circuit breaker is generally composed of a contact system, an arc extinguishing system, an operating mechanism, a trip unit, and a casing.
The function of the circuit breaker is to cut off and connect the load circuit, and cut off the faulty circuit, so as to prevent the expansion of the accident and ensure safe operation. The high-voltage circuit breaker needs to break 1500V, and the current is 1500-2000A arc, and these arcs can be stretched to 2m and still continue to burn without extinguishing. Therefore, arc extinguishing is a problem that must be solved for high voltage circuit breakers.
Low-voltage circuit breakers, also known as automatic air switches, can be used to switch on and off load circuits, and can also be used to control motors that start infrequently. Its function is equivalent to the sum of some or all of the functions of the knife switch, over-current relay, voltage loss relay, thermal relay and leakage protector. It is an important protective device in the low-voltage distribution network.
Low-voltage circuit breakers have multiple protection functions (overload, short circuit, undervoltage protection, etc.), adjustable operating value, high breaking capacity, convenient operation, safety, etc., so they are widely used. Structure and working principle Low-voltage circuit breaker is composed of operating mechanism, contacts, protection devices (various releases), arc extinguishing system and so on.
The main contact of the low-voltage circuit breaker is closed manually or electrically. After the main contact is closed, the free tripping mechanism locks the main contact in the closed position. The coil of the overcurrent release and the thermal element of the thermal release are connected in series with the main circuit, and the coil of the undervoltage release is connected in parallel with the power supply. When the circuit is short-circuited or seriously overloaded, the armature of the over-current release will pull in to make the free tripping mechanism act, and the main contact will disconnect the main circuit. When the circuit is overloaded, the thermal element of the thermal release will generate heat to bend the bimetal sheet, pushing the free release mechanism to act. When the circuit is undervoltage, the armature of the undervoltage release is released. Also activates the free tripping mechanism. The shunt release is used for remote control. During normal operation, its coil is powered off. When distance control is required, press the start button to energize the coil.
Post time: Feb-09-2023
