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 A low noise transformer.
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company.
INVENTOR
Chaudhari Sushil Ekanath of Crompton Greaves Ltd, Conition Monitoring & Diagnostic Research Centre, CG Global R&D Centre, Kanjur (E), Mumbai 400042, Maharashtra, 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.
Particularly, this invention envisages a low noise transformer.
BACKGROUND OF THE INVENTION:
A Transformer is an electrical device that transfers energy from one circuit to another by magnetic coupling without any moving parts. It works on the Principle of Faradays Law of Electromagnetic Induction together with other laws of electricity. When a magnetic flux linked with an electric circuit varies, an electro motive force (voltage) is generated in the electric circuit, proportional to the rate of variation of flux with time.
The basic functional components of the transformer are a core made of magnetic material, a primary winding, and a secondary winding. The primary winding is connected to a source of an alternating current and the secondary winding is connected to the output. As the alternating current flows through the primary winding, the change in current in the primary windings creates a time-varying magnetic flux in the core, which induces a voltage in the secondary windings.
Transformer has a ferromagnetic core. When the core is excited with an Alternating Current supply, it changes in size and shape. The continuous change in size and shape of the ferromagnetic core generates an air column. This generated air column hits the sides of the casing of the transformer and causes objectionable noises.
These wayward movements of air columns may result in inherent turbulence and

vortex formation, which results in heat build-up in the transformer. Hence, there is a need to provide an improved transformer.
OBJECTS OF THE INVENTION:
An object of the invention is to provide a transformer having low noise characteristics.
Another object of the invention is to provide a transformer with enhanced cooling characteristics.
Yet another object of the invention is to provide the use of noise dampening material for reducing objectionable noise in a transformer.
Still another object of the invention is to reduce oil related costs in a transformer.
SUMMARY OF THE INVENTION
According to this invention, there is provided a low noise transformer with enhanced cooling capability, said transformer comprises: at least a dimpled sheet with noise damping material at pre-defined locations in said transformer, said noise damping material being put in the dimples of said dimpled sheet and being placed at pre-defined positions in between cores of said transformer.
Typically, said at least a dimpled sheet with noise damping material is at least a dimpled sheet with painted, coated, or pasted noise damping material.
Preferably, said at least a dimpled sheet is a vertically placed at least a dimpled

sheet between cores at pre-defined places.
Alternatively, said at least a dimpled sheet is a horizontally placed at least a dimpled sheet between cores at pre-defined places.
Typically, said noise damping material is a coating or film applied in micron size as per transformer design and rating.
Preferably, said noise damping material is a coating or film applied in the range from about 0.5mm to about 500μ as per transformer design and rating.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
The invention will now be described in relation to the accompanying drawings, in which:
Figure 1 illustrates an exemplary embodiment of transformer core with dimpled sheet and noise damping material placed in the core.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
According to this invention, there is provided a low noise transformer with enhanced cooling capability.
Figure 1 illustrates an exemplary embodiment of transformer core with dimpled sheet and noise damping material placed in the core.
Reference numeral 12 refers to the stack of windings which form the core.

In accordance with an embodiment of this invention, there is provided at least a dimpled sheet with noise damping material (which is compatible with the transformer components) inside a transformer. Typically, the noise damping material is put in the dimples of the dimpled sheets and is placed at pre-defined positions in between cores of the transformer. Reference numeral 14 refers to dimpled sheet with noise damping material in the stack of windings of the transformer core (in the exemplary embodiment illustrated by Figure 1 of the accompanying drawings).
The noise damping material is applied (painting, coating or pasting) on the dimpled sheet. Typically, the dimpled sheet is placed at specific positions in between cores of the transformer.
The dimple sheet with noise damping material (painting, coating, or pasting) can be mounted in the transformers/reactors as per its rating.
The noise damping material not only absorbs energy, leading to reduction in objectionable noise, but also provides an additional path for the oil to reach the core pack of the transformer, thus aiding in its cooling.
Preferably, the dimpled sheets are placed in horizontally and / or vertically between cores at certain pre-defined places. Preferably, they are placed in vertical direction. These dimples with noise damping material absorb energy generated by core excitation which is causing the objectionable audible noise. The coating or film will be applied in micron size as per the design.
The dimpled sheet is incorporated in the core assembly of the transformer. The

noise damping material is placed on the dimpled sheet which is placed in the core of a transformer.
The size of the coating is preferably ranging from 0.5mm to 500μ. This brings about at least 10% reduction in noise of transformer.
It is to be noted that the number of dimple sheets is proportional to the rating of the transformer. This invention results in reduction in noise level and at the same time results in bringing about cooling.
The use of dimpled sheets along with noise damping material results in guiding the flow of oil.
It is to be understood that designers (persons skilled in the art) can modify or arrange the parts of the invention at different locations too, based on their designing methodology and rating of the electrical equipment which designing is within the scope of this invention.
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 low noise transformer with enhanced cooling capability, said transformer
comprising:
at least a dimpled sheet with noise damping material at pre-defined locations in said transformer, said noise damping material being put in the dimples of said dimpled sheet and being placed at pre-defined positions in between cores of said transformer.
2. A transformer as claimed in claim 1, wherein said at least a dimpled sheet with noise damping material is at least a dimpled sheet with painted, coated, or pasted noise damping material.
3. A transformer as claimed in claim 1, wherein said at least a dimpled sheet is a vertically placed at least a dimpled sheet between cores at pre-defined places.
4. A transformer as claimed in claim 1, wherein said at least a dimpled sheet is a horizontally placed at least a dimpled sheet between cores at pre-defined
• places.
5. A transformer as claimed in claim 1, wherein said noise damping material is
a coating or film applied in micron size as per transformer design and rating.

6. A transformer as claimed in claim 1, wherein said noise damping material is a coating or film applied in the range from about 0.5mm to about 500μ. as per transformer design and rating.