Circuit Breakers

 Circuit Breakers

While a fuse protects a circuit, it is destroyed in the process of opening the circuit. 

Once the problem that caused the increased current or heat is corrected, a new fuse must be placed in the circuit. 

A circuit protection device that can be used more than once solves the problems of replacement fuses. 

Such a device is safe, reliable, and tamper proof. 

It is also resettable, so it can be reused without replacing any parts. 

This device is called a CIRCUIT BREAKER because it breaks (opens) the circuit.

The first compact, workable circuit breaker was developed in 1923. 

It took 4 years to design a device

that would interrupt circuits of 5000 amperes at 120 volts ac or dc. 

In 1928 the first circuit breaker was

placed on the market. 

A typical circuit breaker and the appropriate schematic symbols are shown in figure