Bently Nevada 138700-01 | Shaft Absolute I/O Module

The Bently Nevada 138700-01 shaft absolute I/O module provides precise axial and radial position measurement for 3500 monitoring systems. This module interfaces with proximity probes to detect absolute shaft displacement. The unit delivers isolated channels for critical turbomachinery protection applications.

Technical Specifications

Parameter	Specification
Product Type	Shaft absolute I/O module
Compatibility	Bently Nevada 3500 system
Number of Channels	4 inputs (isolated)
Input Types	Proximity probes (5/8 mm, 8 mm, 11 mm)
Input Signal Range	-2V to -24V DC (probe bias)
Measurement Range	0 to 2.5 mm (radial), 0 to 5 mm (axial)
Resolution	0.01% of full scale
Accuracy	±0.1% of full scale
Frequency Range	0 Hz to 10 kHz (DC-coupled)
Isolation Voltage	500V DC (channel-to-channel)
Dimensions (W x H x D)	241 x 152 x 25 mm
Weight	0.85 kg
Internal Components	4 x isolation amplifiers, 1 x processor, 4 x ADCs, 4 x filters
Signal Processing	DC drift compensation, filtering, linearization
Connector Type	25-pin D-sub (female)
Power Supply	24V DC (from backplane)
Power Consumption	5W (typical)
LED Indicators	4 x status LEDs (channel health)
Operating Temperature	-20°C to +65°C
Storage Temperature	-40°C to +85°C
Protection Class	IP20
Mounting	3500 rack (plug-in)
Approvals	CE, UL, CSA, ATEX

Precise Absolute Shaft Position Measurement

The Bently Nevada 138700-01 provides accurate absolute shaft displacement measurement for rotating machinery. This module detects both axial thrust and radial runout with exceptional precision. The unit supports 5mm, 8mm, and 11mm proximity probes. Users can measure shaft position changes as small as 0.01% of full scale.

Four Galvanically Isolated Input Channels

Four isolated channels provide 500V DC isolation for reliable signal acquisition. This isolation prevents ground loops and protects against electrical noise. Each channel includes independent signal conditioning and DC drift compensation. Users can connect multiple probes without interference between channels.

Wide Measurement Range for Various Applications

The module measures radial displacement from 0 to 2.5 mm for radial bearings. The axial measurement range extends to 5 mm for thrust bearing monitoring. This wide range accommodates various turbine and compressor configurations. Users can configure each channel for specific probe types and ranges.

High-Accuracy DC-Coupled Signal Processing

DC-coupled inputs capture both static and dynamic shaft position changes. The module provides linearization and filtering for precise measurements. High-accuracy conversion ensures ±0.1% of full-scale measurement fidelity. Users can detect both slow drift and rapid position changes reliably.

Specialized Monitoring for Thrust and Radial Bearings

This module excels at measuring axial position for thrust bearing wear detection. Radial displacement measurements identify shaft runout and alignment issues. The module supports both steady-state and transient position monitoring. Users can track shaft position changes over time for predictive maintenance.

Seamless 3500 Rack Integration

The module plugs directly into the 3500 rack backplane for simple installation. A 25-pin D-sub connector provides field wiring for all probe connections. Users can replace modules without system shutdown. The half-height design fits standard 3500 rack configurations efficiently.