In the event of a fault, the Distribution Cabinet can quickly cut off the power supply to prevent the accident from expanding mainly through the following methods.
First, the fuse is a common protective device. When an overload or short-circuit current occurs in the circuit, the fuse (such as a fuse) in the fuse will melt due to the heat generated by the current. Its action speed is very fast, and it can cut off the fault circuit in a short time, preventing the excessive current from causing further damage to the electrical equipment. For example, in a small-power Distribution Cabinet branch circuit, when a short circuit occurs, a fuse with a smaller rated current can be melted within a few milliseconds, thereby effectively isolating the faulty part.
Secondly, the circuit breaker plays a vital role. There are protective elements such as electromagnetic releases and thermal releases inside the circuit breaker. The electromagnetic release can detect a huge current change at the moment of short circuit, generate a strong electromagnetic force to trip the circuit breaker and cut off the circuit. The thermal release determines whether it is overloaded by sensing the heat generated when the current passes through. When the overload reaches a certain level and lasts for a period of time, the thermal release acts to disconnect the circuit breaker. In industrial distribution cabinets, when a short circuit occurs, a circuit breaker with high short-circuit breaking capacity can cut off the power supply in about 0.1 seconds, effectively protecting the safety of equipment and personnel.
In addition, there is a leakage protector. It is mainly used to detect leakage current in the circuit. Once the leakage current is detected to exceed the set value (generally about 30mA), the leakage protector will act quickly to cut off the power supply. This is very effective in preventing accidents such as electric shock and fire caused by leakage. For example, near some distribution cabinets operated by personnel, if there is leakage in the equipment, the leakage protector can react quickly to avoid electric shock accidents.
In order to ensure that these protection devices can work in a timely and effective manner, the distribution cabinet needs to be maintained and inspected regularly. Check whether the fuse is intact, whether the tripping characteristics of the circuit breaker are normal, and whether the leakage detection function of the leakage protector is sensitive. At the same time, coordination between these protection devices is also very important. For example, when designing the protection system of a distribution cabinet, it is necessary to reasonably set the action parameters of fuses, circuit breakers and leakage protectors according to different fault types and circuit parameters, so that they can quickly cut off the power supply in a predetermined order and time when a fault occurs, thereby minimizing the harm of the accident.