External view of a "All-film" H.V. capacitor
1. connection
2. porcelain terminal
3. fixing lug
4. stainless steel cell
5. active part

High voltage capacitors are composed of elementary or partial capacitances generally connected in several serial-parallel groups used to obtain the required electrical characteristics for the unit.

• the nominal voltage of a capacitor depends on the number of groups in series

• the nominal power of a capacitor depends on the number of partial capacitances in parallel per group

Each elementary capacitance is produced using two aluminium foils forming the armaments or the electrodes and high quality specific polypropylene films which are rough for easy impregnation, forming part of the insulating layer.
The wired capacitance assembly, called the "active section" is positioned in a stainless steel cell, equipped with insulated porcelain bushings or terminals used to connect the device. 
After it has been dried and treated, the "active section" is impregnated under a vacuum with a liquid dielectric of the following type :

• non-chlorinated

• non-toxic

• biodegradable

With the polypropylene film, this liquid dielectric, which has a remarkably high chemical stability, a high gas absorption and partial discharge quenching capacity and a flash point of approximately 150°C, ensures total insulation between electrodes.
This "All-film" technology has the following main characteristics :

• very high resistance to strong electrical fields

• very low power losses, enabling considerable savings for high power capacitor banks.