DE3432746A1 - INSULATING OIL FOR ELECTRICAL MEDIUM AND HIGH VOLTAGE DEVICES - Google Patents

Description

hemische Fabrik Wibarco GmbH "..". .-. : 08/27/1984

: - ^: "..: .. ■■: .-. CE-Dl / he

The invention relates to insulating oils for electrical medium and high voltage equipment.

The insulating oils are known to be used for electrical insulation of electrical transformers, switches and cables and capacitors that are operated in the medium and high voltage range are used.

As Ulimann's Encyklopadie der technischen Chemie, 4th ed., Volume 20, pages 607 to 612, describes For example, certain mineral oil fractions are used as insulating oils in medium and high voltage equipment.

Due to their high dielectric constant and their high flash point, halogenated, chlorinated diphenyls are particularly good as insulating oils for medium and high-voltage electrical equipment suitable. However, the use of these insulating oils has shown that they can be used in silent electrical discharges Hydrogen halide can be released, which affects both the electrical medium and high voltage equipment as well as being able to harm the environment. Furthermore, the halogenated diphenyls due to their relatively high viscosity and their poor flowability at low temperatures cannot be used in numerous applications.

Alkylbenzenes with 9 to 16 carbon atoms in the alkyl groups are also used as insulating oils for cables in a mixture with mineral oil.

Dicarboxylic acid esters and polysiloxanes or their fluorinated derivatives are also used as capacitor insulating oils known. However, these must first be generated in complex synthesis processes.

Mixture Factory Wibarco GmbH "" - "" - 08/27/1984

4 34327A6

JP-PS 74 19 084 describes the use of the heavy alkylate obtained in the production of alkylbenzene, which consists of alkylbenzenes and diphenylalkanes, as an insulating oil for transformers. According to this patent, the fraction of the Schweralkylats is used as an insulating oil, which mbar boils at a pressure of 20 at a temperature of about 26O ⁰ C. However, this fraction is less suitable as insulating oil for capacitors and cables.

This gives rise to the task of finding an insulating oil that is based on its physical and chemical properties Properties as an insulating oil for cables and capacitors is particularly well suited.

According to the invention, this object is achieved with the use of the diphenylalkanes according to claim 1 dissolved.

It has been surprisingly found that the fraction of diphenylalkanes from the resulting in the production of linear alkylbenzenes Schweralkylat that mbar boils at a pressure of 20 at a temperature of 230 to 26O ⁰ C, as an insulating oil for electrical medium- and high-voltage devices particularly well suited is.

In the industrial synthesis of linear alkylbenzenes, dialkylbenzenes and diphenylalkanes accumulate in the distillate residue. For this distillation residue is obtained una mbar at a temperature of 230 to 26O ⁰ C the desired mixture of diphenyl alkanes with a chain length of the linear alkyl group of 8-17 carbon atoms by fractional distillation at a pressure of about 20 microns.

hemische Fabrik Wibarco GmbH '- ■■ "-" 08/27/1984

; : -: "-: - ■] - CE-Dlhe

The physical and chemical data given below demonstrate the special properties of the Diphenylalkane fraction, according to the invention as an insulating oil uses M / irdt

Kinematic viscosity _

at 4O ⁰ C (DIN 51562) ^{15 "25 mm / s}

Flash point COC

(DIN 51376) ²⁰ ° " ²³⁰ ° ^C

Pour point (DIN 51597) <-55 ° C viscosity at -18 ⁰ C 1000 - 1300 mPa.s

Aging resistance according to Baader (140 h / 110 ° C _> inhibited oil):

Saponification number <Co, 6 mg KQH / g

Sludge content 0.05 %

Saturation concentration for water at 2O ⁰ C 0.01? Ί

These chemical and physical properties determine the particularly advantageous electrical properties Properties of the insulating oil of the invention:

Breakdown voltage
after drying (DIN 57370)} 80 kV

Dielectric constant at 23 ⁰ C,

60 Hz at 90 ° 60 Hz 2.4 1 kHz 1 kHz 2.4 Dielectric dissipation factor tangent delta at 9O ⁰ C, 2.3 60 Hz 2.3 1 kHz Specific throughput resistance 2. 14th 10 ~ ⁴ <C ι. io ~ ⁴ 10 ¹⁵ ohms. c

hemische Fabrik Wibarco GmbH- - - 08/27/1984

: ■ ·. . ^: "- ..:.: '. ■ CE-Dl / he

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The advantage of using the diphenylalkanes as a Insulating oil lies in its particularly favorable properties, such as the high flash point and at the same time high Dielectric constant, low viscosity and very low pour point. More beneficial Properties of the insulating oil are that it is odorless, practically unsaponifiable, stable to hydrolytic influences, practically immiscible and immiscible with water is hygroscopic. Because of their high gas resistance the diphenylalkane fraction to be used according to the invention is particularly suitable as an insulating oil for high-performance capacitors as well as for cables, it can also be used advantageously as switch oil.

The fraction of the diphenylalkanes can according to the invention can be used as such directly as insulating oil or mixed with an excess of dialkylbenzenes a chain length of the alkyl group of 10 to 14 carbon atoms. Such dialkylbenzenes are known as commercial products. This results in a mixture with the following chemical and physical Characteristics:

Kinematic viscosity 2

at 4O ⁰ C (DIN 51562) ^{25 "35mm / s}

Flash point COC
(DIN 51376) ²²⁰ " ²⁴ ° ^C

Pour point ^. - 6O ⁰ C

(DIN 51597)

Viscosity at -18 ⁰ C 960-1,330 mPa.s.

Aging resistance according to Baader

(140 h / 110 ° C, inhibited oil): saponification number <* 0.6 mg KOH / g sludge content <! 0.05 %

! hemische Fabrik Wibarco 'GmbH 08/27/1984

This mixture is an insulating oil with the following electrical properties:

Breakdown voltage after drying

(DIN 57370) '80 ^kV

Dielectric constant at 23 ⁰ C,

60 at 9O ⁰ C, 60 Hz 1 1 kHz ' Dielectric Hz kHz Loss factor

2 9 , 2 10 -4 2 1 , 2 10 -4 2 15th ,1 Ohm • 2 • < • 10

Dielectric loss tangent delta at 90 C, 60 Hz

1 kHz
Specific volume resistance 4. lO ^ Qhm. cm

The mixture of dialkylbenzenes and diphenylalkanes is also an excellent insulating oil, especially for high-performance capacitors, cables and switches.

To increase the long-term resistance, it has proven useful to add an antioxidant such as 2,6-di-tert-butyl-4-methyl-phenol to the insulating oil in amounts of 0.1 to 3 % customary in practice.

Claims (7)

: hemische Fabrik Wibarco .GmbH ".'..-.. ■ 08/27/1984 Claims
1. Use of diphenylalkanes of the type wherein R, and R- are identical or different linear alkyl radicals with a total of 6 to 15 carbon atoms, with a pour point of ^. - 55 ⁰ C, a flash point of 3 · 200 ⁰ C, a kinematic viscosity of about 20 mm / s according to DIN 51562 and a viscosity at a temperature of -18 C of about 1150 mPa.s, as an insulating oil for electrical equipment and high voltage equipment. 2. Use according to claim 1, characterized in that the insulating oil contains, in addition to the diphenylalkanes, mono- and / or dialkylbenzenes with 8 to 17 carbon atoms in the linear alkyl chain in amounts of ^ 0 to 50 wt. SS. 3. Use according to claims 1 and 2, characterized in that the insulating oil is used as an insulating agent for medium and high voltage cables. 4. Use according to claims 1 and 2, characterized characterized in that the insulating oil as an insulating agent used for medium and high voltage capacitors will. 5. Use according to claims 1 and 2, characterized in that the insulating oil is used as an insulator for medium and high voltage switch. nemische Fabrik Wibarco GmbH '2 / .UfcJ.J.yä4 6. Use according to claims 1 to 5, characterized in that the insulating oil contains an antioxidant in amounts of 0.1 to 3.0 wt .-? O. 7. Process for the production of the insulating oil after Claim 1, characterized in that the diphenylalkanes are distilled off at a temperature of 230 to 260 ⁰ C and a pressure of about 20 mbar from the Schu / eralkylat obtained in the production of linear alkylbenzenes.