Methods for dielectrically insulating electrical active parts

Abstract

Methods for dielectrically insulating electrical active parts The invention concerns methods for dielectrically insulating electrical active parts using certain fluorinated cyano-substituted ethers as well as compositions and apparatus comprising such compounds.

Claims

1. A method for dielectrically insulating an electrical active part, the method comprising the step of: arranging the electrical active part in a gas-tight housing comprising an insulating medium comprising a compound of general formula (I):
NCC.sub.nH.sub.mF.sub.(2n)mOC.sub.nH.sub.mF.sub.(2n+1)m(I) wherein n is 1, 3, 4, or 5 and m is integer between 0 and 2n and wherein n is 1, 2, 3, 4, or 5 and m is integer between 0 and 2n.

2. The method according to claim 1, wherein n is 1.

3. The method according to claim 1, wherein n is 1.

4. The method according to claim 1, wherein m is 0.

5. The method according to claim 1, wherein m is 0.

6. The method according to claim 1, wherein the compound is CF.sub.3OCF.sub.2CN.

7. A composition comprising at least one compound of general formula (I)
NCC.sub.nH.sub.mF.sub.(2n)mOC.sub.nH.sub.mF.sub.(2n+1)m(I) wherein n is 1, 3, 4, or 5 and m is integer between 0 and 2n and wherein n is 1, 2, 3, 4, or 5 and m is integer between 0 and 2n and at least one further compound selected from the group consisting of an inert gas, a perfluorinated or partially fluorinated ketone, a perfluorinated or partially fluorinated ether, a perfluorinated or partially fluorinated ester, a perfluorinated or partially fluorinated cyano compound and a hydrocarbon compound.

8. The composition according to claim 7, comprising CF.sub.3OCF.sub.2CN and at least one compound selected from the group consisting of an inert gas, a perfluorinated or partially fluorinated ketone, a perfluorinated or partially fluorinated ether, a perfluorinated or partially fluorinated ester, a perfluorinated or partially fluorinated cyano compound and a hydrocarbon compound.

9. The composition according to claim 8 comprising CF.sub.3OCF.sub.2CN and the least one compound selected from the group consisting of air, synthetic air, N.sub.2, O.sub.2, CO.sub.2, N.sub.2O, He, Ne, Ar, Xe and SF.sub.6.

10. The composition according to claim 9, comprising CF.sub.3OCF.sub.2CN and N.sub.2.

11. An apparatus for the generation, distribution and/or usage of electrical energy wherein the apparatus comprises an electrical active part arranged in a gas-tight housing, said gas-tight housing containing an insulating medium comprising at least one compound of general formula (I)
NCC.sub.nH.sub.mF.sub.(2n)mOC.sub.nH.sub.mF.sub.(2n+1)m(I) wherein n is 1, 3, 4, or 5 and m is integer between 0 and 2n and wherein n is 1, 2, 3, 4, or 5 and m is integer between 0 and 2n; or containing an insulating medium comprising the composition according to claim 7.

12. The apparatus according to claim 11, wherein the insulating medium comprises CF.sub.3OCF.sub.2CN.

13. The apparatus according to claim 11, wherein the apparatus is a medium-voltage or high-voltage switchgear.

Description

EXAMPLES

Example 1a

Manufacture of CF.SUB.3.OCF.SUB.2.CN

(1) CF.sub.3OCF.sub.2CN is prepared according to Gubanov, V. A. et al., Zhurnal Obshchei Khimii, 1965, Vol. 35, No. 4, pp. 754-755.

Example 1b

Manufacture of the Compositions

(2) As described in WO98/23363, a homogenous mixture consisting CF.sub.3OCF.sub.2CN and N.sub.2 in a volume ratio 1:4 is manufactured in an apparatus comprising a static mixer and a compressor.

(3) Example 2

Provision of an Earth Cable Containing the Dielectrically Insulating Medium of Example 1

(4) The composition of example 1b is directly fed into an earth cable for high voltage, until a total pressure of 10 bar (abs) is achieved in the cable.

Example 3

A Switchgear Containing CF.SUB.3.OCF.SUB.2.CN and N.SUB.2 .in a Volume Ratio 1:4

(5) A switchgear is used which contains a switch surrounded by a gas-tight metal case. The composition of example 1b is passed into the gas tight metal case via a valve until a pressure of 18 bar (abs) is achieved.