Capacitor having high stability with temperature

A metal-clad station comprising a gastight metal enclosure filled with dielectric gas under pressure inside which there are disposed apparatuses including section switches, circuit breakers, and sets of busbars, said station being provided with a capacitive stepdown bridge comprising two capacitors associated with an amplifier for the purpose of measuring tension of one of said apparatuses, wherein one of said capacitors comprises:

• a cylindrical metal body having inside and outside wall surfaces and a geometrical axis;
• a cylindrical high tension electrode coaxial with the body and placed inside said body;
• at least two low tension electrodes constrained to remain in contact against said inside wall surface of the body via an intervening insulated layer,
• said low tension electrodes being disposed symmetrically about said geometrical axis of the body,
• said low tension electrodes being held in place by retaining means that allow them to expand freely;
• and
• a dielectric medium which extends between the high tension electrode and the low tension electrodes, and which is a gas or a vacuum,
• the body being made of a material having an expansion coefficient .alpha.c equal to an expansion coefficient .alpha.h of a material of the high tension electrode, and the expansion coefficient .alpha.c of the body material being related to an expansion coefficient .alpha.b of a material of the low tension electrodes by the following inequalities:
• 1.5<.alpha.b/.alpha.c<2.5