Ignition coil

In order for spark plugs to spark, a high voltage must be discharged across their electrodes. Depending on the ignition system, the discharge voltage exceeds 30,000 V.

Traditional ignition coils consist of two windings: a primary winding with a small number of turns (about 100) thick copper wire (about 0.6 mm²) and a secondary winding with several thousand turns of thinner copper wire (about 0.1 mm²). Both windings surround a lamellar ferromagnetic core. At the signal of the control unit through the integrated ignition power module, the primary winding receives current from the battery (low voltage). As a result of this, an electromagnetic field is formed, which is transmitted to the secondary winding.

If the control unit interrupts this electrical circuit, the electromagnetic field suddenly disappears for a fraction of a second. In this case, a voltage of up to 400 V arises in the secondary winding, which produces a high voltage current pulse (induction) more than 30,000 V. Focus engines have an electronic ignition system with two ignition coils (E1), which send an ignition spark in a 1-3-4-2 operating sequence.