Tripping limitations of residual current devices in photovoltaic installations

In electrical installations with photovoltaic sources of energy, earth fault current may comprise alternating current component and direct current component. The waveform shape of this earth fault current mainly depends on the point of the fault and the properties of a photovoltaic power electronics converter. The waveform shape of the current influences operation of protection devices, especially tripping threshold of residual current devices. This paper considers the effect of the composite waveforms, which may flow in installations with photovoltaic sources of energy, on tripping threshold of residual current devices. Limitations and unexpected behaviour of these devices are discussed.