FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
Cooling system for electrical apparatus
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTORS
Panwar Arya of Crompton Greaves Ltd, Transformer (T3) Division, Plot No. 29, 31 & 32 New industrial area No.l, AKVN, Mandideep 462046, Madhya Pradesh, India, 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 electrical apparatus.
Particularly, this invention relates to cooling system for electrical apparatus, preferably for transformers.
BACKGROUND OF THE INVENTION:
A transformer has tendency to heat up upon continuous use. The capacity of a transformer's performance, such as mobile transformers or stationary transformers located at substations, is impacted greatly by ambient temperature. During the summer, when the demand for electric power is high, ambient temperature can limit substation capacity. Eliminating this seasonal bottleneck will be advantageous for providing uninterrupted service during peak demand periods without having to provide additional transformer capacity to handle the peak loads.
The transformer is filled with oil. This oil heats up as the components in the transformer heats up. For efficient working of the transformer, it is required to maintain the temperature of the oil, which in turn maintains the temperature of the components of the transformer.
While cooling of transformers is known, conventional systems for providing cooling to power transformers has had only limited effectiveness.
Still the need exists to provide effective cooling system for transformers

OBJECTS OF INVENTION:
An object of the invention is to provide a system for cooling an electrical apparatus (transformers) which can cool transformers more effectively.
Another object of the invention is to provide a system for cooling an electrical apparatus (transformer) which is relatively less expensive.
SUMMARY OF THE INVENTION:
According to this invention, there is provided a cooling system for
electrical apparatus having oil. said system comprises: I. chamber filled with cooled nitrogen;
II. oil radiator engulfed in said cooled nitrogen, said oil radiator adapted to receive said oil for exposing said oil to said cooled nitrogen over a larger surface area, thereby causing exchange of heat between said oil and said cooled nitrogen, thereby providing cooled oil for delivery; and
III. nitrogen recycling system adapted to recycle nitrogen from said nitrogen chamber in order to retain the temperature of the nitrogen.
Typically, said chamber is a gaseous nitrogen chamber.
Typically, said oil radiator is a series of pipes through which the oil is channeled.
Typically, said system includes nitrogen circuit valve adapted to regulate flow of nitrogen from the nitrogen chamber to the nitrogen recycling system and from nitrogen recycling system to the nitrogen chamber.

Typically, said system includes a pressure gauge adapted to reveal the pressure of nitrogen.
Typically, said system includes a nitrogen flow meter adapted to show the flow rate of nitrogen for regulating flow of nitrogen from a nitrogen recycling system to nitrogen chamber.
Typically, said system includes a pump adapted to pump nitrogen from said nitrogen recycling system to said nitrogen chamber.
According to another embodiment of this invention, there is provided an electrical apparatus with a nitrogen based cooling system, said electrical apparatus comprises:
a. an electrical apparatus in a transformer housing with oil in said
transformer housing, said housing having a suction conduit and
delivery conduit adapted to allow channels for corresponding
actions of suction and delivery of oil from the transformer housing;
b. a cooling system for electrical apparatus having oil, said system
comprising:
I. chamber filled with cooled nitrogen;
II. oil radiator engulfed in said cooled nitrogen, said oil radiator adapted to receive said oil from said electrical apparatus for exposing said oil to said cooled nitrogen over a larger surface area, thereby causing exchange of heat between said oil and said cooled nitrogen, thereby providing cooled oil for delivery; and III. nitrogen recycling system adapted to recycle nitrogen from said nitrogen chamber in order to retain the temperature of the nitrogen;

wherein oil from the transformer housing is sucked through the suction conduit into the nitrogen filled chamber and into the oil radiator.
Typically, said apparatus includes oil circuit valves adapted to regulate flow of oil from said nitrogen chamber and into said nitrogen chamber.
Typically, said apparatus includes an oil pump adapted to pump oil from said nitrogen cooling chamber to said transformer housing.
Typically, said apparatus includes a flow meter adapted to maintain the flow of pumped oil.
BRIEF DESCRIPTION OF THE ACCOMPNYING DRAWINGS:
The invention will now be described in relation to the accompanying drawings, in which:
Figure 1 illustrates a schematic of the system.
DETAILED DESCRIPTION OF THE ACCOMPNYING DRAWINGS:
As used herein the term "transformer" means a device for converting alternating current at one voltage to alternating current at a second voltage, used in the transmission or distribution of electric power.
According to this invention, there is provided a cooling system for electrical apparatus. Preferably, the electrical apparatus is a transformer.

In accordance with an embodiment of this invention, there is provided an electrical apparatus (transformer core and coils), represented by reference numeral (10), having a suction conduit (12) and delivery conduit (14) adapted to allow channels for corresponding actions of suction and delivery of oil (16) from the transformer housing (18).
In accordance with another embodiment of this invention, there is provided a chamber (20) filled with nitrogen (22). This nitrogen is cooled nitrogen. Preferably, the nitrogen is in its gaseous form. There is further provided an oil radiator (24) engulfed in said cooled nitrogen. The oil radiator exposes the transformer oil to the cooled nitrogen over a larger surface area, thereby causing exchange of heat between the oil and cooled nitrogen, thereby providing cooled oil.
Oil from the transformer housing is sucked through the suction conduit into the nitrogen filled chamber and into the oil radiator. The oil radiator is a series of pipes through which the oil is channeled. Over the course of channeling, the oil gets exposed to the relatively cooler nitrogen over a larger surface area, thereby cooling itself. The cooled oil is then passed through the delivery conduit into the transformer housing. Oil circuit valves (48) are provided to regulate flow of oil from the nitrogen chamber and into the nitrogen chamber. An oil pump (44) pumps oil from the nitrogen cooling chamber to the transformer housing. A flow meter (42) maintains the flow of pumped oil.
In accordance with yet another embodiment of this invention, there is provided a nitrogen recycling system (32) adapted to recycle nitrogen from the nitrogen chamber in order to retain the temperature of the nitrogen from the nitrogen chamber. There is also provided a nitrogen

circuit valve (34) adapted to regulate flow of nitrogen from the nitrogen chamber to the nitrogen recycling system and from nitrogen recycling system to the nitrogen chamber. A pressure gauge (36) reveals the pressure of nitrogen. A nitrogen flow meter (38) shows the flow rate of nitrogen for regulating flow of nitrogen from a nitrogen recycling system to nitrogen chamber. A pump (33) is adapted to pump nitrogen from the nitrogen recycling system to the nitrogen chamber.
While this detailed description has disclosed certain specific embodiments of the present invention for illustrative purposes, various modifications wilt 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 electrical apparatus having oil, said system
comprising:
I. chamber filled with cooled nitrogen;
II. oil radiator engulfed in said cooled nitrogen, said oil radiator adapted to receive said oil for exposing said oil to said cooled nitrogen over a larger surface area, thereby causing exchange of heat between said oil and said cooled nitrogen, thereby providing cooled oil for deliver}'; and III. nitrogen recycling system adapted to recycle nitrogen from said nitrogen chamber in order to retain the temperature of the nitrogen.
2. A system as claimed in claim 1 wherein, said chamber is a gaseous nitrogen chamber.
3. A system as claimed in claim 1 wherein, said oil radiator is a series of pipes through which the oil is channeled.
4. A system as claimed in claim 1 wherein, said system includes nitrogen circuit valve adapted to regulate flow of nitrogen from the nitrogen chamber to the nitrogen recycling system and from nitrogen recycling system to the nitrogen chamber.
5. A system as claimed in claim 1 wherein, said system includes a pressure gauge adapted to reveal the pressure of nitrogen.
6. A system as claimed in claim 1 wherein, said system includes a nitrogen flow meter adapted to show the flow rate of nitrogen for

regulating flow of nitrogen from a nitrogen recycling system to nitrogen chamber.
7. A system as claimed in claim 1 wherein, said system includes a pump adapted to pump nitrogen from said nitrogen recycling system to said nitrogen chamber.
8. An electrical apparatus with a nitrogen based cooling system, said electrical apparatus comprising:
a. an electrical apparatus in a transformer housing with oil in said
transformer housing, said housing having a suction conduit and
delivery conduit adapted to allow channels for corresponding
actions of suction and delivery of oil from the transformer housing;
b. a cooling system for electrical apparatus having oil, said system
comprising:
I. chamber filled with cooled nitrogen;
II. oil radiator engulfed in said cooled nitrogen, said oil radiator adapted to receive said oil from said electrical apparatus for exposing said oil to said cooled nitrogen over a larger surface area, thereby causing exchange of heat between said oil and said cooled nitrogen. thereby providing cooled oil for delivery; and III. nitrogen recycling system adapted to recycle nitrogen from said nitrogen number in order to retain the temperature of the nitrogen:
wherein oii from the transformer housing is sucked through the
suction conduit into the nitrogen filled chamber and into the oil
radiator.

9. An electrical apparatus as claimed in claim 8 wherein, said apparatus includes oil circuit valves adapted to regulate flow of oil from said nitrogen chamber and into said nitrogen chamber.
10.An electrical apparatus as claimed in claim 8 wherein, said apparatus includes an oil pump adapted to pump oil from said nitrogen cooling chamber to said transformer housing.
11.An electrical apparatus as claimed in claim 8 wherein, said apparatus includes a flow meter adapted to maintain the flow of pumped oil.