The MUS/MUSF series control relays are designed for single-phase voltage monitoring in AC or DC systems. They operate without an external power supply by utilizing the measurement voltage they monitor, with the MUS12DC model specifically for DC voltages. These relays offer flexible control functions for overvoltage and undervoltage detection, with options for with or without memory—if equipped with memory, the relay must be powered off to reset. They include a programmable time delay (0.1 to 10 seconds) to ignore minor voltage fluctuations and adjustable hysteresis (5% to 20% of the set voltage), applicable only to the MUS series. All settings are adjusted via front-mounted switches, and changing settings during operation causes the LEDs to flash but does not disrupt operation. The MUSF model features a window function, monitoring voltage within a specified range between lower and upper limits. Available in three models with different voltage ranges, these relays automatically detect AC or DC voltage, are suitable for DIN-rail mounting in a 17.5mm cabinet, and are ideal for applications in industrial automation, power management, and test & measurement.