Bently Nevada 330850-91-CN 3300 XL 25 mm Proximitor Sensor High-Temperature Proximitor

The Bently Nevada 330850-91-CN is a critical component of the 3300 XL 25 mm proximity transducer system, designed by Bently Nevada (now part of Baker Hughes) for high-precision machinery protection. As a 3300 XL 25 mm Proximitor Sensor, this model is specifically engineered to interface with non-contacting 25 mm proximity probes and extension cables to measure Differential Expansion (DE) in large steam turbine generators .

Key Technical Specifications

The 330850-91-CN offers a standard sensitivity of 7.87 V/mm (200 mV/mil) and provides a linear range of 12.7 mm (500 mils), starting from a nominal gap of 0.63 mm . This robust linear range makes it ideal for monitoring the mechanical differences in growth rates between a turbine rotor and its stator casing . The system operates on a -24Vdc power supply and is designed to withstand extreme conditions, with the capability to transmit signals up to 305 meters (1000 feet) to monitoring systems like the Bently Nevada 3500/45 .

Advanced Design and Mounting Flexibility

The "CN" suffix in the part number 330850-91-CN typically denotes specific certifications or configuratio variations suitable for global use . The 3300 XL 25 mm Proximitor Sensor features a thin-profile design that supports two mounting methods: traditional panel mount or high-density DIN-rail installation . It is equipped with SpringLoc terminal strips, which facilitate fast and highly robust field wiring connections without requiring special installation tools .

Environmental Immunity and Compliance

Engineered for harsh industrial environments, the 330850-91-CN provides significantly improved RFI (Radio Frequency Interference) and EMI immunity. This ensures the transducer system is not adversely affected by nearby high-frequency radio signals and helps achieve European CE mark approvals without special mounting considerations .

System Compatibility and Applications

This Proximitor is part of a complete system that requires matching components: a 3300 XL 25 mm Proximity Probe (such as the 330851-02-000-060-10-00-CN) and an extension cable (like the 330854-080-24-CN) . It is primarily used for Differential Expansion measurements, utilizing two transducers observing a collar or ramp to compensate for radial movement and effectively double the measurable range . The 330850-91-CN is backward compatible, allowing it to replace older 7200 series 25 mm and 35 mm systems without requiring changes to monitor configurations .

For reliable, high-temperature machinery protection in steam turbines, the Bently Nevada 330850-91-CN remains the industry standard for accurate rotor position monitoring.