The present disclosure provides a transformer including at least one magnetic core each having at least one window; one primary side winding passing through the at least one window, a wire forming the primary side winding being sequentially covered with a first solid insulating layer, a grounded shielding layer and a second solid insulating layer from inside to outside along a radial direction of the wire, the grounded shielding layer being connected to a reference ground; and at least one secondary side winding, each passing through the at least one window, the primary side winding having a first voltage with respect to the reference ground, the secondary side winding having a second voltage with respect to the reference ground, and the second voltage being greater than 50 times of the first voltage.