The invention relates to an electronic power supply device, particularly a switched-mode power supply, for supplying power to a low-voltage load protected by a protective device, and to a method therefor. The invention also relates to a device for protecting a low-voltage load against an excess current and to an auxiliary power supply device for use with such a protection device. The conceptual core of the invention can be seen in providing measures which ensure that after a fault has been detected, for example a short circuit at the output, a current is supplied for a short period, for example 15 ms, which is of such a magnitude that a protective device can be reliably and quickly tripped. The period for this is selected in such a manner that electronic components, connected loads and feedlines are not damaged and destroyed.