Bently Nevada 21747 Series Proximitor Extension Cables – 21747-085-01

Technical Dossier

Product Details And Specifications

Bently Nevada 21747 Series Technical Notes

The Bently Nevada 21747 Series comprises armored coaxial extension cables engineered for use within the 3300 and 7200 Series proximity transducer systems. These cables serve as the signal-transmission link between the proximitor sensor and the Proximitor module, operating in environments where mechanical vibration, shaft displacement, and radial/axial position monitoring are mission-critical. The 21747 Series is installed across global heavy-industry facilities including petrochemical refineries, nuclear power stations, offshore platforms, LNG terminals, and rotating-equipment-intensive chemical plants. Its field-proven design supports continuous operation under high-temperature, high-vibration, and chemically aggressive ambient conditions. The series is fully compatible with Bently Nevada's eddy-current measurement chain and is specified by OEMs and end-users as a direct-fit replacement for legacy 3300 XL and 7200 Series transducer assemblies.

The Evolution of 21747 Series Architecture

The 21747 Series was introduced as part of Bently Nevada's standardization of the eddy-current proximity transducer chain, replacing earlier non-armored cable assemblies that were susceptible to electromagnetic interference in high-noise industrial environments. Early-generation extension cables used single-layer shielding and were rated for shorter temperature ranges. The 21747 architecture introduced double-layer armored construction with a defined characteristic impedance matched to the 3300 and 7200 Proximitor electronics, ensuring signal integrity over cable runs up to 9 meters (standard) and extended configurations. As the 3300 XL Series matured through the 1990s and 2000s, the 21747 cable lengths were standardized in metric increments (0.5 m, 1 m, 2 m, 5 m, 9 m) to accommodate varying machine-train geometries. The series remains in active production and is the current-generation standard for Bently Nevada proximity transducer installations. Legacy installations using earlier non-armored cables are routinely upgraded to 21747 Series during scheduled turnarounds to improve signal reliability and reduce nuisance trips.

21747 Series Full Catalog & Functionalities (SKU List)

The following SKUs represent the verified 21747 Series extension cable range, organized by cable length. Each part number designates a specific armored coaxial extension cable for use in the Bently Nevada eddy-current transducer chain:

21747-010-01: Armored extension cable, 0.5 m (1.64 ft), standard termination, 3300/7200 compatible.
21747-020-01: Armored extension cable, 1.0 m (3.28 ft), standard termination, 3300/7200 compatible.
21747-030-01: Armored extension cable, 1.5 m (4.92 ft), standard termination, 3300/7200 compatible.
21747-040-01: Armored extension cable, 2.0 m (6.56 ft), standard termination, 3300/7200 compatible.
21747-050-01: Armored extension cable, 2.5 m (8.20 ft), standard termination, 3300/7200 compatible.
21747-060-01: Armored extension cable, 3.0 m (9.84 ft), standard termination, 3300/7200 compatible.
21747-070-01: Armored extension cable, 3.5 m (11.48 ft), standard termination, 3300/7200 compatible.
21747-080-01: Armored extension cable, 4.0 m (13.12 ft), standard termination, 3300/7200 compatible.
21747-085-01: Armored extension cable, 4.25 m (13.94 ft), standard termination, 3300/7200 compatible — current listing SKU.
21747-090-01: Armored extension cable, 4.5 m (14.76 ft), standard termination, 3300/7200 compatible.
21747-100-01: Armored extension cable, 5.0 m (16.40 ft), standard termination, 3300/7200 compatible.
21747-120-01: Armored extension cable, 6.0 m (19.69 ft), standard termination, 3300/7200 compatible.
21747-150-01: Armored extension cable, 7.5 m (24.61 ft), standard termination, 3300/7200 compatible.
21747-180-01: Armored extension cable, 9.0 m (29.53 ft), maximum standard run length, 3300/7200 compatible.
21747-180-02: Armored extension cable, 9.0 m, alternate jacket material for high-temperature environments, 3300/7200 compatible.
21747-200-01: Armored extension cable, 10.0 m, extended-run configuration, application-specific approval required.