Circuit breakers are vital devices that provide safety and protection in electrical systems. They are designed to automatically shut down power in the event of an overload or short circuit. Thermal magnetic circuit breaker is a popular circuit breaker, it has thermal protection and magnetic protection function.

Thermal protection function:

The thermal protection function of the thermal magnetic circuit breaker is responsible for protecting the circuit from overloading. The circuit breaker is equipped with a bimetal for thermal protection. When the bimetal is heated, it bends towards the metal with a small extension, releasing the notch that opens the breaker mechanism to disable the breaker. The bending speed of the bimetal strip is directly proportional to the magnitude of the current passing through the circuit breaker.

Magnetic protection function:

The magnetic protection function of the thermal magnetic circuit breaker is responsible for protecting the circuit from short circuits. Contact between phases or phase to ground may cause a short circuit. The circuit breaker trips instantly to protect the load it is connected to. When the short-circuit current exceeds a certain threshold, the mechanical opening mechanism operates by magnetically induced magnetization.


One of the main advantages of thermal magnetic circuit breakers is their ease of installation, with ancillary equipment that can be installed independently. Including alarm contact, auxiliary contact, undervoltage release, shunt, handle operating mechanism, electric operating mechanism, plug-in device, and pull-out device. The standard kit for each circuit breaker includes connecting bus bars or cable lugs, phase separators, a set of screws and nuts to mount it to the mounting panel.

Precautions for use:

While thermal magnetic circuit breakers offer a high level of protection, users should take some precautions to ensure their safe and efficient operation. First, it is important to choose a circuit breaker that is properly rated for the load it is connected to. Second, it is important to perform regular maintenance and inspections to keep your circuit breakers in top condition. Finally, users should be careful not to overload circuit breakers beyond their rated capacity, as this could damage the equipment and potentially lead to a hazardous situation.

In short, thermal magnetic circuit breakers are essential devices in electrical systems. Its thermal and magnetic protection features ensure safe and efficient system operation, while auxiliary equipment and standard kits make installation and maintenance easy. While users must exercise caution and perform regular inspections and maintenance, thermal magnetic circuit breakers are an excellent choice for protecting circuits from overloads and short circuits.


Post time: May-18-2023