What's the difference between AC and DC?

March 28, 2023

What's the difference between AC and DC? Alternating current and direct current differ in the following points:

First, the direction of the positive and negative poles of alternating current is uncertain, and periodic alternating changes are made at all times. For example, residents use 220V, 50Hz AC mains electricity, 50 cycles per second, and the direction of the positive and negative poles is changed one hundred times;

Second, the alternating current voltage and current strength also change with periodic, and there is a close to the alternating current period of zero crossing time, zero crossing moment circuit no current or tends to be infinitesimal;

Three, alternating current through the inductive load, will produce self-inductive phenomenon, the transformer made of electromagnetic induction principle can easily change the voltage of alternating current (both can be increased or decreased, can also be equivalent isolation output);

Four, alternating current can use the principle of electromagnetic induction and transformer, can carry out different power distribution and line impedance matching, can let the respective circuit to obtain different corresponding power, and ensure that each part is independent and do not affect each other;

Five, the appropriate frequency and voltage of alternating current (especially three-phase alternating current), can have a special effect on inductive load (or capacitive load), such as can directly make the three-phase induction motor produce effective operation.

The above characteristics of alternating current compared with direct current, direct current does not have a great advantage; The characteristic of direct current is that the positive and negative electrodes are fixed,

That is, the direction of the current in the circuit is unchanged, the strength of the current will not change the size of the periodic, can not use the transformer on DC voltage, inductive load on DC is zero, in short, DC compared to AC is very different, a variety of instruments and electrical equipment of the internal circuit are a large number of use of DC, but the external power supply can still make AC, However, it is necessary to use a rectifier and filter circuit to convert alternating current into direct current to make the circuit work normally.

Dc power supply circuit if the use of AC power supply, the circuit can not run normally, or even completely damaged, this is DC voltage compared to AC unique advantages. Only by fully understanding the respective characteristics and advantages of AC and DC can we make better use of them.

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