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, 2005
PROVISIONAL SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
Improved Insulating tank
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTORS
Sumedh Pawar, Yargole Arun Dattatraya and Joshi Kishor Uddhav, of CG Global R&D center, Crompton Greaves Limited, Kanjurmarg(E), Mumbai, Maharashtra, India; all Indian nationals.
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention:

FIELD OF THE INVENTION
This invention relates to Improved Insulating tank for superconducting transformer and also for other applications such as fault current limiters, superconducting magnets and any other product needing very good insulation.
PRIOR ART
Conventionally insulating tank also known as cryostat is made up of Fibre reinforced plastics (FRP) for super conducting transformer applications.
US 510,72,40 discloses a heat insulating double wall tank made up of fibre reinforced plastics (FRP) with vacuum and holding superconducting coils. Outermost enclosure, described as cryostat made of ferromagnetic material (with no double wall and vacuum). Heat insulating double wall tank of FRP is lined along the inner surface of the outermost enclosure, described as cryostat. Also discloses a referigerant gasified in heat insulating tank is exhausted through pipe.
US 632,48,51 discloses a cryostat enclosing insulating tank and transformer core. The cryostat comprises a tank having an outer wall, a non-conducting liner, and a load bearing insulation layer disposed between the wall and the liner. The outer wall of the tank is constructed from a metallic material, such as constructional steel, stainless steel, or aluminum that provides protection against severe internal electrical faults and/or captures and deflects stray magnetic flux generated by the core of the superconducting transformer. In addition, a metallic material is non-gas permeable at ambient temperatures which helps to maintain vacuum pressure. The liner preferably comprises a thin polymer / fiber composite liner. Dielectric shields, in the form of a wire mesh, carbon fibers or metal coated glass can be integrated in the composite liner. The insulation layer comprises a load-bearing thermal insulation material that exhibits sufficient compressive strength to transmit the internal pressure acting on the liner to the outer wall, and that has a thermal conductivity as low as 2 mW/m/K.


OBJECTS OF THE INVENTION
An object of the invention is to provide an improved insulating tank which reduces heat leak into the cryostat so as to minimize the evaporation rate of liquid nitrogen inside the cryostat and hence reduces the need for liquid nitrogen replenishment.
Another object of the invention is to provide the improved insulating tank which reduces heat load on cryocooler and investment in cryocooler
Another object of the invention is to provide the improved insulating tank which saves energy and reduces operating cost.
Another object of the invention is to provide the improved insulating tank which uses in various applications such superconducting transformer, fault current limiters, superconducting magnets and any other product needing very good insulation.
Another object of the invention is to provide the improved insulating tank which provides an enclosure to protect the transformer from weather, mechanical shocks and other environmental effects
Another object of the invention is to provide the improved insulating tank which is easy to fabricate as compared to fiberglass tank
Another object of the invention is to provide the improved insulating tank in which the heat from core is removed by using heat pipes / thermosiphons / thick metallic conductors and rejected to the ambient outside the tank
Another object of the invention is to provide the improved insulating tank in which it is easy to achieve and sustain high vacuum level to minimize the heat load on the cryostat over a long period of time as compared to that in a fibre glass tank.


DESCRIPTION OF INVENTION
According to the invention, there is provided an insulating tank having a multi wall preferably double wall with vacuum and /or insulation between the walls for reducing the heat load on superconducting transformer. The insulating tank consists of double walled enclosure, having a transformer with heat pipes / thermosiphons in the transformer core, cryostat enclosure inside the insulating tank to hold the superconducting coils and liquid cryogen, and superconducting coils inside the cryostat.
According to the invention there is also provided additionally thermal Insulation such as foam, powders such as pearlite within the gap between the insulating tank and cryostat to further reduce the heat load on the cryostat.
According to the invention a space between the outer surface of the cryostat and inner surface of the outer metallic enclosure is additionally evacuated to further reduces the heat load on the cryostat
According to the invention, an insulating tank comprises a double wall enclosure made of metal preferably out of stainless steel or carbon steel etc.
According to the invention, an insulating tank comprises a double wall enclosure with multilayer insulation and vacuum.
According to the invention, an insulating tank comprises a double wall enclosure without multilayer insulation and with vacuum.
In accordance to the present invention, cryostat comprises a FRP enclosure
In accordance to the present invention, cryostat in which the heat from transformer core is removed by using heat pipes / thermosiphons / thick metallic conductors and rejected to the ambient outside the tank


According to the invention, insulating tank reduces heat leak into the cryostat and thus minimizes the evaporation rate of liquid nitrogen inside the cryostat and reduces the need for liquid nitrogen replenishment.
In accordance to the present invention cryostat comprises a liquid cryogen to maintain the superconducting coils in superconducting state.
According to the invention insulating tank encloses the core fully and does not make any electric turn within the core magnetic filed. Additionally insulating tank cut off all radiations coming from outside towards HTS transformer. Multiple insulation and vacuum inside greatly reduces the heat leakage by conduction and convection.
According to the invention, insulating tank having sufficient gap between two tank walls and thus reduces the heat leakage substantially.
In accordance to the present invention, insulating tank is preferably fabricated from stainless steel or carbon steel but not limited to these materials alone.
In accordance to the present invention, the metallic insulating tank does not degas in vacuum and helps achieving vacuum quickly and maintaining for long time and also reflects radiation more effectively.
In accordance to the present invention insulating tank in which the transformer core is enclosed in the tank and remove heat of this core by using heat pipes / thermosiphons / thick metallic conductors.