LabVIEW-based intelligent system of protection against electric shock for photovoltaic installations

Evaluation of shock hazard in installations with photovoltaic sources of energy is more complicated than in a conventional low voltage system. In case of earth fault in photovoltaic generators, that are connected to the AC power public grid, a composite waveform of earth fault current in the installation may occur. For composite waveforms, the safety criteria should be modified. The paper considers the effect of the composite waveforms on the threshold of ventricular fibrillation. A LabVIEW-based computer system for evaluation of shock hazard, according to the modified safety criteria, is presented. The new-idea, intelligent system of electrical safety enables for selective disconnection of supply only when real hazard of the ventricular fibrillation occurs. By using this intelligent system both effective protection against electric shock and high reliability of supply are achieved.