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
PROVISIONAL SPECIFICATION
(See section 10 and rule 13)
TITLE OF INVENTION
Resin curing for the dry type condenser bushing
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company


INVENTORS
Sethumadhavan Thekkeveettil, of Product Technology Centre, CG Global R&D Centre, Crompton Greaves Limited, Kanjur (E), Mumbai 400042, Maharashtra, India, an Indian National
Anthony M Lobo, of Condition Monitoring and Distribution Research Centre, CG Global R&D Centre, Crompton Greaves Limited, Kanjur (E), Mumbai 400042, Maharashtra. India, an Indian National
Mandlik Manoj Kisan, of Product Technology Centre, CG Global R&D Centre, Crompton Greaves Limited, Kanjur (E), Mumbai 400042, Maharashtra, India, an Indian National
Nilesh Suresh Behere of Crompton Greaves Limited, Design Department, Switch Gear (SI) Division, A-3 MIDC, Ambad, Nasik - 422010, Maharashtra, India, an Indian National
PREAMBLE TO THE DESCRIPTION
The following specification describes the invention


The invention relates to method of effecting the gelling and curing process of a resin impregnated bushing core by providing the threshold heat energy required for the gelling and curing reaction, from inside to penetrate through the resin to outside surface of the resin impregnated core, thus ensuring a gelling and curing from inside to outside
The conventional form of carrying out the gelling and curing operation of a resin impregnated bushing core, is by heating the mould containing resin impregnated core in a vessel, where the heat is supplied from the walls of the vessel which in turn heats the mould surface by convection of heat and the heat is penetrated from outside to inside of the resin. This makes the gelling to start from outside and causes the resin shrinkage to happen towards outside which is opposite to the preferred shrinkage towards inside. Sometimes it can happen that the gelling starts from inside as well as outside because the central aluminum mandrel can also achieve the reaction temperature by convection as in the case of metallic mould. In this case the shrinkage can happen from both the sides. Both the above situations can lead to insulation layer separation
It is an object of the invention to provide method of effecting the gelling and curing process of a resin impregnated bushing core by providing the threshold heat energy required for the gelling and curing reaction from inside of the core, thus ensuring a gelling and curing from inside to outside
It is an object of the invention to provide a method of assembly of condenser core winding, with a thin rod type electric heating coil inside the central aluminum mandrel, in
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a metallic mould so as to impregnate it with the epoxy resin system at elevated temperature, 60 - 70C in a vessel under vacuum.
It is another object of the invention to provide a method of assembly of condenser core winding, with a thin rod type electric heating coil inside the central aluminum mandrel, in a metallic mould so as to impregnate it with the epoxy resin system at elevated temperature, 60 - 70C in a vessel under vacuum and ensuring the gelling and curing process to happen preferably from inside to outside.
The present invention relates to a method of effecting inside out gelling and curing of a resin impregnated paper (RIP) condenser bushing. RIP bushing consists of a dried cylindrical core comprising of crepe paper and aluminum foil wound on an aluminum mandrel essentially forming a condenser bushing, impregnated with an epoxy resin system. The epoxy resin system consists of an epoxy resin of bisphenol A type, a hardener of anhydride or cycloahphatic type and a latent accelerator in the proportion of 100: 85 to 90: 0.15 to 0.25. The epoxy resin is unmodified, solvent free and has a medium viscosity of 10000 - 14500 cps at 25C and the hardener has a viscosity of 50 -80. The mixture viscosity is in the range of 40 to 70 cps at 60 - 70 degree centigrade temperature range, at which the impregnation is carried out. The crepe paper wound on the mandrel forming the core has zero or very minimum tension and is 100% stretchable. It has a bulk thickness of 400 microns and has a base thickness of 85 microns and has a liquid absorption capability of about 50% of its own weight. The graded aluminum foil wrapped in the core interleaved with the crepe paper has a thickness of 12 microns.
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The invention relates to the method of assembly of the above said condenser core winding, with a thin rod type electric heating coil inside the central aluminum mandrel, in a metallic mould so as to impregnate it with the epoxy resin system at elevated temperature, 60 - 70C in a vessel under vacuum.
The invention relates to the method of heating so as to effect inside out gelling and curing of the resin impregnated cylindrical winding of crepe paper and aluminium foil, essentially forming the core of a condenser bushing, inside the metallic mould at a temperature of 90 to 120C. After curing this form the hard core of a resin impregnated paper condenser bushing.
The present invention relates to effecting the gelling and curing process of a resin impregnated bushing core by supplying the heat energy from both the sides but the required threshold heat energy for the gelling and curing process from inside to ensure gelling and curing process from inside to outside.
Dated this 19th day of March 2009
(Ivan Bernard Fuller)
ofKhaitan&Co
Agent for the Applicants
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