Break contact

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Breaker contacts , or also breakers , are electrical contacts that open and close a circuit in regular sequence and are designed in different designs depending on the application. They represent a special design of electrical switches . A distinction is made between self- breaker contacts, which continuously interrupt themselves in the structure like an oscillator , and breaker contacts, which are controlled by external influences.

In many areas of application, breaker contacts are replaced in their function by semiconductor switches such as switching transistors , which can close and interrupt electrical circuits without mechanical movements, achieve higher switching frequencies and, compared to breaker contacts, show significantly less wear. In the case of interrupter contacts as an electromechanical component , the ongoing switching on and off leads to contact erosion , which is caused by the switching arc .

Self-breaker contacts

Wagner hammer

Wagner's hammer in an electromechanical doorbell

The Wagner hammer is used, among other things, for electromechanical bells and spark inductors , which are supplied with direct voltage from a battery . With the bell, the mechanical contact movement is used to operate a bell. In the case of the spark inductor, the periodic interruption of the circuit by a transformer generates a high AC voltage which can be used to generate sparks.

Deprez breaker

The Deprez interrupter is a further development of Wagner's hammer, with which up to 40 interruptions per second can be achieved.

Rogetsche spiral

Rogetsche spiral from 1906

The Rogetsche spiral is a historical type of self-breaker contact which was developed by Peter Mark Roget around the year 1835 . The arrangement consists of a vertically suspended wire spiral, similar to a mechanical tension spring, which is immersed in a bowl with mercury at the lower end. Due to the Lorentz force, a current flow through the spiral conductor leads to an attraction of neighboring conductors in the spiral line, with the effect that the spiral contracts slightly. This pulls the lower end of the coil out of the mercury, causing an interruption in the circuit. As the Lorentz force is missing as a result, the spiral relaxes again, dips into the mercury, which closes the circuit again and the process is repeated periodically and the spiral swings up and down.

Breaker contacts

Ignition breaker

Ignition breaker from a Trabant

The ignition interrupter has been used in previously used electromechanical switches in the ignition system of a gasoline engine . The internal combustion engine drives a camshaft, which opens and closes the ignition interrupter periodically and in step with the engine speed. With the help of an ignition coil , the sparks on the spark plugs in the combustion chamber can be triggered.

The ignition interrupter has been almost completely replaced in the vehicle sector by semiconductor electronics such as switching transistors.

Lightning wheel

The lightning wheel is a historical electromechanical arrangement that closes and interrupts an electrical circuit at periodic intervals via a gear wheel .

Turbo inverter

The turbo-inverter is a form of an inverter that is no longer in use today to convert direct voltage into alternating voltage. Liquid mercury is used as the contact material .


  • Günter Springer: Expertise in electrical engineering . 18th edition. Verlag - Europa - Lehrmittel, Wuppertal 1989, ISBN 3-8085-3018-9 .
  • Rudolf Hüppen, Dieter Korp: Car electrics all types . Motorbuchverlag, Stuttgart 1968, ISBN 3-87943-059-4 .

Individual evidence

  1. Roget's Spiral. Retrieved October 24, 2013 .
  2. ^ Otto Lueger: Lexicon of the entire technology and its auxiliary sciences . tape 3 . Stuttgart, Leipzig 1906, p. 414 ( online ).