The EIS is a non-destruktive analysis method to characterize the response of a system to the applied ripple current capabilites. Each system as well as each process can be described and modelled with a combination of resistances, capacities and inductivities. EIS allows a survey of condition of solid materials as well as the analysis of processes like Korrosion, passivation, fuel cells, batteries). With the modelled equivalent circuit, for example a corrosion process can be described and the corrosion resistance can therefore directly be taken from the measurement values.