Industry News

Working principle of circuit breaker

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Three contacts of the circuit breaker in series in three-phase circuit, the electromagnetic tripping coil and heat release heat element is also in series with the main circuit , under voltage release coil is connected in parallel with the main circuit.

When the breaker is closed, three main contacts by the latch hook, to overcome the spring tension, keep closed. And when the electromagnetic tripping device is attracted or heat tripping device of double metal sheet is heated to bend or under voltage release release, in which an arbitrary action, the lever from the top, the hook and the lock disengaged, and the main contact points off the circuit.

When the current through the work coil for generating an electromagnetic tripping device, the electromagnetic force can not be attracted when the current through the armature, in short circuit, and the emergence of large current, electromagnetic force becomes large enough to pull the armature; the main contact is disconnected, cut off the main circuit; if the circuit overload occurs, but it is not up to the current electromagnetic release action, and the heating element through the heat release of the overload current, the bimetallic strip is heated and bent, from the top of the lever, causes the contacts to separate off the circuit, the role of overload protection; if the power supply voltage drops more or loss of voltage, due to electromagnetic force voltage release decreases, the armature release also led to contact and cut off the circuit, so that the under voltage or voltage loss protection.