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 IMPROVED
DIELECTRIC 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 IMPROVED 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 extensively used in transmission and distribution
system to insulate and cool power transformers, shunt reactors, switchgears, capacitor switch, x-ray tubes & high voltage cables etc. The dielectric fluids insulate components with different electrical potential. It also conducts heat generated in the core and winding (coil) to the surface. A good quality dielectric fluid with long term stability properties is vital for the trouble free performance of power transformer, shunt reactors, switchgears, capacitor switch, electrical cables, etc.
[0003] Electrical cables are the backbone of distribution and transmission
system. Transmission cables are either overhead or buried underground. While, the overhead cable do not have any insulation to protect it from the environment except air as an insulation, cable buried underground is constructed with one or more conductors, oil and paper insulation, semi conductive paper, with a protective jacket. Oil filled cable is run in a rigid steel pipe, semi-rigid aluminium or lead sheath. The oil is kept under pressure to prevent formation of voids that would allow partial discharges within the cable insulation. The oil filled cable is under very high electrical stress and requires improved dielectric properties with

extended oxidation stability. The present dielectric fluids available do not have the requisite dielectric properties to cope up with high electric stress long-term.
[0004] In the long run the conventional present generation dielectric fluids
suffer from compatibility with the construction materials, ingress of air, moisture, dust and consequent frequent partial discharges leading to oil degradation and poor dielectric properties
[0005] Dielectric fluids have to conform to international and national
standards. To ensure dielectric fluids have all the necessary attributes for efficient performance, stringent standards have been formulated by International Electrotechnical Committee. IEC 60867:1993 specifies limits for gas absorption property and do not suggest about improved dielectric properties with extended oxidation stability. This standard has not revised after 1993. The oxidation stability is a measure of a chemical reaction that occurs with a combination of the dielectric fluid and oxygen. The rate of oxidation increases with time and leads to an increase in the oil viscosity and deposits of sludge in the equipment. The gas absorption property of the dielectric fluids is the tendency to absorb the gasses such as hydrogen gas or any other gas. The presence of such gasses, which can give rise to partial discharges and leads to insulation breakdown. Although, some of the currently available compositions of the dielectric fluids adhere to the IEC standards, the composition of the dielectric fluids can be improved to offer a better service life to the HV/EHV/UHV cable and other equipment’s and also reduces the maintenance costs.

[0006] Hence, to overcome at least one of the above mentioned problems, there
exists a need for a dielectric fluid composition having improved dielectric properties with better gas absorption property and oxidation stability.
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 improved dielectric properties is disclosed. The dielectric fluid composition comprises a base oil 1 present by weight in a percentage range of about 0% to 60% of the total weight of the dielectric fluid, a base oil 2 present by weight in a percentage range of about 0% to 40% of the total weight of the dielectric fluid, a base oil 3 present by weight in a percentage range of about 0% to 30% 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 0% to 2% of the total weight of the dielectric fluid. Wherein, the dielectric fluid has a negative gassing tendency of less than or equal to -91 µL/minute; the dielectric fluid has a total sludge percentage of less than or equal to 0.06% for a test duration of 500 hours, the dielectric fluid has a acidity of less than or equal to 0.12 mg KOH/g for a test duration of 500 hours and the dielectric fluid has a dielectric dissipation factor at 90°Celsius of less than or equal to 0.04 for a test duration of 500 hours.

[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. 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% to 0.5% of the additive package.
[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 relate to a dielectric fluid
composition having improved gas absorption property and an improved dielectric

property is disclosed. The dielectric fluid composition comprises a base oil 1 present by weight in a percentage range of about 0% to 60% of the total weight of the dielectric fluid, a base oil 2 present by weight in a percentage range of about 0% to 40% of the total weight of the dielectric fluid, a base oil 3 present by weight in a percentage range of about 0% to 30% 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 0% to 2% of the total weight of the dielectric fluid.
[0017] Further, the base oil 1 of the dielectric fluid composition comprises a
naphthenic carbon present by weight in a percentage range of about 10% to 15% of the base oil 1, a paraffinic carbon present by weight in a percentage range of about 8% to 12% of the base oil 1; and an aromatic carbon present by weight in a percentage range of about 78% to 83% 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 an
aromatic carbon present by weight in a percentage range of about 50% to 60% of the base oil 3, a naphthenic carbon present by weight in a percentage range of

about 10% to 20% of the base oil 3 and a paraffinic carbon present by weight in a percentage range of about 25% to 35% of the base oil 3.
[0020] Further, the dielectric fluid composition comprises 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. 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.
[0021] In addition to the above disclosure, the one or more additives of the
dielectric fluid 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% to 0.5% of the additive package. Wherein the oxidation inhibitor may be a hindered phenol anti-oxidant or any other like. Also, the antigassing agent may be a tetra-hydro naphthalene or the like.
[0022] The test results for the dielectric fluid composition of the present
disclosure as per the IEC60867:1993 standards have been disclosed below in Table 1. The results disclosed in Table 1 showed that the composition is in full compliance with IEC 60867:1993 specification limits. The negative impulse breakdown voltage of the dielectric fluid is about 220 kVp. The flash point of the dielectric fluid is around 150°Celsius. The volume resistivity at 90 °Celsius of the dielectric fluid composition is around 7 TΩ-m to 8 TΩ-m. A kinematic viscosity

at 40°celsius is in a range of about 5 mm2/s to 11 mm2/s, at 0 °Celsius is in a range of about 40 mm2/s to 50 mm2/s and at -40 °Celsius is in a range of about 400 mm2/s to 460 mm2/s. The pour point of the dielectric fluid is in a range of around -45°celsius to -55°celsius. The dielectric dissipation factor (Tan delta) at 90°Celsius of the dielectric fluid composition is around 0.00038. The stability under electrical stress and ionization (Gassing) tendency of the dielectric fluid is less than or equal to -91 mm3\min.



[0023] The additional properties result of the dielectric fluid composition is
given in the Table 2 below. The Rotating Vessel Oxidation property test results show a time range of about 451 minutes that leads to the excellent oxidation resistance. The thermal conductivity property shows results of around 0.137 W/mK and Specific Heat Capacity of the oil is around 1600 J/kgK. 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 220 kV that leads to safety during switching surges and lightning surges. The Biodegradability, OECD 301B, CO2 Evolution Test shows a result of greater than 60% that makes the fluid to be environmental friendly. The compatibility (miscibility) of the dielectric fluid composition with other dielectric fluids is good such as natural esters synthetic esters. The oxidation stability of dielectric fluid composition for 500 hours of testing duration shows the total acidity of the dielectric fluid is 0.12mg KOH/g, the total sludge is 0.06% and the dielectric dissipation factor of the dielectric fluid is 0.04 at 90 degree Celsius. As under IEC 60867:1993, there are no limits for 500 hours oxidation stability, the disclosed results are actuals.


[0024] 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 500 Hours respectively. The oxidation inhibitor content for the dielectric fluid composition of the present disclosure seems is better when compared to the Market-1 dielectric fluid. For 500 Hours of testing duration, the total acidity of the new dielectric fluid composition is measured at 0.12 mg KOH/g, total sludge percentage of the dielectric fluid is measured at 0.06% and the dielectric dissipation factor of the dielectric fluid is about 0.04 at 90 degree Celsius as compared with the Market-1 dielectric fluid,

which has the total acidity measured at 2.9 mg KOH/g, the total sludge is measured at 1.8% and the dielectric dissipation factor measured at 0.98 at 90°Celsius substantiating the excellent long term stability of the dielectric fluid composition of the present disclosure.

[0025] The compatibility result with construction materials of the dielectric
fluid composition is disclosed below in the table 4. The characteristics 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 dielectric fluid composition is about 0.003 mg KOH/g for control oil and 0.004 mg KOH/g for aged oil that leads to prevention of acid generation. The interfacial tension IFT for type 1 base oil is about 47 for control oil and 46 for aged oil that leads to prevention of polar compounds generation. The Tan delta at 100°Celsius is about 0.00057 for control oil and 0.0006 for aged oil that again

leads to the prevention of polar compounds generation. The dielectric strength BDV of the dielectric fluid ranges around 77 kV to 78 kV.

[0026] Furthermore, the dielectric fluid composition as disclosed in the
present disclosure may be advantageous in providing improved 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 in HV/ EHV/UHV cable. The low negative gassing tendency of the dielectric fluid composition that increases the service life of the liquid and the equipment in which they are used. 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 Cables.

[0027] It is to be understood that a skilled artisan will recognize the inter
changeability 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 improved dielectric properties and
gas absorption property; the composition comprising:
a base oil 1 present by weight in a percentage range of about 0% to 60% of the total weight of the dielectric fluid;
a base oil 2 present by weight in a percentage range of about 0% to 40% of the total weight of the dielectric fluid;
a base oil 3 present by weight in a percentage range of about 0% to 30% 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 0% to 2% of the total weight of the dielectric fluid;
wherein,
the dielectric fluid has a negative gassing tendency of less than or equal to -91 µL /minute;
the dielectric fluid has a total sludge percentage of less than or equal to 0.06% for a test duration of 500 hours;
the dielectric fluid has a acidity of less than or equal to 0.12 mg KOH/g for a test duration of 500 hours;
the dielectric fluid has a dielectric dissipation factor at 90°Celsius of less than or equal to 0.04 for a test duration of 500 hours.
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 10% to 15% of the base oil 1;
a paraffinic carbon present by weight in a percentage range of about 8% to 12% of the base oil 1; and
an aromatic carbon present by weight in a percentage range of about 78% to 83% 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 paraffinic 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:
an aromatic carbon present by weight in a percentage range of about 50% to 60% of the base oil 3;
a naphthenic carbon present by weight in a percentage range of about 10% to 20% of the base oil 3; and
a paraffinic carbon present by weight in a percentage range of about 25% to 35% of the base oil 3.
5. 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.
6. 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% to 0.5% of the additive package;

7. The dielectric fluid composition as claimed in claim 6, wherein the oxidation inhibitor comprises a hindered phenol anti-oxidant.
8. The dielectric fluid composition as claimed in claim 6, wherein the antigassing agent comprises tetra-hydro naphthalene.
9. The dielectric fluid composition as claimed in claim 1, wherein the base oil 1 has a boiling range of greater than or equal to 330°celsius.
10. The dielectric fluid composition as claimed in claim 1, wherein the base oil 2 has a boiling range of greater than or equal to 300°celsius.
11. The dielectric fluid composition as claimed in claim 1, wherein the base oil 3 has a boiling range of greater than or equal to 400°celsius.
12. The dielectric fluid composition as claimed in claim 1, wherein a dielectric dissipation factor at 90 °Celsius is 0.00038 and a volume resistivity at 90 °Celsius is around 7 TΩ-m to 8 TΩ-m
13. The dielectric fluid composition as claimed in claim 1, wherein a flash point is in a range of around 140°celsius to 160°celsius.
14. The dielectric fluid composition as claimed in claim 1, wherein a kinematic viscosity at 40°celsius is in a range of about 5 mm2/s to 11 mm2/s, at 0 °Celsius is in a range of about 40 mm2/s to 50 mm2/s and at -40 °Celsius is in a range of about 400 mm2/s to 460 mm2/s.
15. The dielectric fluid composition as claimed in claim 1, wherein a pour point is in a range of around -45°celsius to -55°celsius.

Signature:
Name: Dinkar Agrawal (2502) Date:14 /June/2017