Description:MAINTENANCE-FREE OPTICAL CURRENT TRANSFORMER (OCT) WITH SOLID CORE INSULATOR AND MANUFACTURING PROCESS THEREOF” FIELD OF INVENTION [001] This invention relates to Maintenance-free Optical Current Transformer (OCT) with solid core insulator and manufacturing process thereof. [002] The optical Current Transformer is a high current measurement equipment, which is used in high voltage substations, for metering and protection requirements. BACKGROUND OF THE INVENTION [003] 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. [004] Optical CTs use high voltage hollow insulators, which are of polymeric/composite type, with polarization maintaining optical fiber cable, passing through its inner hollow space. Also, some form of sealing is required for the insulator’s hollow space, to ensure moisture-free inner space, which is a must for any high voltage device. If proper sealing is not implemented, it would lead to flashover and catastrophic failure of the equipment, under high voltage condition. The moisture-free sealing arrangement is implemented either by using vacuum or pressurized inert gas or dry air filling, inside hollow insulator, that carries the optical fiber cable. [005] Current Transformers (CT) are used in high voltage (HV) substations for measurement of continuous and short circuit current. Current measurement is required in substation for control and protection, as well as for metering and billing purposes. Conventional current transformers which have been used for decades in HV substations, work on the principle of electromagnetic induction based current sensing. [006] This HV design arrangement requires maintenance, with regular monitoring of vacuum or gas/air pressure in OCT, during service. [007] In order to address the aforesaid drawbacks, the present invention has been introduced for development of a solid core insulator type OCT, which is totally maintenance-free and does not require any periodic maintenance in terms of vacuum or gas pressure monitoring, during service. The invention also covers the method of manufacturing maintenance-free OCT, using a novel process and the developed system, to implement the process. Prior Art [008] Various innovations and patents cover the different optical techniques and technologies of current sensing, developed for Optical Current Transformers. These techniques are based on Faraday effect which is implemented using either polarimetry or interferometry approach. Patent (ref US3708747) covers the invention of Optical Current Transformer and the invention provides an OCT which is precise and uses the compensation method, which considerably reduces the electric power consumption. Patent (ref US5304920) also titled Optical Current Transformer describes an OCT which is insensitive to environmental influences (temperature fluctuations, vibration etc.), has small dimensions and can be produced in a simple manner. Both the above mentioned patents are related to invention that mainly focusses and covers optics based current sensing technology of OCTs. [009] A Patent (ref US8933686B2) titled, single phase optical current transformer, describes an OCT specifically developed for measuring single phase currents. The invention covers various elements required for optical current sensing viz. a cylindrical container, an electrical conductor arranged in container, a Faraday element etc. and their arrangement for implementing current sensing. [0010] Similarly, a Patent (ref. 20110084688A1) which is related to 3-phase Faraday Optical assembly, provides a method and system for measuring current in 3- phase cable assembly using optical technique. [0011] As mentioned above, mostly all the patents and innovations in the field of Optical current transformers, cover aspects and components related to optics based current sensing technologies, and the design arrangements to implement the same. However, high voltage design aspects, and specifically maintenance-free construction of optical CTs, from the point of view of high voltage design, as claimed in this patent, is not covered in any of the above referred patents/innovations. OBJECTS OF THE INVENTION [0012] Primary object of the invention is to provide Maintenance-free Optical Current Transformer (OCT) with solid core insulator and manufacturing process thereof. [0013] An object of the invention is to provide Maintenance-free Optical Current Transformer (OCT) with solid core insulator and manufacturing process thereof, which obviates shortcomings of the prior art(s). [0014] Another object of the invention is to provide a solid type insulating sealing compound, for polymeric hollow insulator, of an optical Current Transformer (OCT). [0015] Still another object is to provide Process of manufacturing solid core polymeric insulator, with embedded optical fiber, using the insulated sealing compound. [0016] These and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present invention is illustrated. SUMMARY OF INVENTION [0017] One or more drawbacks of conventional systems and process are overcome, and additional advantages are provided through the apparatus/composition and a method as claimed in the present disclosure. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be part of the claimed disclosure. [0018] Optical Current Transformers (OCTs) are a new generation of substation current transformers, which uses light waves to measure current flowing in high voltage lines/bus bars. OCTs offer tremendous technical and operational advantages over conventional CTs, and thus they are gradually replacing the conventional CTs, in HV substations. Moreover, to implement smart and digital substation concepts in transmission area, utilities are using devices like OCTs for precise and accurate current measurement. [0019] The present invention caters to the development of a maintenance-free optical current transformer and a process of manufacturing the same. [0020] The Present invention involves the following: - Identifying and finalizing a process of evaluating solid insulation compound, to develop solid core type polymeric insulator, with embedded optical fiber. -Developing a process to manufacture solid core type maintenance-free optical current transformer. -Design and development of a system/module to process solid insulation compound, for manufacturing solid core polymeric insulator, with embedded optical fiber. -Development of a novel maintenance-free Optical CT using solid core fiber embedded insulator, optical sensing module and other High Voltage-Low Voltage components. [0021] The main inventive features/steps of the invention have been indicated in the principal claims and subsidiary features/steps have been depicted in the dependent claims. [0022] 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. [0023] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure. [0024] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS [0025] The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and processes that are consistent with the subject matter as claimed herein, wherein:- [0026] Figure 1 shows: Flow chart for evaluating solid insulation compound to develop solid core Optical CT of the present invention. [0027] Figure 2 shows: Flow chart of manufacturing Optical CTs, solid core insulator with embedded optical fiber. [0028] Figure 3 shows: A system for processing solid insulation compound and manufacturing maintenance-free optical CT according to the present invention. [0029] Figure 4 shows: Construction of Maintenance-free Optical Current Transformer (OCT) with solid core insulator in accordance with the present invention. [0030] The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily 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. DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS: [0031] While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure. [0032] The present invention makes a disclosure regarding a technology pertaining to Optical Current Transformer being a next generation high current measurement equipment, which is used in high voltage substations, for metering and protection requirements. [0033] Traditionally magnetic core based, oil filled, current transformers are used in substations, which work on the electromagnetic induction principle. Optical CT which works on Faraday Effect uses light waves to measure current flowing in high voltage lines. Optical CT offers significant technical and operational advantages as compared to traditional CTs. [0034] Optical Current Transformers (OCTs) use delicate and light weight optical components and fibers, instead of heavy duty rugged magnetic cores, paper & oil insulation and copper cables, used in conventional CT design. Thus, internal construction of optical CT is entirely different from conventional CTs. Normally, the optical components and fibers used in OCTs do not require any specific maintenance, but the high voltage components, particularly the polymeric hollow insulator, which carries the optical fiber, requires regular maintenance in terms of pressurized inert gas/dry air or vacuum monitoring, for ascertaining the insulation integrity and insulator sealing condition, during service. The innovation described here-in, caters to the design of a novel Optical CT, that is totally maintenance-free, during service at site. [0035] Now, reference may be made to Figure 1 illustrating the step-wise approach for choosing and evaluating the solid insulation compound used for developing maintenance-free optical CT. The overall expected properties of the proposed insulation compound, from the point-of-view of ease in manufacturing of optical CT, as well as meeting all the stringent electrical and mechanical requirements, for outdoor installation are as follows: i) The compound should be liquid or less viscous gel type, that is easily flowable and preferably comes in 2 parts, which on mixing slowly solidifies/cures as soft solid material, that is not hard or brittle, as it has to encapsulate/embeds the delicate optical fiber. ii) Solidification should be at room temperature with no special curing requirements iii) Solidified compound to exhibit good di-electric strength, as required for HV application iv) Solidified compound to exhibit good mechanical and thermal stability, to withstand extreme outdoor weather conditions v) Should be compatible with optical fibers and Fiber Reinforced Plastic (FRP) tube, of the hollow insulator. [0036] For evaluating the chosen solid encapsulation compound, a sample/test piece is prepared, using a small FRP tube (length approx. 200 mm, inner diameter 50 mm). The tube is filled and cured with solid insulation compound and also embeds a small optical fiber cable. Once the sample is ready, following needs to be tested and evaluated: 1. Physical verification of sample in terms of sealing and securing the optical fiber inside FRP tube 2. Testing for insulation resistance (IR) of the sample to meet requirement. 3. Testing for di-electric properties of the sample by undertaking high voltage tests. 4. Testing for partial discharge (PD) behavior of the sample to verify bubble-free/void-less curing of the insulation compound. 5. Testing the sealing property of sample in terms of water and moisture ingress for long period of time 6. Testing the bonding or adhesion of insulation compound, with FRP tube, and embedded optical fiber 7. Testing the effect of temperature variation (hot & cold), on the sealing property of insulation compound Based on the test results of the above proposed methodology, best suitable solid insulation compound, meeting all the requirements is finalized. [0037] Figure 2 shows the process of manufacturing OCTs solid core insulator with embedded optical fiber. It may be noted that the actual insulator used in typical 400kV substation has a length of approx. 4 meters and an internal hollow space (volume approx. 30 liters), for carrying the optical fiber cable. As a part of this innovation, the insulator hollow space has to be sealed/filled with chosen solid insulation compound, ensuring that it cures the soft solid material, that is void or bubble-free across the 4-meter insulator length. To start-with, firstly we need to manually measure the 2 parts of solid insulation compound, as per defined mixing ratio. Once the 2-parts is ready, these parts are poured in one container and mixed thoroughly using automated/motorized mixing machine. Parallely, the fiber optic sensor head module of the OCT, is assembled to the HV side flange of the polymeric hollow insulator, and the optical fiber coming out from the bottom of the sensor head unit, is routed through the insulator hollow tube, to the LV side of the insulator. At the LV end of the insulator a degassing module is assembled, and the optical fiber cable is safely secured inside it, as a spool. The