Product Overview

The Bently Nevada 991-25-50-01-01 is a specialized 2-wire axial displacement transmitter designed to facilitate continuous thrust monitoring for industrial rotating assets. This module functions as a signal conditioner that interfaces directly with a 3300 NSv proximity probe, converting the high-frequency eddy current signal into a standardized 4-20 mA analog output. Optimized for Original Equipment Manufacturers (OEMs), the 991-25-50-01-01 allows for the integration of shaft position data into PLCs, DCS, or SCADA systems without the requirement for a dedicated rack-based monitoring system. It provides a critical safety layer by tracking the static position of a shaft relative to the thrust bearing, ensuring early detection of axial movement that could lead to catastrophic internal contact.

Hardware Parameters and Key Technical Characteristics

The 991-25-50-01-01 is engineered for precision in space-constrained installations, offering a robust electrical interface for harsh industrial environments.

• Model Number 991-25-50-01-01

• Measurement Type Axial Thrust (Static Displacement)

• Measurement Range 1.0 mm to 1.0 mm (40-0-40 mils) or 0.6 mm to 0.6 mm depending on configuration

• Transducer Compatibility Designed for 3300 NSv Proximity Probes

• System Length 5.0 Meters (16.4 feet) total length (Option -50)

• Output Signal 4 to 20 mA DC proportional to axial position

• Diagnostic Port Non-isolated "Prox Out" coaxial connector for dynamic signal analysis

• Mounting Type 35 mm DIN-rail clips (Option -01)

• Agency Approvals CSA, ATEX, and IECEx multi-certification for hazardous areas (Option -01)

• Excitation Voltage +12 to +35 Vdc (Loop-powered)

• Casing Material Polyphenylene sulfide (PPS) with 304 Stainless Steel base

Industrial Applications and Operational Use Cases

This thrust transmitter is a staple in Turbine Supervisory Instrumentation (TSI), particularly for assets where the small form factor of the 3300 NSv probe is required.

• Centrifugal Air Compressors Monitoring thrust bearing wear during high-load operations to prevent impeller-to-shroud contact.

• Small Steam Turbines Tracking axial displacement during startup and thermal expansion phases to maintain mechanical clearances.

• Industrial Process Pumps Providing real-time thrust position data to plant control systems for automated alarm and shutdown logic.

• High-Speed Motors and Fans Safeguarding rolling-element or fluid-film bearings against excessive axial loading.

• OEM Integration Serving as the standard displacement sensing solution for integrated machinery protection packages.