Product Overview

The Bently Nevada 3308878-91-05 is a high-precision signal conditioner designed for the 3300 XL 50 mm Transducer System. This specialized Proximitor sensor is engineered to provide an exceptionally long linear measurement range of 27.9 mm (1.1 inches), making it the industry standard for tracking large-scale mechanical shifts in power generation equipment. Its primary function is to convert the eddy current signals from a 50 mm proximity probe into a stable voltage output, allowing plant operators to monitor the relative thermal growth between a turbine's stationary and rotating components. This sensor is a critical link in ensuring the structural safety of multi-megawatt steam turbine generators.

Key Technical Characteristics

• Model Number 330878-91-05

• System Type 3300 XL 50 mm Series

• Linear Range 27.9 mm (approx. 1100 mils)

• Standard Output 0.394 V/mm (10.0 mV/mil)

• Frequency Response 0 Hz (DC) to 1.0 kHz

• Approvals Multiple Agency Approvals (Option 05: CSA, ATEX, IECEx)

• Interchangeability Backwards compatible with legacy 7200 50 mm systems

• Mounting DIN-rail or bulkhead mounting plate

• Shielding Integrated RFI/EMI protection for signal stability in power plant environments

Industrial Applications

The 330878-91-05 is predominantly utilized for Differential Expansion (DE) and Rotor Expansion (RX) measurements on large steam turbines. By observing a thrust collar or a ramped target on the shaft, the sensor provides essential data to prevent the turbine rotor from making axial contact with the stator during thermal transients (startup and cooldown). It is frequently configured in redundant pairs on a single collar for high-reliability applications or in complementary "push-pull" arrangements to effectively double the measurable range on massive machinery. This sensor allows for the seamless upgrading of older 7200-series 50mm systems without the need to reconfigure monitor rack scaling, provided the probe and extension cable are updated as a complete system.