A Fault Tree Approach Focusing on Electromagnetic Interference

Compatibility with respect to Electromagnetic Interference (EMI) is an important property of all electric and electronic systems. Consequently, functional safety standards require that EMI is considered. In contrast to other properties, EMI is usually not treated in a statistical sense, i.e. a system is considered compatible if it succeeds to withstand a certain level of disturbances. This paper aims to discuss this approach and suggests to differentiate two types of interferences. The first type, which is the normal EMI and which is typically of comparatively low power, may occur at any time during normal operation. Consequently, the system has to fully comp with such disturbers. The second type of EMI is caused by component failures. This type of disturbances is responsible for high power levels. However, as it is only present in case of component failures, it may be treated similar to other faults in the system. We describe how this approach allows for integrating interference caused by component faults into a Fault Tree Analysis of the system.