Uninterruptible duplexed power system, and unit plug-in structure for uninterruptible duplexed power supply system

It is an object of the present invention to provide an uninterruptible duplexed power supply system that is highly reliable and has excellent durability, with which a more compact size and higher efficiency are both achieved, and with which a malfunction of the power supply circuit can be repaired in a live state. The present invention is characterized in that there are provided a first unit 4 and a second unit 6 having their own power supplies 1, a main component 10 to which the outputs of the first unit 4 and second unit 6 are inputted is equipped with a secondary DC output circuit 8 and a battery-side converter circuit 13, the first unit 4 and the second unit 6 can be attached to and detached from the main component 10 in a live state.