How should the shielding layer of the power transformer in the edge box be properly grounded?

The edge computing box's built-in AC-DC power transformer features distributed capacitance coupling between the primary and secondary sides, and a common-mode noise shielding layer grounding strategy that determines the suppression effect. A single shielding layer should be connected to the primary side DC bus or ground. Connecting it to the secondary side will introduce noise into the secondary winding. For double shielding layers, the inner side should be connected to the primary side, and the outer side to PE. It is recommended to add copper foil shielding with a thickness of 0.1mm and a width equivalent to the winding width during transformer winding, and to bring out a grounding pin. Simultaneously, at the transformer output, add a common-mode inductor CML4532A-101T (named CML common-mode inductor 4532, size 4.5×3.2mm, 101T, inductance 100μH). Enhanced filtering is achieved through testing. Adding a transformer shielding layer and proper grounding to the edge computing box power supply reduces conducted emission spikes of 0.5MHz by 18dB.