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
An insulative lead-out structure of a transformer APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTORS
Sanidhya Vats and Denny Chelladurai of Crompton Greaves Ltd, T3 Division, Mandideep, Bhopal - 462046, Madhya Pradesh, India, both Indian Nationals
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF THE INVENTION
This invention relates to an insulative lead-out structure of a transformer. BACKGROUND OF THE INVENTION
A lead-out structure for connecting the lead-out transformer winding to a bushing in a large rating EHV (extra high voltage) power transformer generally comprises 3 or 5 insulation layers. Generally, such a structure comprises a L-shaped hollow copper tube carrying a wire therein one end of which is connected to the lead-out transformer winding and the other to a bushing end. Around the hollow copper tube, a circular pressboard sheet is provided in a spaced apart relationship with the copper tube. Depending upon the application and insulation requirement, further layers of circular pressboard sheets in a spaced apart relationship with each other are provided. Oil (for providing insulation) is filled in the clearances between the copper tube and circular pressboard sheets and between two pressboard sheets.
The higher the voltage rating of the transformer higher is the insulation requirement. Consequently, the number of pressboard sheets (insulation layers) also goes up thereby increasing the cost. Moreover, assembling multiple layers of circular pressboard sheets around the copper tube is complex, time consuming, costly and requires skilled labour.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention, there is provided an insulated lead-out structure of a transformer comprising an electrically conducting rod adapted to be electrically connected to a lead-out transformer winding at one end thereof and to a bushing end at the other end thereof, the conducting rod comprising a coating of an insulating material on an outer surface thereof, an insulating paper sheet wrapped on said coating and a modular insulating sheet held around the insulating paper sheet in a spaced apart relationship therewith by means of spacers, the modular insulating sheet bulging at the other end of the rod and extending therebeyond for

receiving the bushing end therein and insulating the electrical connection between the conducting rod and the bushing end.
According to a preferred embodiment of the invention, the conduction rod is made up of copper and L-shaped. Enamel is coated on the outer surface of the conducting rod and the insulating paper sheet is crepe paper. The spacing between the modular sheet and the conducting rod is 10 mm. The lead-out structure is clamped on an outer surface of a wall of the transformer for support.
These and other aspects, features and advantages of the invention will be better understood with reference to the following detailed description, accompanying drawings and appended claims, in which,
Fig 1 is a cross sectional view of an insulative lead-out structure of a transformer according to a preferred embodiment.
As shown in Fig 1, the insulative lead-out structure of a transformer according to a preferred embodiment comprises a L-shaped circular electrically conducting rod 1 made up of copper. One end 4 of the conducting rod is connected to a lead-out transformer winding and the other end 5 to a bushing end (not shown). For insulating purposes, an outer surface of the conducting rod 1 is coated with an insulating material such as enamel. However, other types of insulative coatings can also be used. Further insulation is provided by wrapping the enamel coated conducting rod 1 with an insulating paper sheet 2. A crepe paper is preferred but other types of insulating paper sheets may also be used. A circular modular insulating sheet 3 is held around the crepe paper wrapped enamel coated conducting rod 1. A spacing of around 10mm is maintained between the conducting rod 1 and the modular insulting sheets 3 by means of spacers preferably made from pressboard sheets. The spacing is filled with oil for provide further insulation. The modular insulting sheet 3 may be either continuous throughout the length of the L-shaped conducting rod 1 or made up of multiple pieces assembled together. The modular insulating sheet 3 is extending beyond the other end 5 of the

conducting rod 1 as well as bulging out 6 for receiving a generally V-shaped bushing end therein. The bulging portion 6 also provides more space around the connection point of the bushing end 5 and the conducting rod 1. The lead-out structure is clamped on an outer surface of the wall of transformer for providing support thereto.
According to the invention, the insulative lead-out structure is inexpensive, simple, easy to construct, assemble and install on the transformer and without compromising on the insulation requirements.
Although the invention has been described with reference to a specific embodiment, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiment, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the scope of the invention as defined in the appended claims.

We claim:
1. An insulated lead-out structure of a transformer comprising an electrically conducting rod adapted to be electrically connected to a lead-out transformer winding at one end thereof and to a bushing end at the other end thereof, the conducting rod comprising a coating of an insulating material on an outer surface thereof, an insulating paper sheet wrapped on said coating and a modular insulating sheet held around the insulating paper sheet in a spaced apart relationship therewith by means of spacers, the modular insulating sheet bulging at the other end of the rod and extending therebeyond for receiving the bushing end therein and insulating the electrical connection between the conducting rod and the bushing end.
2. The insulated lead-out structure as claimed in claim 1, wherein the electrically conducting rod is made up of copper.
3. The insulated lead-out structure as claimed in claim 1 is an L-shaped structure.
4. The insulated lead-out structure as claimed in claim 1, wherein the coating material is enamel.
5. The insulated lead-out structure as claimed in claim 1, wherein the insulating paper sheet is a crepe paper.
6. The insulating lead-out structure as claimed in claim 1, wherein the clearance between the modular insulating sheet and the paper wrapped coated rod is 10mm.
7. The insulating lead-out structure as claimed in claim 1 is clamped to an outer surface of a wall of the transformer.