Circuit breaker is a switching device that interrupts the faulty current and performs the function of a switch thus protecting the electrical system from damage. Its basic function is to interrupt current flow to protect equipment and to prevent the risk of fire. Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation.
Fuse is an electrical safety device that operates to provide overcurrent protection of an electrical circuit. Its essential component is a metal wire or strip that melts when too much current flows through it, thereby stopping or interrupting the current. A fuse is an automatic means of removing power from a faulty system; often abbreviated to ADS (Automatic Disconnection of Supply). Circuit breakers can be used as an alternative to fuses, but have significantly different characteristics.
How does circuit breaker Work?
A circuit breaker works on the same principle as a fuse. It opens the circuit immediately as soon as the current rises close to the unsafe rate, but you can employ it again contrary to the fuse. The usual circuit breaker includes a simple switch attached to either an electromagnet or a bimetallic strip.
The electromagnet or the bimetallic strip is connected to the circuit that is being monitored. When there is an overload or a short circuit, the current in the circuit increases. This causes the electromagnet to generate a strong magnetic field or the bimetallic strip to bend due to heat. This force pushes the switch open and breaks the circuit.
The switch can be reset manually or automatically after the fault is cleared. Some circuit breakers also have indicators that show whether they are tripped or not.
How does fuse work?
A fuse works by using the heating effect of the current. It has a metal wire or strip that has a low melting point and a high resistance. When the current in the circuit exceeds a certain level, the wire or strip gets too hot and melts, breaking the circuit and stopping the current flow.
A fuse is designed to protect the circuit and the device from damage caused by overcurrent, short circuit, or power surge. Different types of fuses have different current ratings and time-current characteristics. The current rating is the maximum current that the fuse can carry without melting. The time-current characteristic is the relationship between the current flowing through the fuse and the time required to trip the fuse.
The fuse works only once and has to be replaced after it melts¹⁴. Some fuses have indicators that show when they are blown. A fuse should be selected according to the circuit specifications and the ambient temperature.
What’s the Difference Between Circuit Breaker and Fuse?
A circuit breaker and a fuse are both devices that protect an electrical circuit from damage caused by excess current. However, they have some differences in how they work and their advantages and disadvantages. Here are some of the main differences:
- A fuse is a metal wire or strip that melts when the current exceeds a certain level, while a circuit breaker is an electrical switch that trips when the current exceeds a certain level.
- A fuse can only be used once and has to be replaced after it melts, while a circuit breaker can be reused many times by resetting it after it trips.
- A fuse is cheaper than a circuit breaker, but a circuit breaker may be more cost-effective in the long run due to its reusable nature.
- A fuse provides protection against overcurrent only, while a circuit breaker provides protection against overcurrent, short circuit, and ground fault.
- A fuse has a faster response time than a circuit breaker, but a circuit breaker has an on/off function that allows you to turn off the circuit without removing it.
- A fuse is simpler and smaller than a circuit breaker, but a circuit breaker is more convenient and safer to use.
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