Low-voltage circuit breaker is also called air switch or automatic switch, which is equivalent to a combination of knife switch, fuse, thermal relay, over-current relay and under-voltage relay, etc. It is a kind of manual switch function and can automatically perform under-voltage and loss-voltage. , Overload and short circuit protection appliances. The protection function is relatively complete and easy to adjust. It can continue to be used after the fault trip, but the price is more expensive than the fuse.

A fuse is an electrical appliance that fuses the melt with the heat generated by itself when the current exceeds the specified value, disconnects the circuit, and achieves the purpose of short-circuit and overcurrent protection. The fuse is a one-time device, and it needs to be replaced and disposed after it is blown. It is a cheap and widely used protection control element.