Capacitor with high thermal stability for shielded electrical lines

A capacitor of high thermal stability for carrying out measurements on a gas-insulated high-voltage line, comprising:

• a high-voltage electrode extending in a longitudinal direction,
• a cylindrical printed circuit coaxially surrounding said high-voltage electrode, said cylindrical printed circuit comprising an electrically conductive track forming a low-voltage electrode, and
• a frame comprising a cylindrical inside surface coaxially surrounding said cylindrical printed circuit held by said frame,
• wherein said cylindrical printed circuit is slit along a generatrix of the cylinder that it forms and said frame comprises guide means for holding said cylindrical printed circuit near the cylindrical inside surface and allowing said cylindrical printed circuit to expand along said cylindrical inside surface, and
• wherein the guide means are two profiled rings fixed along the cylindrical inside surface of the frame, said profiled rings each having an L-shaped section to form with said cylindrical inside surface two circular grooves facing each other and each having a U-shaped section, the cylinder that the cylindrical printed circuit forms having its bases nested in the two circular grooves.

A capacitor of high thermal stability for carrying out measurements on a gas-insulated high-voltage line, comprising:

• a high-voltage electrode extending in a longitudinal direction,
• a cylindrical printed circuit coaxially surrounding said high-voltage electrode, said cylindrical printed circuit comprising an electrically conductive track forming a low-voltage electrode, and
• a frame comprising a cylindrical inside surface coaxially surrounding said cylindrical printed circuit held by said frame,
• wherein said cylindrical printed circuit is slit along a generatrix of the cylinder that it forms and said frame comprises guide means for holding said cylindrical printed circuit near the cylindrical inside surface and allowing said cylindrical printed circuit to expand along said cylindrical inside surface, and
• wherein said cylindrical printed circuit has coefficients of thermal expansion ax, ay respectively in the longitudinal direction and along its periphery that are related to the coefficient of thermal expansion ac of the frame by the condition:
• 0.75
• ≤
• a
• x
• +
• a
• y
• a
• c
• ≤
• 1.25
• .