Circuit breakers are necessary for us to use in circuits, which can quickly cut off and connect load circuits, as well as cut off faulty circuits, protecting electrical equipment.

At the same time, it can also efficiently distribute electrical energy, and can be directly used as a switch to control infrequently started motors. The ability to automatically cut off a circuit if there is a fault in the circuit.

Now let's introduce two common circuit breakers: one with leakage protection, and the other without leakage protection.

This is a disconnector with leakage protection function, which we often see in the process of using electricity and can be used as a main switch. As can be seen from the switch panel, this leakage protection switch can also adjust the leakage current of leakage tripping and the action time of tripping. When selecting the allowable leakage protection action value, we generally choose a leakage protection current greater than 0.3 A, as this switch is generally used as a master switch. The leakage protection for some branches is a 0.3 A switch. If the main switch is not greater than 0.3 A, the main switch will trip if there is a leakage fault in the circuit. In this way, the impact range will become larger, so when we set the leakage protection value of the main switch, we will choose to be greater than 0.3 A.

This is the content structure of the leakage protection switch. As can be seen from the picture, there are tripping coils, zero sequence current transformers, circuit boards, arc extinguishing devices, and so on. If the unbalanced current in the circuit exceeds the set value, the trip coil action will trip the switch, thereby protecting the electrical equipment in the circuit.

This is a circuit breaker without leakage protection, and also a circuit breaker commonly used as a main switch, with short circuit and overload protection functions.

The internal structure of this circuit breaker is simpler than that of a circuit breaker with leakage protection, and the part of the trip coil circuit is missing. In fact, this circuit breaker can be equipped with a multi-functional fault protector and release to achieve leakage protection, phase loss protection, undervoltage protection, and other functions.

In my maintenance experience, I encountered a circuit breaker with leakage protection as the main switch. If there is a leakage condition in a branch circuit, it will lead to a loss of the main switch, and we will also have trouble finding the leakage point.