DE1219555B - Use of an alkylation product of benzene as an impregnation oil for high-voltage oil cables - Google Patents

Description

Use of an alkylation product of benzene as an impregnating oil for high-voltage oil cables Impregnating oils for high-voltage oil cables must be specific Have properties that can be summarized as follows: (a) A viscosity, which is as low as it can be with the necessary small amount of liquid. (The low viscosity reduces the pressure drop that occurs as a result of flow of the oil occurs in the longitudinal direction of the cable; the low volatility is with that Manufacturing process required and facilitates joining between lengths of cable.) (b) Good absorption capacity for gases in the ionized space. This absorbency depends mainly on the presence of a sufficient amount of unsaturated hydrocarbons, especially of aromatics in the oil.

(e) A very low power factor that becomes constant over time remain.

(d) Sufficient fluidity at the lowest working temperature used; Paraffin must not be precipitated at this temperature. It exists a need for impregnating oils for oil cables whose fluidity is as great as possible, especially in countries with long cable runs due to local conditions must be laid without expansion vessels.

The well-known very thin oils are in most cases too volatile and insufficiently absorb gas under the electrical stresses.

It is known to waste products of benzene alkylation with a viscosity of about 1200 cSt can be used as insulating oils for earth and pressure cables. For Such insulating oils are unsuitable for oil cables because of their high viscosity.

It is also known t-alkylbenzenes having 8 to 20 carbon atoms to be used as oils in the tertiary alkyl radical where there is high resistance to oxidation is absolutely necessary, e.g. B. as brake fluid, lubricant or transformer oil. In the case of oil cables, the impregnating oil must not have a high level of resistance to oxidation.

One also knows insulating oils for electrical purposes, the alkylbenzenes contain, which by reacting chlorinated Fischer-Tropsch paraffins with Benzene according to F r i e d e 1- C r a f t s are produced. The length of the alkyl chain is indefinite. These oils have too high a viscosity and a too high freezing point and are therefore not suitable for oil cables which, among other things, have to do with thin fluid arrives even in the cold.

The invention consists in using an alkylation product of benzene as an impregnating oil for high-pressure oil cables, which is obtained by alkylating benzene with a mixture of halogenated, aliphatic hydrocarbons with 12 carbon atoms in the molecule and purifying the product obtained an adsorbent substance and has the following properties: Molecular weight ....... 200 to 400 Specific weight (15 ° C) .............. 0.87 to 0, 90 Ignition point in an open bowl (Marcuss on; ° C). . . . . . . . . . . . over 130 viscosity (cSt; 20 ° C) .. 1.0 to 35 pour point (according to ASTM test standard D 97-47; ° C) below - 40 paraffin separation (-20 ° C) ........... None Power factor (100 ° C.) below 0.005 The impregnating oil used according to the invention has all of the necessary properties specified above, in particular sufficient absorption capacity for gases with low viscosity even at low temperatures.

As an adsorbent for refining, it is expedient to use Silica gel, fuller's earth, aluminum oxide or activated carbon. The temperature at which the Treatment with the adsorbent running can be room temperature or a higher temperature.

The products used according to the invention are known. The manufacture of the products used is not claimed here. Example An alkylbenzene mixture with a viscosity of 12 cSt at 20 ° C and a molecular weight of about 250, which has been obtained by alkylating benzene with a mixture of chlorinated aliphatic hydrocarbons having 12 carbon atoms according to Frie -de 1- C rafts, is at 105 ° C treated with 1% fuller's earth for 15 minutes. After decanting and filtering, an impregnating oil for oil cables is obtained with the following properties: Specific weight at 15 ° C. 0.8769 ignition point in an open bowl (Marcusson; IC) 135 viscosity (cSt; 20 ° C.). . . . . . . . 12.5 pour point (according to ASTM test standard D 97-47; ° C). . . . . . . . -60 Paraffin separation at o -200 C .................. no power factor at 100 ° C .... 0.001

Claims (1)

Claim: Use of a known alkylation product of benzene as an impregnating oil for high-voltage oil cables, which has been produced by alkylation according to Friedel-Crafts of benzene with a mixture of halogenated, aliphatic hydrocarbons with 12 carbon atoms in the molecule and cleaning of the product obtained with an adsorbent substance and has the following properties: Molecular weight ....... 200 to 400 Specific gravity (15 ° C) .............. 0.87 to 0.90 Ignition point in an open bowl (Marcusson ; ° C). . . . . . . . . . . . over 130 viscosity (cSt; 20 ° C) .. 10 to 35 pour point (according to ASTM test standard D 97-47; ° C) below - 40 paraffin separation (-20 ° C) ........... None Power factor (100 ° C) below 0.005 Documents considered: German Patent No. 922 848; German Auslegeschrift No. 1008 437; French Patent Nos. 977 621, 977 966, 981206, 988 906; 992 968, 977 620; British Patent Nos. 493,715, 416,379, 711793, 732,900; U.S. Patent No. 2,810,769.