A circuit breaker refers to a switching device that can switch, carry, and break the current in normal circuit conditions, and can break the current in abnormal circuits within a specified time. It can also be used to distribute electrical energy, infrequently start asynchronous motors, protect power lines and motors, and automatically cut off the circuit in the event of severe overload, short circuit, and undervoltage faults, Its function is equivalent to a combination of fuse switches and over/under heat relays. They are generally composed of contact systems, arc extinguishing systems, operating mechanisms, releases, shells, etc. The importance of testing circuit breakers. Circuit breakers may remain idle for several years, but if a fault occurs, a large kiloampere fault current must gradually separate within a few milliseconds. The main errors that occur on circuit breakers are incorrect behavior, coil short circuits, mechanical connection damage/wear, or insulation materials. Therefore, it is necessary to regularly and carefully test the circuit breaker. Circuit breakers play a crucial role in protecting expensive equipment from fault damage by reliably connecting and disconnecting power sources; This requires on-site testing during installation and regular maintenance testing during its service life to demonstrate its reliability, in order to prevent costly faults and even issues that may endanger the safety of the substation. Therefore, regularly testing the performance of circuit breakers is an essential and cost-effective part of any maintenance strategy