What are the main differences between DC circuit breakers and AC circuit breakers?

The main differences between DC circuit breakers and AC circuit breakers are as follows:

Difference in arc extinguishing principle:

·AC circuit breakers utilize the zero crossing characteristics of AC power (50/60Hz periodic zero crossing) to achieve natural arc extinguishing.

·DC circuit breakers need to be equipped with forced arc extinguishing devices such as magnetic blow out chambers/metal grids (DC without natural zero crossing points).

Differences in contact system:

·The contact material of the AC circuit breaker should be suitable for high-frequency switching (commonly silver alloy).

·DC circuit breaker contacts require higher arc resistance performance (commonly copper tungsten alloy).

Characteristics of the release device:

·The error of the AC thermal magnetic release increases by more than 10% in DC applications (IEC standards allow ± 20% error).

·DC dedicated release devices need to consider unidirectional current characteristics.

Voltage level:

·The nominal voltage of an AC circuit breaker is the effective value (such as AC 400V).

·The nominal voltage of a DC circuit breaker is a constant value (such as DC 250V).

Typical application scenarios:

·AC circuit breaker: power grid distribution, motor protection, etc.

·DC circuit breakers: photovoltaic systems, rail transit, telecommunications base stations, etc.