(EP855098-A1)      An arrangement to give an uninterruptable power supply (UPS) to at least one consumer has the energy taken from the AC grid and if there is an fault on the grid, the energy is taken from a fuel cell. The fuel cell (8) is connected at its output to at least one inverter(7) whose output in turn passes to the consumer(s) with a switch(4) linking the grid (6). If the grid voltage drops below a certain threshold, the switch opens. When the voltage is over the threshold, the switch is closed and the fuel cell is in stand-by mode, but when the switch opens, it supplies power to the consumer(s). The switch is in series with a choke (5).    ADVANTAGE -   Rapidly provides the necessary voltage to the consumer if the mains voltage drops.    (DE19538381-C2)      An arrangement to give an uninterruptable power supply (UPS) to at least one consumer has the energy taken from the AC grid and if there is an fault on the grid, the energy is taken from a fuel cell. The fuel cell (8) is connected at its output to at least one inverter(7) whose output in turn passes to the consumer(s) with a switch(4) linking the grid (6). If the grid voltage drops below a certain threshold, the switch opens. When the voltage is over the threshold, the switch is closed and the fuel cell is in stand-by mode, but when the switch opens, it supplies power to the consumer(s). The switch is in series with a choke (5).    ADVANTAGE -   Rapidly provides the necessary voltage to the consumer if the mains voltage drops.    (EP855098-B1)      An arrangement to give an uninterruptable power supply (UPS) to at least one consumer has the energy taken from the AC grid and if there is an fault on the grid, the energy is taken from a fuel cell. The fuel cell (8) is connected at its output to at least one inverter(7) whose output in turn passes to the consumer(s) with a switch(4) linking the grid (6). If the grid voltage drops below a certain threshold, the switch opens. When the voltage is over the threshold, the switch is closed and the fuel cell is in stand-by mode, but when the switch opens, it supplies power to the consumer(s). The switch is in series with a choke (5).    ADVANTAGE -   Rapidly provides the necessary voltage to the consumer if the mains voltage drops.    (US6011324-A)      An arrangement to give an uninterruptable power supply (UPS) to at least one consumer has the energy taken from the AC grid and if there is an fault on the grid, the energy is taken from a fuel cell. The fuel cell (8) is connected at its output to at least one inverter(7) whose output in turn passes to the consumer(s) with a switch(4) linking the grid (6). If the grid voltage drops below a certain threshold, the switch opens. When the voltage is over the threshold, the switch is closed and the fuel cell is in stand-by mode, but when the switch opens, it supplies power to the consumer(s). The switch is in series with a choke (5).    ADVANTAGE -   Rapidly provides the necessary voltage to the consumer if the mains voltage drops.