A very simple electronic fuse can be built using electronic diagram below. These electronic fuse does not need to be replaced, can be "repaired" by simply pressing a button. By pressing S button current comes through Th thiristor and Rs resistor to the consumer .
After releasing button Th triac remains in conduction state, if the current passing through it does not fall below a certain value, holding current. To cancel the holding current is used resistor Rs and transistor T .
If the voltage exceeds Rs conduction voltage of the junction -emitter of transistor T, the transistor begins to conduct. Resistance value of Rs should measure at least 0.2 ohms. Rs must be dimensioned so multiply of the disconnection safety current and the value of Rs, to be equal to 0.7 V.
Resistance Rg is sized depending on the size of the supply voltage Ub: Ub equals value-1k.
