High-Frequency Behavior of Residual Current Devices

The purpose of this paper is to analyze the behavior of residual current devices at frequencies higher than the rated one. Many experiments are carried out by measuring tripping current and time of devices of different typology, produced by different manufacturers. The attention is mainly devoted to verify the satisfaction of the current-time safety curve at high frequency and experiment tripping and immunity to unwanted tripping in the presence of harmonics. Conduced tests show that the behavior of residual current devices at high frequency is strongly influenced by their typology rather than the values assumed by their physical parameters. In addition, a mathematical model is developed, and simulations are compared with measurements showing satisfactory agreement in the entire frequency range under study.