Residual Current Operated Devices (RCDs) are the protective instruments of safe operation for power system. RCDs are important components for safety against indirect contacts in low voltage installations, and employed for protection against electric shock and earth faults. In order to develop a new rule of RCD tripping directly by the human body current while shocking, it is very important to detect and identify the contact current of the human body in the summation leakage current on the low-voltage electric power grid. The new methods can solve the above problems of RCD. So, the tripping characteristics of a series of products from different RCD manufacturers were tested and analyzed under sinusoidal currents. Thus, it obtained the basic characteristics of the RCD and found out the rules and problems. The results of this study will be theoretical significant, and also can guide to developing intelligent instruments and equipment of RCD for smart grid.
