The circuit shown triggers a relay when the current rises up to a value depending on R1 according the table bellow. The relay is used to turn of the low protecting it from high voltages. The lamp indicates when the circuit is activated, S1 is used to reset the circuit. Input voltage can be in the range between 9 and 30 V and the lamp is rated according the voltage of the circuit. LED can replace the lamp.
Protection for Power Supplies
