The Bently 135145-01 is a Hydro Tachometer/Keyphasor Module designed for the Bently Nevada 3500 Machinery Protection System. This four-channel module is specifically engineered for monitoring hydroelectric turbines. It accepts inputs from proximity probes or magnetic pickups to provide crucial measurements, including rotor speed, acceleration, and a precise once-per-turn Keyphasor reference signal. The module plays a vital role in machinery diagnostics and protection, ensuring the safe and reliable operation of hydro turbine generator sets by supplying critical data to the monitoring system.