R3-38 (panel mounting)
The fuse is blown and the principle is Joule's law. Joule's Law: The heat generated by a current through a conductor is proportional to the square of the current, proportional to the resistance of the conductor, and proportional to the time of energization. Joule's law mathematical expression: Q = I2Rt, the derived formula has Q = UIt and Q = U22 / R × t. All the work done by the current in the fuse generates heat, that is, the electric energy is all converted into internal energy, and then Q=W. Therefore, when I or U is greater than the rated value, Q becomes larger, so that the fuse cannot be dissipated in time to overheat, resulting in a blow.