2. Silicon carbide and spark gap arresters

At a much higher cost [in HTA (20 kV) ratio of around 3 and in HTB (400 kV) ratio of 100], the lightning arrester avoids most of the disadvantages inherent in the spark gap principle.

Its advantages over the spark gap are :

• a much narrower spread of ignition voltage;

• spontaneous arc extinction;

• a residual voltage at the arrester's terminals that is non-zero after triggering, thus preventing the transmission of a cut-off voltage wave;

• insensitivity (up to a point) to external aggressions.