The Bently Nevada 3500/40M Proximity Monitor is a 4-channel module within the 3500 Series machinery protection system, designed to monitor vibration and position parameters using proximity transducers . It accepts input from Bently Nevada approved proximity probes, conditions the signal, and compares the processed measurements against user-programmable alarm setpoints for continuous machinery protection .

Using the 3500 Rack Configuration Software, each of the four channels can be independently programmed to perform a variety of critical measurement functions . These include Radial Vibration for shaft relative motion, Thrust Position for axial rotor position, Differential Expansion, Eccentricity for slow-speed runout, and REBAM (Radial Eccentricity Bearing Analysis Measurement) . The module features front panel LEDs for OK, TX/RX, and Bypass status, providing clear operational feedback .

The 3500/40M offers high measurement accuracy, with Direct, Gap, 1X, and 2X filtered amplitudes accurate to within ±0.33% of full scale . It has a total input impedance of 10 kΩ for the standard I/O and consumes 7 watts of power . The module is a fundamental component for protecting critical rotating machinery such as steam turbines, compressors, and pumps by providing reliable, real-time data on shaft dynamics .