FORM 2
THE PATENTS ACT, 1970
COMPLETE SPECIFICATION
(See Section 10)
DOUBLE DECK BUS BAR SYSTEM
numbered as dated
INVENTORS:
1. AMITCHATURVEDI
APPLICANT:
LARSEN & TOUBRO LIMITED
L&T House, Ballard Estate, P.O. Box No 278, Mumbai, 400 001, Maharashtra,
INDIA


DOUBLE DECK BUS BAR SYSTEM
A) TECHNICAL FIELD
[0001] The present invention relates to busbars and more particularly to the busbars arrangement employed for reducing power loss and better heat dissipation.
B) BACKGROUND OF THE INVENTION
[0002] Conventionally, as shown in Figure. 1, busbar 10 systems comprise of rectangular or profiled busbars 10 juxtaposed in multiplicity to achieve higher current ratings. To achieve higher current ratings, of a particular phase more busbars 10 are added by the side and this addition is done for the other phases as well. It is quite a well known fact that whenever an AC current flows through a multiplicity of busbars 10, there is a significant amount of distortion in the current distribution among the busbars 10 on account of mutual field interactions. The phenomenon is known as proximity effect. The effect becomes more pronounced as the current rating and the number of busbars 10 increase. The effect of shift in the current density distribution within the busbars 10 cross-section could be to one side or the other depending on the direction of the current in the nearby conductors. Also due to the varying degree of the proximity effect on a given busbar 10 due to adjacent phase busbars 10 and due to adjacent busbars 10 in the same phase, the current density distribution gets distorted heavily resulting in increased power


loss. However due to the effect of magnetic field interactions among various conductors, such an arrangement is not very effective in terms of the current distribution.
[0003] US patent discloses granted to Holec Systemen en Componenten B.V. discloses a bus-bar conductor system for electrical high voltage systems, wherein electrically conducting bus-bars are mounted in an enclosing compartment. A common support body for supporting one or more supporting insulators, to which the bus-bars are attached, extends freely or essentially freely in the compartment in the longitudinal direction of the bus-bars. The support body is preferably supported by support elements arranged at the outer ends of the compartment. The support body can itself be designed as a conducting bus-bar.
[0004] One of the means to lessen this effect is interleaving of conductors (as shown in Figure 2) which essentially involves the sand-witching of busbars 10 of different phases between each other. However, within a packet the conductors are placed side by side thereby having a significant proximity effect and a consequent redistribution of current in them. Such a situation is however objectionable and accordingly needs an improvement. Accordingly it is an object of the present invention to device such an arrangement which eliminates at least one of the above mentioned drawbacks.


C) SUMMARY OF THE INVENTION
[0005] The present invention is based on the principle of reducing the proximity effect amongst plurality of conductors and which becomes predominant at high current ratings. The busbar arrangement in the present invention so produced with the disposition of various bars in a manner to minimize the effect of mutual magnetic fields, giving rise to an efficient busbar system. The disposition of the various busbars into a unique system gives rise to less heat generation better heat dissipation. The busbar system so formed is used in applications such as switchgear and the likes.
[0006] According to an aspect of the present invention, busbar arrangement for reducing power loss and better heat dissipation for switchgears and the like, the arrangement comprises of at least three double decks for retaining the busbars wherein each of the double deck corresponds to a single phase. Further, at least one busbar is disposed in each deck of the double deck, wherein the busbars disposed in each of the double deck are in same phase. A connecting means joins each of the busbar in the double deck. The busbars are arranged in such a manner that each of the busbar in the double deck is in symmetrical position with respect to the other busbars in the vicinity.
[0007] Preferably, the busbars retained in each of the double deck are spaced apart and the connecting means occupies the space between the busbars in the double deck.


[0008] Preferably, in each of the deck of a particular double deck a plurality of busbars juxtaposed and substantially separated is retained.
[0009] Preferably, another set of three double decks is combined with the system of three double decks wherein each of the double deck of the set corresponds to a single phase.
[0010] Preferably, each of the busbar in the double deck may be horizontally retained thereby exposing two surfaces of the busbar. Alternatively, each of the each of the busbar in the double deck may also be vertically retained.
[0011] Other objects, features and advantages of the invention will be apparent from the drawings, and from the detailed description that follows below.
D) BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
[0013] FIGURE. 1 shows the conventional busbar arrangement.


[0014] FIGURE.2 shows another conventional busbar arrangement.
[0015] FIGURE.3 shows the front view of the busbar arrangement according to an embodiment of the present invention.
[0016] FIGURE.4 illustrates one of the methods of connection of the connecting means with the busbars arrangement of Figure 3.
[0017] FIGURE.5 shows the perspective view of the whole busbars arrangement with the connecting means according to an embodiment of the present invention.
[0018] FIGURE.6 shows the interleaved busbars arrangement according to an embodiment of the present invention.
E) DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0019] The present invention relates to busbars and more particularly to the busbars arrangement employed for reducing power loss and better heat dissipation. The present invention would be better understood in conjunction with a following description of various embodiments and the figures that details the working principle of the present invention.


[0020] In the following description, references to the drawings, certain terms are used for conciseness, clarity and comprehension. It is assumed by one skilled in the art that there are to be no unnecessary limitations implied from such references, besides the limitations imposed by the prior art, because such terms and references are used for descriptive purposes only and intended to be broadly construed. Furthermore, the description and the drawings are for illustrative purposes only and not to be construed as limited to the exact details shown, depicted, represented, or described. Further, Reference in the specification to the phrases like "one embodiment", or "another embodiment" etc. means that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the above-mentioned phrase in various places in the specification are not necessarily all referring to the same embodiment.
[0021] Now referring to Figures 3, 4 and 5 which itself explains one of the embodiments of the present invention in which Busbars arrangement for reducing power loss and better heat dissipation for switchgears and the like, the arrangement comprises of at least three double decks for retaining the busbars wherein each of the double deck corresponds to a single phase. Further the arrangement also includes at least one busbar disposed in each deck of the double deck in a manner that the busbars disposed in each of the double deck are in same phase. The busbars are joined by a connecting means in the double deck. The


arrangement of the busbars is such that each of the busbars in the double deck is in symmetrical position with respect to the other busbars in the vicinity.
[0022] Reference in the specification to the phrases like "one embodiment", or "another embodiment" etc. means that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the above-mentioned phrase in various places in the specification are not necessarily all referring to the same embodiment.
[0023] As shown in Figure 3, there are three double decks 12 for retaining the busbars 10 wherein the three double decks 12 corresponds to three phases indicated by the letters R, Y and B. Each of the double decks 12 has two decks 14 in one particular arrangement and placed one above the other and retains at least one busbar 10 each into the deck 14. For the purpose of clarification it is to be understood that the word "deck" and "double-deck" refers just to clarify the whole arrangement by retaining the busbars 10 therein. A plurality of conductors in one row comprising a multi-phase busbar system is being called as a "deck" herein. From the figures pertaining to the present invention, two such "deck" can be seen juxtaposed one above the other or besides each other, hence the name "double-deck". The name has been given purely based on the disposition of the conductors in the busbar system and the advantages of the system are on account of the same. Each of the busbars 10 in a double deck 12 is in similar phase and this holds same to the other bus bars retained in the other two double decks 12. The busbars 10 in the


other two double decks 12 are in their respective phases making the three different phases of busbars 10. The distances of a given busbar from the other busbars 10 in its vicinity is symmetrical with respect to the other flat of the same phase in the other deck 14. This ensures that the busbars 10 within a phase lie in regions in space which have a symmetrical flux distribution with respect to each, thereby, resulting in similar current density distributions and equal current sharing in them. As shown in Figure 3, two busbars 10 each into the respective three phases of the double deck 12 and marked by letters Rl and R2, Yl and Y2, Bl and B2 are shown. It becomes quite clear from the figure to understand that the distance of Yl and Y2 from Rl is the same as distance of Yl and Y2 from R2. Similarly, the distance of Bl and B2 also remains same from Rl and R2. This holds true for all the busbars 10 Yl, Y2 and Bl, B2. Owing to the arrangement of the busbars 10 and carefully analyzing the drawbacks of the prior arrangements, due to the symmetry achieved in the arrangement there is an equal distribution of current density throughout the whole arrangement and because of this disposition of the busbars 10, the arrangement gives rise to less heat generation better heat dissipation. Also the magnetic fields cancel each other, in one of the embodiments of the invention, at the time of short-circuit, resulting in considerable reduction in the forces during a fault. Various current ratings are derived from deleting one or more conductors from the arrangement or/and by changing the cross-section of the conductors. The supporting arrangement is such that the busbars 10 can be simply slid into the cavities thereby resulting in an easy assembly.


[0024] The power loss due to the distorted current density distribution within various busbars 10 as compared to the conventional arrangements too is reduced, thereby resulting in a relatively lower heat generation. The very disposition of the conductors in this invention, such that the conductors of a phase for a given packet lie in a iso-flux region results in even current sharing amongst the bars, thereby minimizing the power losses.
[0025] Further, in the double deck 12 arrangement, only two busbars 10 lie in a vertical plane. The next busbar(s) is (are) at a considerably larger distance, the distance being the separation between two adjacent phases. This disposition, utilizes both the vertical faces of all busbars 10 effectively for heat dissipation, thereby limiting the temperature rise. Double deck 12 arrangement ensures equal current sharing between the conductors of a given packet within a phase. At times, various profiled sections are also deployed for use as busbars 10. However, their use is more from the point of view of ease of assembly and tap-off and is limited to lower current ratings.
[0026] According to one embodiment of the present invention each of the busbar in the double deck 12 is horizontally retained thereby exposing two surfaces of the busbar 10. Alternatively each of the each of the busbar 10 in the double deck 12 is vertically retained thereby exposing two surfaces of the busbar 10. Due to this heat dissipation is more efficient in the bus bar system.


[0027] According to another embodiment of the present invention and as shown in Figure 6, another set of three double decks 12 is combined with the system of three double decks 12 as explained earlier in the preferred embodiments. Each of the double deck 12 of the set corresponds to a single phase. In this embodiment, the busbar 10 in the double deck 12 is interleaved. This arrangement is extremely useful where conductors of relatively lower conductivity like aluminum but not restricted to aluminium alone, are used or the higher current ratings are demanded. In this case, each phase has four busbar 10 placed in the disposition shown in the figure, wherein, the system so formed is a double deck-interleaved system. This is in effect a modular extension of the double-deck system. The range of busbar 10 thickness which can be used is 2 mm to 20 mm and the range of the width of the busbar 10 is 20 mm to 200 mm. it is to be noted that in this embodiment also the distances of a given busbar 10 from the other busbar 10s in its vicinity is symmetrical with respect to the other flat of the same phase in the other deck 14. This ensures that the busbars 10 within a phase lie in regions in space which have a symmetrical flux distribution with respect to each, thereby, resulting in similar current density distributions and equal current sharing in them.
[0028] According to various embodiments the conductors are placed in two decks 14 with a gap suitable to accommodate a connecting means 16 like bolts, screw or the like or any other connecting means 16 of similar type to produce a good electrical joint with any conducting links 18 connecting to the busbars 10. Such links 18 are connected to tap-off power or supply power to the said busbar 10 assembly. The gap between the two decks


14 provides a continuous slot to accommodate the fastening means for connection, thereby obviating the need of punching holes on the buses for connection to the said links. This provides an advantage in terms of standardization and ease of assembly. However, holes can be punched for the same purpose, in case the material of the busbars is relatively soft, with hardness compared to that of aluminium.
[0029] The foregoing description of the invention has been described for purposes of clarity and understanding. It is not intended to limit the invention to the precise form disclosed. Various modifications may be possible within the scope and equivalence of the appended claims.


CLAIMS
WHAT IS CLAIMED IS:
1. Busbars arrangement for reducing power loss and better heat dissipation for
switchgears and the like, the arrangement comprising:
at least three double decks for retaining the busbars wherein each of the double deck
corresponds to a single phase and including;
at least one busbar disposed in each deck of the double deck, the busbars disposed in
each of the double deck are in same phase; and
a connecting means to join each of the busbar in the double deck, the busbars are
arranged in such a manner that each of the busbar in the double deck is in
symmetrical position with respect to the other busbars in the vicinity.
2. The arrangement as claimed in claim 1, wherein each of the busbar in the double
deck
is horizontally retained thereby exposing two surfaces of the busbar.
3. The arrangement as claimed in claim 1, wherein each of the each of the busbar in
the
double deck is vertically retained thereby exposing two surfaces of the busbar.


4. The arrangement as claimed in claim 1, wherein the busbars retained in each of the double deck are spaced apart.
5. The arrangement as claimed in claim 4, wherein the connecting means occupies the space between the busbars in the double deck, but is not limited to the same.
6. The arrangement as claimed in claim 1 further comprising, another set of three
double
decks is combined with the system of three double decks.
7. The arrangement as claimed in claim 5, wherein each of the double deck of the set corresponds to a single phase.
8. The arrangement as claimed in claim 1, wherein in each of the deck of a particular double deck a plurality of busbars juxtaposed and substantially separated is
retained.
9. The arrangement as claimed in claim 1, wherein each of the busbar is in
symmetrical
position with any of the busbar retained in the deck.


10. The arrangement as claimed in clam 1, wherein the connecting means is a
fastening
means like screw, nut bolt or the like compatible with the arrangement.
11. The arrangement as claimed in claim 1, wherein the connections for tap-off is
made
by means of conducting links and connecting means.
12. The arrangement as claimed in claim 11, wherein the connections to the tap-off to
the said busbars is done by punching holes to accommodate the connecting means
therein.


15

ABSTRACT
Busbars arrangement for reducing power loss and better heat dissipation for switchgears and the like, the arrangement comprising a system for retaining the busbars, the system having at least three double decks for retaining the busbars wherein each of the double deck corresponds to a single phase and including, at least one busbar disposed in each deck of the double deck, the busbars disposed in each of the double deck are in same phase and a connecting means to join each of the busbar in the double deck, the busbars are arranged in such a manner that each of the busbar in the double deck is in symmetrical position with respect to the other busbars in the vicinity.
12 Claims, 6 Drawing Sheets.