Claims:1. A gas insulated switchgear panel (1) which dissipates heat energy generated inside the enclosure to the surrounding medium, said switchgear panel (1) comprising:
at least one inbuilt end cover (2) positioned on adjacent side(s) of the switchgear panel (1);
at least one stiffener (3);
plurality of first holes (6) positioned on bottom of the inbuilt end cover (2);
plurality of second holes (7) positioned on top of the inbuilt end cover (2);
wherein the stiffener(s) (3) is welded on the inbuilt end cover(s) (2) forming a converging diverging nozzle (8) with a throat (4) adapted to channelize the heat generated inside the enclosure to the surrounding medium.

2. The gas insulated switchgear panel (1) as claimed in claim 1 wherein the stiffener(s) (3) are of C-cross section.

3. The gas insulated switchgear panel (1) as claimed in claim 1 wherein the converging diverging nozzle (8) with the throat (4) has a rectangular varying cross section.

4. The gas insulated switchgear panel (1) as claimed in claim 1 wherein the throat (4) is positioned where the heat generation is maximum in the switchgear panel (1).

5. The gas insulated switchgear panel (1) as claimed in claim 1 wherein the plurality of first holes (6) positioned on the bottom of the inbuilt end cover (2) is adapted to provide a continuous supply of fresh surrounding air (5) from outside the switchgear panel (1).

6. The gas insulated switchgear panel (1) as claimed in claim 1 wherein the plurality of second holes (7) positioned on the top of the inbuilt end cover is adapted to discard heated air outside the switchgear panel (1).

7. The gas insulated switchgear panel (1) as claimed in claim 1 wherein the end cover(s) (2) is bolted to the switchgear panel (1) using hardware means.
, Description:TECHNICAL FIELD OF THE INVENTION

The invention relates to the field of switchgears and switchgear cabinets in general, and more particularly to a temperature rise performance improvement of medium voltage gas insulated metal enclosed switchgear.

BACKGROUND OF THE INVENTION

Due to rapid increase in demand of electric power, requirement of high current switchgear is growing and it has become very challenging to design switchgear with minimum dimensions as heat generated in switchgear due to large current is high.When such a high current switchgear like 1250A is under continuous operation at full rated load, heat is continuously generated inside enclosure and if this rate of heat generation is high compared to rate of heat dissipation then on a long run of switchgear may reduce service life and reliability as it deteriorates both mechanical and electrical properties of components inside enclosure which may further lead to partial or full breakdown of switchgear with risk of safety and Power security.

In existing switchgear with additional heat exchanger for improved thermal performance, it is difficult to design sealed enclosure in hermetic manner such as IP66 (dust tight). Thus also, this special arrangement will significantly increase cost of switchboard.

Reference has been made to US7032835. It discloses a nozzle system which includes a plurality of circumferentially distributed convergent flaps, divergent flaps and inter-flap seals which circumscribe an engine centerline and define the radial outer boundary of a core gas path. Each divergent flap includes a multiple of cooling channels. Cooling airflow enters each channel through a corresponding intake and exits each channel through a set of discharge ports. The divergent flap intakes are arranged downstream of the hinge axis such that the intakes are selectively covered by the adjacent divergent flap seals. As the nozzle transitions between the open position and the closed position, the divergent flap seals move relative to the divergent flap longitudinal axis to modulate the cooling airflow that enters the separate intakes. A relatively large quantity of cooling airflow is directed through all the intakes to provide significant convective cooling of the divergent section during afterburner operations. In a relatively closed or non-afterburning position, the divergent flap seals are constricted toward the divergent flap longitudinal axis such that a lesser number of intakes are exposed to the cooling airflow. The cooling airflow which does not pass through the divergent flaps due to the blocked intakes combines with the core airflow and increases non-afterburning engine efficiency due in part to the associated decrease in pressure and momentum loss and increases efficiency of the engine. In this document convergent divergent nozzle is being cooled.

Reference has also been made to US4705455.This document discloses a coolant passage through a wall to be cooled, such as the wall of a hollow airfoil, is shaped and oriented to eject coolant fluid therefrom within the boundary layer of hot gases flowing over the surface to film cool the wall downstream of the outlet. The passage includes a metering portion near its inlet, followed by a diffusing portion and nozzle portion. The nozzle portion, adjacent the outlet, simultaneously diverges and converges in mutually perpendicular directions to produce a more uniform coolant velocity profile, which results in increased coolant area coverage and improved cooling effectiveness.

In order to solve the above problems, the prior art high current switchgear cabinets will typically employ a large volume, and to use an additional cooling fan for forced cooling. However, not only such a manner that a higher cooling equipment operating costs, reduce reliability and may potentially increasing the footprint of the device.
For this reason, there is a dire need to develop a switchgear cabinet, which dissipates heat energy generated inside the enclosure to the surrounding medium with minimum added cost or any external efforts so that the switchgear can be safe and provide reliable operation.
SUMMARY OF THE INVENTION
The following disclosure presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.

An object of present invention is to overcome the problems of prior art.

Another object of present invention is to provide a switchgear cabinet, which dissipates heat energy generated inside the enclosure to the surrounding medium.

Another object of present invention to provide a switchgear cabinet, which dissipates heat energy generated inside the enclosure to the surrounding medium without using any external power source which is aiding the process.

Yet another object of present invention is to provide a switchgear cabinet, which uses a converging diverging nozzle inbuilt cover for dissipating the generated heat outside the enclosure.

Yet another object of present invention is to provide a switchgear cabinet, which uses a converging diverging nozzle in which uses rectangular varying cross section.

Yet another object of present invention is to provide a switchgear cabinet, which uses a converging diverging nozzle inbuilt cover where neither nozzle nor the equipment on which it is mounted is moving.

Yet another object of present invention is to provide a switchgear cabinet, which uses a flow of air which is totally natural for dissipating the generated heat to the surrounding from the enclosure.

One aspect of present invention is to provide a switchgear cabinet for better temperature rise performance of gas insulated switchgear panel, which dissipates heat energy generated inside the enclosure to the surrounding medium without using any external power source which is aiding the process. It uses a converging diverging nozzle inbuilt end cover having nozzle with rectangular varying cross section. The construction of the nozzle for dissipating the heat outside the cabinet is such that it uses the natural surrounding air for the process without using any external power source for dissipating the generated heat outside the switchgear cabinet.

The gas insulated switchgear panel of the present invention dissipates heat energy generated inside the enclosure to the surrounding medium where the said switchgear panel comprises at least one inbuilt end cover positioned on adjacent side(s) of the switchgear panel, at least one stiffener, plurality of first holes positioned on bottom of the inbuilt end cover, plurality of second holes positioned on top of the inbuilt end cover, wherein the stiffener(s) is welded on the inbuilt end cover(s) forming a converging diverging nozzle with a throat adapted to channelize the heat generated inside the enclosure to the surrounding medium.

Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

The above and other aspects, features and advantages of the embodiments of the present disclosure will be more apparent in the following description taken in conjunction with the accompanying drawings, in which:

Figure 1 illustrates the switchgear (1) with the end cover (2) according to one of the embodiments of the present invention.

Figure 2 illustrates the exploded view of the switchgear (1) with the end cover (2) according to one of the embodiments of present invention.

Figure 3 illustrates the working principle of the switchgear (1) with the inbuilt converging diverging nozzle (8) in the end cover (2) according to one of the embodiments of present invention.

Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may not have been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding, but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustration purpose only and not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents.

The present disclosure relates to switchgear cabinets in general, and particularly to a temperature rise performance improvement of gas insulated metal enclosed switchgear. The present invention is directed to provide a switchgear cabinet for better temperature rise performance of gas insulated switchgear panel, which dissipates heat energy generated inside the enclosure to the surrounding medium without using any external power source which is aiding the process. It uses a converging diverging nozzle inbuilt end cover having nozzle with rectangular varying cross section. The construction of the nozzle for dissipating the heat outside the cabinet is such that it uses the natural surrounding air for the process without using any external power source for dissipating the generated heat outside the switchgear cabinet.

It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, a reference to "a component surface" includes a reference to one or more of such surfaces.

All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments belong. Further, the meaning of terms or words used in the specification and the claims should not be limited to the literal or commonly employed sense but should be construed in accordance with the spirit of the disclosure to most properly describe the present disclosure.

The terminology used herein is for the purpose of describing particular various embodiments only and is not intended to be limiting of various embodiments. As used herein, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising" used herein specify the presence of stated features, integers, steps, operations, members, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, members, components, and/or groups thereof. Also, Expressions such as "at least one of," when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.

The present disclosure will now be described more fully with reference to the accompanying drawings, in which various embodiments of the present disclosure are shown. The present disclosure may, however, be embodied in many different forms and should not be construed as being limited to the various embodiments set forth herein, rather, these various embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the present disclosure. Furthermore, a detailed description of other parts will not be provided not to make the present disclosure unclear. Like reference numerals in the drawings refer to like elements throughout.

Figure 1 illustrates the switchgear with the end cover (2) according to one of the embodiments of the present invention where the end covers (2) are bolted on both the adjacent sides of the switchgear cabinet (1).

Figure 2 illustrates the exploded view of the switchgear (1) with the end cover (2) according to one of the embodiments of present invention where the stiffeners (3) of C-cross section are welded to the end covers forming the converging diverging nozzle.

Figure 3 illustrates the working principle of the switchgear (1) with the inbuilt converging diverging nozzle (8) in the end cover (2) according to one of the embodiments of present invention. This figure depicts the entire working of the converging diverging nozzle as the plurality of first holes (6) positioned at the bottom of the inbuilt end cover (2) which provides a continuous supply of fresh surrounding air from outside the switchgear panel (1) and a plurality of second holes (7) positioned at the top of the inbuilt end cover (2) which is adapted to discard heated air outside the switchgear panel (1).

The invention uses idea of converging diverging nozzle with increased length of throat. Nozzle is used generally to increase velocity of fluid. A nozzle is a generally a pipe of varying circular cross sectional area and can be used to control rate of flow, speed, direction, mass, shape or pressure of the stream that passes through them. In a nozzle, the velocity of fluid increase at the expense of pressure energy. Nozzle is generally used in power producing equipment such as turbine, compressor, IC engines etc., where it is used to increase the velocity of fluid at cost of decrease in pressure. Where as in switchgear there is no movement of fluid involved during normal operation. So it’s out of the box to use nozzle in such equipment. Most of the places the flow of fluid inside the nozzle is forced and requires some external aid. Nozzles have been rarely used to improve heat transfer from any equipment or from its associated part. If it has been used then there is a definite movement of that equipment or its associated part. But in case of this invention the switchgear or its associated part is static.

The concept is practically made feasible by welding stiffeners of c- cross section to the end covers of switchgears. The arrangement is shown in figure 2. The throat (4) area is made at the place where the heat generation is maximum. After welding is done the end cover is bolted to the switchgear. There is mesh of small holes (6, 7) on top and bottom of end cover in order to allow air to pass.

In fig-3 the throat (4) region of the converging diverging nozzle inbuilt end cover is shown. The construction is done in such a way that the throat comes at the place where the generation of heat is highest. The air around the hot area of the panel (1) is heated up and becomes light. The heated air moves up and thus reduces the pressure there. This makes a negative pressure in the throat (4) region. Air from surrounding rushes from bottom and fills the area. This process continues. In this way there is continuous convection of heat generated inside the panel. The converging diverging nozzle (8) inbuilt end cover (2) acts like natural driving mechanism which drives outside air inside with increased velocity and improves the temperature rise performance of metal enclosed switchgear panel (1). This concept can be applied in any heat generating electrical and mechanical equipment.

According to the equation of continuity, with decrease in the area there is an increase in the velocity of the fluid i.e. area of cross section is inversely proportional to the velocity of the flow of the fluid. So velocity will be maximum at the minimum area of cross section of flow. Thus the velocity will be maximum at the throat (4) region. The convective heat transfer coefficient will improve with velocity. It is also evident that with increase in velocity and increase in mass of air the amount of heat taken from the hotspot will be high.

In implementation, the present invention provides a gas insulated switchgear panel (1) which dissipates heat energy generated inside the enclosure to the surrounding medium. It comprises at least one inbuilt end cover (2) positioned on adjacent sides of the switchgear panel (1), at least one stiffener (3), plurality of first holes (6) positioned on bottom of the inbuilt end cover (2)’ plurality of second holes (7) positioned on top of the inbuilt end cover (2) wherein the stiffener(s) (3) is welded on the inbuilt end cover(s) (2) forming a converging diverging nozzle (8) with a throat (4) adapted to channelize the heat generated inside the enclosure to the surrounding medium.

In implementation, the present invention uses stiffener(s) (3) are of C-cross section for forming the converging diverging nozzle (8) with a throat (4) where the nozzle so formed has a rectangular varying cross section wherein the throat (4) is positioned where the heat generation is maximum in the switchgear panel (1).

In implementation, the present invention uses a plurality of first holes (6) positioned on the bottom of the inbuilt end cover (2) is adapted to provide a continuous supply of fresh surrounding air (5) from outside the switchgear panel (1) and plurality of second holes (7) positioned on the top of the inbuilt end cover is adapted to discard heated air outside the switchgear panel (1).

Some of the non-limiting advantages of present invention are as follows:

1. It uses nozzle where the neither nozzle nor the equipment on which it is mounted is moving.
2. There is no external power source which is aiding the process.
3. The flow of air is totally natural.
4. In switchgear, due to space constraint, it is not possible to use varying cross section nozzle. So a rectangular varying cross section is being used.
5. The design is simple and it has easy manufacturability.
6. There is significant improvement in temperature rise performance
7. High repeatability and high reliability.
8. The cost associated is very less.