The Bently Nevada 330180-91-05 is a compact DIN-rail mount miniaturized proximitor signal conditioner engineered exclusively for 3300 XL 25mm large-range eddy current proximity probe systems used for measuring large shaft differential expansion, heavy axial thrust displacement, and wide-range valve position feedback on steam turbines and heavy industrial rotating machinery. The 91 internal calibration series design delivers specialized signal conditioning circuitry tuned to the unique coil impedance characteristics of 25mm large-diameter probes, producing a linear analog output calibrated to 0.787 V/mm sensitivity with a full 12.7mm (500 mil) total linear measurement range, vastly exceeding the displacement capacity of standard 8mm probe proximitors. Designed for space-restricted junction boxes and compact local instrument enclosures where full-size rack-mount proximitors cannot fit, this compact unit retains all core functional performance of larger 330850 series 25mm proximitors within a streamlined small aluminum housing with simplified screw terminal wiring connections. Rated for maximum 5-meter total transducer system cable length (1m integrated probe cable + 4m extension cable), the module operates on standard -17.5 VDC to -26 VDC industrial DC power supplies across ambient temperatures of -40°C to 85°C. Built-in electronic protection circuits defend against reverse polarity power connection, overvoltage spikes, and output short-circuit faults to avoid field failure from wiring mistakes or electrical noise surges. A single buffered analog output terminal provides clean linear displacement signals compatible with all Bently 3500 monitor rack input cards, plant DCS control systems, and portable vibration data collectors. Factory calibrated to match the response curve of 330851 series 25mm large probes and 330854 series 25mm extension cables, this compact 25mm proximitor is fully compliant with API 670 standards for large-displacement machinery protection applications. Turbine and reliability engineers utilize this space-saving mini proximitor for steam turbine differential expansion monitoring and heavy thrust bearing position measurement, where wide-range displacement tracking is mandatory to prevent catastrophic rotor-casing rub damage during thermal startup and load transients.