How does the high-speed fuse operate? The chart on this slide shows the performance of current and voltage inside a high-speed fuse during its operation. During normal conditions, there is a balance in heat transfer and the fuse element continues to carry current. The voltage drop across the fuse is only a few millivolts. When a short circuit occurs, there is an immediate rise of current flowing through the elements, melting the bridges and generating an arc inside the fuse, which in turn is quenched or extinguished by the quartz silica sand filler material. An arc-voltage will appear across the fuse terminals until the arc is quenched. The arc-voltage is slightly higher than the system voltage. As the arc is fully quenched, the system voltage appears across the fuse terminals, creating an open circuit condition. This entire phenomena happens in less than 5 milli-seconds. This is the principle behind how a high-speed fuse operates. The benefits of high-speed fuses are their fasting acting capability, and the highest quality materials to help quench the arcs during short circuit conditions.