Bently Nevada 3500/40 125680-01 Proximitor I/O Module

Critical Technical Specifications

Parameter	Specification
Manufacturer	Bently Nevada (GE Measurement & Control)
Model Number	3500/40 125680-01
Product Type	Proximitor I/O Module
Chassis Compatibility	Bently Nevada 3500 Series Rack
Total Channels	4 independent channels
Probe Options	3300 XL 5mm and 8mm proximity transducers
Input Signal Range	-1.0 Vdc to -20.0 Vdc
Internal Excitation	-24 Vdc nominal probe supply
Buffered Output	-1.5 Vdc to -20.0 Vdc per channel
Front Interface	20-pin ARINC 404 style connector
Backplane Connection	24-pin male header
Module Width	25 mm (1.0 inch)
Module Height	241 mm (9.5 inches)
Module Depth	200 mm (7.9 inches)
Unit Weight	0.9 kg (2.0 lbs)
Typical Power Draw	10 Watts
Bulk Capacitance	100 µF for power ride-through
Calibration Cycle	12 months recommended

Functional Overview and Signal Conditioning

This module acts as a dedicated front-end processor for the 3500 Series monitoring framework. It accepts raw high-frequency signals from eddy current proximity probes. The 3500/40 125680-01 then translates these inputs into linear DC voltage outputs. Each of the four channels operates completely independently from the others. Therefore, you can configure each channel for different measurement types simultaneously. Common applications include radial vibration, thrust position, and rotor eccentricity monitoring. The module also provides buffered outputs for each channel on the front panel. These outputs allow technicians to connect portable analyzers without disturbing the main system.

Processing Architecture and Measurement Accuracy

The module employs precision peak detection and signal averaging internally. This design ensures stable measurements despite fluctuating rotor conditions. Moreover, the Bently Nevada 3500/40 125680-01 includes automatic gap voltage monitoring for each probe. This feature alerts operators to potential transducer degradation or mechanical drift. The module also incorporates a high-pass filter for AC vibration components. Additionally, a low-pass filter isolates the DC gap signal for position measurements. Consequently, the module delivers accurate data for both protection and predictive maintenance strategies.

Mechanical Layout and Connectivity Features

The module’s slim 25 mm profile maximizes rack density in crowded cabinets. Its 241 mm height matches all other 3500 Series modules perfectly. The 200 mm depth also accommodates standard rear cable routing and termination panels. Furthermore, the 20-pin ARINC front connector provides a rugged, military-grade interface. This connector ensures secure signal transmission even in high-vibration environments. The rear backplane connector handles power distribution and system data exchange. The internal 100 µF capacitor bank provides essential energy storage for power interruptions. This capacitance allows the 125680-01 to ride through short-duration voltage sags.

Operational Conditions and Compliance

The module operates reliably across a 0°C to +65°C ambient temperature range. Non-operating storage tolerates -40°C to +85°C extremes. The unit also complies with CE and RoHS directives for global deployment. Install the module in a clean, climate-controlled cabinet to prevent contamination. The module performs automatic self-checks upon insertion into a powered rack. This auto-diagnostic routine verifies internal circuitry and channel integrity. Routine recalibration every 12 months sustains long-term specification adherence.