1a, 1b online, double-conversion UPS
    2 UPS input
    3 rectifier
    4 inverter
    5 UPS output
    6 bypass switch
    7 control unit
    8 battery
    9a, 9b electrical appliance
    10 power grid (AC mains)
    11a, 11b appliance section
    12a, 12b short-circuiting switch
    13a . . . 13h circuit breaker
    14 override input
    15a, 15b fault arc detection device
    16a, 16b current detector
    17a . . . 17f light detector
    18 battery switch
    A fault arc