What is the working principle of a circuit breaker?
1 Answers
The working principle of a circuit breaker is that when a short circuit occurs, the magnetic field generated by a large current (generally 10 to 12 times the normal current) overcomes the reaction force spring, causing the trip unit to pull the operating mechanism and instantly trip the switch. In the case of overload, the current increases, heat intensifies, and the bimetallic strip deforms to a certain extent, pushing the mechanism to act (the larger the current, the shorter the action time). Below is detailed information about circuit breakers: 1. Professionally, a circuit breaker is called a circuit interrupter. Its function is to cut off and connect load circuits, as well as to disconnect faulty circuits, preventing accidents from escalating and ensuring safe operation. High-voltage circuit breakers must interrupt arcs with voltages of 1500V and currents of 1500-2000A. These arcs can stretch up to 2m and continue to burn without extinguishing. Therefore, arc extinguishing is a critical problem that high-voltage circuit breakers must solve. 2. The principle of arc blowing and extinguishing mainly involves cooling the arc to weaken thermal ionization. On the other hand, blowing the arc lengthens it, enhancing the recombination and diffusion of charged particles. Simultaneously, it disperses the charged particles in the arc gap, quickly restoring the insulating strength of the medium. Low-voltage circuit breakers, also known as automatic air switches, can be used to connect and disconnect load circuits, as well as to control infrequently started motors. Their functions are equivalent to the combined or partial functions of knife switches, overcurrent relays, undervoltage relays, thermal relays, and leakage protectors. They are an important protective device in low-voltage distribution networks.
