitor's input specification. As of 2026, the PR6423 series is in the mature/end-of-life phase of its product lifecycle. Bently Nevada (a Baker Hughes company) has transitioned new installations toward the 330500 and 330900 series, but the installed base of PR6423 systems in operating plants remains substantial, driving sustained demand for spare and replacement units.

PR6423 Full Catalog & Functionalities (SKU List)

The following SKUs represent the documented PR6423 series product range. Each entry identifies the probe length, cable configuration, and driver/proximitor pairing. All models produce a nominal −18 VDC output at 2 mm gap with a sensitivity of 7.87 V/mm (200 mV/mil).

PR6423/000-000: 8 mm probe, 0.5 m integral cable, no connector — bare-end OEM configuration for custom installations.
PR6423/001-000: 8 mm probe, 1 m integral cable, standard Bently Nevada connector, general-purpose radial vibration sensing.
PR6423/002-000: 8 mm probe, 2 m integral cable, standard connector, short-reach pedestal mounting.
PR6423/003-000: 8 mm probe, 3 m integral cable, standard connector, mid-range turbine bearing housing.
PR6423/005-000: 8 mm probe, 5 m integral cable, standard connector, most common field-installed length for steam turbines.
PR6423/007-000: 8 mm probe, 7 m integral cable, standard connector, extended-reach compressor train applications.
PR6423/009-000: 8 mm probe, 9 m integral cable, standard connector, large frame gas turbine pedestals.
PR6423/010-110: 8 mm probe, 10 m integral cable, armored jacket, high-vibration environment rating — the base probe assembly for the PR6423/010-110 CON021 system.
PR6423/010-110 CON021: Complete transducer system — 10 m armored probe + CON021 proximitor/driver; outputs −18 VDC nominal; API 670 compliant; used in radial vibration and axial position channels on 3300/3500 racks.
PR6423/015-000: 8 mm probe, 15 m integral cable, standard connector, long-reach installation for elevated turbine decks.
PR6423/015-110: 8 mm probe, 15 m armored cable, high-vibration/high-temperature jacket, refinery and petrochemical service.
CON011: Proximitor/driver module, 5 m system length, DIN-rail mount, −18 VDC output, pairs with PR6423/005-xxx probes.
CON021: Proximitor/driver module, 10 m system length, DIN-rail mount, −18 VDC output, standard pairing for PR6423/010-xxx probes; field-replaceable without probe removal.
CON031: Proximitor/driver module, 15 m system length, DIN-rail mount, −18 VDC output, pairs with PR6423/015-xxx probes.
CON041: Proximitor/driver module, extended-range, 20 m system length, used in large-frame machinery with remote junction boxes.
PR6423/010-110 CON031: Cross-length system assembly — 10 m probe with 15 m-rated CON031 driver; used when cable routing requires additional slack; requires gap voltage recalibration.
PR6423/005-110: 8 mm probe, 5 m armored cable, high-vibration jacket, compressor and pump applications with mechanical interference risk.

Sourcing Hard-to-Find & Obsolete PR6423 Parts

The PR6423 series entered the mature/declining phase of its lifecycle as Bently Nevada shifted its standard offering to the 330500 and 330900 transducer families. However, the replacement of an entire transducer system in an operating plant — including re-drilling probe bosses, re-routing cable trays, and reconfiguring monitor cards — represents a capital expenditure that most operators defer until a major turnaround. This creates a sustained multi-year demand for PR6423 spare units, particularly the CON021 and CON031 proximitor modules, which are the most failure-prone components due to their active electronics.

DriveKNMS maintains a dedicated inventory of PR6423 probes, extension cables, and CON0xx driver modules sourced from decommissioned plant equipment, authorized surplus channels, and OEM overstock. All units are inspected, tested, and documented before dispatch. For end-users operating under long-term service agreements (LTSAs) or multi-year maintenance contracts, DriveKNMS can provide consignment stock arrangements and priority allocation for critical spare classifications.

Quality Control for the PR6423 Range

The PR6423 system's performance is determined by the calibrated interaction between three components: the probe tip, the extension cable, and the proximitor/driver. Substituting any single component without verifying system-level gap voltage and sensitivity introduces measurement error that can trigger false trips or, more critically, mask genuine shaft excursions. DriveKNMS applies the following test protocol to all PR6423 units prior to shipment:

Each probe is bench-tested against a calibrated AISI 4140 steel target at 2 mm nominal gap, with output voltage verified at ±0.1 VDC of the −18 VDC specification. Extension cable continuity and insulation resistance (IR) are measured at 500 VDC; any cable exhibiting IR below 100 MΩ is rejected. CON0xx proximitor modules are powered at nominal 24 VDC supply and tested across the full gap range (0–2.5 mm) to verify linearity within ±0.5% of the published sensitivity curve. Complete system assemblies (probe + cable + driver) are tested as a matched set and shipped with a test certificate recording gap voltage, sensitivity, and supply current.