FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
AND
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION Cooling system for transformers
APPLICANTS :
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR (S):
Kumar Rajeev, of Crompton Greaves Ltd, Transformer (T2) Division, Plot No. Tl & T2, MTAKVN Industrial Area, Malanpur (District Bhind) -477116, Madhya Pradesh, India; an Indian National.
PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

Field of the Invention:
This invention relates to the field of transformers and cooling systems, thereof. Particularly, this invention relates to cooling system for transformers.
Background of the Invention:
Transformers are an integral part of power systems in order to step up voltage, step down voltage and the like functions. Transformer is a device which transfers electrical energy from one circuit to another through inductively coupled conductors i.e. through transformer's coils. The transformer coils are immersed in oil which acts as an insulator and dielectric medium. As the coils heat, the oil heats. There are heat exchangers provided for directly cooling the oil by forcing it out of the transformer housing, cooling it externally, and then forcing it back in.
The transformer housing subsequently gets heated due to the heated transformer oil.
The rate of flow of transformer oil in and out of the transformer housing is dependent upon the degree to which the oils heats and the degree to which cooling is required. The taxation of the associated heat exchanger, is therefore, based on this rate of flow. Increasing the force i.e. pump rating for inflow and outflow of oil can lead to enhanced and quicker cooling. Radiator banks are used for purposes of cooling in a heat exchanger. Often to increase cooling efficiency the number of radiators is increased which leads to increase cost as well as weight of transformer.

There is a need to reduce the taxation on heat exchangers and to provide a system to cool transformer housing.
Prior Art:
WO0163629 discloses an insulation oil cooling type dry transformer without using spacer in winding of primary and secondary coils. JP56107508 discloses a liquid container especially for a transformer. GB2132031 discloses a cooling device for forced circulating type oillfilled electric apparatus. KR20040096817 discloses a system and method for cooling transformers.
Each of the above mentioned prior art relates to adding extra elements of substantial weight or incorporating substantial changes to the existing design. None of the prior art disclosures mentions the use of existing elements and members of the transformer assembly for the purposes of enhanced cooling.
Objects of the Invention:
An object of the invention is to cool transformer housings.
Another object of the invention is to cool transformer housings and transformer oil therein.
Yet another object of the invention is to enhance / abet the function of existing cooling / heat exchanging mechanisms for a transformer.

Still another object of the invention is to prevent increase in the number of radiators for enhancing cooling efficiency of a transformer.
An additional object of the invention is to reduce the number of fins in the radiator of heat exchangers used for cooling transformers.
Summary of the Invention:
According to this invention, there is provided a cooling system for transiormers, said cooling system comprises:
a. transformer housing with stiffener elements running along the exterior of
said housing, characterized in that, said stiffener elements are interconnected
to each other by means of interconnecting pipe elements to provide a fluid
passageway between them for allowing flow of oil through said stiffener
elements and interconnecting pipe elements, therebetween, said fluid
passageway jacketing said transformer housing, substantially, to cool said
transformer housing as well as said oil within;
b. heat exchanger adapted to receive said oil for purposes of cooling; and
c. pump for facilitating movement of transformer oil from said stiffener
elements and said interconnecting pipe elements to said heat exchanger or
from said heat exchanger to said stiffener elements and said interconnecting
pipe elements, or both.
Typically, said stiffener elements are ribs or conduits along the height of the housing.
Typically, said oil is transformer oil.
Typically, said pump is a suction pump

Alternatively, said pump is a delivery pump
Alternatively, said pump is a pump system of suction pumps and delivery pumps.
Brief Description of the Accompanying Drawings:
The invention will now be described in relation to the accompanying drawings, in which:
Figure 1 illustrates a schematic front isometric view of the cooling system for transformers;
Figure 2 illustrates a schematic top isometric view of the cooling system for transformers; and
Figure 3 illustrates a schematic side view of the cooling system for transformers.
Detailed Description of the Accompanying Drawings:
According to this invention, there is provided a cooling system for transformers.
Figure 1 illustrates a schematic front isometric view of the cooling system (100) for transformers. Figure 2 illustrates a schematic top isometric view of the cooling system for transformers. Figure 3 illustrates a schematic side view of the cooling system for transformers.
In accordance with an embodiment of this invention, there is provided a transformer housing (10) with stiffener elements (12) running along the exterior of the housing. These stiffener elements are ribs or conduits along the height of the

housing. These already placed stiffener elements are characterized to aid in cooling said transformer housing and the transformer oil within.
In accordance with another embodiment of this invention, there are provided interconnecting pipe elements (14) adapted to interconnect said stiffener elements in order to provide a fluid passageway between them. The term, 'fluid passageway' is meant to be understood in a manner such that a fluid (19) can seamlessly flow through the stiffener elements and interconnecting pipe elements without hindrance. The additional of the interconnecting pipe elements is not a major change or addition and does not add substantially to the weight of the transformer housing. There is oil, preferably transformer oil, which is injected to flow and circulate through the fluid passageway formed by the stiffener elements (12) and interconnecting pipe elements (14). Thus fluid passageway jackets the entire transformer housing, substantially, to cool the transformer housing as well as the transformer oil within. The transformer oil is cooled in order to cool the transformer housing by forced convection.
In accordance with yet another embodiment of this invention, there is provided a heat exchanger (16) adapted to receive the transformer oil for purposed of cooling. There is provided a pump (18) or a plurality of pumps for facilitating this movement of transformer oil from the stiffener elements (12) and interconnecting pipe elements (14) to the heat exchanger (16) or from the heat exchanger to the stiffener elements (12) and interconnecting pipe elements (14), or both. The pumps may, therefore, be suction pumps, delivery pumps, or both.

Cooling of the transformer housing may take place due to forced convection and conduction as well as latent heat of fluid circulating through box stiffener elements.
By way of experiments, It was analysed that cooling efficiency of this transformer with the cooling system of this invention is better than cooling efficiency of normally cooled transformer. The number of fins in the radiator (of the earlier heat exchanger used for transformer oil cooling) could also be decreased by using this method and system of cooling.
While this detailed description has disclosed certain specific embodiments of the present invention for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We claim,
1. A cooling system for transformers, said cooling system comprising:
a. transformer housing with stiffener elements running along the exterior of
said housing, characterized in that, said stiffener elements are interconnected
to each other by means of interconnecting pipe elements to provide a fluid
passageway between them for allowing flow of oil through said stiffener
elements and interconnecting pipe elements, therebetween, said fluid
passageway jacketing said transformer housing, substantially, to cool said
transformer housing as well as said oil within;
b. heat exchanger adapted to receive said oil for purposes of cooling; and
c. pump for facilitating movement of transformer oil from said stiffener
elements and said interconnecting pipe elements to said heat exchanger or
from said heat exchanger to said stiffener elements and said interconnecting
pipe elements, or both.
2. A system as claimed in claim 1 wherein, said stiffener elements are ribs or conduits along the height of the housing.
3. A system as claimed in claim 1 wherein, said oil is transformer oil.
4. A system as claimed in claim 1 wherein, said pump is a suction pump
5. A system as claimed in claim 1 wherein, said pump is a delivery pump

6. A system as claimed in claim 1 wherein, said purmp is a pump system of suction pumps and delivery pumps.