Description:“A MEDIUM VOLTAGE ELECTRICAL BUSHING FOR INSULATING MEDIUM VOLTAGE CONDUCTOR AND METHOD OF PREPARATION THEREOF”

FIELD OF INVENTION
[0001] The present invention relates to medium voltage electrical bushing for electric traction application. The present invention more particularly relates to medium voltage electrical bushing used in electric traction application to be used in most extreme environmental condition and a method of preparation.

BACKGROUND OF THE INVENTION
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Medium voltage electrical bushing for electric traction and/or electrical mobility application accommodates high voltage conductors to which high voltage is applied. In order to shield and insulate the high voltage conductor from other components and from outside, the apparatus is firmly attached to a grounded metal enclosure via fastening with suitable metal fittings.
[0004] In order to hold the high voltage conductor firmly to the electrically grounded metal enclosure, in a position sufficiently far away from the grounded enclosure to avoid dielectric breakdown, an insulator is provided with metal fittings to the enclosure.
[0005] The medium voltage electrical bushing for electric traction application should satisfy required insulation requirement and should have proper mechanical strength enough and for this purpose the insulators are processed with aluminum filled or silica filled epoxy resin system. A material, such as epoxy, is usually selected which has a coefficient of expansion similar to the metal/copper conductor so as to minimize the possibility of voids being formed at the critical interface where the insulator meets the conductor. This is because such voids are subjected to high electrical fields at the critical insulator-conductor interface region, which can lead to ionization within the voids, flashover and a reduced life expectancy for the insulator. This high electrical field at this critical region approaches a value equal to the product of the field at the inner conductor in the gas and the dielectric constant of the insulator.
[0006] Conventional high voltage insulating products such as spacer insulator and/support insulator uses epoxy-anhydride resin system to mold or cast the products.
[0007] Conventional cast epoxy insulating products for air insulated switchgear applications are molded with epoxy-anhydride resin system having silica filler or alumina filler / additives in the system, with single central electrode and electrically grounded metal enclosure.
[0008] A state of art, US4458100, a common insulator used for supporting the inner high voltage conductor within the outer conductor. A material, such as epoxy, is selected which a coefficient of expansion similar to the metal has selected for the inner conductor so as to minimize the possibility of voids being formed at the critical interface where the insulator meets the conductor.
[0009] Another state of art, US7795541B, relates to an insulating device for medium or high voltage electrical equipment in the shape of a disc inside an enclosure acting as a support for an electrical conductor. The disc is made of thermoplastic polyester. The disc can be worked starting from a thick board using conventional machining tools and it can be provided with particular arrangements, for example to facilitate its assembly or connection of conductors supported on it.
[0010] The need exists for an insulator which accommodates the high voltage conductors in a common electrically insulated enclosure and the need also exists for the less expensive insulator with three high voltage conductors and which replaces the common metallic conductor with bushes to reduce the final weight and cost of the insulator.
[0011] The need exists for less expensive insulator resin systems and manufacturing process for the manufacture of high voltage insulating products such as cast epoxy insulator and other high voltage insulating products, which are void free and which meet the depicted high voltage insulation requirements.
[0012] These challenges collective of the contemporary medium voltage electrical bushing hinder the efficiency and reliability. Thus, there is a pressing need to achieve the same.
OBJECTS OF THE INVENTION
[0013] Some of the objects of the present disclosure, which at least one embodiment herein satisfy, are listed herein below.
[0014] It is an object of the present subject matter to provide title, which overcomes the aforementioned and other drawbacks existing in the prior art fixture and methods.
[0015] It is a principal object of the present subject matter to introduce a medium voltage electrical bushing to insulate medium voltage conductors within the metal enclosures of locomotives or electric traction systems.
[0016] It is another object of the present subject matter to provide a lightweight and cost-effective medium voltage electrical bushing suitable for electric traction applications.
[0017] It is another significant object of the present subject matter to provide an elastomeric composition for the bushing, providing superior weathering, tracking resistance, and hydrophobicity to withstand extreme environmental conditions.
[0018] It is another significant object of the present subject matter to propose the the bushing to accommodate electrical systems operating between 1 kV and up to 36 kV, ensuring efficient voltage insulation.
[0019] It is another significant object of the present subject matter to propose t a method utilizing epoxy resin composition for manufacturing the insulator, involving additive mixing, molding, and gelling processes to achieve desired geometry and properties.
[0020] These and other objects and advantages of the present subject matter will be apparent to a person skilled in the art after consideration of the following detailed description taking into consideration with accompanied drawings in which preferred embodiments of the present subject matter are illustrated.
SUMMARY OF THE INVENTION
[0021] This summary is provided to introduce the concept of a medium voltage electrical bushing for insulating medium voltage conductor and a method of preparation of medium voltage electrical bushing. The concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0022] The present invention relates to a medium voltage electrical bushing for insulating medium voltage conductor and a method of preparation of medium voltage electrical bushing for insulating medium voltage conductor. The medium voltage electrical bushing serves to insulate medium voltage conductors in various applications comprises of a medium voltage conductor, an insulator attached to the conductor, and a brass bush acting as both a mechanical stopper and support for fasteners during connection to other conductors, such as those in overhead lines. Additionally, a metallic flange linked to the insulator facilitates the connection of the bushing to a grounded metal enclosure, typically found in locomotives or electric traction systems.
[0023] To further understand the characteristics and technical contents of the present subject matter, a description relating thereto will be made with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit the scope of the present subject matter.
[0024] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0025] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of improved fixture or methods or structure in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which
[0026] Fig. 1 illustrates a cross sectional view of a medium voltage electrical bushing for insulating medium voltage conductor for electric traction in accordance with the disclosure;
[0027] Fig. 2a illustrates a exploded view of a metallic flange as the circular shaped aluminum alloy insert or flange a in accordance with the disclosure;
[0028] Fig. 2b illustrates a exploded view of a metallic flange as Stainless Steel (S.S) or aluminum alloy bushes in accordance with the disclosure; and
[0029] Fig. 3 illustrates the flow chart of a method of manufacturing medium voltage electrical bushing for insulating high voltage conductor for electric traction application in accordance with an embodiment of the present disclosure.
[0030] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
[0031] A few aspects of the present disclosure are explained in detail below with reference to the various figures. Example implementations are described to illustrate the disclosed subject matter, not to limit its scope, which is defined by the claims. Those of ordinary skill in the art will recognize a number of equivalent variations of the various features provided in the description that follows.
[0032] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0033] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the “invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0034] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.
[0035] Various embodiments are further described herein with reference to the accompanying figures. It should be noted that the description and figures relate to exemplary embodiments and should not be construed as a limitation to the subject matter of the present disclosure. It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the subject matter of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the subject matter of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof. Yet further, for the sake of brevity, operation or working principles pertaining to the technical material that is known in the technical field of the present disclosure have not been described in detail so as not to unnecessarily obscure the present disclosure.
[0036] The present invention relates to a medium voltage electrical bushing for insulating medium voltage conductor and a method of preparation of medium voltage electrical bushing for insulating medium voltage conductor.
[0037] The present invention relates to a medium voltage electrical bushing for medium voltage applications which has enhanced dielectric properties such as capacitance, tan delta value, partial discharge with optimized insulation. The medium voltage electrical bushing used in electric traction application to be used in most extreme environmental condition with protective weather sheds.
[0038] Also, the present invention further describes a method of producing medium voltage electrical bushing for medium voltage applications using epoxy resin composition (the epoxy resin composition filled with micro structured spherical glass bubbles as filler / additive content) which will enhance the electrical properties and at the same time reduces the weight of the final product.
[0039] Fig. 1 illustrates a cross sectional view of a medium voltage electrical bushing for insulating medium voltage conductor for electric traction in accordance with the disclosure.
[0040] The medium voltage electrical bushing (100) comprises several integral components designed to facilitate the insulation and connection of medium voltage conductors within the electrical systems of locomotives or electric traction systems. At its core is the medium voltage conductor (1), serving as the primary pathway for medium voltage current. Coupled directly with the conductor is the insulator (3), a crucial component responsible for preventing the flow of electricity between the conductor and external elements, thereby ensuring electrical insulation. Working in tandem with the conductor and insulator is the brass bush (2), strategically positioned to provide mechanical support and serve as a stopper during the connection process to other conductors from overhead lines. Its sturdy construction aids in securing the medium voltage conductor (1) firmly in place. The metallic flange (4) is connected to the insulator (3), which plays a pivotal role in anchoring the bushing (100) to a grounded metal enclosure within the locomotive or electric traction system. The flange(4) not only provides structural stability but also facilitates seamless integration of the bushing into the broader electrical infrastructure.
[0041] Fig. 2a illustrates a exploded view of a metallic flange as the circular shaped aluminum alloy insert or flange a in accordance with the disclosure. In the original design of the medium voltage electrical bushing, as depicted in Figure 2(a), a circular-shaped aluminum alloy inserts or flange (4) is utilized which serves a crucial function in the structure of the bushing, facilitating its connection to other elements within the electrical system. Aluminum alloy, known for its lightweight yet durable properties, was chosen for this insert to ensure both structural integrity and ease of handling during installation.
[0042] Fig. 2b illustrates a exploded view of a metallic flange as Stainless Steel (S.S) or aluminum alloy bushes in accordance with the disclosure. The aluminum alloy insert is replaced with stainless steel (S.S) or aluminum alloy bushes (4). By substituting the aluminum insert with stainless steel or aluminum alloy bushes, significant weight reduction is achieved without compromising structural integrity. This enhancement not only streamlines the installation process but also ensures greater resilience and longevity, particularly in demanding operational environments.
[0043] Fig. 3 illustrates the flow chart of a method of manufacturing medium voltage electrical bushing for insulating high voltage conductor for electric traction application in accordance with an embodiment of the present disclosure. A method of manufacturing a medium voltage electrical bushings for insulating medium voltage conductors in electric traction applications(300) comprises of configuring(302) a mould with a first half and a second half interacting along a parting plane , forming(304) a cavity corresponding to the medium voltage electrical bushing within the mould , positioning(306) a nozzle at the first half of the mould for discharging liquefied material into the cavity , closing(308) the mould by relative movement of the first half with respect to the second half until the cavity is sealed , injecting(310) a polymer composite dough and a liquefied material through the nozzle and opening(312) the mould by relative movement of the first half with respect to the second half and removing the bushing from the mould cavity.
[0044] At the step 302, a mould is prepared with two halves, typically made of durable materials such as metal or composite. These halves interact along a parting plane, meaning they can be separated and joined together.
[0045] At the step 304, within the mould, a cavity is created. This cavity is shaped to correspond to the desired shape and size of the medium voltage electrical bushing.
[0046] At the step 306 ,a nozzle is placed at the first half of the mould. This nozzle serves as the entry point for discharging liquefied material into the cavity formed in the mould.
[0047] At the step 308, the mould is closed by bringing the first half and the second half together. This is achieved through relative movement, such as clamping or pressing, until the cavity is completely sealed.
[0048] At the step 310, once the mould is sealed, a polymer composite dough and liquefied material are injected into the cavity through the nozzle. The polymer composite dough provides structural integrity and insulation properties, while the liquefied material may serve various purposes such as enhancing insulation or providing additional properties to the bushing.
[0049] At the step 312, after the injection process is complete, the mould is opened by moving the first half away from the second half. This allows access to the newly formed medium voltage electrical bushing within the cavity. The bushing is then removed from the mould cavity.
[0050] In a preferred embodiment a mold for making of medium voltage electrical bushing for insulating medium voltage conductor (1) for electric traction application in comprises: two-part mold in which, a second half of the mold interacting with the first half of the mold along a parting plane, at least one cavity corresponding to bushing encompassed by the first and the second half of the mold. The mold further comprises at least one adapter suitable to receive and temporarily hold a conductor during injection molding of the bushing, one injection nozzle arranged at the first half and second half of the mold discharging directly or indirectly into the cavity. The injection mold comprises the at least one adapter which form part of one of the mold halves. In a preferred embodiment that at least one adapter is selected in cylindrical shape. Thus at least one adapter having a clamping means to temporarily receive and hold the conductor. One or more adapter is arranged displace-able independent of a movement of the mold halves.
[0051] In one embodiment the injection nozzle discharges into the cavity through a gap designed to act as a thin film gate, and this gap is interconnected to a mould cavity of required geometry/dimensions into which the material is to be discharged. The gap is a variable geometry in circumferential direction and/or have several segments. The material is injected by one distribution channel arranged at a circumferential position with respect to the bushing geometry. The distribution channel partially encompasses the bushing. In a preferred embodiment the distribution channel is separated in segments.
[0052] In one embodiment the injection compression molding process increases the advantages of the injection molding process, which helps to reduce residual stress in the part through the evenly distributed pressure throughout the mold cavity during the compression step. The pressure distribution which leads to a superior surface quality, when used in combination with a mirror polished mold cavity surface. Also, the bushing surface having a surface roughness that is as low as possible resides in that electric field is locally less intensified at the insulator surface compared to bushing surface having a higher roughness.
[0053] In a preferred embodiment the so-derived additive-mixed polymer mix is now poured into an alloy steel mold with required geometry and dimension depending on the dimension and geometry/profile of the composite body is fabricated.
[0054] In one embodiment, to fabricate the bushing which is a composite body by molding with the homogeneous resin mix prepared according to the former one by providing alloy steel die fabricated to the required dimension of the bushing and letting into the mold the homogeneous resin mix which is in low viscosity liquid state under a pressure of 2-4 atmospheres. In a preferred embodiment, another way to fabricate the composite body by maintaining the temperature of the mold at about 130-150 deg. C, thereby keeping the epoxy mix under these conditions in the mold for a period of 30-50 minutes for gelling and then post curing the insulator (3) in an air-circulating oven for a period of 8-12 hours at 130-140 deg. C to help in cohesive bonding of the resin and the hardener system.
[0055] These moulds comprise of two halves interacting along a parting plane, encompassing at least one cavity corresponding to the bushing. This injection moulding process utilizes the automatic pressure gelation (APG) technique, with the nozzle facilitating the precise delivery of material into the mould. The adapters, often cylindrical in shape, play a crucial role in receiving and temporarily holding the brass bush and conductor during the moulding process, ensuring proper alignment and positioning.
[0056] The composition of a polymer mixes for high voltage insulation comprises of a base polymer in a range of 90 to 100 parts by weight, an inorganic additive system comprising micro structured alumina or silica powder in a range of 40 to 70 parts by weight, a pigment in a range of 0.5 to 2.0 parts by weight, an accelerator in a range of 0.5 to 2.0 parts by weight and a carboxylic acid anhydride hardener in a range of 90 to 100 parts by weight.
[0057] The base polymer is selected from a group of epoxy resin comprising of Bisphenol and the base polymer is incorporated with 2%-10% content by volume of hollow glass microsphere to reduce density and increase volume.

[0058] The chemical composition is illustrated in Table.1 below, by injection compression moulding in which the inorganic additive system comprising i) micro structured alumina (40-70 part by weight), ii) white or brown pigment (0.5 – 2.0 part by weight), iii) accelerator (0.5 – 2.0 part by weight) and in the desired proportion are to be mixed homogeneously with the epoxy resin Biphenyl ‘A’ (90 – 100 parts) along with the carboxylic acid anhydride hardener (90 – 100 parts) in a mixing chamber for a period of 6 – 10 hours using a homogenizer by maintaining a temperature of the mixing chamber in the range of 60-650C with counter vacuum level in the range of 4-5 Torr in order to get an additive-mixed polymer dough. The range of formulations comprising inorganic additive and the polymer along with its counter hardener is furnished in the Table 1.
Table 1: Composition of the Composite Body
Micro structured alumina or silica filler/additive system (part by weight) Pigment white or brown color (part by weight) Accelerator (part by weight) Bisphenol ‘A’ (parts be weight) Carboxylic acid anhydride as hardener (parts by weight)
40-70 0.5 – 2.0 0.5 – 2.0 90 – 100 90 – 100

[0059] The so-derived additive-mixed polymer mix is now poured into an alloy steel mold with required geometry and dimension depending on the dimension and geometry/profile of the composite body to be fabricated. The same bushing is tested electrical properties as mentioned in Table.2. Test results confirm that the developed bushing as in FIG.1 complies with the international standards.
[0060] In one eembodiment for the fabrication of the a medium voltage electrical bushing (3), the inorganic additive system comprising i) micro structured silica (40-70 part by weight), ii) brown pigment (0.5 – 2.0 part by weight), iii) accelerator (0.5 – 2.0 part by weight) and in the desired proportion are to be mixed homogeneously with the epoxy resin Bisphenol ‘A’ (90 – 100 parts) along with the carboxylic acid anhydride hardener (90 – 100 parts) in a mixing chamber for a period of 6 – 10 hours using a homogenizer by maintaining a temperature of the mixing chamber in the range of 60-650C with counter vacuum level in the range of 4-5 Torr in order to get an additive-mixed polymer dough. The range of formulations comprising inorganic additive and the polymer along with its counter hardener is furnished in the Table 1.
[0061] In one embodiment for the fabrication of the medium voltage electrical bushing (3), the inorganic additive system comprising i) micro structured spherical glass bubbles (2-10 part by weight), ii) brown pigment (0.5 – 2.0 part by weight), iii) accelerator (0.5 – 2.0 part by weight) and in the desired proportion are to be mixed homogeneously with the epoxy resin Bisphenol ‘A’ (90 – 100 parts) along with the carboxylic acid anhydride hardener (90 – 100 parts) in a mixing chamber for a period of 6 – 10 hours using a homogenizer by maintaining a temperature of the mixing chamber in the range of 60-650C with counter vacuum level in the range of 4-5 Torr in order to get an additive-mixed polymer dough. The range of formulations comprising inorganic additive and the polymer along with its counter hardener is furnished in the Table 2.
Table 2: Composition of the Composite Body
Micro structured spherical glass bubbles filler/additive system (part by weight) Pigment white or brown color (part by weight) Accelerator (part by weight) Bisphenol ‘A’ (parts be weight) Carboxylic acid anhydride as hardener (parts by weight)
2-10 0.5 – 2.0 0.5 – 2.0 90 – 100 90 – 100

[0062] In a preferred embodiment the Bisphenol ‘A’ epoxy resin is a reaction product of Bisphenol ‘A’ with epichlorohydrin or the like, which is known in the art. The Bisphenol ‘A’ epoxy resin used in the medium voltage electrical bushing for insulating high voltage conductor (1) for electric traction application usually has an epoxy equivalent of 170 or more. Suitable heat curing hardeners of carboxylic acid anhydride type matching with the epoxy resins are selected based on the requirement.
[0063] In a preferred embodiment the identified polymers are of Bisphenol ‘A’ epoxy resin, which is a reaction product of Bisphenol ‘A’ with epichlorohydrin or the like that normally has an epoxy equivalent of 170 or more. However, the additive system along with the process mentioned is also applicable to similar group of polymers.
[0064] In a preferred embodiment the selected polymer is Bisphenol ‘A’, a hardener, carboxylic acid anhydride is also to be used along with the polymer for accelerating the setting and hardening process of the polymer. The hardener is selected on the basis of compatibility of mixing and hardening process to that of its base polymer. In one embodiment, another equivalent hardener is also used with base polymer.
[0065] In a preferred embodiment a silica or alumina filled epoxy resin formulation is used for improved capacitance, Tan delta, partial discharge extinction voltage level and breakdown voltage level. The silica or alumina filled epoxy resin formulation is with protective weather sheds for protection against severe environmental conditions.
[0066] In a preferred embodiment the 2% to 10% content by volume of hollow glass microsphere filler in the epoxy matrix can reduce the density of the resin system and increase the volume of the resin system, which can help to easily fill up the intra-molecular voids thereby improving the electrical, mechanical, thermal properties. Due to the availability of more surface area for these fillers, suitable filler composition improves the properties of the molded epoxy bushing.
[0067] The invention would be more understood in terms of taking various examples, which are explained in the following:
EXAMPLES OF EMBODIEMENT:
Example 1:
[0068] The medium voltage electrical bushing for insulating high voltage conductor (1) for electric traction application with medium voltage conductor (1) supported by circular shaped aluminum metal insert/aluminum flange (4) which is connected to electrically grounded enclosure are manufactured as per the chemical composition mentioned in Table.1 above, by injection compression molding in which the inorganic additive system comprising i) micro structured alumina or silica (40-70 part by weight), ii) white pigment (0.5 – 2.0 part by weight), iii) accelerator (0.5 – 2.0 part by weight) and in the desired proportion are to be mixed homogeneously with the epoxy resin Biphenyl ‘A’ (90 – 100 parts) along with the carboxylic acid anhydride hardener (90 – 100 parts) in a mixing chamber for a period of 6 – 10 hours using a homogenizer by maintaining a temperature of the mixing chamber in the range of 60-650C with counter vacuum level in the range of 4-5 Torr in order to get an additive-mixed polymer dough. The range of formulations comprising inorganic additive and the polymer along with its counter hardener is furnished in the Table 1. The so-derived additive-mixed polymer mix is now poured into an alloy steel mold with required geometry and dimension depending on the geometry/profile of the composite body to be fabricated. The same bushing is tested for electrical properties as mentioned in Table.2. Test results confirm that the developed bushing as in Fig.1 complies with the international standards.
EXAMPLE 2:
[0069] A medium voltage electrical bushing for insulating high voltage conductor (1) for electric traction application with medium voltage conductor (1) supported by circular shaped aluminum metal /aluminum bushes (fig 2b) instead of circular shaped aluminum metal insert/aluminum flange (4) (fig 2a) as mentioned in Example 1 which are interposed at specified locations in circular shape manner connected to electrically grounded enclosure are manufactured as per the chemical composition mentioned in Table.1 above, according to steps mentioned in Fabrication/Manufacturing of the bushes (2) mentioned bushing is tested for electrical properties as mentioned in Table.2. Test results confirm that the developed bushing as in Fig.1 complies with the international standards.
EXAMPLE 3:
[0070] A medium voltage electrical bushing for insulating high voltage conductor (1) for electric traction application with high voltage conductor (1) supported by Stainless Steel (S.S) metal bushes (fig 2b) instead of circular shaped aluminum metal insert/aluminum flange (4) (fig 2a) as mentioned in Example 1 which are interposed at specified locations in circular shape manner connected to electrically grounded enclosure are manufactured as per the chemical composition mentioned in Table.1 above, according to steps mentioned in Fabrication/Manufacturing of the bushes (2) mentioned in example 1. The same bushing is tested electrical properties as mentioned in Table.2. Test results confirm that the developed bushing as in Fig.1 complies with the international standards.

ADVANTAGES OF THE INVENTION

[0071] The proposed method has the following advantages over the contemporary prior arts:
• Enhanced Insulation: Incorporation of microstructure alumina or silica powder significantly boosts insulation properties, ensuring reliable performance even in high voltage environments.
• Superior Strength: The inclusion of inorganic additives reinforces the polymer matrix, resulting in medium voltage electrical bushings with exceptional mechanical strength, reducing the risk of breakdown or failure.
• Customizable Formulation: The formulation allows for tailored adjustments, facilitating customization to meet specific performance criteria and application requirements.
• Accelerated Production: Integration of an accelerator expedites the curing process, reducing production time and enhancing manufacturing efficiency without compromising quality.
• Environmental Sustainability: By incorporating hollow glass microspheres to reduce density and increase volume, the invention promotes material efficiency and potentially reduces environmental impact, aligning with sustainable manufacturing practices.

TEST RESULT:

[0072] The derived composite body / bushing is subjected to the requisite dielectric tests like proof voltage, dissipation factor, and breakdown voltage as per the specified test procedures to obtain the properties enlisted in Table 3.
Table 3. Properties of a bushing composite body
AC high voltage withstand test (one minute) Dissipation factor Partial discharge test
More than 100 kV 0.00010 – 0.00012 PD less than 5 pct.
[0073] In a preferred embodiment the silica filled epoxy resin formulation reduces weight and size of the insulator (3). The insulator (3) having reduced weight as enlisted in Table 4.
Table.4 Weight of the insulator composite Body
Weight of the bushing Body with ceramic insulation system in kgs Weight of the bushing Body composite insulation system in kgs (Silica or Alumina s filer/additive system) Weight of the bushing Body composite insulation system in kgs (micro structured spherical glass bubbles)
40-50 25-30 18-20

WORKING OF INVENTION:
[0074] The present invention enhances medium voltage electrical bushings for industries like power distribution, renewable energy, EV charging, rail transportation, and manufacturing. Improved insulation, strength, and efficiency promote reliability and sustainability, addressing diverse industry needs in modern infrastructure.

[0075] The above description does not provide specific details of the manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art are capable of choosing suitable manufacturing and design details.

[0076] Further, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other fixture or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.

[0077] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.

[0078] It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different fixture or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
, Claims:1. A medium voltage electrical bushing (100) for insulating medium voltage conductor, the medium voltage electrical bushing (100) comprising:

a medium voltage conductor (1);
an insulator (3) coupled with the medium voltage conductor (1);
a brass bush (2) connected to the medium voltage conductor (1), configured as a mechanical stopper and support for fasteners during connection to another conductor from an overhead line; and
a metallic flange (4) connected to the insulator (3) connecting the bushing (100) to a grounded metal enclosure of a locomotive / electric traction system.
2. The medium voltage electrical bushing (100) as claimed in the claim 1, wherein the metallic flange (4) is configured to accommodate various shapes including a circular-shaped alloy insert / flange.
3. The medium voltage electrical bushing (100) as claimed in the claim 1 or 2, wherein the metallic flange (4) is made up of one / more compatible metal, alloy / composite, wherein the one / more compatible metal comprises of aluminum and stainless steel.
4. A method of manufacturing a medium voltage electrical bushings for insulating medium voltage conductors in electric traction applications(200), the method(300) comprising:
configuring(302), a mould with a first half and a second half interacting along a parting plane;
forming(304), a cavity corresponding to the medium voltage electrical bushing within the mould;
positioning(306), a nozzle at the first half of the mould for discharging liquefied material into the cavity;
closing(308), the mould by relative movement of the first half with respect to the second half until the cavity is sealed;
injecting(310),a polymer composite dough and a liquefied material through the nozzle; and
opening(312), the mould by relative movement of the first half with respect to the second half and removing the bushing from the mould cavity.
5. The method as claimed in the claim 4, wherein the moulds for manufacturing medium voltage electrical bushings comprises of:
a first half and a second half interacting along a parting plane;
at least one cavity corresponding to the bushing, encompassed by the first and second halves;
at least one adapter for holding a conductor during injection moulding; and
an injection nozzle arranged at the first and second halves of the mould for discharging liquefied material into the cavity.
6. The method as claimed in the claim 4 or 5, wherein the mould is an injection mould, using automatic pressure gelation (APG) technique in the first half of the mould and the nozzle is an injection nozzle arranged at the first half and second half of the mould for discharging liquefied material into the cavity.
7. The method as claimed in the claim 5, wherein the injection mould comprises at least one adapter which forms part of one of the mould halves, wherein the adapter has a cylindrical shape, wherein the mould comprises at least one adapter to receive and temporarily hold the brass bush (2) and the conductor (1) during the moulding, wherein at least one adapter comprises of clamping means to temporarily receive and hold the conductor (1).
8. The method as claimed in the claim 5, wherein the injection nozzle discharges into the cavity through a variable geometry gap designed as a thin film gate, interconnected to the mould cavity, and arranged with one / more distribution channels partially encompassing the bushing, wherein the distribution channel is segmented, and the injection nozzle is arranged to inject material through one / more segments of the distribution channel.
9. The method as claimed in the claim 5, wherein the composition of a polymer mixes for high voltage insulation comprises of:
a base polymer in a range of 90 to 100 parts by weight;
an inorganic additive system comprising micro structured alumina / silica powder in a range of 40 to 70 parts by weight;
a pigment in a range of 0.5 to 2.0 parts by weight;
an accelerator in a range of 0.5 to 2.0 parts by weight; and
a carboxylic acid anhydride hardener in a range of 90 to 100 parts by weight.
10. The method as claimed in the claim 5, wherein the base polymer is selected from a group of epoxy resin comprising of Bisphenol, wherein the base polymer is incorporated with 2%-10% content by volume of hollow glass microsphere to reduce density and increase volume.