FIELD OF THE INVENTION
The present invention generally relates to a three phase common enclosure type gas insulated switchgear, particularly to a three phase common enclosure type gas insulated bus bar module. The invention relates to an improved three phase gas insulated multi-port bus bar module for three phase electrical system with independent phase support insulator.
BACKGROUND OF THE INVENTION
The three phase gas insulated bus bar is used to interconnect three phase electric power systems. This module shall have the provision to make the connection with any type of insulation system through appropriate equipment like bushing. This bus bar module shall also make the inter connection between different three phase gas insulated modules. The gas insulated bus bar module consists a metallic chamber with SF6 gas and has need-based multiple ports and are located at a pre-defined angle. This shall lead to involvement of complex procedure / tools to manufacture a bus bar system. The angular orientation of ports was required for mounting of terminal bushings at an angle, which would provide safe working clearances for the rated and test voltages. Further, angled conductors to suit the said orientation are essential for efficient current transfer.

Suitable end terminations and shields were provided to make the high voltage electric field to become more and more uniform. In practical electric power systems it is often required to integrate the new gas insulated electric system with existing air insulated electric system. In such circumstances there is a need of a suitable system which interconnect those two electric systems.
RU 2523429 discloses a gas insulated bus bar module in which the bus bars are arranged in a row and enclosure dimensions increase significantly with system voltage . In conventional arrangements, the bus of one phase of a three-pole bus bar is made with bends and curves around the bends of adjacent phases. Hence electrostatic field levels are quite high. Figure 1 shows a conventional bus bar arrangement. Following are some of the drawbacks with these arrangements.
1. If the bus bar arrangement is in a row, the dimensions of enclosure are quite high. Compactness of equipment is limited.
2. If the bus bar arrangement is in a row, there is a resultant magnetic field on the grounded enclosure and may result to eddy currents for some type of enclosure materials.

3. In the conventional right angled arrangement, current transfer takes place through complex machined terminals, bends etc.
4. In the conventional right angled arrangement, uniform electrostatic field levels between the phases are quite difficult to achieve because of HT crossings across bus bar phases.
5. In some of the conventional bus bar arrangements Patent No.
DE 3137783 and US 7485807 each bus bar is supported by bulky insulated spacers.
6. The integration of bus bars to other modules of GIS involved complex machining of the components.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose an improved three phase Gas insulated multi-port bus bar module for three phase electrical system with independent phase support insulator.

Another object of the invention is to propose an improved three phase Gas insulated multi-port bus bar module for three phase electrical system with independent phase support insulator, in which the bus bars located at the vertices of a right angled configuration or at the mid points of an equivalent square configuration or any arbitrary angled configuration of the module.
A still another object of the invention to propose an improved three phase Gas insulated multi-port bus bar module for three phase electrical system with independent phase support insulator, in which the high voltage terminating shield is profiled so as to optimize electrostatic field levels.
Yet another object of the invention is to propose an improved three phase Gas insulated multi-port bus bar module for three phase electrical system with independent phase support insulator, in which a predefined gas gap between high voltage conductor and the insulator is maintained.
A further object of the invention is to propose an improved three phase gas insulated multi-port bus bar module for three phase electrical system with independent phase support insulator, in which a predefined insulator thickness and gas gap between the high voltage shield integrated in the independent phase support insulator and the grounded enclosure is maintained.

A still further object of the invention is to propose an improved three phase gas insulated multi-port bus bar module for three phase electrical system with independent phase support insulator, which provides current transfer from a bus to the independent phase support insulator using an HT integrator.
Another object of the invention is to propose an improved three phase gas insulated multi-port bus bar module for three phase electrical system with independent phase support insulator, which includes LT shield around LT connection to optimize electrostatic field levels on the surface, volume of the support insulator and around the tri-junction.
SUMMARY OF THE INVENTION
Accordingly, there is provided an improved three phase Gas insulated multiport bus bar module for three phase electrical power systems in which "conductors (bus bars) with "termination shields" are placed in a metal enclosure in right angled configuration comprising "angled terminals" and "straight conductors" to extend the current transfer from the bus bars in a radial direction through a "current transfer bridge" with "current transfer bridge shield" via at least one "metallic port"; independent phase integrated HT shield in insulators has good

profiled radius so that the electric field stress on the surface is within working limit. There are profited shields at the low voltage side of the support insulator to optimize electrostatic field levels along the insulator surface. The gas and the insulation thickness between independent phase integrated HT shield in insulator and grounded enclosure are optimized for limiting electrostatic field levels. Thus the present invention teaches a three phase common enclosure type gas insulated switchgear particularly to a three phase common enclosure type gas insulated bus bar module. Gas-insulated bus bars are enclosed in a metal encapsulation that is filled with an insulation gas e.g. SF6 or N2 or mixture of these gases or mixture with any other compatible gas
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention is described with the help of Figures 1 to 6, where; Figure 1: Conventional Bus bar arrangements.
Figure 2: Configuration of independent phase support insulators with high voltage ports according to the invention.
Figure 3: Independent phase support insulator for three phase compact GIS.

Figure 4 : Integrated HT shield for independent phase support insulator.
Figure 5 : LT shield for LT connection of Independent phase support insulator.
Figure 6 : Invented three phase compact Bus bar module with independent phase support insulators.
DETAILED DESCRIPTION OF THE INVENTION
A compact gas insulated bus bar comprises three bus bars [01] in single grounded metallic enclosure [02]. Three bus bars [01] are made of high electrical conductivity material to enable efficient current flow with minimal loss and is insulated from the grounded metallic enclosure [2] with designed SF6 gas density. Figure 2 shows Configuration of independent phase support insulators with high voltage ports according to the invention. An independent phase support insulator [03] is made of SF6 gas compatible filled epoxy material. The support insulator [03] holds each of the bus bars [01] through a socket/HT Integrator [04] in such a configuration where each bus bar [01] is placed at the

vertices of a right angled triangle or equilateral triangle or a predefined angle in a grounded metallic enclosure [02] filled with SF6 gas at designed density. Figure 3 shows the design of independent phase Support insulator. Each Support Insulator consists of well profiled integrated HT shield [05]. Integrated shield [05] is profiled in such a way that electrical stress on surface of the support insulator shall be optimal/ minimal. Figure 4 shows the invented integrated shield [05] which is profiled in such a way that there will be working electric stress on the surface of insert and there should be no insulation breakdown between high voltage and low voltage part. As desired, electrostatic field level at tri-junction point (junction of gas, metal and epoxy insulation) is much less than that E-field level on the HT conductor. Profile of integrated shield [05] decides the volumetric and surface stresses of the independent phase support insulator [03].
The independent phase support insulator [03] consists of LT terminal [06], Figure 5 shows the design of LT terminal in support insulator. This terminal Is used to fasten the independent phase support insulator [03] to grounded metallic enclosure [02]. A novel LT terminating shield [07] also fastened to the LT terminal [06] to optimize the electric field levels along the insulator surface as well as at the tri-junctions formed by metal-SF6 gas-insulator. The electric field stress on the surface of support insulator will be considerably lower than that of

metallic surface. Each bus bar is supported by the.support insulators and each of the bus bar [01] is ended with a termination shield [08], which controls the electric stress between the bus bars [01] and bus bars to the grounded enclosure [02]. The gas gap, Gl [038A] between bus bar [01] and insulator part [03B] has been optimized to limit electric stresses on the individual phase support insulator [03].
The grounded metallic enclosure [02] which encloses the bus bars [01] consists of a plurality of angularly/linear disposed ports [09]. These ports are used to commensurate to other insulating media like gas or liquid or solid or combination of them. The ports [09] on metallic enclosure [02] are made radially at a designed angle to keep electrical connection between phase-phase and phase-ground of insulated terminal connections. The angled terminal [10] and a straight conductor/terminal [11] transfers current from the bus bar [01] to high voltage terminal of other insulation media or gas insulated module through a current transfer bridge [12]. Each of a plurality of current transfer bridges [12] is integrated with current transfer bridge shields [13] and designed in such a way that the radial electric filed between the current transfer bridge shields [13] and the metallic enclosure [02] is almost uniform. The angled terminals [10], straight

terminal [11], current transfer bridge [12], current transfer bridge shields [13] and HT integrator [04] are made of high electrical conductivity material to maintain efficient current transfer with minimal power losses. Bus bar is supported by support insulator with appropriate HT integrators [04]. The gas gap [03C] and insulator thickness [03D] between HT Integrated shield [05] and grounded enclosure have been optimized to limit electric stresses on the individual phase support insulator [03]. Unless gas gap, G2 contributes more than 80% of total insulation, the electric stresses cannot be reduced below required levels. In absence of this, the surface electrical stress on insulator part [03E] is so high that it leads to flash over towards grounded LT terminal.
The straight terminal [11] extends the electrical connection orthogonally from the bus bar [01] to other insulation media whereas the angled terminals [10] extend the electrical connection radially at a designed angle from bus bars [01] to other insulation media. The angled terminals [10] are profiled at a designed angle equal to the angle of the angular ports [06] on the metallic enclosure [02] to keep the uniform electric stresses around the angled terminals [08], between the bus bars [01] and between the bus bar [01] and the grounded metallic enclosure [02]. The angled terminal [10] / straight terminal [11] provide the flexibility in design; these shall rotate radially at any desired angle based on the requirement. Figure 6 shows the bus bar arrangement with independent phase support insulator according to the invention.

WE CLAIM :
1. An improved three phase Gas insulated multi-port bus bar module for three phase electrical systems, comprising a plurality of bus bar [01] enclosed in a metallic chamber and terminated with multiple shields [08] and sockets / HT integrators [04] arranged in right angled or at any arbitrary angle configuration with uniform electric stress between phase-phase and phase-ground; an independent phase support insulator [03] to hold the three phase bus bar module; at least one angled terminal [10] / straight terminal [11] with a current transfer bridge [12], a plurality of current transfer bridge shields [13] and HT integrators [04] extending the current transfer from the bus bars [01 to an insulating medium which can be gas or liquid or solid or combination thereof.
2. The three phase bus bar module as claimed in claim 1, wherein the metallic chamber consists of angularly/linearly dispensed ports [09] for extending the terminal connection from the bus bars [01] in any desired angle radially to the bus bars [01].
3. The three phase bus bar module as claimed in claim 1 or 2, wherein the angled terminals [10] / straight terminal [11] provides flexible rotary extension from the bus bars [01] at any angle in radial direction.

4. The three-phase bus bar module as claimed in claim 1, wherein a profiled angled conductor [10] is disposed between the bus bar module and the HT integrators [04] which is connected to the insulation media.
5. The three-phase bus bar module as claimed in claim 1, wherein the current transfer bridge [12] with shield [13] is enabled to integrate the HT integrators [04] to said angled conductors [10] for an effective current transfer.
6. The three phase bus bar module as claimed in claim 1, wherein the
independent phase support insulator [03] comprises electric stress controlled HT
integrating shield [05] and LT shield [07], wherein a first gas gap Gl [03A] from
the bus bar to an epoxy body [03B] controls the electric field across the insulator
and improves withstand-able voltage, and wherein a second gas gap, G2 [03C]
and insulator thickness [03D] between the HT integrated shield [05] and the
grounded enclosure is optimized to limit electric stresses on the individual phase
support insulator [03].
7. The three-phase bus bar module as claimed in claim 1, wherein the current transfer from the independent phase support insulator [03] to bus bar [01] is made by using HT integrator [04].

8. The three-phase bus bar as claimed in any one of the preceding claims wherein the angled terminal (10) and the straight conductor (11) transfers current from bus bar (01) to a high voltage terminal of the gas insulated module through the current transfer bridge (12) and the associated current transfer bridge shield (13).