Product Overview

The Bently Nevada 330878-91-00 is a high-performance 3300 XL series Proximitor Sensor specifically engineered to drive 50 mm proximity probes. As the signal conditioning heart of the transducer system, this device generates a radio frequency (RF) signal to the probe and converts the returned eddy current data into a standardized analog voltage. This specific model is designed for ultra-long-range displacement measurements, offering the most extensive linear range in the Bently Nevada eddy current product line. It is a critical component of Turbine Supervisory Instrumentation (TSI), providing the high-fidelity data required to protect massive rotating assets from structural damage caused by thermal growth.

Technical Characteristics and Hardware Parameters

The 330878-91-00 is built to maintain signal stability over long distances and within the electrically noisy environments of power generation facilities.

• Model Number 330878-91-00

• System Compatibility Optimized for 3300 XL 50 mm Proximity Probes

• Linear Measurement Range 27.9 mm (1100 mils)

• System Length 9.0 meters (approx. 29.5 feet) total system configuration

• Output Signal Analog DC voltage proportional to gap distance

• Scale Factor 0.394 V/mm (10 mV/mil) or 0.787 V/mm (20 mV/mil) depending on target material

• Mounting Configuration Integrated DIN-rail mounting base

• RFI/EMI Immunity Advanced shielding to prevent interference from radio frequency and electromagnetic sources

• Interchangeability Fully compatible with standard 3300 XL 50 mm extension cables and probes without manual calibration

Industrial Applications and Operational Use Cases

The primary role of the 330878-91-00 is to facilitate the monitoring of "large-scale" movement where standard 8 mm or 25 mm sensors lack the necessary measurement depth.

• Differential Expansion (DE) Monitoring Measuring the relative thermal growth between a turbine's rotor and its casing during startup, heat-up, and shutdown cycles.

• Rotor Expansion Tracking Monitoring the absolute longitudinal movement of the rotor in large steam turbine generators to ensure internal clearances are maintained.

• Hydroelectric Generator Thrust Tracking the axial position of large-diameter vertical shafts in hydroelectric units.

• Casing Expansion Providing displacement data for structural monitoring where expansion exceeds 25 mm.

• Predictive Maintenance Interfacing with Bently Nevada 3500/45 Position Monitors to provide automated alarm and trip logic to prevent rotor-to-stator contact.

By utilizing the 50 mm coil technology, the 330878-91-00 ensures that operators have visibility into the mechanical behavior of the machine throughout its entire thermal envelope, significantly reducing the risk of catastrophic "rubs" and unplanned outages.