Figure 2-17.Circuit breaker construction.
The ARC EXTINGUISHER confines, divides, and extinguishes the arc drawn between contacts each
time the circuit breaker interrupts current. The arc extinguisher is actually a series of contacts that open
gradually, dividing the arc and making it easier to confine and extinguish. This is shown in figure 2-18.
Arc extinguishers are generally used in circuit breakers that control a large amount of power, such as
those found in power distribution panels. Small power circuit breakers (such as those found in lighting
panels) may not have arc extinguishers.
Figure 2-18.Arc extinguisher action.
TERMINAL CONNECTORS are used to connect the circuit breaker to the power source and the
load. They are electrically connected to the contacts of the circuit breaker and provide the means of
connecting the circuit breaker to the circuit.
The TRIP ELEMENT is the part of the circuit breaker that senses the overload condition and causes
the circuit breaker to trip or break the circuit. This chapter will cover the thermal, magnetic, and thermal-