An AC inrush current testing device is disclosure. The AC inrush current testing device includes a grid voltage peak point calculator, a grid voltage period and timing detector, a switch, an autotransformer, and a main relay. The grid voltage period and timing detector is connected to an AC power source and the grid voltage peak point calculator. A movable contact of the switch is connected to the AC power source. A first winding of the autotransformer is connected to the AC power source, a second winding of the autotransformer, and a first stationary contact of the switch. A third winding of the autotransformer is connected to a second stationary contact of the switch and the second winding. The main relay is electrically connected to the grid voltage peak point calculator, the second winding, and the third winding. A method for testing AC inrush current is further disclosed.
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