Abstract: A backup apparatus includes a contactor, a first rectifier circuit, an auxiliary power supply circuit, a first switch, a second switch, and a controller. The contactor includes a coil connected to the auxiliary power supply circuit through the second switch and a main contact switch connected to a power grid. The first rectifier circuit is connected to the power grid through the first switch, and the first rectifier circuit is connected to the coil. When the first switch is turned on, the first rectifier circuit supplies power to the coil. After the main contact switch is turned on, the controller controls the second switch to be turned on and the first switch to be turned off. When the second switch is turned on and a voltage of the power grid is lower than a voltage threshold, an input capacitor in the auxiliary power supply circuit supplies power to the coil.