A DIELECTRIC FLUID HAVING ULTRA-LOW POUR POINT AND BETTER DIELECTRIC PROPERTIES
BACKGROUND
[0001] Embodiments of the present disclosure relate to a dielectric fluids, and more particularly, to a dielectric fluid composition
[0002] Dielectric fluids are in use in the high voltage, extra high voltage and ultra-high voltage equipments for cooling and quenching the Arc. Dielectric fluids also used as an insulator for wide applications such as in high voltage, extra high voltage and ultra-high voltage equipments for insulating between the windings and different components in the apparatus.
[0003] Dielectric Fluids ability to function efficiently and effectively depend on number of important properties. These includes dielectric breakdown voltage, impulse breakdown voltage, power factor, viscosity, flash point, pour point, negative gassing tendency, potential corrosive sulphur, thermal conductivity, heat capacity, poly cyclic aromatic content, poly chlorinated biphenyl content and others. The International Standards like IEC, ASTM, BS, DIN, LIS, and AU have prescribed standards to be followed by operating equipment manufacturers, utilities and users from the point of view of quality adherence. [0004] In the high altitude terrain where the temperatures can be well below the zero degree Celsius call for dielectric fluid with extreme low pour point and good cooling characteristics right from cold start. The present global standards

prescribe dielectric fluids with maximum -40 Celsius which can be insufficient in
the very high altitude area and extreme cold conditions.
[0005] Further, IEC60296: 2012 specification limits, has mentioned the pour
point of less than or equal to -40°Celsius. Although, some of the currently
available compositions of the dielectric fluids adhere to the IEC standards, the
composition of the dielectric fluids can be further improved to improve a service
life of various extra high and ultra-high voltage equipment and reduce their
maintenance costs.
[0006] Hence, to overcome at least one of the above mentioned problems, there
exists a need for a dielectric fluid having ultra-low pour point and superior
dielectric properties.

SUMMARY
[0007] This summary is provided to introduce a selection of concepts, in a simple manner, which are further described in the detailed description of the invention. This summary is neither intended to identify key or essential inventive concepts of the subject matter, nor to determine the scope of the invention.
[0008] In an embodiment of the present disclosure, a dielectric fluid composition having ultra-low pour point and superior dielectric properties is disclosed. The dielectric fluid composition comprises a base oil 1 present by weight in a percentage range of about 0% to 85% of the total weight of the dielectric fluid, a base oil 2 present by weight in a percentage range of about 0% to 45% of the total weight of the dielectric fluid, a base oil 3 present by weight in a percentage range of about 0% to 8%> of the total weight of the dielectric fluid and one or more additives selected from an additive package present by weight in a percentage range of about 1% to 2% of the total weight of the dielectric fluid. Wherein, the dielectric fluid has a pour point in a range of about -50°Celsius to -70°Celsius.
[0009] In another embodiment of the present disclosure, a dielectric fluid composition is disclosed. The composition comprising one or more additives from the additive package in combination with the specific percentages of base oil 1, base oil 2 and base oil 3 is disclosed. Wherein, the one or more additives selected from the additive package comprises at least one from the group of an oxidation inhibitor present in a percentage range of about 0.08% to 0.4% of the additive package, an anti-gassing agent present in a percentage range of about 0.01% to

0.5% of the additive package, a pour point depressant present in a percentage range of about 40 mg/kg to 140 mg/kg of the additive package, an anti-foaming agent present in a percentage range of about 2 mg/kg to 15 mg/kg of the additive package and the mixtures there of.
[0010] To further clarify the advantages and features of the present invention, a more particular description of the invention will follow by reference to specific embodiments thereof, which are illustrated in the appended tables. It is to be appreciated that these tables depict only typical embodiments of the invention and are therefore not to be considered limiting in scope. The invention will be described and explained with additional specificity and detail with the appended tables.

DETAILED DESCRIPTION
[0011] For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the tables and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as would normally occur to those skilled in the art are to be construed as being within the scope of the present invention.
[0012] It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.
[0013] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such a process or method. Similarly, one or more devices or sub-systems or elements or structures or components preceded by "comprises... a" does not, without more constraints, preclude the existence of other devices, sub-systems, elements, structures, components, additional devices, additional sub-systems, additional elements, additional structures or additional components. Appearances of the phrase "in an embodiment", "in another

embodiment" and similar language throughout this specification may, but not necessarily do, all refer to the same embodiment.
[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention belongs. The system, methods, and examples provided herein are only illustrative and not intended to be limiting.
[0015] Embodiments of the present invention will be described below in detail with reference to the accompanying tables.
[0016] Embodiments of the present disclosure relates to a dielectric fluid composition having ultra-low pour point and improved dielectric properties. The dielectric fluid composition comprises a base oil 1 present by weight in a percentage range of about 0% to 85% of the total weight of the dielectric fluid, a base oil 2 present by weight in a percentage range of about 0% to 45% of the total weight of the dielectric fluid, a base oil 3 present by weight in a percentage range of about 0% to 8%> of the total weight of the dielectric fluid and one or more additives selected from an additive package present by weight in a percentage range of about 1% to 2% of the total weight of the dielectric fluid. Wherein, the dielectric fluid has a pour point in a range of about-50°Celsius to -70°Celsius.
[0017] Further, the base oil 1 of the dielectric fluid composition comprises a naphthenic carbon present by weight in a percentage range of about 45% to 55% of the base oil 1, a paraffinic carbon present by weight in a percentage range of

about 35%) to 45% of the base oil 1 and an aromatic carbon present by weight in a percentage range of about 5% to 12% of the base oil 1.
[0018] Further, the base oil 2 of the dielectric fluid composition comprises an aromatic carbon present by weight in a percentage range of about 75% to 85% of the base oil 2, a naphthenic carbon present by weight in a percentage range of about 10%) to 15%) of the base oil 2 and a paraffinic carbon present by weight in a percentage range of about 5% to 10% of the base oil 2.
[0019] Further, the base oil 3 of the dielectric fluid composition comprises a naphthenic carbon present by weight in a percentage range of about 40% to 50% of the base oil 3, a paraffinic carbon present by weight in a percentage range of about 50%) to 60%) of the base oil 3 and an aromatic carbon present by weight in a percentage range of about 0.5% to 2% of the base oil 3.
[0020] Furthermore, the one or more additives of the dielectric fluid are selected from the additive package comprising at least one from the group of an oxidation inhibitor, an anti-gassing agent, a pour point depressant, an anti-foaming agent and the combinations thereof.
[0021] Further, the dielectric fluid composition as claimed in claim 1 wherein the one or more additives selected from the additive package comprises at least one from the group of an oxidation inhibitor present in a percentage range of about 0.05%) to 1.0% of the additive package, an anti-gassing agent present in a percentage range of about 0.01% to 0.5% of the additive package, a pour point depressant present in a percentage range of about 40 mg/kg to 120 mg/kg of the

additive package, an anti-foaming agent present in a percentage range of about 2mg/kg to 15 mg/kg of the additive package; and the mixtures there of.
[0022] Further, the base oil 1 has a boiling range of greater than or equal to 290°celsius. The base oil 2 has a boiling range of greater than or equal to 330°celsius. The base oil 3 has a boiling range of greater than or equal to 300°celsius.
[0023] The test results for the dielectric fluid composition of the present disclosure as per the IEC 60296:2012 standards have been disclosed below in Table 1. The results disclosed in Table 1 showed that the composition is in full compliance with IEC 60296:2012 specification limits. The kinematic viscosity of the dielectric fluid composition at 100°celsius is in a range of about 1 mm /s to 3
9 9 9
mm /s, at 40 °Celsius is in a range of about 7 mm /s to 9 mm /s, at -30 °Celsius is
9 9
in a range of about 600 mm /s to 700 mm /s and at -40 °Celsius is in a range of
9 9
about 950 mm /s to 1050 mm /s. The breakdown voltage of the dielectric fluid composition is in a range of about 86 kV minutes. The density at 20 °Celsius of the dielectric fluid composition is around 0.872 g/ml. The pour point of the dielectric fluid is less than or equal to about -68°Celsius. The dielectric dissipation factor at 90°Celsius of the dielectric fluid composition is about 0.00074. The Interfacial Tension IFT of the dielectric fluid composition is about 46 mN/m. The antioxidant additives of the dielectric fluid composition is about 0.35%. The gassing tendency of the dielectric fluid composition is +5uL/minute. The oxidation stability of the dielectric fluid composition for 500 hours of testing

duration shows that the total acidity of the dielectric fluid is equal to or less than 0.04 mg KOH/g, the total sludge in the dielectric fluid is less than or equal to 0.001% and the dielectric dissipation factor of the dielectric fluid is less or equal to 0.0023 at 90 degree Celsius.

[0024] The additional properties result of the dielectric fluid composition are given in the Table 2 below. The Rotating Vessel Oxidation property test results show a time range of about 334 minutes that leads to the excellent oxidation resistance. The thermal conductivity property shows a results of around 0.130 W/mK. The dielectric fluid composition also leads to the faster cooling of the equipment. The negative impulse breakdown voltage shows a result that is greater than 207 kV that leads to safety during switching surges and lightning surges. The Biodegradability, OECD 301B, C02 Evolution Test shows a result is inherently biodegradable that makes the fluid to be environmental friendly. The

compatibility (miscibility) of the dielectric fluid composition is good with other dielectric fluids such as natural esters and synthetic esters.
[0025] Further, the test results for comparison of the dielectric fluid composition with the market-1 dielectric fluid is given below in the Table 3. The test was conducted for duration of about 0 Hours and 500 Hours respectively. The oxidation inhibitor content for the dielectric fluid composition of the present disclosure seems better when compared to the Market-1 dielectric fluid. For 500 Hours of testing duration, the total acidity of the dielectric fluid composition as disclosed in the present disclosure is measured at 0.04 mg KOH/g, total sludge percentage of the present dielectric fluid is measured at 0.001% and the dielectric dissipation factor of the present dielectric fluid is about 0.0023 at 90 degree

Celsius substantiating its excellent long term stability as compared to market 1 dielectric fluid. Also, the gassing tendency of the dielectric fluid composition when compared to the market-1 dielectric fluid is +5 uL/minute that demonstrates better gas absorbing properties and improves the service life of the equipment in which they are used. The kinematic viscosity at -30°Celsius of the dielectric fluid composition is about 619 mm /s, when compared to the market-1 dielectric fluid i.e. 730 mm /s that demonstrates that the dielectric fluid as disclosed in the present disclosure provides excellent cooling capability. Similarly the pour point of the dielectric fluid is about -68°Celsius, when compared to the market 1 dielectric fluid i.e. -63°Celsius that again demonstrates the capability of the dielectric fluid as disclosed in the present disclosure to provide efficient results when used in EHV/UHV equipment's at very high altitude regions.

[0026] Further, the test results for comparison of the dielectric fluid composition with the market-2 dielectric fluid is given below in the Table 4. The test was conducted for duration of about 0 Hours and 500 Hours respectively. The oxidation inhibitor content for the dielectric fluid composition of the present disclosure seems better when compared to the Market-2 dielectric fluid. For 500 Hours of testing duration, the total acidity of the dielectric fluid composition as disclosed in the present disclosure is measured at 0.04 mg KOH/g, total sludge percentage of the dielectric fluid is measured at 0.001% and the dielectric dissipation factor of the dielectric fluid is about 0.0023 at 90 degree Celsius substantiating its excellent long term stability as compared to market 2 dielectric fluid. Also, the gassing tendency of the dielectric fluid composition is about +5 uL/minute, when compared to the market 2 dielectric fluid i.e. +39 uL/minute, that demonstrates better gas absorbing properties and improves the service life of the equipment in which they are used. The kinematic viscosity at -30°Celsius of the dielectric fluid composition is about 619 mm /s, when compared to the market-2 dielectric fluid i.e. 926 mm /s that demonstrates that the dielectric fluid as disclosed in the present disclosure provides excellent cooling capability. Similarly the pour point of the dielectric fluid is about -68°Celsius, when compared to the market 2 dielectric fluid i.e. -48°Celsius that again demonstrates that the dielectric fluid as disclosed in the present disclosure provides efficient results when used in EHV/UHV equipment's at very high altitude regions.

[0027] Further, the test results for comparison of the dielectric fluid composition with the market-3 dielectric fluid is given below in the Table 5. The test was conducted for duration of about 0 Hours and 500 Hours respectively. The oxidation inhibitor content for the dielectric fluid composition of the present disclosure seems better when compared to the Market-3 dielectric fluid. For 500 Hours of testing duration, the total acidity of the dielectric fluid composition as disclosed in the present disclosure is measured at 0.04 mg KOH/g, total sludge percentage of the dielectric fluid is measured at 0.001% and the dielectric dissipation factor of the dielectric fluid is about 0.0023 at 90 degree Celsius substantiating its excellent long term stability as compared to market 3 dielectric fluid. Also, the gassing tendency of the dielectric fluid composition is about +5

uL/minute, when compared to the market 3 dielectric fluid i.e. +37 uL/minute, that demonstrates better gas absorbing properties and improves the service life of the equipment in which they are used. The kinematic viscosity at -30°Celsius of the dielectric fluid composition is about 619 mm /s, when compared to the market-3 dielectric fluid i.e. 750 mm /s that demonstrates that the dielectric fluid as disclosed in the present disclosure provides excellent cooling capability. Similarly the pour point of the dielectric fluid is about -68°Celsius, when compared to the market 3 dielectric fluid i.e. -61°Celsius that again demonstrates that the dielectric fluid as disclosed in the present disclosure provides efficient results when used in EHV/UHV equipment's at very high altitude regions.

[0028] Furthermore, the dielectric fluid composition as disclosed in the present disclosure may be advantageous in providing an extended oxidation stability because of the reduction in acid formation and sludge accumulation. Also, the dielectric fluid provides low gassing tendency with excellent flow-ability sub-zero temperature with superior resistance to oxidation and excellent long term dielectric properties. The dielectric fluid composition delays or slows down the oxidation which will ensure good healthy liquid insulation and thereby extending the active life of both the liquid insulation and solid insulation. As a result the dielectric fluid composition ensures the overall reliable performance of Power Transformers, Shunt Reactors and other EHV/UHV equipments. The dielectric fluid composition has excellent flow-ability also at sub-zero temperatures with flash point (PMCC) more than or equal to 148°C because of good dielectric properties such as density, DDF, break down voltage and others with very low total sulphur content.
[0029] It is to be understood that a skilled artisan will recognize the interchange ability of various features from different embodiments and that the various features described, as well as other known equivalents for each feature, may be mixed and matched by one of ordinary skill in this art to construct additional systems and techniques in accordance with principles of this disclosure. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

WHAT IS CLAIMED IS:
1. A dielectric fluid composition having ultra-low pour point and improved
dielectric properties; the composition comprising:
a base oil 1 present by weight in a percentage range of about 0% to 85% of the total weight of the dielectric fluid;
a base oil 2 present by weight in a percentage range of about 0% to 45% of the total weight of the dielectric fluid;
a base oil 3 present by weight in a percentage range of about 0% to 8%> of the total weight of the dielectric fluid; and
one or more additives selected from an additive package present by weight in a percentage range of about 1% to 2% of the total weight of the dielectric fluid;
Wherein, the dielectric fluid has a pour point in a range of about -50°Celsius to -70°Celsius.
2. The dielectric fluid composition as claimed in claim 1, wherein the base
oil 1 comprises:
a naphthenic carbon present by weight in a percentage range of about 45%) to 55% of the base oil 1;
a paraffinic carbon present by weight in a percentage range of about 35%) to 45% of the base oil 1; and
an aromatic carbon present by weight in a percentage range of about 5% to 12% of the base oil 1.
3. The dielectric fluid composition as claimed in claim 1, wherein the base
oil 2 comprises:
an aromatic carbon present by weight in a percentage range of about 75% to 85% of the base oil 2;
a naphthenic carbon present by weight in a percentage range of about 10%) to 15%) of the base oil 2; and

a paraffmic carbon present by weight in a percentage range of about 5% to 10% of the base oil 2.
4. The dielectric fluid composition as claimed in claim 1, wherein the base
oil 3 comprises:
a naphthenic carbon present by weight in a percentage range of about 40% to 50%) of the base oil 3; and
a paraffmic carbon present by weight in a percentage range of about 50% to 60% of the base oil 3.
a aromatic carbon present by weight in a percentage range of about 0.5% to 2% of the base oil 3.
5. The dielectric fluid composition as claimed in claim 1, wherein the base oil 1 has a boiling range of greater than or equal to 290°celsius.
6. The dielectric fluid composition as claimed in claim 1, wherein the base oil 2 has a boiling range of greater than or equal to 330°celsius.
7. The dielectric fluid composition as claimed in claim 1, wherein the base oil 3 has a boiling range of greater than or equal to 300°celsius.
8. The dielectric fluid composition as claimed in claim 1, wherein the one or more additives are selected from the additive package comprising at least one from the group of an oxidation inhibitor, an anti-gassing agent, a pour point depressant, an anti-foaming agent and the combinations thereof.
9. The dielectric fluid composition as claimed in claim 1 wherein the one or more additives selected from the additive package comprises at least one from the group of:
an oxidation inhibitor present in a percentage range of about 0.08% to 0.4%) of the additive package;

an anti-gassing agent present in a percentage range of about 0.01% to 0.5% of the additive package;
a pour point depressant present in a percentage range of about 40 mg/kg to 140 mg/kg of the additive package;
an anti-foaming agent present in a percentage range of about 2mg/kg to 15 mg/kg of the additive package; and the mixtures there of.
10. The dielectric fluid composition as claimed in claim 9, wherein the oxidation inhibitor comprises a hindered phenol anti-oxidant.
11. The dielectric fluid composition as claimed in claim 9, wherein the antigassing agent comprises from any one of CI to C12 aromatic hydrocarbons.
12. The dielectric fluid composition as claimed in claim 1, wherein a kinematic viscosity at 100°celsius is in a range of about 1 mm /s to 3
9 9 9
mm /s, at 40 °Celsius is in a range of about 7 mm /s to 9 mm /s, at -30
9 9
°Celsius is in a range of about 600 mm /s to 700 mm /s and at -40 °Celsius
9 9
is in a range of about 950 mm /s to 1050 mm /s
13. The dielectric fluid composition as claimed in claim 1, wherein a density of the dielectric fluid at 20°Celsius is in a range of about 0.5 g/ml to 0.9 g/ml.
14. The dielectric fluid as claimed in claim 1, wherein a dielectric dissipation factor of the dielectric fluid at 90°Celsius is in a range of about 0.0007 to 0.003.
15. The dielectric fluid composition as claimed in claim 1, wherein an anti-oxidant additive of the dielectric fluid is in a percentage range of about 0.08% to 0.4%.

16. The dielectric fluid composition as claimed in claim 1, wherein a negative impulse breakdown voltage of the dielectric fluid is greater than or equal to210kVp.