Study on the Factors Affecting the Electromagnetic Shielding Effectiveness of Double Insulation and Double Shielding High-Voltage Test Hall

External electromagnetic waves are coupled into the high-voltage hall through the holes and slits which will reduce its electromagnetic shielding effectiveness and affect the internal electrical equipment and related tests. In order to explore the influence of holes and slits on the electromagnetic shielding effectiveness of the high-voltage hall, the high-voltage hall was equivalent to a double-layer shielded metal cavity. A simulation model was established and the shielding effectiveness of the double-layer shielded metal cavity with holes was numerically simulated based on the finite element electromagnetic simulation software. The influences of shielding layer spacing, cavity wall thickness, aperture shape, number and arrangement on electromagnetic shielding effectiveness of double-layer metal cavity are studied. The results show that the shielding effectiveness of the cavity with holes decreases with the increase of external electromagnetic frequency; increasing the distance between shielding layers and the thickness of cavity wall can improve the shielding efficiency to a certain extent; circular holes have little effect on the shielding effectiveness of the cavity; the number and arrangement of holes affect the shielding effectiveness of the cavity. The research results have certain guiding significance for the shielding and optimization design of the high-voltage hall.