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 ruki 13)
TITLE OF THE INVENTION
A low loss core clamping structure for transformers
APPLICANT
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR(S)
Bhuramurthy Jaisairam of Crompton Greaves Limited, Analytics Centre, Global R&D Centre, Bhaskara building, Crompton Greaves Ltd, Kanjurmarg (East), 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 electronic and electrical equipment.
Particularly, this invention relates to transformers and clamping structures for transformers.
Specifically, this invention relates to a low loss core clamping structure 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 an electrical device which transfers electrical energy from one circuit to another through inductively coupled conductors i.e. through transformer's coils. 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 transformer coils are immersed in oil which acts as an insulator and dielectric medium.
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 time-varying voltage in the secondary windings.

There is insulation medium between the windings and the windings and core of the transformer, flitch plates, frames which forms the core coil assembly of the transformer. This insulation may be gas insulation, the gas being sulfur hexafluoride gas (SF6).
There is a clamping structure for cores of a transformer. This clamping structure refers to Metallic or wooden structure used to clamp the core and windings. According to the prior art, these are metal or steel structures. When the metallic Frame structures are nearer to the windings and in the vicinity of flux, Eddy currents are induced in the frame structures according to the faradays law of electromagnetic induction, which Contributes major stray loss in it.
There is a need to reduce the stray losses.
OBJECTS OF THE INVENTION:
An object of the invention is to provide a core clamping structure for a transformer which reduces stray losses.
Another object of the invention is to provide a core clamping structure for a transformer which reduces flux induced due to Eddy current formation.
Yet another object of the invention is to provide a relatively inexpensive core clamping structure for a transformer.
Still another object of the invention is to provide a core clamping structure for a transformer so that there is reduction in weight, hotspots and average temperature inside the transformer.

An additional object of the invention is to provide a core clamping structure for a transformer so that increase in lifetime of transformer and overall efficiency of the transformer is improved.
SUMMARY OF THE INVENTION:
According to this invention, there is provided a transformer with low loss core clamping structure, said structure comprises an operative top plate and an operative bottom plate such that said operative top plate and said operative bottom plate line up over and below windings of said transformer, characterised in that, a frame projection for winding supports in a top and bottom frame is positioned away from the winding along the length of said frame, towards the mid axis between the main limb and side limb of the transformer, and at the ends of the said operative top and bottom frame such that said windings rest on said wooden support elongate bar.
So the frame projections are not in the vicinity of magnetic field produced by the windings and the induced eddy currents in the frame projections is less. Consequently, stray losses occurring in the clamping structures of the transformer reduce.
According to this invention, there is also provided a low loss core clamping structure for transformers, said structure comprises an operative top plate and an operative bottom plate such that they line up over and below windings of said transformer, characterised in that, a wooden support elongate bar is positioned on top of said operative bottom plate such that said windings rest on said wooden support elongate bar.
According to this invention, there is also provided a transformer with low loss core clamping structure, said structure comprises an operative top plate and an operative

bottom plate such that they line up over and below windings of said transformer, characterised in that, a wooden support elongate bar is positioned on top of said operative bottom plate such that said windings rest on said wooden support elongate bar.
Typically, said wooden support elongate bar is common to three windings of said transformer.
Typically, wooden support elongate bar is fitted to the frame projection through bolts.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 illustrates a core clamping structure, of the prior art, for a transformer; and
Figure 2 frame assembly of the core clamping structure of Figure 1.
The invention will now be described in relation to the accompanying drawings, in which:
Figure 3 illustrates a core clamping structure, for a transformer; and
Figure 4 frame assembly of the core clamping structure of Figure 3.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 illustrates a core clamping structure, of the prior art, for a transformer.
Figure 2 frame assembly of the core clamping structure of Figure 1.

Windings (12) are shown linearly aligned adjacent each other. The windings may be Copper windings. The core is represented by reference numeral 14. A core clamping assembly holds the core and windings. The frame of the core clamping assembly is shown in Figure 2 of the accompanying drawings. The clamping assembly comprises a top plate (16a) and a bottom plate (16b) such that they line up over and below the windings respectively. The bottom plate (16b) comprises support plates (18) of metal or Mild Steel in order to provide bottom support to each of the windings. Even the top plate and bottom plate are of metal or Mild Steel. Therefore, Eddy currents get induced in the frame structure. Also, stray losses can be seen in this type of frame structure.
According to this invention, there is provided a low loss core clamping structure for transformers
Figure 3 illustrates a core clamping structure, for a transformer.
Figure 4 frame assembly of the core clamping structure of Figure 3.
In accordance with an embodiment of this invention, there is provided a top plate (16a) and a bottom plate (16b) such that they line up over and below the windings (12) respectively. There is provided a wooden support elongate bar (20) on top of the bottom plate (16b) such that the windings (12) rest on the wooden support elongate bar (20). Therefore, there is no Eddy current formation and there is reduction in stray losses. Also, cost of the transformer reduces due to elimination of metal or steel.
The wooden support elongate bar (20) is common to the three windings.

The technical advancement of this invention lies in provisioning a wooden support elongate bar on a core clamping assembly such that there is reduction in Eddy current formation, reduction in hotspot temperature, reduction in weight and cost, reduction in stray losses, reduction in average temperature rise, and therefore results in improved overall efficiency of the transformer.
The technical advancement of this invention also lies in provisioning the location of the frame projections. The frame projection for winding supports in the top and bottom frame is modified and positioned away from the winding along the length of the frame, towards the mid axis between the main limb and side limb of the transformer, and at the ends of the said operative top and bottom frame such that said windings rest on said wooden support elongate bar.
The wooden support elongate bar is fitted to the frame projection through bolts.
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 loss core clamping structure for transforrriers, said structure comprising an operative top plate and an operative bottom plate such that they line up over and below windings of said transformer, characterised in that, a wooden support elongate bar being positioned on top of said operative bottom plate such that said windings rest on said wooden support elongate bar.
2. A low loss core clamping structure for transformers as claimed in claim 1 wherein, said wooden support elongate bar is fitted to said frame projection through bolts.
3. A transformer with low loss core clamping structure, said structure comprising an operative top plate and an operative bottom plate such that said operative top plate and said operative bottom plate line up over and below windings of said transformer, characterised in that, a frame projection for winding supports in a top and bottom frame is positioned away from the winding along the length of said frame, towards the mid axis between the main limb and side limb of the transformer, and at the ends of the said operative top and bottom frame such that said windings rest on said wooden support elongate bar.
4. The low loss core clamping structure for transformers as claimed in claim 3, wherein said wooden support elongate bar being common to three windings of said transformer.

5. A transformer with low loss core clamping structure, said structure comprising an operative top plate and an operative bottom plate such that they line up over and below windings of said transformer, characterised in that, a wooden support elongate bar being positioned on top of said operative bottom plate such that said windings rest on said wooden support elongate bar.
6. The transformer with low loss core clamping structure as claimed in claim 5, wherein said wooden support elongate bar being common to three windings of said transformer.