5. Breakdown phenomena in industrial applications

Industrial practice calls for the use of liquids with widely differing physico-chemical properties; moreover, their implementation, environmental qualities due to the design and operating constraints of the equipment vary considerably; for example:

• mineral oil in power transformers comes into contact with various insulating materials and solids, resulting in the inevitable presence, over time, of particles, water and gases, a tendency to oxidize, and the possibility of generating and transporting charges by friction (the oil ensures cooling of the device by forced circulation); the volumes of liquids are considerable (they can reach several tens of cubic meters), and the gaps of free liquid are sometimes very large (ª 1 m in the vicinity of high-voltage outlets);

• The situation is very different in an all-film...