Schneider circuit breaker working principle

Circuit breakers generally consist of a contact system, an arc extinguishing system, an operating mechanism, a trip unit, a housing, and the like.

When a short circuit occurs, a magnetic field generated by a large current (typically 10 to 12 times) overcomes the reaction force spring, and the tripping device pulls the operating mechanism to actuate and the switch trips instantaneously. When overloaded, the current increases and the heat builds up. The bimetal deforms to a certain degree and pushes the mechanism (the greater the current, the shorter the operating time).

There are now electronic type, the use of transformers to collect the current of each phase, compared with the set value, when the current is abnormal, the microprocessor sends out a signal to make the electronic trip unit drive the operation mechanism.

The role of the circuit breaker is to cut off and connect the load circuit, and cut off the fault circuit to prevent accidents from expanding and ensure safe operation. The high-voltage circuit breaker to break 1500V, current 1500-2000A arc, these arcs can be extended to 2m and continue to burn without extinguishing. Therefore, arc extinguishing is a problem that high voltage circuit breakers must solve.

The principle of arc quenching is mainly to cool the arc to weaken the heat release. On the other hand, the arc is used to stretch the arc to reinforce the compounding and diffusion of charged particles, and at the same time, the charged particles in the arc gap are blown away, and the dielectric strength of the medium is rapidly restored.

Low-voltage circuit breakers, also known as automatic air switches, can be used to switch on and off the load circuit and can also be used to control motors that do not start very often. Its function is equivalent to some or all of the functions of the switch, over-current relay, voltage-loss relay, thermal relay and leakage protector, etc. It is an important protection appliance in low-voltage distribution network.

Low-voltage circuit breakers have a variety of protection functions (overload, short circuit, undervoltage protection, etc.), adjustable operating values, high breaking capacity, easy operation, and safety, and are therefore widely used. Structure and working principle Low-voltage circuit breakers consist of operating mechanisms, contacts, protection devices (various trip units), and arc extinguishing systems.

The main contacts of the low-voltage circuit breaker are manually operated or electrically closed. After the main contact is closed, the free tripping mechanism locks the main contact in the closing 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 supply. When the circuit is short-circuited or severely overloaded, the armature of the over-current release pulls in, causing the free tripping mechanism to act, and the main contact opens the main circuit. When the circuit is overloaded, the thermal element of the thermal release heats up to bend the bimetal and push the free tripping mechanism. When the circuit is under voltage, the armature of the undervoltage release releases. The free trip mechanism is also actuated. The shunt release is used as a remote control. In normal operation, the coil is powered off. When a distance control is required, the start button is pressed to energize the coil. The armature drives the free trip mechanism to make the main touch. Disconnect.

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