Loading patent…
AssigneeSocieta' Cavi Pirelli S.p.A.
InventorPaolo G. Priaroggia
Estimating the term…
Method for improving the dielectric strength of insulation not subject to fluid pressure and used to insulate a conductor element, such as the conductor of a cable, an insulator, etc., subjected to direct current high voltage in which, during or prior to service use thereof, the insulation is subjected continuously or intermittently to a varying amplitude, direct current voltage. The amplitude of the variation is small relative to the average value of the direct current voltage and the frequency of the variation, preferably, is less than 60 Hz. Also, apparatus for providing the voltage of varying amplitude including an alternating current generator in series between the direct current source and the conductor element and inductor in parallel with the generator, the inductor having a low ohmic resistance and a high reactance relating, respectively, to the ohmic resistance and reactance of the generator.
A method for improving the dielectric strength with respect to a direct current voltage of the insulation around a conductor element for forming part of a direct current power transmission system, said insulation being without fluid pressure thereon, said method comprising subjecting said insulation throughout its length to a direct current voltage of a predetermined magnitude applied to said conductor and varying the amplitude of said direct current voltage throughout the length of said insulation at a periodic rate, said amplitude being varied by an amount less than said predetermined magnitude and less than an amount which will cause voltage breakdown in said insulation.
A high volage, direct current, electric power transmission system comprising a conductor element with insulation therearound, said insulation being without fluid pressure thereon, a source of high voltage, direct current connected to said conductor element at a first point for supplying a direct current voltage of a predetermined magnitude to said conductor element and to a load at a second point remote from said first point for supplying direct current to said load, and means connected to said source for varying the voltage supplied to said conductor element throughout its length at a periodic rate, said amplitude being varied by an amount less than said predetermined magnitude and less than an amount which will cause voltage breakdown of said insulation.
Dependencies are inferred from the claim text.