AC (alternating current) and DC (direct current) are two different types of current, and there are significant differences between them, mainly reflected in the polarity, current direction, frequency, use, and output voltage.

Polarity and Current Direction

‌AC (alternating current) ‌ The polarity is called the neutral line and the live line, the current direction is constantly changing, the periodic change. For example, the common lighting change law is sine wave, and the direction of the current changes alternately.

‌DC (direct current) ‌ the polarity is called positive and negative, the direction of current always remains the same, can only flow from the positive to the negative.

 Frequency

‌AC (alternating current) ‌ Specifies the frequency, such as 50Hz, indicating how fast the direction of the current changes.

‌DC ‌ There is generally no frequency parameter, because the direction of its current is constant.

 Use

‌AC (alternating current) ‌ is widely used in daily life and work, such as lights, motors and so on.

‌DC is mainly used in various electronic instruments, electrolytic, electroplating, DC electric drive and other special fields.

Output Voltage

‌AC ‌The common output voltage is 220V and 380V.

‌DC ‌The common output voltage is 30V, 6.0V, 90V, 12V and so on.

 Transformer Demand

Because the direction of AC current is constantly changing, the transformer needs to be changed to adapt to different electrical equipment, while the direction of DC current is constant, usually no transformer is required to change voltage.