Reverse protection diode

When operating multiple power supply units in parallel, if the outputs of each power supply become unbalanced, a reverse voltage is applied from the power supply with the higher output to the one with the lower output. A diode connected in series with each power supply to prevent this reverse voltage is referred to as a reverse protection diode. The reverse protection diode is inserted so that it is forward-biased with respect to the supply voltage of each power source. When the outputs of each power supply unit are equal, current flows in the forward direction; however, if they become unbalanced and a reverse voltage is applied, it prevents current from flowing in the reverse direction, thereby protecting the power supply units.