Low-voltage circuit breakers-also known as automatic air switches-are primarily utilized in low-voltage AC and DC power grids. They are capable of manually or electrically switching circuits on and off, while also providing protection for circuits or electrical equipment against faults such as overloads, short circuits, and undervoltage. Furthermore, they can be employed for the infrequent starting of electric motors, serving as a critical electrical device for both control and protection.
A low-voltage circuit breaker is a switching device capable of making and breaking not only normal load currents and overload currents but also short-circuit currents. In addition to their control function within a circuit, low-voltage circuit breakers incorporate various protective features, including protection against overloads, short circuits, undervoltage, and leakage currents.
Low-voltage circuit breakers can be classified in numerous ways: based on their application category, they are divided into selective types (featuring adjustable protection parameters) and non-selective types (featuring fixed protection parameters); based on their arc-extinguishing medium, they are categorized as air-type or vacuum-type (with domestically produced models predominantly being air-type).
The capacity range of low-voltage circuit breakers is extensive, spanning from a minimum of 4A to a maximum of 5000A. These devices are widely deployed across various levels of feeder lines within low-voltage power distribution systems, as well as for the power control of diverse mechanical equipment and the control and protection of electrical terminal loads.