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„Device tripped. Lives saved.“

Circuit breakers

By interrupting the current in the event of a short-circuit or overload, they prevent potential fire hazards: Circuit breakers. These safety devices, which were first manufactured in 1924 by Hugo Stotz in Mannheim, are now established components in all electrical installations, where they ensure the safety of all the circuits present, irrespective of the different current intensities and cut-off characteristics. In an emergency, the current is cut off by means of a bimetal strip which bends as it is heated by the current passing through it and trips the cut-off mechanism or, alternatively, by an inductive electromagnetic effect that is triggered in response to a short-circuit.

At the same time, circuit breakers can also be activated manually using the actuator lever, for example when performing maintenance work or for the temporary disconnection of an electric circuit. All in all, circuit breakers are highly complex components that have to operate absolutely securely and reliably. This precision and reproducibility can be guaranteed using Bihler technology because the majority of the required components (magnetic assembly, trip mechanism, arc extinguisher and thermal assembly) can be manufactured flawlessly and in top quality on Bihler’s systems.


Magnetic assembly

The magnetic assembly used in circuit breakers ensures that the current is interrupted in the event of a short-circuit. It consists of a coil, magnetic core, armature, magnetic yoke, fixed contact and terminal (box terminal). This unit can be manufactured as a complete assembly on a BZ 2-12 processing center at a speed of up to 125 finished parts per minute. However, Bihler technology also makes it possible to manufacture all the components as individual parts. For example, the magnetic yoke can be manufactured on a GRM 80E or a GRM 80P stamping and forming machine at up to 160 parts per minute. The stamped, bended box terminals can also be produced extremely efficiently as separate items – at up to 240 parts per minute on a GRM 80P stamping and forming machine or at up to 360 parts per minute on a BZ 2-7 processing center or a MC 120 Multicenter.

Trip mechanism

The positive trip mechanism is a key element of the circuit breaker. It ensures that the breaker trips immediately in an emergency, even if the switch is pressed or held in the “On” position. The trip mechanism can also be used to reset the circuit breaker manually after it has tripped or has been deliberately used to interrupt the current. This free-moving component can be manufactured, for example, on a BIMERIC BM 4500 servo production and assembly system, which includes the infeed of the individual parts and their combination into a subassembly. The individual parts themselves can be produced using progressive manufacturing techniques or on Bihler systems.

Arc extinguisher

In circuit breakers, the arc extinguisher, which is also known as a deionization chamber, extinguishes the arcs that typically occur in the event of a short-circuit. Arc extinguishers consist of a set of metal plates that are electrically isolated from each other. The fully-machined components can be manufactured highly efficiently on a GRM 80E or GRM 80P stamping and forming machine, sometimes at speeds of up to 220 parts per minute.

Thermal assembly

The thermal assembly causes the electric circuit to be interrupted if the electric current intensity results in overheating. The circuit is broken by means of a bimetal strip that bends further in the presence of high temperatures and actuates mechanical elements that cause the moving contact to separate from the fixed contact. The thermal assembly also comprises a moving contact and a box terminal. The complete assembly can be manufactured as a finished unit on a BIMERIC BM 4500 servo production and assembly system at a maximum speed of 120 parts per minute. The manufacture of the required individual components can be integrated in the overall process and the parts can also be fed in preassembled.  


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