After the circuit breaker trips, whether we plan to perform repairs or try to close, we must know the cause of the last trip to narrow the scope of the suspected fault. Circuit breakers have two major protection functions-overload (short-circuit is a special form of overload) protection and leakage protection. So how can we know whether the circuit breaker tripped due to overload or leakage? In fact, by observing the circuit breaker after tripping, it can be recognized at a glance.

(PS: This article only applies to leakage circuit breakers. If the circuit breaker has no leakage protection function, it can be concluded after tripping that the circuit breaker has tripped due to overload.)

reset button

If there is a line of small words on your circuit breaker that says "press when closing", you need to observe the button pointed by the arrow next to this line of words. This button is called the "reset button"

This button is normally in the same plane with the entire circuit breaker panel. When a leakage occurs in the circuit, the reset button will protrude and cannot be closed (not closed). In other words, if the reset button protrudes after the trip, it proves that there is leakage in the circuit; if the reset button does not protrude after the trip, it proves that there is an overload in the circuit.

The existence of the reset button, on the one hand, is to show the user the reason for the trip. On the other hand, it is to prevent personnel from operating the circuit breaker by mistake and injuring the user of the circuit.

Display screen

There is also a circuit breaker, which has no function of "preventing personnel from misoperation" and can only display the cause of the trip. It looks like the following

The location of this display screen is also not fixed, each brand of circuit breaker has its own location. Some brands will be installed in the position of the reset button, and some will be installed on the opening and closing handles.

After the circuit breaker works normally, is manually opened or overloaded, the color of the display does not change, it is always blue or green. When a leakage occurs in the circuit, the display will turn red to remind the user of the reason for the trip.