Influences on safety issues for inverter supplied grid structures

Abstract

In the field of low voltage systems protection devices like fuses and residual current devices (RCDs) are generally implemented. Because of their high sensitivity residual current devices are very commonly used for protection against electric shock. A part for the fact that inverters may produce voltages with considerable harmonic content also RCDs deserves special attentions. Due to the increasing number of electrical equipment in the low voltage grid producing disturbing currents different RCD types (type AC, A and B) are investigated under certain conditions. For example the influence of disturbing non-sinusoidal, pulse-shaped currents or harmonics in the fault current regarding on the tripping current or on the tripping time of the RCD is analyzed.