Circuit Breaker With Three-stage Protection Function

Generally speaking, a circuit breaker with three-stage protection functions of overload long delay, short circuit short delay and short circuit instantaneous protection can achieve selective protection. Most main lines (including the outlet end of the transformer) use it as the main protection switch. . Circuit breakers that do not have the short-circuit short-delay function (only overload long-delay and short-circuit instantaneous two-stage protection) cannot be used for selective protection. They can only be used in branch circuits. IEC92 "Marine Electrical" points out: A circuit breaker with three-stage protection focuses on its operating short-circuit breaking capacity value, while a circuit breaker used in branch lines should ensure that it has sufficient ultimate short-circuit breaking capacity value.
No matter what kind of circuit breaker it is, it has two important technical indicators: Icu and Ics. However, as a circuit breaker used on a branch line, it can only meet the rated limit short-circuit breaking capacity. A more common bias is to prefer the big to the right, thinking that the big is safe. However, if it is too large, it will cause unnecessary waste (for the same type of circuit breaker, the H-type high breaking type is 1.3 to 1.8 times more expensive than the S-type ordinary type). Therefore, there is no need for the circuit breaker on the branch line to blindly pursue its operating short-circuit breaking capacity index. For circuit breakers used on main lines, they must not only meet the requirements of the rated limit short-circuit breaking capacity, but also the requirements of the rated operating short-circuit breaking capacity. If only the rated limit short-circuit breaking capacity Icu is used to measure whether its breaking capacity is qualified or not, It will bring unsafe risks to users.
The circuit breaker is a basic low-voltage electrical appliance. The circuit breaker has overload, short-circuit and under-voltage protection functions, and has the ability to protect lines and power supplies.
The main technical indicators are rated voltage and rated current. Circuit breakers have different functions according to different applications, with many varieties and specifications, and many specific technical indicators.
Free tripping of the circuit breaker: At any time during the closing process of the circuit breaker, if the protective action connects the tripping circuit, the circuit breaker can be disconnected completely and reliably, which is called free tripping. A circuit breaker with free tripping can ensure that when the circuit breaker is closed and a short-circuit fault occurs, it can be disconnected quickly to avoid expanding the scope of the accident.