Application of the mechanistic arc model to DC current limiting fuses

The arc behaviour of DC current limiting fuses was simulated by the application of the recent mechanistic model, originally presented for AC, which until now has not been used in DC studies. The experimental investigation was made over samples following VDE Standards, NH type, sizes 00 and 1, using notched silver ribbons having 5 to 7 restrictions, embedded in quartz sand. The tests, more than two hundred shots, were done in an SCR supply of 550 V, 17.5 ms with currents from 180 A to 1300 A, whose results are very close to the models. A linear relationship between the current density and the ignition-deionisation dV/dt is presented and compared with the elsewhere published AC normal values. It is concluded that the mechanistic model can be also applied successfully to the simulation of DC fuses arc behaviour, decreasing in that way the expensive and time consuming high power tests. Following the shots done using a different type of quartz sand, it is preliminary proposed the application of the dv/dt prepeak and postpeak slopes as a filler characteristic parameter.