Abstract: The arc flip-flop with rated current of 500 A is taken as the research object.The mathematical modeling and analysis were carried out for the tin layer plated on the flip-flop melt with a thickness of 5μm.The simulation model of arc flip-flop was established by using the electrothermal coupling module of COMSOL platform.The simulation results show that the per-arc time of the flip-flop under 4 kA overload current is 7.5 seconds,and then the arc trigger test sample with tin plating thickness of 5 μm was made.The pre-arc characteristic test was carried out.The test results are basically consistent with the simulation results.On this basis,the pre-arc time under different tin plating thickness was studied.The simulation results show that the thinner the tin plating thickness is,the shorter the pre-arc time of the trigger is.

Key words: metallurigical effect, plating thickness, pre-arc time, resistivity