How to choose the upper and lower levels of the circuit breaker in the small power distribution unit?

In the small power distribution unit, the selection of the upper and lower levels of the circuit breaker should be carried out according to the characteristics of the load current and the circuit. Generally speaking, a circuit with a high load needs to use a larger circuit breaker to ensure the safety and stability of the circuit. Therefore, in the small power distribution unit, circuit breakers of different sizes and types are usually selected according to the size and characteristics of the circuit load. In addition, the level of the circuit breaker should be determined according to the importance and use of the circuit. For important circuits and equipment, high-level circuit breakers should be used to ensure the reliability and safety of the circuit. At the same time, when selecting a circuit breaker, parameters such as its short-circuit capacity and rated current also need to be considered to ensure that they match the circuit. In short, when selecting the upper and lower levels of the circuit breaker in the small power distribution unit, multiple factors such as load size, circuit characteristics, short-circuit capacity and rated current should be considered comprehensively, and relevant national standards and safety regulations should be followed to ensure the safety and stability of the circuit run.