The Bently Nevada 125840-01 is a High Voltage AC Power Input Module (PIM)  in the 3500/15 Monitoring Series. The 3500 power supply module accepts a variety of input voltages and converts them to voltages acceptable to other 3500 modules. Any 3500 power supply module can power the entire rack. When two power supply modules are installed in a rack, removing or inserting either module will not interrupt rack operation.