Inrush current

At power-up of the power device, a larger-than-normal current flows due to charging current of internal capacitors. As the charging of the capacitors progresses due to the transient phenomenon, the current value decreases, and once fully charged, it stabilizes at a normal level. The maximum value of the input current during the period from startup to steady state is called inrush current. Since inrush current can negatively affect the power device, many devices include a safety function that limits input current at startup.