POWER SUPPLY UNIT FOR THE PROVISION OF AT LEAST ONE SWITCHABLE POWER OUTPUT

The invention relates to a power supply unit for providing switchable power output, comprising at least one power input UIN and at least one voltage measuring device. The voltage measuring device monitors the voltage of the power input UIN. When the input voltage is reduced to an inclining threshold value Uthres lower than definition or exceeds the change rate threshold value, one or a plurality of power output will be cut off, and the input voltage (UIN, t1) will be measured at a first time point t1, and the input voltage (UIN, t2) will be measured again at a second time point t2 after the first preset time (td1). If the input voltage at the second time point is larger than that at the first time point, it is assumed that at least one power output has short circuit.