FORM 2 THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE "A DIELECTRIC FLUID COMPOSITION HAVING GAS ABSORBING
PROPERTIES"
APPLICANT
RAJ PETRO SPECIALITIES PVT LTD,
2A-D, DOSHI TOWERS 156, POONAMALLEE HIGH ROAD
KILPAUK, CHENNAI, TAMIL NADU - 600 010
INDIA.
The following specification particularly describes the invention and the manner in
which is to be performed.

A DIELECTRIC FLUID COMPOSITION HAVING GAS ABSORBING
PROPERTIES
BACKGROUND
[0001] Embodiments of the present disclosure relate to dielectric fluids, and more particularly, to a dielectric fluid composition.
[0002] Dielectric fluid insulation system is integral part of power transformers, switchgears, capacitors, switches, and many other extra high voltage or ultra-high voltage equipments. Apart from its function as insulation medium the dielectric fluid also perform the role of heat transfer by cooling the various sub system in the equipment.
[0003] Dielectric fluid's ability to function efficiently and effectively depends on number of properties. The number of properties includes but not restricted to flash point and fire point, gas absorption, thermal conductivity, viscosity over a range of temperatures, heat capacity, dielectric breakdown voltage, impulse breakdown voltage, power factor, pour point and others. The International Standards Organizations such as the American Society for Testing and Materials (ASTM), the International Electrotechnical Commission (TEC), the British Standard (BS) and the German Standard DIN specifications use a combination of these properties to provide standard to be strictly adhered to.
[0004] The dielectric fluids require exceptional long term stability to withstand extended periods of severe thermo-electric stress. As the dielectric fluid ages

resistance to oxidation will come down causing degradation progressively evolving acids, sludge, gasses etc.
[0005] The performance of extra high voltage or ultra-high voltage equipment's such as bushings , instrument transformers, capacitors and cables is affected by the presence of degradation products like volatile gasses, which can give rise to frequent partial discharges, breakdown of insulation and possibly the risk of explosion.
[0006] The gas absorbing property of any dielectric fluid has been recognized as an important factor in characterization although no specification limits has been prescribed under IEC60296: 2012. However, for special applications, this standard recommends gassing tendency suggests a maximum of +5uL/min as measured by test method IEC60628:1985. ASTM D3487: 2016 has a maximum limit of+30 uL/min as measured by ASTM D2300: 2012. Although the currently available compositions of the dielectric fluids adhere to the International Standards, there are certain inadequacies in this regard. In our view the composition of the dielectric fluids can be further improved to offer a longer service life for the good of various extra high voltages and ultra-high voltage equipments and also reduce maintenance costs.
[0007] Hence, to overcome at least one of the above mentioned deficiencies, there exists a need for an improved dielectric fluid composition having gas absorbing properties.
SUMMARY

[0008] 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.
[0009] In an embodiment of the present disclosure, a dielectric fluid composition having negative gassing tendency has been disclosed. The composition comprises a type 1 base oil composition, a type 2 base oil composition 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. Also, the dielectric fluid has a negative gassing tendency of about less than or equal to -5 uL/minute.
[0010] In another embodiment of the present disclosure, a dielectric fluid composition having negative gassing tendency has been disclosed. The composition comprises a type 1 base oil composition comprises a base oil 1 present by weight in a percentage range of about 0% to 90% of the total weight of the type 1 base oil, a base oil 2 present by weight in a percentage range of about 0% to 15% of the total weight of the type 1 base oil. Also, the type 2 base oil composition further comprises a base oil la present by weight in a percentage range of about 0% to 65% of the total weight of the type 2 base oil, a base oil 2a present by weight in a percentage range of about 0% to 55% of the total weight of the type 2 base oil, a base oil 3a present by weight in a percentage range of about 0% to 10% of the total weight of the type 2 base oil.

[0011] 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
[0012] 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.
[0013] 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.
[0014] 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.
[0015] 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.
[0016] Embodiments of the present invention will be described below in detail with reference to the accompanying tables.
[0017] Embodiments of the present disclosure relate to a dielectric fluid composition having negative gassing tendency; the composition comprising a type 1 base oil composition, a type 2 base oil composition 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 negative gassing tendency of about less than or equal to -5 uL/minute.
[0018] Further, the type 1 base oil composition comprises a base oil 1 present by weight in a percentage range of about 0% to 90% of the total weight of the type 1 base oil, a base oil 2 present by weight in a percentage range of about 0% to 15% of the total weight of the type 1 base oil.

[0019] Similarly, the type 2 base oil composition comprises a base oil la present by weight in a percentage range of about 0% to 65% of the total weight of the type 2 base oil, a base oil 2a present by weight in a percentage range of about 0% to 55% of the total weight of the type 2 base oil, a base oil 3a present by weight in a percentage range of about 0% to 10% of the total weight of the type 2 base oil.
[0020] Further to the above disclosure. The base oil 1 of the type 1 base oil composition comprises a paraffinic carbon present by weight in a percentage range of about 50% to 60% of the base oil 1, a naphthenic carbon present by weight in a percentage range of about 40% to 44% of the base oil 1, an aromatic carbon present by weight in a percentage range of about 0% to 2% of the base oil 1.
[0021] Further to the above disclosure. The base oil 2 of the type 1 base oil composition comprises a naphthenic carbon present by weight in a percentage range of about 10% to 14% of the base oil 2, a paraffinic carbon present by weight in a percentage range of about 6% to 8% of the base oil 2; and an aromatic carbon present by weight in a percentage range of about 75% to 80% of the base oil 2.
[0022] Further to the above disclosure. The base oil la of the type 2 base oil composition comprises a naphthenic carbon present by weight in a percentage range of about 40% to 50% of the base oil la, a paraffinic carbon present by weight in a percentage range of about 54% to 57% of the base oil la, an aromatic

carbon present by weight in a percentage range of about 0.5% to 2% of the base oil la.
[0023] The base oil 2a of the type 2 base oil composition comprises, a naphthenic carbon present by weight in a percentage range of about 50% to 55% of the base oil 2a, a paraffinic carbon present by weight in a percentage range of about 35%) to 45% of the base oil 2a; and an aromatic carbon present by weight in a percentage range of about 6% to 10%> of the base oil 2a.
[0024] The base oil 3a of the type 2 base oil composition comprises a naphthenic carbon present by weight in a percentage range of about 10%> to 15% of the base oil 3a, a paraffinic carbon present by weight in a percentage range of about 5% to 8%> of the base oil 3a and an aromatic carbon present by weight in a percentage range of about 75% to 85% of the base oil 3a.
[0025] Further with respect to the above embodiments. The base oil 1 of the type 1 base oil composition has a boiling range of greater than or equal to 300°celsius. The base oil 2 of the type 1 base oil composition has a boiling range of greater than or equal to 330°celsius. The base oil la of the type 2 base oil composition has a boiling range of greater than or equal to 300°celsius. The base oil 2a of the type 2 base oil composition has a boiling range of greater than or equal to 290°celsius. The base oil 3a of the type 2 base oil composition has a boiling range of greater than or equal to 330°celsius.
[0026] Further with respect to the above embodiments The one or more additives selected from the additive package comprises 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.
[0027] Furthermore, 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 0.4% of the additive package, a pour point depressant present in a percentage range of about 10 mg/kg to 40 mg/kg of the additive package and 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 the additive package.
[0028] The test results for the type 1 base oil composition of the dielectric fluid composition of the present disclosure as per the IEC60296:2012 standards have been disclosed below in table 1. The type 1 base oil composition may be paraffinic base oil blending composition. 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 type 1 base oil composition at 40°celsius is
9 9
about 8 mm /s to 9 mm2/s, at 20 °Celsius is in a range of about 15 mm /s to 16
9 9 9
mm /s, at -30°Celsius is in a range of about 280 mm /s to 290 mm /s. The negative impulse breakdown voltage of the type 1 base oil composition is in a range of about 200 kVp to 300 kVp. The relative permittivity of the type 1 base oil composition is in a percentage range of about 1.7% to 3%. The specific resistance at 90 °Celsius of the type 1 base oil composition is around 800 Ohm-

cm. The aniline point of the type 1 base oil composition is in a range of about 70°C to 93°Celsius. The antioxidant additives of the type 1 base oil composition is in a percentage range of about 0.08% to 0.4%. The gassing tendency of the type 1 base oil composition is -5 uL/minute.

[0029] The additional properties of type 1 base oil composition of the dielectric fluid composition for example paraffinic base oil blending composition is disclosed in the below table 2. The boiling range of the type 1 base oil composition is greater than or equal to 305°Celsius that improves the safety. The kinematic viscosity of the type 1 base oil composition at -40°Celsius is around 578 mm /s that provides excellent flow ability at sub-zero temperatures. The rotating vessel oxidation property test results shows a time range of about 430 minutes that leads to the excellent oxidation resistance. The thermal conductivity property of the type 1 base oil composition shows a results of around 0.135 W/mK and Specific Heat Capacity of the type 1 base oil composition is around 1890 J/kgK. The type 1 base oil composition of the dielectric fluid composition also leads to the faster cooling of the equipment. The negative impulse breakdown voltage of the type 1 base oil composition shows a result that is greater than 260 kV that leads to safety during switching surges and lightening surges. The Biodegradability, OECD 301B, C02 Evolution Test shows a result of greater than 60% that makes the fluid to be environmental friendly. The compatibility (miscibility) of the present dielectric fluid composition is good with other dielectric fluids such as natural esters and synthetic.



[0030] The compatibility results with construction materials for type 1 base oil composition are disclosed below in the table 3. The characteristics of the type 1 base oil composition of the dielectric fluid composition after ageing for about 164 hours at 100°Celsius for control oil and aged oil is disclosed in the table below. The neutralization value of the type 1 base oil composition is about 0.005 mg KOH/g for control oil and 0.003 mg KOH/g for aged oil that leads to prevention of acid generation. The interfacial tension IFT for type 1 base oil composition is about 47 for control oil and 44 for aged oil that leads to prevention of polar compounds generation. The Tan delta at 100°Celsius is about 0.00034 for control oil and 0.0006 for aged oil that again leads to the prevention of polar compounds generation. The specific resistance for type 1 base oil composition is
19 19
about 25 x 10 T Ohm cm for control oil and 23 xlO T Ohm cm for aged oil that again leads to prevention of polar compounds generation.



[0031] The test results for the type 2 base oil composition of the dielectric fluid composition of the present disclosure as per the IEC 60296:2012 standards have been disclosed below in table 4. The type 2 base oil composition is a naphthenic base oil blending composition. The results disclosed in Table 4 showed that the composition is in full compliance with IEC 60296:2012 specification limits. The kinematic viscosity of the type 2 base oil composition at 40°celsius is about 9 mm2/s to 10 mm2/s, at 0 °Celsius is in a range of about 48 mm2/s to 50 mm2/s. The negative impulse breakdown voltage of the type 2 base oil composition is in a range of about 220-250 KVp. The specific resistance at 90 °Celsius of the type 2 base oil composition is around 800 Ohm-cm. The aniline point of the type 2 base oil composition is in a range of about 70°C to 105°Celsius. The antioxidant additives of the type 2 base oil composition is in a percentage range of about 0.08% to 0.40%. The carbon type analysis using Fourier transform infrared spectroscopy for aromatic carbon, paraffinic carbon and naphthenic carbon is around 9%, 45%, 47% respectively. The gassing tendency of the type 2 base oil composition is -5 uL/minute.

[0032] The additional properties of type 2 base oil composition of the dielectric fluid composition for example naphthenic base oil blending composition is disclosed in the below Table 5. The boiling range of the type 2 base oil composition is equal to 300°Celsius that improves the safety. The kinematic viscosity of the type 2 base oil composition at -40°Celsius is around 2469 mm /s that provides better flow ability at sub-zero temperatures. The rotating vessel oxidation property test results shows a time range of about 352 minutes that leads to the excellent oxidation resistance. The thermal conductivity property of the type 1 base oil composition shows a results of around 0.128 W/mK and Specific

Heat Capacity of the type 1 base oil composition is around 1800 J/kgK. The type 2 base oil composition of the dielectric fluid composition also leads to the faster cooling of the equipment. The negative impulse breakdown voltage of the type 2 base oil composition shows a result that is greater than 240 kV that leads to safety during switching surges and lightening surges. The Biodegradability, OECD 301B, C02 Evolution Test shows a result of inherently biodegradable and environmental friendly. The compatibility (miscibility) of the present dielectric fluid composition disclosed is good with other dielectric fluids such as natural esters and synthetic esters.


[0033] The compatibility results with construction materials for type 2 base oil composition is disclosed below in the Table 6. The characteristics of the type 2 base oil composition of the dielectric fluid composition after ageing for about 164 hours at 100°Celsius for control oil and aged oil is disclosed in the table below. The neutralization value of the type 2 base oil composition is about 0.005 mg KOH/g for control oil and 0.003 mg KOH/g for aged oil that leads to prevention of acid generation. The interfacial tension IFT for type 2 base oil composition is about 45 for control oil and 42 for aged oil that leads to prevention of polar compounds generation. The Tan delta at 100°Celsius is about 0.006 for control oil and 0.007 for aged oil that again leads to the prevention of polar compounds generation. The dielectric strength BDV of the type 2 base oil composition is about 77 kV for control oil and 79 kV for aged oil.

[0034] Furthermore, the dielectric fluid composition as disclosed in the present disclosure may be advantageous in providing superior dielectric properties such as lighter in density, excellent flow-ability at -40°C, excellent dielectric

dissipation factor (DDF) with very low total Sulphur content that thereby increases the active life of the insulation system and Extra high voltage (EHV) or Ultra high Voltage (UHV) equipments. The negative gassing tendency of the dielectric fluid composition is very low, that increases the service life of the liquid and the equipment in which they are used. The dielectric fluid composition has excellent flow-ability also at sub-zero temperatures because of good dielectric properties such as density, DDF, break down voltage and others. The dielectric fluid composition delays or slows down partial discharges which will ensure good healthy liquid insulation and solid insulation. Overall the dielectric fluid composition as disclosed in the present disclosure ensures the overall reliable performance of bushings, instrument transformers and other Extra high voltage (EHV) or Ultra high Voltage (UHV) equipments.
[0035] 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 negative gassing tendency; the
composition comprises:
a type 1 base oil composition;
a type 2 base oil composition; 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 negative gassing tendency of about less than or equal to -5 uL/minute.
2. The dielectric fluid composition as claimed in claim 1, wherein the type 1
base oil composition comprises:
a base oil 1 present by weight in a percentage range of about 0% to 90% of the total weight of the type 1 base oil;
a base oil 2 present by weight in a percentage range of about 0% to 15% of the total weight of the type 1 base oil;
3. The dielectric fluid composition as claimed in claim 1, wherein the type 2
base oil composition comprises:
a base oil la present by weight in a percentage range of about 0% to 65%) of the total weight of the type 2 base oil;
a base oil 2a present by weight in a percentage range of about 0% to 55%o of the total weight of the type 2 base oil;
a base oil 3a present by weight in a percentage range of about 0% to 10%) of the total weight of the type 2 base oil.
4. The dielectric fluid composition as claimed in claim 2, wherein the base
oil 1 comprises:

a paraffinic carbon present by weight in a percentage range of about 50% to 60% of the base oil 1;
a naphthenic carbon present by weight in a percentage range of about 40% to 44% of the base oil 1.
an aromatic carbon present by weight in a percentage range of about 0% to 2% of the base oil 2.
5. The dielectric fluid composition as claimed in claim 2, wherein the base
oil 2 comprises:
a naphthenic carbon present by weight in a percentage range of about 10% to 14% of the base oil 2;
a paraffinic carbon present by weight in a percentage range of about 6%> to 8%> of the base oil 2; and
an aromatic carbon present by weight in a percentage range of about 75% to 80% of the base oil 2.
6. The dielectric fluid composition as claimed in claim 3, wherein the base
oil la comprises:
a naphthenic carbon present by weight in a percentage range of about 40% to 50% of the base oil la;
a paraffinic carbon present by weight in a percentage range of about 54%) to 57% of the base oil la;
a aromatic carbon present by weight in a percentage range of about 0.5% to 2% of the base oil la.
7. The dielectric fluid composition as claimed in claim 3, wherein the base
oil 2a comprises:
a naphthenic carbon present by weight in a percentage range of about 50%) to 55%) of the base oil 2a;

a paraffinic carbon present by weight in a percentage range of about 35% to 40% of the base oil 2a; and
an aromatic carbon present by weight in a percentage range of about 6%> to 10%) of the base oil 2a.
8. The dielectric fluid composition as claimed in claim 3, wherein the base
oil 3a comprises:
a naphthenic carbon present by weight in a percentage range of about 10%o to 15%) of the base oil 3 a;
a paraffinic carbon present by weight in a percentage range of about 5%o to 8%> of the base oil 3 a; and
an aromatic carbon present by weight in a percentage range of about 75%o to 85% of the base oil 3a.
9. The dielectric fluid composition as claimed in claim 2, wherein the base oil 1 has a boiling range of greater than or equal to 300°celsius.
10. The dielectric fluid composition as claimed in claim 2, wherein the base oil 2 has a boiling range of greater than or equal to 315°celsius.
11. The dielectric fluid composition as claimed in claim 3, wherein the base oil la has a boiling range of greater than or equal to 300°celsius.
12. The dielectric fluid composition as claimed in claim 3, wherein the base oil 2a has a boiling range of greater than or equal to 290°celsius.
13. The dielectric fluid composition as claimed in claim 3, wherein the base oil 3a has a boiling range of greater than or equal to 330°celsius.
14. 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, an anti-gassing agent, a pour point depressant, an anti-foaming agent and the combinations thereof.
15. 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 0.4%) of the additive package;
a pour point depressant present in a percentage range of about 10 mg/kg to 40 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 the additive package.
16. The dielectric fluid composition as claimed in claim 1, wherein a DDF is around 0.0001 and a specific resistance at 90 °Celsius is around 800 Ohm-cm.
17. The dielectric fluid composition as claimed in claim 1, wherein a aniline point is in a range of around 70°celsius to 105°celsius.
18. The dielectric fluid composition as claimed in claim 1, wherein a kinematic viscosity at 40°celsius is in a range of about 8 mm /s to 10
9 9 9
mm /s, at 20 °Celsius is in a range of about 15 mm /s to 16 mm /s, at 0
9 9
°Celsius is in a range of about 45 mm /s to 50 mm /s, at -30°Celsius is in
9 9
a range of about 280 mm /s to 300 mm /s and
19. The dielectric fluid composition as claimed in claim 1, wherein a negative
impulse breakdown voltage is in a range of about 200 kVp to 300 kVp.

20. The dielectric fluid composition as claimed in claim 1, wherein a Relative Permittivity is in a percentage range of about 1.7% to 3%.
21. The dielectric fluid composition as claimed in claim 15, wherein
the dielectric fluid has a long term stability with negative gassing tendency of about less than or equal to -5 uL/minute.