Electromagnetic compatibility (EMC)

Electromagnetic fields which are too strong can cause malfunctions in electronic equipment (radio, ABS, onboard computer, etc.). Therefore, they must be kept within a harmless range.
Electromagnetic fields

Wherever electric current flows, electromagnetic fields are formed, such as with mobile phones and radio waves.

Such electromagnetic fields also occur during ignition. They increase considerably in intensity at the time of each "spark breakaway" on the centre electrodes of the spark plug – resulting in strong voltage peaks along the cable.

However, since strong electromagnetic fields can cause malfunctions in electronic equipment - the radio, control units for the engine or gear unit or the ABS - they must be kept within a harmless range.

Spark breakaway with and without resistance.
Spark breakaway with and without resistance

For this purpose, ignition cables are equipped with electrical resistors. These limit the voltage peaks during the spark breakaway and during the discharge of the ignition coil. In the process, the energy from existing voltage and current strength is applied in a different energy-time relationship.

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