P10. What is flash over?

Process of discharge for the Corona effect: (A), (B), (C). In the dark one, a pale light generally is observed around the high-voltage handle and in the surface of the insulator of the sparkling plug, while the engine is functioning. This phenomenon, generally call of "Corona discharge", happens due the ionization, that occurs when the gas molecules if separate in free electrons and ions loaded positively. If the air is highly ionized, its insulation is reduced and occurs the partial discharge, its results in a pale blue light. The Corona discharge occurs in the days of rain or when the surface of the insulator is dirty. It has minimum effect in the performance of the spark plug, except when the discharge it reaches the terminal bolt (as it shows figure C), allowing the formation of the voltaic arc (flash over). This arc provokes misfires, and to prevent it, the NGK produces its sparks with edges corrugated in the superior part of the insulator.