Experimental research ondirect current switchgear

Fundamental changes in energy supply have lately led to an increasing use of DC technology for example in electric vehicles. The electrical requirements of switchgear and protective devices for low-voltage direct current grids are technically sophisticated. System voltages up to 600 volts and nominal currents of several 100 amperes are the normal load conditions in modern automotive direct current grids. Powerful lithium-ion accumulators, used as energy sources, are able to generate fault currents of several kilo amperes in case of electrical failures. Furthermore there are special demands from the automotive industry considering volume, weight and on-state power losses. To ensure full personal protection it is necessary to control the system parameters properly in every operating condition. Applied switchgear and protective gear have to be able to conduct, make and break every possible rated current or fault current. Therefore these systems have been investigated, which lead to the testing of samples of commercial switchgear in order to derive their suitability in electric car grids. Investigations include the current carrying and break capacity of commercially available contactors as well as the influence of the electromechanical actuator.