Influence of Automotive Harnesses on Conducted Emissions

Conducted emissions for components and modules are normally measured with a maximum cable length of 20 cm to the stabilization network. However, the cable harness used on automotive vehicles shows a vast amount of different wire lengths. Emission measurements can thus only give limited information about the behavior of the system connected to a real harness system. Especially within the filter development process, the later connected cable harness can not be easily considered. In the worst case, this leads to high radio disturbance levels within the vehicle, however the module passed all component tests in respect to CISPR25. The paper gives an overview how the connected harness influences the filter attenuation and how to consider the effect during the development process.