Semi Conductor Fuses are fast acting and power limiting fuses that are sensitive to both current and voltage in an electric circuit. This fuse has a rating of 250 Amps and a voltage rating at 150 AC/100 DC. Fuses are a necessary component in an electrical circuit because they offer an essential protection by acting as the weakest point in a circuit. When a current is too strong, the fused element inside a fuse will heat up and break so that the current can no longer complete the circuit.