The document provides information about circuit breakers, including: 1) A circuit breaker is a device that can automatically or manually close or open an electrical circuit under normal or abnormal conditions. 2) It operates using two contacts, two coils, and pilot devices to sense faults and trip the circuit. When a fault is detected, the tripping coil energizes to separate the contacts. 3) An arc is produced when the contacts separate but current continues through the arc. Circuit breakers must extinguish the arc quickly.