Since the mains voltage is generally 220V AC, and many electrical equipment needs to use 5V, 12V or 24V DC, it is necessary to use an AC adapter power supply to convert the 220V AC voltage to the DC mode for normal operation of electrical equipment.
Generally speaking, the input voltage of the AC adapter power supply commonly used in the world is in the range of 100-240V. According to the standards of different countries and regions, there are various specifications such as national standard, Japanese regulation, American regulation, British regulation, Australian regulation and so on