3. Zinc oxide arresters

In the 1960s, varistors made of zinc oxide ceramics came onto the market to protect electronic circuits.

As early as 1970, manufacturers began developing surge arresters using these ceramics. For electrical engineers, these components offer two essential advantages:

• on the one hand, they have such a high non-linearity coefficient that they can be used as surge arresters without spark gaps, where the active part remains permanently energized;

• secondly, their high energy absorption capacity means they can be used on all networks, from electronics to very high voltage (225 or 400 kV) power transmission, both to protect equipment against atmospheric overvoltages (lightning), and against slow overvoltages, known as maneuvering overvoltages, if the application so requires.

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