FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
1. Title of the invention: AN ELECTRICAL INSULATOR
2. Applicant(s)
NAME
NATIONALITY
ADDRESS
RAYCHEM RPG PVT. LTD
Indian
463, Dr Annie Besant Road, Worli, Mumbai, Maharashtra 400 030, India
3. Preamble to the description
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it is to be performed.
1
FIELD OF THE INVENTION
[001]
The present invention relates in general to insulators and is particularly concerned with the details of construction of a polymeric 5 insulator hardware and fittings.
BACKGROUND OF THE INVENTION
[002]
High voltage electrical insulators may be used in power plants, transmission substations, distribution substations, overhead transmission lines or high voltage power equipments. Traditionally High voltage electrical 10 insulators have been constructed of glass, ceramic or porcelain. These materials allowed the manufacturing of insulators such as post insulators and cap and pin suspension insulators. Under normal conditions, these insulators give a long service life despite exposure to weathering, mild contamination, and electrical stress and leakage currents. However, under 15 conditions of severe contamination, frequent cleaning or coating with silicone grease-like compounds is found necessary to prevent excessive leakage currents.
[003]
The ceramic and porcelain insulators are heavy and bulky. They also require specialized assembly fixtures or processes and are difficult to 20 handle and carry. The ceramic insulators are brittle and can easily be chipped or broken. Composite insulators (also called polymeric insulators) are preferred nowadays because of their advantages over the porcelain and glass insulators.
[004]
A polymeric electrical insulator generally comprises a FRP (fiber-25 reinforced plastic) rod forming the core of the insulator, an insulation overcoat member in the form of multiple sheds (also called fins) made of polymeric material arranged on the outer surface of the FRP rod and secured end fittings clamped at both end portions of the FRP rod. The end fittings are generally made of some electrically conducting material. In order 30 to satisfy requirement for a high tensile strength, the metal fitting is usually comprised of a high-tension steel or ductile cast iron. The polymeric 2
insulator is electrically connected in the circuit from the end fittings.
[005]
The end fittings are generally in the form of hollow cylinders with one end closed forming a sleeve portion with a bore. The two end portions of the FRP rod are inserted in the sleeve portion of the end fitting and the end fitting is then fixedly secured to the FRP rod by compressing the end fitting 5 radially inwards onto the FRP rod to firmly clamp the rod. By crimping the end fitting radially inwards, the region of the FRP rod aligned with the end fitting is uniformly clamped to integrally connect the end fitting with the FRP rod and prevent withdrawal of the FRP rod to form the polymeric insulator.
[006]
There are other forms of composite insulators where the end fitting 10 is made of porcelain and are fixed on the FRP rod with metallic fixtures. Alternatively, the porcelain end fitting is joined to the FRP rod ends by cementing. The arrangement wherein the metallic end fitting is cemented to the FRP rod has proved unsatisfactory due to the difference in the coefficients of expansion between the metal and the FRP. This reaction to 15 the changes of temperature causes the cement to crack and deteriorate, resulting in decrease of the operating characteristics of the insulator to such an extent that it must either be repaired or replaced.
[007] Similarly, in the arrangement wherein the metal end fitting is crimped and is in direct contact with the FRP rod, the different coefficients of 20 expansion of the metal and FRP may cause cracking of the FRP or loosening of the joint. Moreover, the arrangement wherein the FRP is moulded into the end fitting is subject to the same inherent disadvantages as in the other cases where the metal fitting is in direct contact with the insulating FRP rod. 25
[008] Due to the rigidity of the metal end fitting which is considerably higher than that of the FRP rod, even a slight unevenness in the outer surface of the rod end portion or the inner surface of the bore of the end fitting may cause a local deformation in adjacent outer surface region of the FRP rod, giving rise to a residual internal stresses. In such situation, when 30 the composite insulator is subjected to an axial tensile force, the internal stresses are multiplied in the end portion of the FRP rod which is clamped 3
within the sleeve
of the end fitting, causing a high degree of stress concentration and thereby giving rise to damages or breakage of the rod within a relatively short period. This results in failure of the composite insulator to perform its intended function as per requirement and the insulator is discarded even before use. 5
[009] During a flashover in electrical insulators, electricity flashes directly from a conducting end to a grounded end of the insulator. The electricity travel gap between the conducting end and the grounded end is called the “creepage length”. The flashover happens when the creepage length is reduced due to depositions of water, dirt, debris, salts, air-borne material, 10 and air pollution on the insulator surface and provide a low resistance path for the electrical current. To prevent this phenomenon, insulators are made in many different sizes to provide different creepage lengths, as determined by operating voltages and environmental conditions of the insulators. The creepage distance in air is known, thus insulators must be made of various 15 sizes in order to increase this distance and match the appropriate size insulator for the required voltage. However, the method of crimping the end fitting on the end portions of the FRP rod is done at the plant and restricts any changes to be done as per the shape and size of the insulator requirement on site. 20
[0010]
Replacing the crimping process by the use of adhesives to join the end fitting with end portion of the FRP rod has been attempted, however the required pull-out strength was not achieved.
[0011] In view of the limitations inherent in the available composite 25 insulators, there exists a need for an improved method for connecting the end fitting with the FRP rod and an adhesive which overcomes the disadvantages of the prior art and which can be used in a simple, cost effective, reliable, secure and environmentally friendly manner.
[0012] The present invention fulfils this need and provides further 30 advantages as described.
BRIEF DESCRIPTION OF THE DRAWINGS
4
[0013]
The advantages and features of the present invention will become better understood with reference to the following more detailed description taken in conjunction with the accompanying drawings. The use of the same reference number in different figures indicate similar or identical features and components. 5
[0014] FIG. 1 illustrates a cross sectional view of an electrical insulator, according to one embodiment of the present invention;
[0015] FIG. 2A illustrates a cross sectional view of an end fitting of the electrical insulator, according to one embodiment of the present invention; 10
[0016] FIG. 2B illustrates an isometric view of an insulating rod of the electrical insulator, according to one embodiment of the present invention.
[0017]
FIG. 3 illustrates a method of producing an electrical insulator, 15 according to an example implementation of the present subject matter;
[0018]
FIG. 4 illustrates a method of producing an electrical insulator, according to another example implementation of the present subject matter; 20
[0019]
It may be noted that throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements. The figures are not necessarily to scale, and the size of some parts may be exaggerated to more clearly illustrate the example shown. Moreover, the drawings provide examples and/or implementations consistent with the 25 description; however, the description is not limited to the examples and/or implementations provided in the drawings.
DETAILED DESCRIPTION
[0020]
In the following description, for purposes of explanation, numerous 30 specific details are set forth in order to provide a thorough understanding of 5
the present invention. It will be apparent, however, to one skilled in the art
that the present invention may be practiced without these specific details.
[0021]
As used herein, the term ‘plurality’ refers to the presence of more than one of the referenced item and the terms ‘a’, ‘an’, and ‘at least’ do not 5 denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.
[0022]
Reference herein to “one embodiment” or “another embodiment” means that a particular feature, structure, or characteristic described in 10 connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Further, the 15 diagrams representing one or more embodiments of the invention do not inherently indicate any particular order nor imply any limitations in the invention.
[0023]
The present subject matter provides an electrical insulator that 20 overcomes the above-described problems associated with the conventional electrical insulator by providing an improved joint between an insulating rod and end fittings of the electrical insulator.
[0024]
In an example, the electrical insulator comprises an insulating rod 25 made of a first insulating material. The rod comprises two end portions and a middle portion. An outer surface of the insulating rod at each of the two end portions may comprise plurality of coupling members. The electrical insulator may also comprise a pair of end fittings made of an electrically conducting material. Each end fitting in the pair of end fittings comprises a 30 hollow sleeve having a closed end and an open end to allow one of the two end portions to be inserted therein. Further, an inner surface of each end 6
fitting in the pair end fittings may comprise plurality of complementary
coupling members formed thereon. Each end fitting in the pair of end fittings may be fixedly attached to one of the end portions inserted therein using an adhesive. The plurality of coupling members formed on the outer surface of each of the two end portions accommodates the plurality of complementary 5 coupling members formed on the inner surface of respective end fitting when the end portion is inserted in the end fitting.
[0025] Formation of coupling members, such as grooves on the outer surface of insulating rod and complementary coupling members, such as 10 protrusions on the inner surface of end fittings increases a surface area of contact between the insulating rod and the sleeves of end fittings, thereby doubling the pull-out strength of the joint between the insulating rod and the end fittings as compared to a smooth surface. Further, formation of a layer of adhesive between the outer surface of insulating rod comprising coupling 15 members and the inner surface of end fittings comprising complementary coupling members increases adhesive strength, since the pull-out strength thus obtained is equivalent to mechanical joint. Since the end fitting need not to be moulded as part of the insulating rod or to be crimped, it can be joined with the insulating rod on site as per the requirement eliminating the 20 need of complex tools for joining the insulating rod and end fittings as compared to other methods such as crimping and mechanical fixtures. The adhesive boding does not allow any loosening of the joint and prevents any slippage between the insulating rod and the end fittings, which may otherwise lead to insulator failure. 25
[0026] The above and other features, aspects, and advantages of the subject matter will be better explained with regard to the following description and accompanying figures. It should be noted that the description and figures merely illustrate the principles of the present subject 30 matter along with examples described herein and should not be construed as a limitation to the present subject matter. It is thus understood that 7
various arrangements may be devised that, although not explicitly described
or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and examples thereof, are intended to encompass equivalents thereof. Further, for the sake of simplicity, and without limitation, the same numbers are used throughout 5 the drawings to reference like features and components.
[0027] FIG. 1 illustrates an electrical connector 100, according to an example embodiment of the present subject matter. The electrical insulator 100 comprises an insulating rod 102 made of a first insulating material. In 10 an example, the first insulating material may be a polymeric material such as a fiber reinforced plastic (FRP). The insulating rod 102 may comprise two end portions 106 and a middle portion 110 between the two end portions 106. In an example, a cross-section of the insulating rod 102 may be of any geometric shape such as circular, oval, rectangular, triangular, hexagonal 15 and the like. In an example, the insulating rod 102 is cylindrical in shape.
[0028]
In an example implementation, the middle portion 110 of the insulating rod 102 is coated with a second insulating material. In an example, the second insulating material may be a polymeric material and is 20 different than the first insulating material. The coating of second insulating material forms a polymeric shed over the middle portion 110 of the insulating rod 102.
[0029]
In an example, an outer surface of the insulating rod 102 at each of 25 the two end portions 106 may comprise plurality of coupling members 112. In an example, the plurality of coupling members 112 may be a plurality of grooves formed on the outer surface of the insulating rod 102 at the two end portions 106. In an example, the plurality of grooves 112 are threaded grooves. In another example, the grooves 112 may be of any shape such 30 as circular groove, helical groove, spiral groove or a combination of these 8
groves. In another example, the coupling members may be any pattern
formed on the outer surface of the insulating rod.
[0030]
The electrical insulator 100 may also comprise a pair of end fittings 104. Each end fitting 104 in the pair of end fittings 104 may be made of an 5 electrically conducting material such as a conducting metal, porcelain, composite material or a combination thereof. In an example, each end fitting 104 in the pair of end fittings comprises a hollow sleeve 108. The hollow sleeve 108 may have a closed end and an open end to allow one of the two end portions 106 to be inserted therein. The cross-section of the hollow 10 sleeve 108 may be similar to the cross-section of the insulating rod 102.
[0031]
In an example, an inner surface of each end fitting 104 in the pair end fittings may comprise plurality of complementary coupling members 114 formed thereon. The plurality of complementary coupling members 114 of 15 an end fitting 104 are to be accommodated in the plurality of coupling members 112 of an end portion 106 of the insulating rod 102 when the end portion 106 of the insulating rod 102 is inserted in the end fitting 104. Accordingly, a shape of plurality of complementary coupling members 114 corresponds to a shape complementary to that of the plurality of coupling 20 members 112. Thus, if plurality of coupling members 112 are plurality of grooves 112, then plurality of complementary coupling members 114 may be plurality of protrusions 114 formed on the inner surface of the end fittings 104. In an example, the plurality of protrusions 114 are threaded protrusions to correspond to the threaded grooves 112 formed on outer surface of the 25 insulating rod 102. In another example, the protrusions 114 may be of any shape such as circular protrusions, helical protrusions, spiral protrusions or a combination of these protrusions. In another example, the complementary coupling members 114 may be any complementary pattern formed on the inner surface of an end fitting 104 corresponding to the plurality of coupling 30 members 112 formed on the outer surface of the insulating rod 102.
9
[0032] In an implementation of the present subject matter, each end fitting 104 in the pair of end fittings may be fixedly attached to one of the end portions 106 inserted therein using an adhesive. The plurality of coupling members 112 formed on the outer surface of each of the two end portions 106 accommodates the plurality of complementary coupling members 114 5 formed on the inner surface of respective end fitting 104 when the end portion 106 is inserted in the end fitting 104. For instance, if plurality of coupling members 112 are plurality of grooves and plurality of complementary coupling members 114 are plurality of protrusions, the plurality of protrusions 114 on the inner surface of the end fitting 104 are 10 accommodated in the plurality of grooves 112 on the outer surface of the end portion 106 inserted in the end fitting 104. When an end portion 106 of the insulating rod 102 is inserted in an end fitting 104, a layer of adhesive 116 is formed between the plurality of coupling members 112 formed on the outer surface of the end portion 106 and the plurality of complementary 15 coupling members 114 formed on the inner surface of the end fitting 106. In an example, a thickness of the layer of adhesive 116 formed between an end portion 106 from amongst the two end portions 106 and the respective end fitting 104 is in a range of 0.20 ± 0.05 mm.
20
[0033]
In an example, the adhesive may be a material suitable for the purpose to join two dissimilar materials such as FRP and metal, FRP and porcelain, FRP and composite material and other such combinations. In one embodiment of present invention, the adhesive may comprise component A and component B in a ratio of 2:1. The component A may include epoxy 25 resin in a range of 73.55 to 92.5 percentage in weight, grafted base resin with at least one of rubber block copolymer and flexible copolymer in a range of 5 to 15 percentage in weight, glass oxide chemical in a range of 1 to 5 percentage in weight, treated fumed silica in a range of 1 to 5 percentage in weight, and Titanium dioxide (TiO2) in a range of 0.5 to 1.5 percentage in 30 weight. 10
[0034]
In an example, the component B may include polyamide in a range of 98 to 99 percentage in weight, polyalkyl polyamine as 1 percentage in weight and fumed Silica or TiO2 in a range of 0 to 1 percentage in weight.
[0035]
In an example, the component A and B may be separately prepared 5 and mixed in a ratio 0f 2:1 and allowed to cure at room temperature to form rigid joint.
[0036]
In one embodiment of the present invention, the component A may include epoxy resin as 75 percentage in weight, grafted base resin with at 10 least one of rubber block copolymer and flexible copolymer as 15 percentage in weight, glass oxide chemical as 4 percentage in weight, treated fumed silica as 5 percentage in weight and TiO2 as 1 percentage in weight. Similarly component B may include polyamide as 98.5 percentage in weight, polyalkyl polyamine as 1 percentage in weight and fumed Silica 15 or TiO2 as 0.5 percentage in weight.
[0037]
The base resin is grafted or modified with rubber or flexible block copolymer to optimize the adhesion shear and bulk modulus and cross-link density of adhesive of the present invention to achieve synergistic property 20 balance. In one embodiment of the present invention, the grafted base resin with at least one of rubber block copolymer and flexible Copolymer may include at least one of Nitrile Butadiene Rubber NBR, Carboxyl-terminated Butadiene Acrylonitrile CTBN, Styrene-Ethylene-Butylene-Styrene SEBS, Styrene-Butadiene-Styrene SBS, Styrene-Butadiene BS, Chloroprene 25 Rubber CR, Natural Latex, Butadiene Rubber BR.
[0038]
The adhesive of the present invention is suitable for joining similar or dissimilar materials such as polymers, composites, alloy etc. The curing of the adhesive may happen at room temperature or elevated temperature, 30 which can be done at manufacturing site or at the installation site.
11
[0039]
In one preferred embodiment of the present invention, the component A and B are mixed in a ratio of 2:1. The processing properties of the adhesive used are as per below table:
Processing Properties:
Parameter
Value
Tolerance
I
Appearance (A/B)
Yellowish/ Brownish
II
Specific Gravity (A / B) in gm/ cc
1.49/ 0.96
±0.05
III
Viscosity (A / B) @RT in cps
40K/ 45K
±10K
IV
Pot life (A+B) in Minutes
30
±5
V
Mixing Ratio A : B in %
100:50
±2%
VI
Storage life (A & B) in Month
12/ 6
±1
5
[0040]
FIG. 2A illustrates an isometric view of the insulating rod 102 in accordance with an example embodiment of the present subject matter. In the embodiment illustrated in FIG 2A, the plurality of grooves 112 formed on the outer surface of the insulating rod 102 at the two end portions 106 are circular grooves. The circular groove may be a groove which is 10 perpendicular to the axis of the FRP rod and the sleeve of end fitting. In an example, the circular groove has a depth of 0.5 mm and a pitch as 7 mm. A pitch of groove may be understood as a length of a portion comprising the grooves to the groove number. FIG 2B illustrates a cross-sectional view of an end fitting 104 in accordance with an example embodiment of the present 15 subject matter. In the embodiment illustrated in FIG 2A, the cross-sectional view is illustrated along an axis of the end fitting 104, passing through its 12
centre and the plurality of
complementary coupling members 114 formed on the inner surface of the end fitting are plurality of circular protrusions.
[0041]
FIG. 3 illustrates a method 200 of producing an electrical connector, according to an example implementation of the present subject matter. 5
[0042]
At block 202, a layer of adhesive is applied on an outer surface of each of two end portions 106 of an insulating rod 102 and on an inner surface of each end fitting 104 in a pair of end fittings. In an example, the adhesive is an epoxy resin adhesive described above. The insulating rod 10 102 may be made of a first insulating material and the pair end fittings 104 may be made of an electrically conducting material. The first insulating material may be a polymeric material such as FRP. In an example, a middle portion 110 is formed between the two end portions 106 of the insulating rod 102 and may be coated with a second insulating material. In an 15 example, the second insulating material may be a polymeric material different than the first polymeric material. Each end fitting 104 in the pair of end fittings may comprise a hollow sleeve 108 having a closed end and an open end to allow one of the two end portions 106 of the insulating rod 102 to be inserted therein. Further, plurality of coupling members 112 such as 20 grooves may be formed on an outer surface of each of the two end portions 106 to accommodate plurality of complementary coupling members 114 such as protrusions formed on an inner surface of each end fitting 104 when the corresponding end portion 106 is inserted in the end fitting 104. 25
[0043]
At block 204, an end portion 106 from amongst the two end portions 106 of the insulating rod 102 is inserted in an end fitting 104 in the pair of end fittings 104.
[0044] At block 206, the layer of adhesive 116 is allowed to be cured for a 30 predetermined period of time to fixedly attach the end portion 106 to the respective end fitting 104.
13
[0045]
FIG. 4, illustrates a method 300 of producing an electrical connector, according to another example implementation of the present subject matter.
[0046] The method starts at block 302 with providing a pre-fabricated 5 insulting rod 102 and a pair of end fittings 104. The insulating rod 102 1may comprise two end portions 06 and a middle portion 110 between the two end portions 106 such that each end portion 106 of the insulating rod 102 is adapted to be connected to an end fitting 104 in the pair of end fittings. In an example, the insulating rod 102 may be a solid cylindrical rod made of 10 FRP material. The cross section of the insulating rod 102 is not limited to circular and in another embodiments, it may have other cross-sectional shapes also such as triangular, rectangular or polygonal. In an example, a polymeric shed is pre-molded on the insulating rod 102 leaving the two end portions 106 of the insulating rod 102 uncovered. These two end portions 15 106 are used to make joint with the end fittings 104.
[0047] In an example, each end fitting 104 in the pair of end fittings 104 comprises a hollow sleeve 108 having an open end and a closed end. The open end of each end fitting is adapted to receive an end portion 106 of the 20 insulating rod 102 and dimensions of the end fittings 104 are matched with the insulating rod 102 so as to achieve a tight fit. In an example, an inner cross-sectional shape of each end fitting 104 is same as a cross-sectional shape of the insulating rod 102. In one embodiment of the present invention, each end fitting 104 is made of metal, porcelain, composite material or a 25 combination of these.
[0048]
At block 304, an outer surface of the insulating rod 102 at the two end portions 106 is etched to form a plurality of grooves 112 and an inner surface of each end fitting 104 in the pair of end fittings 104 is etched to 30 form a plurality of protrusions 114.
14
[0049] At block 306, an epoxy resin adhesive is applied on the inner surface of each end fitting 104 in the pair of end fittings 104 and on the outer surface of the insulating rod 102 at each of the two end portions 106. In an example, the epoxy resin adhesive is the above-described adhesive comprising the component A and the component B. 5
[0050] At block 308, the outer surface of each end portion 106 having adhesive applied thereon is aligned with the inner surface of an end fitting 104 in the pair of end fittings 104 having adhesive applied thereon.. To align the outer surface of an end portion 106 with the inner surface of the 10 respective end fitting 104, the end portion 106 is inserted in the respective end fitting 104. The plurality of grooves 112 formed on the outer surface of each of the two end portions 106 accommodates the plurality of protrusions 114 formed on the inner surface of respective end fitting 104 when the end portion 106 is inserted in the end fitting 104. An assembly of the insulating 15 rod 102 and the end fittings 104 is kept for some time to allow the adhesive to cure for a prespecified time to make joint between the end portions 106 of the insulating rod 102 and the respective end fitting 104 permanent. The adhesive after curing forms a solid layer 116 and takes the shape of the space between the grooves 112 of the insulating rod 102 and the 20 protrusions 114 of the end fittings 104. For example, the adhesive forms a zig-zag layer 116 by filling in a space between the grooves 112 of the end portions 106 and the protrusions 114 of the end fittings 104 as illustrated in FIG.1. In one embodiment of the present invention, the thickness of the layer of adhesive 116 between the grooves 112 of insulating rod 102 and the 25 protrusions 114 of the end fittings 104 ranges from 0.2 millimeter to 1 millimeter. In a preferred embodiment of the present invention, the thickness of the layer of adhesive may be 0.2 millimeters. Adhesive layer with a thickness of in a range of 0.20 ± 0.05 mm between the protrusions 114 on the internal surface of sleeves 108 of the end fitting 104 and the grooves 30 112 on the outer surface of the insulating rod 102 provides more than double value of pullout strength as compared to available commercial grades of
15
structural adhesive for similar applications on a standard design by gluing
of this adhesive, which is easy to deploy for any similar bonding applications.
[0051]
Further, other standard procedures used in gluing or affixing two 5 surfaces using adhesive such as surface preparation including cleaning, treatment, air venting and the like are performed as available in the state of the art.
[0052]
The electricial insulator of the present invention may provide 10 advantages as below:
- Joining of dis-similar materials: Coupling members 112 such as grooves on the outer surface of the insulating rod 102 and the complementary coupling members 114 such as protrusions formed on the inner surface of the end fittings 104 along with adhesive 15 applied between the inner surface of the end fittings 104 and the outer surface of the insulating rod 102 allow to effectively join the insulating rod 102 and the end fittings 104 made of two dissimilar materials, for example, FRP with at least one of metallic, porcelain, and composite material 20
-
Increased contact area: Formation of coupling members 112 such as grooves on the outer surface of insulating rod 102 and complementary coupling members 114 such as protrusions on the inner surface of end fittings 104 increases a surface area of contact between the insulating rod 102 and the sleeves of end fittings 102, 25 thereby doubling the pull-out strength of the joint between the insulating rod 102 and the end fittings 104 as compared to a smooth surface.
-
Increased Adhesive strength: formation of a layer of adhesive 116 between the outer surface of insulating rod 102 comprising coupling 30 members 112 and the inner surface of end fittings 104 comprising complementary coupling members 114 increases adhesive strength, 16
since the pull
-out strength thus obtained is equivalent to mechanical joint.
- On-site installation: Since the end fitting 104 need not to be moulded as part of the insulating rod 102 or to be crimped, it can be joined with the insulating rod 102 on site as per the requirements. 5
- No Slip Back: The adhesive boding does not allow any loosening of the joint between the end portions 106 of the insulating rod 102 and the end fittings 104 and prevent any slippage between the insulating rod 102 and the end fittings 104, which may lead to insulator failure.
- Ease of installation: Eliminates the need of complex tools for joining 10 the insulating rod 102 and the end fittings 104 as compared to other methods such as crimping and mechanical fixtures.
- High Strength: High strength is provided in the joint between the insulating rod 102 and the end fittings 104 and the strength is equivalent to a mechanical joint, which means the the conventional 15 electrical insulator having mechanical joining of the insulating rod 102 and the end fittings 104 can be replaced with the presently disclosed electrical insulator 100 in an easy and convenient way.
-
Scalable: Electrical insulators having different shapes and sizes can be made easily. 20
[0053]
Although a particular exemplary embodiment of the invention has been disclosed in detail for illustrative purposes, it will be recognized to those skilled in the art that variations or modifications of the disclosed invention, including the rearrangement in the configurations of the parts, 25 changes in steps and their sequences may be possible. Accordingly, the invention is intended to embrace all such alternatives, modifications and variations as may fall within the spirit and scope of the present invention.
[0054]
The foregoing descriptions of specific embodiments of the present 30 invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise 17
forms disclosed, and obviously many modifications and variations are
possible in light of the above teaching.
I/We Claim:
1. An electrical insulator (100) comprising:
an insulating rod (102) made of a first insulating material, the insulating rod (102) comprising two end portions (106) and a middle portion (110), wherein an outer surface of the insulating rod (102) at each of the two end portions (106) comprises plurality of coupling members (112);
a pair of end fittings (104) made of an electrically conducting material, wherein each end fitting (104) in the pair of end fittings (104) comprises a hollow sleeve (108) having a closed end and an open end to allow one of the two end portions (106) to be inserted therein, wherein an inner surface of each end fitting (104) in the pair end fittings comprises plurality of complementary coupling members (114) formed thereon,
wherein each end fitting (104) in the pair of end fittings is fixedly attached to one of the end portions (106) inserted therein using an adhesive, and
wherein the plurality of coupling members (114) formed on the outer surface of each of the two end portions (106) is to accommodate the plurality of complementary coupling members (114) formed on the inner surface of respective end fitting (104) when the end portion (106) is inserted in the end fitting (104).
2. The electrical insulator (100) as claimed in claim 1, wherein the first insulating material is a fiber reinforced polymer (FRP).
3. The electrical insulator (100) as claimed in claim 1, wherein the middle portion (110) is coated with a second insulating material, the second insulating material is a polymeric material and different than the first insulating material.
4. The electrical insulator (100) as claimed in claim 1, wherein the plurality of coupling members (112) comprises plurality of grooves and the plurality of complementary coupling members (114) comprises plurality of

protrusions.
5. The electrical insulator (100) as claimed in claim 4, wherein the plurality of grooves (112) are threaded grooves and the plurality of protrusions (114) are threaded protrusions.
6. The electrical insulator (100) as claimed in claim 1, wherein the adhesive comprises compound A and a compound B mixed in a ratio of 2:1.
7. The electrical connector (100) as claimed in claim 6, wherein the compound A comprises: epoxy resin in a range of 73.55 to 92.5 percentage in weight; grafted base resin with one of rubber block and flexible copolymer in a range of 5 to 15 percentage in weight; glass oxide chemical in a range of 1 to 5 percentage in weight; treated fumed silica in a range of 1 to 5 percentage in weight; and Titanium dioxide TiO2 in a range of 0.5 to 1.5 percentage in weight.
8. The electrical connector (100) as claimed in claim 6, wherein the compound B comprises: polyamide in a range of 98 to 99 percentage in weight; polyalkyl polyamine as 1 percentage in weight; and one of fumed silica and TiO2 in a range of 0 to 1 percentage in weight.
9. The electrical connector (100) as claimed in claim 7, wherein the grafted base resin with at least one of rubber block copolymer and flexible copolymer includes at least one of Nitrile Butadiene Rubber NBR, Carboxyl-terminated Butadiene Acrylonitrile CTBN, Styrene-Ethylene-Butylene-Styrene SEBS, Styrene-Butadiene-Styrene SBS, Styrene-Butadiene BS, Chloroprene Rubber CR, Natural Latex, Butadiene Rubber BR.
10. The electrical connector (100) as claimed in claim 1, wherein a thickness of a layer of adhesive (116) formed between an end portion from amongst the two end portions (106) and the respective end fitting (104) is in a range of 0.20 ± 0.05 mm.
11. A method (200) of producing an electrical connector (100), the
method comprises:

Applying (202) a layer of adhesive (116) on an outer surface of each of two end portions (106) of an insulating rod (102) and on an inner surface of each end fitting (104) in a pair of end fittings (104), wherein the insulating rod (102) is made of a first insulating material and the pair end fittings (104) is made of an electrically conducting material, wherein each end fitting (104) in the pair of end fittings comprises a hollow sleeve (108) having a closed end and an open end to allow one of the two end portions (106) of the insulating rod (102) to be inserted therein, and wherein plurality of coupling members (112) are formed on an outer surface of each of the two end portions (106) to accommodate plurality of complementary coupling members (114) formed on an inner surface of each end fitting (104) when the corresponding end portion (106) is inserted in the end fitting (104);
Inserting (204) an end portion (106) from amongst the two end portions (106) of the insulating rod (102) in an end fitting (104) in the pair of end fittings (104); and
Allowing (206) the layer of adhesive (116) to be cured for a predetermined period of time to fixedly attach the end portion (106) to the respective end fitting (104).