Power supply comprising a ciruit for limiting inrush currents.

摘要

The power supply serves to convert an alternating voltage, supplied by an electric mains, into a desired voltage and comprises rectifier means (1) with input terminals (3) for receiving the alternating voltage and output terminals (5) for supplying a pulsating direct voltage, a first capacitor (7) which is connected parallel to the output terminals, an inverter (9) with input terminals (11) which are connected to the first capacitor, and a current limiting circuit which is connected between one of the output terminals of the rectifier means and an electrode of the first capacitor in order to limit the inrush current occurring when the power supply is switched on. The current limiting circuit comprises a parallel connection of a first resistor (15) and a first switching element (17), the first switching element being operative to be in an electrically non-conductive state upon switching on of the power supply and to change over to an electrically conductive state some time after switching on. In order to establish the state of the first switching element (17), there are provided detection means (20) which cooperate with the start circuit (21) which is operative to generate a start signal for the inverter (9). When the detection means (20) establish that the first switching element (17) is in the conductive state, they prevent activation of the start circuit (21). Consequently, the power supply cannot operate if the first switching element (17) is short-circuited by a defect.