Why are DC circuit breakers better than fuses?

choose the circuit breaker choose the fuse DC circuit breaker fuse blade box

A circuit breaker is an electrical switch which powered automatically. It helps to protect an electrical circuit from damage due to excess current. Although fuses are small and cheap, it can’t reset. It must need to replace. But a circuit breaker can be reset.

Also, a DC circuit breaker can last for a long time in high-temperature applications. But fuses last for a short period, especially at high temperatures. DC Circuit breakers interrupted the current flow when it detected a fault.

Fuses are still used in industry in the USA and many countries. In a computer motherboard, fuses are quite good rather than breakers. But fuses can explode if there is too much energy.

Cost-wise a fuse is much cheaper initial cost, they are usually physically smaller, too. Fuses are small and cheap.

My experience is in power systems, not consumer devices. I HATE fuses. A shunt trip on an upstream breaker is almost always better. 75% of the time the designer misuses fuses. In most consumer cases, the fuse is really there to keep the source from dropping out and a fire, not to protect load damage. That said, in a car or a computer motherboard, fuses are hard to beat. Except that fuse blade box.

However, converse to the question, some cool facts:

The Advantages of the Fuse:

1. Fuses interrupt a circuit by driving current to zeros through an internal arc. So, many manufacturers, create the fuse blade box, it haves 4 way, 6 way, 12way, etc, the fuse take on or off, very easy, it is very convenient.
fuse blade box
2. The arc voltage is ~2x the system voltage. If you want to interrupt faster, put two fuses in series. Generally they will both overlap arcing, and the arc voltage will be 4x the system voltage, driving current to zero twice as fast.

3. The fuse characteristics will determine the system spikes during interruption. Some are soft with minimal overvoltage, some are fast, hard and spikey.

4. All the inductive energy in the circuit must be turned to heat in the fuse (or breaker). If there is too much energy, the fuse will explode. This determines the current and voltage rating of the fuse, but in reality, it is the amount of inductive energy that sets the rating, just like L/R in a breaker rating.

Convenience-wise:

DC circuit breaker has a number of advantages 

1. Its resettable so you don’t have to go out and find a new one if DC circuit breaker trips from accidental overcurrent. if the fuse, must be replaced.
Car audio inline DC circuit breaker case
2. And the DC circuit breaker always the right value - no temptation to replace it with a proper physical fit but wrong current fuse after tripping, so its much safer.

3. The DC circuit breaker ease of use - since its resettable, its easy to just try it and not worry about destroying another fuse.

4. Usually doesn’t require disassembly to fix.

5. DC Circuit Breakers last a long time. Fuses (particularly semiconductor fuses) have limited life, particularly in high temperature applications.

6. DC Circuit Breakers can have various trip curves, even programmable. Fuses are strictly thermally controlled. Coordinating fuses in a distribution system is a real chess match!


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