Product Overview

The Bently Nevada 138708-01 is a specialized Proximity Input I/O Module designed for the 3500 Machinery Protection System. This module serves as the primary hardware interface for proximity transducer systems, including the 3300 XL series. It is specifically engineered to support "Shaft Absolute" vibration measurements by processing signals from displacement sensors. By facilitating the high-speed acquisition of radial vibration and axial position data, the 138708-01 provides the raw data necessary for the 3500/42M Proximitor Monitor to perform real-time machinery protection. This component is vital for detecting early-stage mechanical faults such as shaft unbalance, misalignment, and bearing clearance issues in high-speed rotating assets.

Hardware Parameters and Key Technical Characteristics

The 138708-01 is built to industrial standards, offering high-fidelity signal conditioning and robust protection against electromagnetic interference.

• Model Identification 3500/42M (I/O Component)

• Order Number 138708-01

• Module Type Proximity Input I/O with Internal Terminations

• Measurement Support Radial Vibration, Axial Thrust, Eccentricity, and Shaft Absolute displacement

• Transducer Compatibility Engineered for use with 3300 and 3300 XL 5mm, 8mm, and 11mm Proximity Transducer Systems

• Termination Style Internal Terminations (Integrated compression screw terminals for direct field wiring)

• Signal Accuracy ±0.1% of full-scale measurement range

• Isolation 500 Vrms galvanic isolation between field inputs and the rack backplane

• Physical Weight 0.40 kg

• Chassis Dimensions 2.5 cm x 11.2 cm x 24.2 cm

• Environmental Rating Rated for continuous operation in temperatures from -30°C to +65°C

Industrial Applications and Operational Use Cases

The 138708-01 Shaft Absolute I/O module is a cornerstone of Turbine Supervisory Instrumentation (TSI) in various heavy industries.

• Power Generation Turbines Monitoring shaft centerline motion and absolute vibration in large-scale steam and gas turbines to prevent catastrophic rotor failure.

• Petrochemical Centrifugal Compressors Tracking high-frequency radial vibration to identify fluid-film bearing instabilities and oil whirl.

• Critical Process Pumps Surveillance of axial thrust position to ensure mechanical seal integrity and prevent internal impeller contact.

• Industrial Electric Motors Continuous monitoring of shaft-to-bearing clearances in high-horsepower motors driving process fans and blowers.

• Predictive Maintenance Programs Utilizing the buffered dynamic signal outputs to feed data into System 1 software for advanced spectral analysis and machine health trending.