FR2794566A1 - Dielectric insulating oil compositions based on mineral oils containing polyarylalkanes with improved gas absorption properties, useful in electrical equipment such as transformers and capacitors - Google Patents

Abstract

A small quantity of polyarylalkane compounds is introduced to improve the gassing properties of the dielectric composition. A dielectric oil mixture comprises 99 - 70% of a mineral oil and 1 - 30% of a polyarylalkane composition selected from :- -compositions (I) consisting of a mixture of products of formula (A) :- -in which n1 and n2 = 0 or 1, containing products(A) such that n1 + n2 = 0 , and products (A) in which n2 = 1 ; and products(B) of formula :- -compositions (II) consisting of a mixture of two products (C) and (D) where :- product (C) is a mixture of isomers of formula :- -in which p1 and p2 = 0, 1 or 2, with p1 + p2 is less than or equal to 3 ; and product (D) is a mixture of isomers of formula :- p<1>1, p<2>1 and p4 = 0, 1 or 2 and p<1>1+p<2>1+p<1>2+p<2>2+ p3+p4+p5 =2 or less -compositions(III) comprising a mixture of two products (A1) and (A2) such that :- (A1) is a mixture of isomers of formula :- -m1 and m2 = 0. 1 or 2, and m1 + m2 is less than or equal to 3 ; (A2) is a mixture of isomers of formula :- -q1 and q2 = 0, 1 or 2 and q1 + q+2 is less than or equal to 3 ; At least one of compounds (A1) and (A2) is an isomer having three benzene nuclei ; and -compositions(IV) comprising two products (A1) and (A2) with the addition of a compound (E1), (E2) or (E3) as follows :- (E1) is a mixture of isomers of formula :- -r<1>1, r<2>1 and R4 = 0, 1 or 2 ; r<1>2, r<2>2, r3, r<1>3 and r5 = 0 or 1 ; and r<1>1 + r<2>1 + r<1>2 + r<2>2 + r3 + r<1>3 + r4 + r5 is less than or equal to 2 ; R1 and R2 = H ; (E2) is an isomer or isomer mixture of formula (E1), save that R1 and R2 are Me and coefficients r are replaced by s of similar significance ; (E3) is an iosomer or isomer mixture of formula(E1) save that R1 and R2 are different and represent H or Me and coefficients r are replaced by t of similar significance ;

Description

<B> COMPOSITION </B> DIELECTRIC <B> HAVING </B> <B> </B> ABSORPTION <B> OF </B> GAS The present invention relates to a dielectric composition <B> to </ B > mineral oil base for electrical equipment with improved gas absorption.

Mineral oils are widely used as insulating oils in various electrical equipment such as transformers, capacitors.

These mineral oils include compounds of different nature such as paraffinic chains, saturated cyclic compounds designated naphthenic, mono- and polyaromatics.

Mono- and polyaromatics give mineral oils better dielectric properties such as better breakdown voltage or so-called gassing properties.

Gas absorption is characteristic of the behavior of an oil under a high electric field.

In the presence of gaseous hydrogen, the oil can either produce more gas in which case, it is called "gas-evolving", or absorb hydrogen, it is then called "gas-adsorbing". gas).

<B> It </B> is sought after for electrical equipment of so-called "gas-absorbing" oils.

Polyaromatics are diverse and varied in nature, but most are considered carcinogenic. Also, in order to reduce the content of polyaromatics in mineral oils, they undergo a hydrogenation treatment. This treatment, however, has the drawback of eliminating in particular the monoaromatics considered to be not very toxic.

The Applicant has observed that the use of small amounts of compounds of the diphenylalkane family made it possible to improve the gas absorption property of mineral oils.

dans laquelle nl et n2=0 ou<B>1</B> et qui contient des produits<B>(A)</B> tels que n<B>1 +</B> n2<B≥ 0</B> et des produits<B>(A)</B> tels que n<B>1 +</B> n2<B≥ 1.</B> The subject of the invention is therefore a dielectric composition for electrical devices, characterized in that it consists of a mineral oil and an amount at most equal to <B> 10% </B> by weight of a (methylbenzyl) xylene or a mixture of products of formula <B> (A): </B>

where nl and n2 = 0 or <B> 1 </B> and which contains <B> (A) </B> products such as n <B> 1 + </B> n2 <B≥ 0 </ B> and <B> (A) </B> products such as n <B> 1 + </B> n2 <B≥ 1. </B>

The product <B> A </B> can be prepared by condensation of chloride (methylbenzyl) with xylene in the presence of a Friedel and Crafts catalyst. We obtain a mixture of products <B> with </B> 2 and <B> 3 </B> cores.

Preferably, a mixture will be used containing <B> 85% </B> by weight of a product <B> (A) </B> in which n <B> 1 = </B> n2 <B≥ 0 </B> and <B> 15% </B> by weight of a product <B> (A) </B> in which n <B> 1 = 0 </B> and n2 <B≥ 1 < / B> (hereinafter referred to as XX mixture).

According to the present invention, a dielectric composition will preferably be used containing <B> 1% to 5% </B> by weight of a (methylbenzyl) xylene or of a mixture of products of formula <B> (A). </B>

The gas absorption property was evaluated using the method described in the <B> 628 </B> standard of the International Electrotechnical Commission <B> (CEP. </B>

According to this method, the interface between a column of liquid and a volume of hydrogen is subjected <B> to </B> electric discharges between 2 electrodes placed <B> at </B> different potentials.

We follow the evolution of the gas volume as a function of time.

We have prepared different blends of a "gas-evolving" mineral oil and XX blend which have been evaluated according to the CEI <B> 628-A at 800C method. </B>

<B> COMPOSITION </B><SEP> ABSORPTION <SEP><B> OF </B><SEP> GAS
<tb><B><U>EN</U></B><U><SEP> lil / min </U>
<tb><U><SEP> mineral oil <SEP><B> + </B><SEP> 5.4 </U>
<tb><U> Mineral <SEP> oil <SEP> plus <SEP> 2 <SEP><B>%</B><SEP> in <SEP> weight <SEP> of <SEP> XX <SEP><B> -5 </B></U>
<tb><U> Mineral <SEP> oil <SEP> plus <SEP><B> 5 <SEP>% </B><SEP> in <SEP> weight <SEP> of <SEP> XX <SEP><B> 12.8 </B></U>
<tb><U><SEP> mineral oil <SEP> plus <SEP><B> 19 <SEP>% </B><SEP> of <SEP> XX <SEP><B> 22.7 </ B ></U>

Claims (1)

<B> CLAIMS </B> Dielectric composition for electrical appliances, characterized in that it consists of a mineral oil and a quantity by weight at most equal to <B> 10% </B> of a ( methylbenzyl) xylene or a mixture of products of formula <B> (A): </B>

where nl and n2 = 0 or <B> 1 </B> and which contains <B> (A) </B> products such as n <B> 1 + </B> n2 <B≥ 0 </ B> and <B> (A) </B> products such as n <B> 1 + </B> n2 <B≥ 1. </B> <I> 2. </I> Composition according to claim <B> 1, </B> characterized in that the mixture of products of formula <B> (A) </B> contains <B> 85% </B> by weight of a product of <B> f </B> formulates <B> (A) </B> in which n <B> 1 = </B> n2 <B≥ 0 </B> and <B> 15% </B> by weight of a product <B> (A) </B> in which n <B> 1 = 0 </B> and n2 <B≥ 1. </B> <B> <I> 3. </I> </ B> Composition according to one of claims <B> 1 </B> or 2, characterized in that it contains <B> 1% to 5% </B> by weight of (methylbenzyl) xylene or of a mixture of products of formula <B> (A). </B>