FORM 2
THE PATENTS ACT 1970
(39 of 1970)
AND
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rulel3)
1. TITLE OF THE INVENTION:
"MUSTARD OIL BASED INSULATING FLUID COMPOSITION AND PROCESS FOR PREPARATION THEREOF"
2. APPLICANT:
(a) NAME: SAVITA OIL TECHNOLOGIES LIMITED
(b) NATIONALITY: Indian Company incorporated under the
Companies Act, 1956
(c) ADDRESS: 66/67, Nariman Bhavan, Nariman Point, Mumbai - 400 021
Maharashtra, India.
3. PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the invention and the manner in which it is to be performed:

TECHNICAL FIELD OF THE INVENTION:
The present invention relates to an insulating fluid composition based on Mustard Oil (a natural ester). More particularly, the present invention relates to a biodegradable Mustard Oil. based insulating fluid composition, comprising of a mixture of chemically modified Mustard Oil and alkyl esters of mustard oil fatty acids in the ratio of 70:30 to 100:0 along with additives and pour point depressant. The present invention also relates to a process for preparation of said Mustard Oil based insulating fluid composition and to a method of insulating the electrical devices thereof. The said composition is used as insulating fluid for electrical devices.
BACKGROUND AND PRIOR ART:
Mineral Oils are being used as insulating fluids for more than a century. An insulating fluid in a transformer has two main functions. First, it dissipates heat generated during operation and acts as a coolant. Secondly, it provides dielectric properties to the transformer. In addition, it also has to be compatible with the material of construction of transformers. It also has high dielectric strength and low dielectric dissipation factor which are key requirements for insulation effectiveness.
Although mineral oil satisfies functional requirements reasonably well, they lack the following important features, viz.
1. They can't be classified as non-flammable, having a low flash point of 140°C
2. They are not environmentally friendly as they are classified as non-biodegradable
In 1930's a fluid known as askarel (PCB, Polychlorinated biphenyl) were partly substituted with mineral oils wherever non-flammability was an issue. However, PCB's were eventually banned world-wide due to carcinogenicity. PCB's are also nonbiodegradable.
The transformer industry has always been looking for fluids which are functionally good and at the same time usable in environmentally sensitive areas like forests or marine environment. The industry has also been seeking the development of non-flammable

fluids with high flash point and fire point so that they may be used in areas close to high-rise buildings, shopping malls etc.
Prior art is described in a set of US Patents (U.S.Pat.No.6,037,537 filed Mar. 14, 2000, U.S. Pat. No.6,184,459 Bl filed Feb.6, 2001, U.S. Pat. No.6,352,655 Bl filed Mar. 5, 2002, U.S. Pat. No.6,613,250 B2 filed Sep. 2, 2003, U.S. Pat. No.6,398,986 Bl filed Jun. 4, 2002, U.S. Pat. No.6,905,638 B2 filed Jun. 14, 2005 assigned to Cooper industries),which attempts to take care of the above concerns. These Patents do talk about the use of food grade vegetable oils which include castor, coconut, corn, cottonseed, crambie, jojoba, lesquerella, linseed, olive, palm, rapeseed (canola), safflower, sunflower, soya, and veronia or their blends. These oils are claimed to be good insulating fluids finding applications in distribution and power transformers.
However, these compositions are based on blends of vegetable oils mentioned above. The most important difference in comparison to the present invention is that the above mentioned vegetable oils are not based on Mustard Oil. The said Patent Applications do not explicitly mention Mustard Oil. The present invention is based on Mustard oil and modifications thereof. Further, chemical modification is not part of Cooper industry's Patents, whereas chemical modification is an essential feature of the present invention.
Further another U.S. Pat.7,048,875 B2 filed on May. 23, 2006 assigned to ABB describes the invention of BIOTEMP which is based on Sunflower oil which is genetically modified or speciallybreeded to make high-oleic vegetable oils suitable for insulating applications. This also differs significantly from the present invention in two respects: Firstly the present invention is based on Mustard oil whereas ABB's invention is based on Sunflower Oil. Secondly the product of present invention is based on Chemical Modification unlike Biotemp which is a natural ester from genetically modified or speciallybreeded seeds.
Similarly an Australian Patent assigned to Wray & Associates (Pub. No. WO/2007/041,785) also describes the use of a product which is based on genetically modified vegetable oils to produce high oleic oils as insulating fluids. The vegetable oils used in this Patent Publication are selected from castor oil, coconut oil, corn oil,

cottonseed oil, linseed oil, olive oil, palm oil, peanut oil, grapeseed oil, canola oil, safflower oil, sunflower oil, and soybean oil, high oleic variants thereof, and mixtures thereof. This publication also differs from the present invention for the reason that the present invention is based on Mustard oils and modifications thereof.
There is one more Patent assigned to Wavely Light & Power (U.S. Pat.6,340,658 filed 2002, U.S. Pat.5,958,851 filed Nov. 5, 1998), which describes the use of selectively hydrogenated soyaoil subjected to winterization and blended with methyl esters of soya fatty acids as thinners. The present invention differs significantly from this patent also in several respects. Firstly by using mustard oil, the costly winterization step is completely eliminated. The oil chosen by the present inventor is rich in Monounsaturated Fatty Acid (Erucic acid about 46% to 50%, Oleic acid 9% to 12%) and poor in Saturated fatty acid (About 3% to 5%). The latter is present in soya in substantial quantities and contributes to wax content, necessitating the costly winterization step. Secondly, the Patent above uses methyl esters of soya fatty acids as the thinners up to a concentration of 20%. Methyl esters can potentially cause deterioration of rubber seals used in a transformer. Whereas the present invention uses a long chain ester of mustard oil fatty acids. This innovative .approach at once solves twe three issues: 1. No adverse interaction with seals in a transformer. 2. It can provide some improvement in pour point. 3. Thirdly, use of methyl esters (ME) even @ 5% level would significantly reduce flash & fire points.
US Patent No. 6280659 relates toa method for manufacturing vegetable seed oil based electrical insulating fluid wherein the vegetable seed oil is selected from the group consisting of sunflower seed oil, rapeseed oil, meadowform seed oil, and jojoba oil.
In view of the above explanation, it is the primary objective of the present invention to provide biodegradable insulating fluid compositionbased on a blend of chemically modified puremustard oil and a specifically chosen long chain alkyl ester, namely alkyl ester of CMO (Chemically Modified Mustard Oil) fatty acidstogether with additives which confers technically unique benefits as outlined above.

SUMMARY OF THE INVENTION:
In accordance with the above objective, the present invention provides mustard oil based biodegradable insulating fluid composition comprising a mixture of chemically modified refined, bleached &deodorized(RBD) Mustard Oil optionally in combination with long chain alkyl esters of chemically modified mustard oil fatty acidsin the ratio of 70:30 to 100:0 along with additives and pour point depressant, which confers technically unique benefits when used in transformers, capacitors, switch gears, electric cables.
In another aspect, the process for preparation of mustard oil based biodegradable insulating fluid composition is described below;
a) Chemically modifying refined, bleached &deodorized (RBD) mustard oil to obtain fatty acid composition as first component consisting of mono-unsaturated fatty acids in the range of 55 to 75%; di-unsaturated fatty acid in the range of 12 to 18% and tri-unsaturated fatty acid in the range of 1 -4%;
b) Esterification of the fatty acids of chemically modified mustard oil (CMMOFA) with alcohols in presence of catalysts to obtain long chain alkyl esters of CMMOFA as second component;
c) Blending the first component with the second component in the ratio of 70:30 to 100:0; and
d) Purifying the mixed blend of step (c) by passing through a column of strongly basic anion exchange resin Type 1 and adsorbents such as bentonite or alumina prior to adding additives and pour point depressants to obtain desired insulating fluid.
The chemical modification includes hydrogenation of RBD oil using commercially available selective supported Nickel catalyst or Platinum catalyst. The conditions of hydrogenation are varied to achieve the above selective compositions.
In an aspect, the process for preparing the second component includes transesterificationwhere alcohols are selected from heptanol, octanol, isooctanol, decanolor mixtures thereof with the chemically modified mustard oil fatty acid using sodium methoxide as catalyst.

In another aspect, the present invention provides mustard oil based biodegradable insulating fluid composition comprising chemically modified (RBD) Mustard Oil consisting of mono-unsaturated fatty acids in the range of 55 to 75%; di-unsaturated fatty acid in the range of 12 to 18% and tri-unsaturated fatty acid in the range of 1-4%;, along with additives and pour point depressants for electrical devices.
In yet another aspect, the present invention provides mustard oil based biodegradable insulating fluid composition comprising pure RBD Mustard oil without chemical modification, along with additives and pour point depressants for electrical devices. The said composition comprises long chain alkyl esters of CMMOFA in the range of 0-30%.
In another aspect, the present invention provides a method of insulating the electrical devices and to the use of the said insulating.fluid in electrical devices.
In another aspect, the present invention provides an environmental friendly, insulating fluids which are fully biodegradable as per ASTM D 5864 and having good oxidation resistance, good electrical properties and high flash and fire properties.
BRIEF DESCRIPTION OF FIGURE:
Figure 1: Oxidation Stability Test @ 120°C and change in viscosity @ 40°C in cSt
DETAILED DESCRIPTION OF THE INVENTION:
The invention will now be described in detail in connection with certain preferred and optional embodiments, so that various aspects thereof may be more fully understood and appreciated. However, any skilled person will appreciate the extent to which such embodiments could be extrapolated in practice.
The present invention discloses mustard oil based biodegradable insulating fluid composition comprising a mixture of chemically modified refined, bleached & deodourized (RBD) Mustard Oil optionally in combination with long chain alkyl esters of chemically modified mustard oil fatty acids in the ratio of 70:30 to 100:0 together with additives and pour point depressant, having good oxidation and electrical properties,

shows improved flash and fire points when used in transformers, capacitors, switch gears, electric cables.
The invention uses RBD (refined, bleached & deodorized) mustard oil as the source of raw material. RBD mustard oils are well known in the commerce and are readily available. The technologies for RBD are well known and they are readily supplied by several vendors.
The present invention concerns chemical modification of RBD mustard oils to produce oleic and erucic acid rich vegetable oils (rich in monounsaturated fatty acids).
The components in the current mustard oil based bio-degradable insulating fluid are described in detail herein below:
FIRST COMPONENT
The first component of the present invention includes Chemically Modified RBD Mustard Oil, which is used to achieve certain targeted fatty acid compositions and better low temperature properties.
The chemical modification is based on the premise that mono-unsaturated fatty acids confer the best oxidative stability. Although fully saturated fatty acids are known to give even better stability, they are not preferred due to poor low temperature properties. Therefore, the present invention is directed to get minimum saturated fatty acids, minimize the di-unsaturated and tri-unsaturated fatty acids and maximize mono-unsaturation.
Accordingly, the chemically modified RBD mustard oilcontains mono-unsaturated fatty acid in the range of 55% to 75%, preferably 60% to 70%, di-unsaturated fatty acid in the range of 12% to 18%, preferably 12% to 15% and tri-unsaturated fatty acid in the range of 1% to 4%, preferably as low as possible.

The chemical modification of RBD oil is carried out using commercially available selective supported Nickel catalyst or Platinum catalyst. The conditions of' hydrogenation are varied to achieve the above selective compositions.
SECOND COMPONENT
The second component consists of long chain alkyl esters of chemically modified mustard oil fatty acids (CMMOFA) in the formulation of the insulation fluids to contro1 viscosity. In choosing this component, care is taken to minimize adverse effects on lowering of flash & fire points and also possible effects on transformer seal materials.
The second component can be varied from 5% to 20% in the formulation- The second component is as important as the first component CMO in conferring functional properties (to the insulating fluid) as well as acting as a thinner.
Accordingly in one preferred embodiment, the long chain alkyl ester of chemically modified mustard oil fatty acid (CMMOFA) is obtained by esterification reaction with the alcohols selected from heptanol, octanol, isooctanol, decanol, or mixtures thereof.
In one preferred embodiment, the second component consists of alkyl ester of fatty acid with heptanol or octanol.
In another preferred embodiment, the second component consists of alkyl ester of fatty acids with isooctanol or decanol.
In yet another preferred embodiment, the second component consists of alkyl esters of heptyl, octyl, isooctyl and decyl alcohols or mixtures thereof.
Esterification to prepare the above esters is carried out by conventional methods using PTSA and/or Tin based heterogeneous or homogeneous catalysts.

The esters above may also be prepared by transesterification methods by reacting the alcohols with the chemically modified Mustard oil, using sodium methoxide as the catalyst.
In an embodiment, the first component is blended with the second component in the ratio of 70:30 to 100:0, preferably 90:10 to 80:20, more preferably 90:10 to 95:5 to obtain the insulating fluids of the present invention.
The above blends are passed through the typical resin systems (Strongly basic anion exchange resin Type 1), which are commercially available in order to remove the free fatty acids. This then further purified to remove polar impurities to improve electrical properties of the insulating fluids.
Then the blends are percolated through granular earth, which is thermally activated or may be percolated through acid activated clays such as Bentonite.
In yet another embodiment, the blends are purified by passing through activated Alumina adsorbents which are commercially available. Optionally the blends may be vacuum filtered.
THIRD COMPONENT
Most of all vegetable oils contain primarily unsaturated fatty acids (mono-, di-, tri-unsaturated fatty acids). Due to presence of these fatty acids they are more susceptible to oxidation upon exposure to free oxygen in presence of metal catalyst like copper. The oxidation process of these oils leads to formation of the polymerization products. These polymerization products tend to show marked increase in viscosity and the oils correspondingly show decrease in insulating properties. These products also reduce the efficiency of dissipating the heat generated during the usage of transformers. The degree of polymerization is proportional to the temperature as well as the extent of exposure of oil to the oxygen.

To the oil blends as described above and purified as above, is added one or more
additives to improve oxidation stability of the fluids. The additives may be selected from
Phenolic and/or aminic antioxidants. They may be used alone or in combination in the %
by weight ranging from 0.1 to 1.2 %. They are selected from the following:
PentaerythritolTetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), Octylated
Phenyl-Alpha-Naphthylamine(octylatedn-phenyl-l-naphthylamines), Triphenylphosphorothionate and alpha-, beta- or delta-tocopherol (Vitamin E), DPA (Diphenyl amine), BHT (Butylatedhydrotoluene),TBHQ (Mono tertiary butyl hydroquinone), BHA (Butylatedhydroxyanisole), ascorbylpalmitate (rosemary oil), Propyl gallate etc.
The oxidation stability is tested as per IEC 61125 METHOD C.
The performance of dielectric fluids in extreme cold conditions is important. The established mineral oils which are used as insulating fluids have considerably lower pour points and also have better cold flow properties than vegetable oils. A typical insulating fluid needs pour point below-20°C. The insulating fluids in current invention alone are insufficient by themselves for lowering pour point. Hence pour point depressants are added to the current formulation to improve the operational range of insulating fluids.
In one embodiment of the present invention, pour point depressants (PPD) are added to the formulation to improve low temperature properties. These may be selected from polymethacrylates or polyolefins based compounds. The blended oils may be fortified with pour point depressants to improve pour points of the fluids. They may be used alone or in combination.
The addition levels may vary from 0.1 to 1.2 %. The resulting fluid will have pour points varying from -18°C to -21°C.
Typically, the various products prepared of the current invention have water content (IEC 60814): lOOppm to 175ppm. Neutralization Value (IEC 62021): 0.030 to 038, Flash Point (ASTM D92):290°C to 295°C, Fire Point (ASTM D92):320°C to 325°C. Pour Point (ISO 3016): -18°C to -21°C, Viscosity (ISO 3014) @ 40°C:40 cSt to 46 cSt, Viscosity (ISO

3014) @ 100°C:9.5 cSt to 11 cSt, Break Down Voltage: 70kV to 75kV, Dielectric Dissipation Factor (IEC 60247) @ 90°C: 2% to 3%.
Accordingly, in a preferred embodiment, the present invention discloses Mustard oil based biodegradable insulating fluid composition characterized in that the said composition comprises a mixture of chemically modified (RBD) Mustard Oil consistingof mono-unsaturated fatty acids in the range of 55 to 75%; di-unsaturated fatty acid in the range of 12 to 18% and tri-unsaturated fatty acid in the range of 1-4%; optionally in combination with long chain alkyl esters of chemically modified mustard oil in the ratio 70:30 to 100:0, along with additives and pour point depressant exhibiting good oxidation resistance, good flash and fire points, for electrical devices.
In another embodiment, the present invention provides mustard oil based biodegradable insulating fluid composition comprising a mixture of chemically modified (RBD)Mustard Oil consisting of mono-unsaturated fatty acids in the range of 55 to 75%; di-unsaturated fatty acid in the range of 12 to 18% and tri-unsaturated fatty acid in the range of 1-4%;, along with additives and pour point depressants for electrical devices.
In yet another embodiment, the present invention provides mustard oil based biodegradable insulating fluid composition comprising pure RBD Mustard oil without chemical modification, along with additives and pour point depressants for electrical devices. The said composition comprises long chain alkyl esters of CMMOFA in the range of 0-30%.
In another preferred embodiment, the present invention provides a process for preparation of mustard oil based biodegradable insulating fluid which includes the following steps;
a) Chemically modifying refined, bleached & deodorized (RBD) mustard oil to obtain fatty acid composition as first component consisting of mono-unsaturated fatty acids in the range of 55 to 75%; di-unsaturated fatty acid in the range of 12 to 18% and tri-unsaturated fatty acid in the range of 1-4%;
b) Esterifying the fatty acids of chemically modified mustard oil (CMMOFA) with alcohols selected fromheptanol, octanol, isooctanol, decanol or mixtures thereof

in presence of PTSA and or tin based heterogeneous or homogenous catalysts to obtain long chain alkyl esters of CMMOFA as second component;
c) Blending the first component with the second component in the ratio 70:30 to 100:0; and
d) Purifying the mixed blend of step (c) by passing through a column of strongly basic anion exchange resin Type 1 and adsorbents such as bentonite or alumina prior to adding additives and pour point depressants to obtain desired insulating fluid.
According to the process, refined, bleached & deodorized (RBD) mustard oil is chemically modified by subjecting said RBD mustard oil to hydrogenation using commercially available supported nickel or platinum catalystsunder hydrogen pressure of 5-7kg/cm2 at a temperature of about 125-135°C to obtainfatty acid composition as first component comprising mono-unsaturated fatty acids in the range of 55 to 75%; di-unsaturated fatty acid in the range of 12 to 18% and tri-unsaturated fatty acid in the range of 1-4%.
The fatty acids of chemically modified mustard oil (CMMOFA) are prepared by splitting the chemically modified mustard oil using sodium hydroxide followed by cone. H2SO4 by methods known in the art.
The so obtained fatty acids of chemically modified mustard oil (CMMOFA) are allowed to react with alcohols selected from heptanol, octanol, isooctanol, decanol or mixtures thereof in presence of PTSA (p-Toluenesulfonic acid)and or tin based heterogeneous or homogenous catalysts to obtain long chain alkyl esters of CMMOFA as second component..
In an aspect of the invention, the second component can be obtained by transesterification method by reaction of alcohols selected from heptanol, octanol, isooctanol, decanolor mixtures thereof with the chemically modified mustard oil in presence of sodium methoxide as catalyst.

The first component is now blended with the second component in the ratio in the range of 70:30 to 100: 0, preferably between 90:10 to 80:20, most preferably between 90:10 to 95:5.
The above blends are passed through the typical resin systems (Strongly basic anion exchange resin Type 1), which are commercially available in order to remove the free fatty acids. This is then further purified to remove polar impurities to improve electrical properties of the insulating fluids.
Accordingly, the blends are percolated through granular earth, which is thermally activated or may be percolated through acid activated clays such as Bentonite.
In yet another embodiment, the blends are purified by passing through activated Alumina adsorbents which are commercially available. Optionally the blends may be vacuum filtered.
To improve the oxidation stability and low temperature properties, to the blend of insulation fluid which is purified as described above is added additives and pour point depressants.
The additives may be selected from Phenolic and/or aminic antioxidants. They may be used alone or in combination in % by weight from 0.1 to 1.2 %. They are selected from the following:
PentaerythritolTetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), Octylated
Phenyl-Alpha-Naphthylamine(octylaten-phenyl-1 -naphthylamines), Triphenylphosphoro-thionate and alpha-, beta- or delta-tocopherol (Vitamin E), DPA (Diphenyl amine), BHT (Butylated hydroxy toluene),TBHQ (Mono tertiary butyl hydroquinone), BHA (Butylated hydroxy anisole), ascorbylpalmitate (rosemary oil), Propyl gallate etc.
The pour point depressants (PPD) are selected from polymethacrylates or polyolefins based compounds in the range 0.1-1.2%

The resulting product will have water content (IEC 60814) varying from lOOppm to 175 ppm and neutralization value (IEC 62021) in the range from 0.03 to 0.038, depending upon the nature of treatment.
The base fluid has Break Down Voltage in the range of 70 kV to 75 kV (in 2.4 mm gap). Dielectric Dissipation Factor @ 90°C is in the range of 2% to 3%.
Oxidation stability is measured by determining the variation of viscosity with time. Figure 1 shows the importance of chemical modification. The samples which are not chemically modified (made as per patents assigned to Cooper Power Systems) showed a big increase in viscosity while the chemically modified fluid as per the present invention shows relatively less increase in viscosity with time of oxidation. (Higher the viscosity, lower the cooling efficiency of the fluid).
Further Table-2 highlights the significance of use of higher alcohol based fatty acid esters for imparting higher flash & fire points. Use of methyl esters as a thinning agent suggested by patents publication assigned to Wavely Light & Power (U.S. Pat.6,340,658 filed 2002, U.S. Pat.5,958,851 filed Nov. 5, 1998), show a big drop in flash & fire point in comparison to the values obtained from our invention also they shows adverse effects on seals. Fluids of our invention show values of flash point and fire point much better than ASTM standard specifications (ASTM D6871 -03). One corollary of the Table 2 is that in the practice of this invention one can optionally use CMMO without any second component to achieve a very high flash point of 320°C and fire point of 340°C. In this case, however, the viscosity of the fluid will also be 51 cSt @ 40°C.
In another preferred embodiment, the present invention discloses a method of insulating the electrical devices comprising, providing, a mixture of chemically modified (RBD) Mustard Oil consisting of mono-unsaturated fatty acids in the range of 55 to 75%; di-unsaturated fatty acid in the range of 12 to 18% and tri-unsaturated fatty acid in the range of l-4%optionally in combination with long chain alkyl esters of chemically modified mustard oil fatty acid in the ratio 70:30 to 100:0, along with additives and pour point depressant and placing the insulating fluid in the electrical devices.

The chemically modified Mustard Oil as described above is obtained by hydrogenation of refined, bleached & deodourized (RBD) mustard oil in presence of nickel or platinum catalysts, whereas the long chain alkyl esters of chemically modified mustard oil is obtained by esterification of the fatty acids of chemically modified mustard oil (CMMOFA) with alcohols selected from heptanol, octanol, isooctanol, decanol or mixtures thereof in presence of PTSA and or tin based heterogeneous or homogenous catalysts.
Alternately, the long chain alkyl esters of chemically modified mustard oil is obtained by trans-esterification of chemically modified mustard oil with alcohols selected from heptanol, octanol, isooctanol, decanolor mixtures thereof using sodium methoxide as catalyst.
The additives are selected from phenolic and/or aminic antioxidants such as PentaerythritolTetrakis(3-(3,5-Di-Tert-Butyl-4-Hydroxyphenyl)Propionate), Octylated Phenyl-AIpha-Naphthylamine, , TriphenylPhosphorothionate, and alpha-, beta- or delta-tocopherol (Vitamin E), DPA (Diphenyl amine), BHT (Butylated hydroxy toluene),TBHQ (Mono tertiary butyl hydroquinone), BHA (Butylated hydroxy anisole), ascorbylpalmitate (rosemary oil), Propyl gallate in the range of 0.1 to -1.2 % by weight.
The pour point depressant are selected from polymethacrylates or polyolefins based compounds either alone or in combination in the range of 0.1- 1.2 % by weight.
In another preferred embodiment, the present invention discloses use of Mustard oil based biodegradable insulating fluid for insulating electrical devices such as transformers, capacitors, switch gears or electric cables.
ADVANTAGES:
The mustard oil based insulating fluid of the current invention is environmentally friendly (biodegradable), have good oxidation ressitance, good electrical properties and high flash and fire properties and can be used in transformers, switch gears, capacitors and electrical cables.

The following examples, which include preferred embodiments, will serve to illustrate the practice of this invention, it being understood that the particulars shown are by way of example and for purpose of illustrative discussion of preferred embodiments of the invention.
EXAMPLES:
Example 1: (for component one) Chemically modified mustard oil (CMO) is prepared by hydrogenating the refined mustard oil by using nickel catalyst under hydrogen pressure of 6kg/cm2 and temperature of 130°C to get monounsaturated fatty acids in range of 58% di-di-unsaturated fatty acid in the range of 12 to 18% and tri-unsaturated fatty acid content below 3.5%.
Example 2: (for component two) Fatty acids of chemically modified mustard oil (CMMOFA) are prepared by splitting the chemically modified mustard oil by using sodium hydroxide and later by concentrated sulphuric acid by well-known methods. Heptyl ester of CMMOFA (chemically modified mustard fatty acids) is prepared by reacting Heptyl alcohol with CMMOFA by using a catalyst like Para Toluene sulphonic acid and/or sulphuric acid at a temperature of 180°C.
Example 3: (for component two) Octyl esters of CMMOFA is prepared by reacting octyl alcohol with CMMOFA by using a catalyst like Para Toluene sulphonic acid and/or sulphuric acid at a temperature of 180°C.
Example 4: (for component two) Decyl esters of CMMOFA is prepared by reacting Decyl alcohol with CMMOFA by using a catalyst like Para Toluene sulphonic acid and/or sulphuric acid at a temperature of 180°C.
Example 5: (for component two) Heptyl esters of CMMOFA is prepared by transesterification of heptyl alcohol with CMMOFA by using sodium methoxide as a catalyst at a temperature of 110 C.

Example 6: (for component two) Octyl esters of CMMOFA is prepared by transesterification of octyl alcohol with CMMOFA by using sodium methoxide as a catalyst at a temperature of 110°C.
Example 7: (for component two) Decyl esters of CMMOFA is prepared by transesterification of Decyl alcohol with CMMO by using sodium methoxide as a catalyst at a temperature of 110°C.
Example 8: The blends of component one (CMMO from example 1) and component two (from example 2) were prepared in the ratio 70:30.
Example 9: The blends of component one (CMMO from example 1) and component two (from example 3) were prepared in the ratio 90:10.
Example 10: The blends of component one (CMMO from example 1) and component two (from example 4) were prepared in the ratio 85:15.
Example 11: The purification of blend prepared in Example 9 is done by passing it through typical resin systems (Strongly basic anion exchange resin type 1), which are commercially available in order to remove the free fatty acids. Then these blends are allowed to pass through thermally activated Bentonite clay in ratios of about 20% by weight of blends in order to remove the other polar impurities.
Example 12: The antioxidant PentaerythritolTetrakis (3-(3,5-Di-Tert-Butyl-4-Hydroxy-phenyl)Propionate)is added 0.8% by weight % in purified blends in example 11.
Example 13: The antioxidant Octylated Phenyl-Alpha-Naphthylamineis added 0.6% by weight % in purified blends in example 11.
Example 14: The antioxidant TriphenylPhosphorothionateis added 0.7% by weight % in purified blends in example 11.

Example 15: The antioxidant DPA (Diphenyl amine) is added 0.4% by weight % in purified blends in example 11.
Example 16: The antioxidant BHT (Butylatedhydrotoluene) is added in 0.8% by weight % in purified blends in example 11.
Example 17: The antioxidant TBHQ (Mono tertiary butyl hydroquinone) is added 0.8 % by weight in purified blends in example 11 -
Example 18: The pour point depressant polymethacrylate is added 0.1% by weight % in Purified blends in example 15.
Example 19: The pour point depressant polyolefinsis added 0.2 % by weight % in Purified Blends in example 15.
Example 20: Final blend in example 18 has water content (IEC 60814): 150ppm, Neutralization Value (IEC 62021): 0.036, Flash Point (ASTM D92): 292°C, Fire Point (ASTM D92):322°C. Pour Point (ISO 3016): -18°C to -21°C, Viscosity (ISO 3014) @ 40°C: 45 cSt, Viscosity (ISO 3014) @ 100°C :10.8 cSt, Break Down Voltage: 72kV, Dielectric Dissipation Factor (IEC 60247) @90°C: 2.5%.
Table 1: Comparison of pour points using methyl esters versus alkyl esters as a blend component

CMMO + Methyl Ester OF CMMOFA POUR POINT
In°C CMMO + ALKYL ESTER OF CMMOFA POUR POINT
% CMMO % Methyl Ester OF CMMOFA
% CMMO % Alkyl Esters OF CMMOFA In°C
100% 0% -5 100% 0% -5
97.5% 2.5% -6 97.5% 2.5% -7
95% 5% -6 95% 5% -8
92.50% 7.50% -7 92.50% 7.50% -8
90% 10% -7 90% 10% -9

Table 2: Flash Point and Fire Point Comparative Table

CMMO + METHYL ESTER OF CMMOFA FLASH POINT
In°C FIRE POINT
In°C CMMO + ALKYL ESTER OF CMMOFA FLASH POINT
In°C FIRE POINT
% CMMO %Methyl
Ester OF
CMMOFA

% CMMO % Alkyl
Esters of
CMMOFA
In°C
100% 0% 320 340 100% 0% 320 340
97.5% 2.5% 284 303 97.5% 2.5% 295 318
95% 5% 264 285 95% 5% 290 315
92.50% 7.50% 248 267 92.50% 7.50% 290 314
90% 10% 242 261 90% 10% 288 310

WE CLAIM,
1. Mustard oil based biodegradable insulating fluid composition characterized in that the said composition comprises a mixture of chemically modified Mustard Oil consisting of mono-unsaturated fatty acids in the range of 55 to 75%; di-unsaturated fatty acid in the range of 12 to 18% and tri-unsaturated fatty acid in the range of 1-4% optionally in combination with long chain alkyl esters of chemically modified mustard oil in the ratio 70:30 to 100: 0, along with additives and pour point depressant exhibiting good oxidation resistance, good flash and fire points, for electrical devices.
2. Mustard oil based biodegradable insulating fluid composition according to claim 1; wherein said additivesare selected from phenolic and/or aminic antioxidants. such as PentaerythritolTetrakis (3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate), (octylated n-phenyl-1-naphthylamines), Triphenylphosphorothionate, and alpha-, beta- or delta-tocopherol (Vitamin E), DPA (Diphenyl amine), BHT (Butylatedhydrotoluene), TBHQ (Mono tertiary butyl hydroquinone), BHA (Butylatedhydroxyanisole), ascorbylpalmitate (rosemary oil) and Propyl gallate either alone or in combination thereof.
3. Mustard oil based biodegradable insulating fluid composition according to claim 2; wherein said additives are in the range of 0.1- 1.2% by weight.
4. Mustard oil based biodegradable insulating fluid composition according to claim 1; wherein said pour point depressants are selected from polymethacrylates or polyolefinsbased compoundsaddedeither alone or in combination thereof.
5. Mustard oil based biodegradable insulating fluid composition according to claim 4; wherein the pour point depressants are in the range of 0.1- 1.2% by weight.
6. Mustard oil based biodegradable insulating fluid composition according to claim 1, characterized in that the said composition comprises a mixture of chemically modified (RBD) Mustard Oil consisting of mono-unsaturated fatty acids in the

range of 55 to 75%; di-unsaturated fatty acid in the range of 12 to 18% and tri-unsaturated fatty acid in the range of 1-4%; along with additives and pour point depressant for electrical devices.
7. Mustard oil based biodegradable insulating fluid composition comprising pure (RBD) Mustard oil without chemical modification, long chain alkyl esters of CMMOFA in the range of 0-30% along with additives and pour point depressants for electrical devices.
8. Mustard oil based biodegradable insulating fluid composition according to claims land 7, wherein the electrica) devices are selected from transformers, capacitors, switch gears or electric cables.
9. The process for preparation of Mustard oil based biodegradable insulating fluid according to claim 1, comprises
a) Chemically modifying refined, bleached & deodorized (RBD) mustard oil to obtain fatty acid composition as first component consisting of mono-unsaturated fatty acids in the range of 55 to 75%; di-unsaturated fatty acid in the range of 12 to 18% and tri-unsaturated fatty acid in the range of 1-4%;
b) Esterifying the fatty acids of chemically modified mustard oil (CMMOFA) with alcohols selected from heptanol, octanol, isooctanol, decanol or mixtures thereof in presence of PTSA and or tin based heterogeneous or homogenous catalysts to obtain long chain alkyl esters of CMMOFA as second component;
c) Blending the first component with the second component in the ratio 70:30 to 100:0; and
d) Purifying the mixed blend of step (c) by passing through a column of strongly basic anion exchange resin Type 1 and adsorbents such as bentonite or alumina prior to adding additives and pour point depressants to obtain desired insulating fluid.

10. The process for preparation of Mustard oil based biodegradable insulating fluid according to claim 1, optionally comprises trans-esterification of chemically modified mustard oil fatty acid ester with alcohols selected from heptanol, octanol, isooctanol, decanolor mixtures thereofin presence of sodium methoxide as catalyst.
11. A method of insulating the electrical devices comprising;
providing a mixture of chemically modified Mustard Oil consisting of mono-unsaturated fatty acids in the range of 55 to 75%; di-unsaturated fatty acid in the range of 12 to 18% and tri-unsaturated fatty acid in the range of 1 -4% optionally in combination with long chain alkyl esters of chemically modified mustard oilin the ratio of 70:30 to 100:0, along with additives and pour point depressant and placing the insulating fluid in the electrical devices.
12. The method of insulating the electrical devices according to claim 11, wherein the electrical devices are selected from transformers, capacitors, switch gears or electric cables.
13. The method of insulating the electrical devices according to claim 11, wherein long chain alkyl esters of chemically modified mustard oil is obtained by esteriflcation of fatty acids of chemically modified mustard oil (CMMOFA) with alcohols selected from heptanol, octanol, isooctanol, decanol or mixtures thereof in presence of PTSA and or tin based heterogeneous or homogenous catalysts.
14. The method of insulating the electrical devices according to claim 11, wherein long chain alkyl esters of chemically modified mustard oil is optionally obtained by trans-esterification of chemically modified mustard oil fatty acids with alcohols selected from heptanol, octanol, isooctanol, decanolor mixtures thereof using sodium methoxide as catalyst.
15. The method of insulating the electrical devices according to claim 11, wherein additives are selected from phenolic and/or aminic antioxidants, such as as

PentaerythritolTetrakis (3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate), (octylated n-phenyl-1-naphthylamines), Triphenylphosphorothionate, and alpha-, beta- or delta-tocopherol (Vitamin E), DPA (Diphenyl amine), BHT (Butylatedhydrotoluene), TBHQ (Mono tertiary butyl hydroquinone), BHA (Buty)atedhydroxyanisole), ascorbylpalmitate (rosemary oil) and Propyl gallate in the range of 0.1-1.2% by weight either alone or in combination thereof.
16. .The method of insulating the electrical devices according to claim 11, wherein pour point depressants are selected from polymethacrylates or polyolefin based compounds either alone or in combination thereof in the range of 0.1-1.2% by weight.
17. Use of Mustard oil based biodegradable insulating fluid according to any of the preceding claims for insulating electrical devices such as transformers, capacitors, switch gears or electric cables.