Research And Realization Of Fault Arc Signal Emulation Technology

Arc Fault Circuit Interrupter(AFCI) had been compulsively promoted in developed countries like America. With the publishment of national standard as Arcing Fault Detectors(GB14287.4) in 2014, household arc fault protective device is likely to achieve fast development. Market survey showed that several relevant enterprises, like CHNT and XiYu, had been developing AFCI devices.As fault arc experiments often accompany with problems like tedious experiments and toxic gases, emulation of real fault arc signal using power electronic components was proposed in this paper. Several methods in arc fault signal emulation was introduced and compared before concluding that the key to emulating arc fault signals is to rebuild arc fault current. Four circuit topologies were designed, of which, three circuits, including low voltage current regulating circuit and two load-type circuits, were designed at length. Principles in choosing MOSFET working in non-switching mode were discussed. Analytic expression from grid voltage to drain current was obtained by fitting the measured transfer characteristic. Both computation and simulation were conducted on circuit noise issues, plus its contribution to drain current. Arc fault testing system was constructed to acquire arc fault current waves, which were further utilized in simulation of the four circuits. Pre-compensation distributed floating control method was proposed to meet speed and accuracy requirement in rebuilding arc fault current. Variable D/A transfer interval method was used to solve synchronization problems in outputing current signals. Software programs of load-type circuits and low voltage current regulating circuit were presented. Prototype of the two electronic load based circuit and low voltage current regulating circuit were designed and made, plus several experiments were conducted to verify the performance of them. The results indicated that all the prototypes are eligible in reconstructing fault arcing current. Commodification were to be conducted with low voltage current regulating circuit for its preciseness in reconstructing fault arcing current.