Equipment chassis and housing design for EMC

This article consists of a collection of slides from the author's conference presentation. Conductive housing provides shielding for electric fields at all frequencies and magnetic fields at frequencies above 10KHz. Housing design should consider the material's conductivity, thickness and the size and density of the breaches on it. At Kilo Hz and below, magnetic materials should be used for magnetic field shielding. Housing seams should be carefully handled to reduce RF leakage. When used, I/O filters should be grounded to the chassis/housing and placed as close as possible to the I/O points. Connecting PCB grounds to the chassis/housing can reduce radiated emissions from cables. Grounding should be as close as possible to the I/O points. Grounding wires should be as short as possible. When capacitors are used for decoupling to chassis/housing, their values, types and voltages should be carefully selected not to impact the signal functions, to bear the application voltages and to meet safety current leakage requirements. Cable shielding connected with the chassis/housing can reduce radiated emissions from cables. If possible, connection should be made in 360°g. Non conductive I/O connections can prevent radiated emissions from cables. The above methods are advantageous with respect to RF and transient immunity too.