1. The magnitude of the current varies. The current of alternating current varies periodically, while the size of direct current is fixed and does not change.
2. The different uses of current. AC power is generally used in circuit breakers, air switches, and power circuit transmission. Direct current is commonly used in electronic instruments and power drives.
3. The difference in the direction of current. The direction of alternating current is not fixed and changes with the cycle. For direct current, the direction of direct current is fixed and starts from positive to negative.
4. Differences in current characteristics. In alternating current, there is a zero point, and voltage waves can generate positive or residual waves. Therefore, corresponding arc extinguishing equipment can be used for circuit switching. However, direct current does not have zero crossing, making it impossible to manufacture circuit breakers.