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
A dual distribution high voltage power transformer
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTORS
Vanage Manish Madhukar and Vaidya Sameer Sharadchandra of Crompton Greaves Ltd, Tl, Transformer Division, Kanjur Marg (E), Mumbai 40Q 042, Maharashtra, India, both Indian Nationals.
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
The invention relates to a dual distribution high voltage power transformer transmitting power to over head as well as underground load cables. BACKGROUND OF THE INVENTION
A dual distribution high voltage (HV) power transformer transmits power to over head as well as underground HV cables through a branched winding cable of the core coil assembly of the transformer. Each branch extends through an oil to air and oil to oil bushing of the transformer for connection to the over head and underground cable respectively. Usually, the oil to air bushing is mounted on top of a cable box of the transformer while the oil to oil bushing is enclosed therein. The cable box is mounted to a wall of the transformer tank through a high voltage disconnecting chamber. Conventionally, the winding cable extends through the high voltage disconnecting chamber into the cable box where it is branched for connection to the over head and underground cables. Usually, at the testing site of the transformer, only the over head cable connection of the transformer is required to be tested. Owing to the design of the transformer, the entire assembly of the cable box is required to be installed to the transformer which is a time consuming and complicated process as well as requires skilled manpower. Also, a transformer with the cable box installed takes up a lot of space in the testing bay. There is a scope of eliminating the need of the cable box being installed to the transformer for testing only the overhead load connection of the
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transformer thereby saving a good time in testing the transformer. A transformer without the cable box in the testing bay will free up a lot of space therein.
OBJECTS OF THE INVENTION
An object of the invention is to provide a dual distribution high voltage power transformer wherein a cable box is not required to be installed thereto for testing the overhead cable connection of the transformer thereby rendering the testing of the transformer easy and less time consuming.
Another object of the invention is to provide a dual distribution high voltage power transformer which occupies less space in the testing bay for testing the overhead cable connection of the transformer. DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a dual distribution high voltage power transformer comprising a core coil assembly mounted in a transformer tank filled with transformer oil, the transformer further comprising of an oil to air high voltage terminal assembly and an oil to oil high voltage terminal assembly, wherein the oil to air high voltage assembly comprising of a high voltage turret mounted on the transformer tank and an oil to air bushing mounted on the turret; the oil to oil high voltage terminal assembly comprising of a high voltage disconnecting chamber mounted to a wall of the transformer tank, a cable box mounted to the high voltage disconnecting chamber and an oil to oil high voltage bushing enclosed within the high voltage disconnecting chamber, further a winding cable of the core coil assembly is branched within the transformer tank,
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each branch being extended through the to the oil to air and oil to oil bushings for outputting power to an over head and underground cable respectively .
The following is a detailed description of the invention with reference to the accompanying drawings, in which
Fig 1 is a cross-sectional view of a high voltage power transformer.
Fig 2 is cross sectional view of the high voltage power transformer in the testing mode.
Fig 1 is a cross-sectional view of a high voltage (HV) power transformer. The transformer comprises of a core coil assembly (not shown in the figure) mounted in a transformer oil filled transformer tank 1. The transformer further comprises of an oil to air and oil to oif HV terminal assemblies through which the winding cable 2 of the of core coil assembly extends for connection with overhead and underground cables (not shown in the fig) respectively. The oil to air HV terminal assembly comprises of an oil filled HV turret 3 located on the transformer tank 1. A HV oil to air bushing 4 is provided on the HV turret 3. The HV oil to air bushing 4 is essentially a hollow cylindrical tube like structure made up of porcelain for enclosing and insulating a high tension winding cable. The HV oil to oil terminal assembly comprises of a transformer oil filled HV disconnecting chamber 5, a transformer oil filled cable box 6 and an oil to oil bushing 7. The HV disconnecting chamber 5 is essentially a passage integral with the wall of the transformer tank 1 projecting there from and partially enclosing the oil to oil bushing 7. The transformer oil filled cable box 6 is an elbow shaped hollow cylindrical structure having openings at its opposite ends. One end is mounted to the free end of the HV disconnecting chamber 5 while the other end points downwardly towards the ground. The
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one end of the cable box 6 encloses the other partial structure of the oil to oil bushing 7 while the other end facing the ground encloses a cable sealing terminal end 8 which is connected to the underground cable. A connector cable is provided between the oil to bushing 7 and the cable sealing terminal end 8 for an electrical connection between the cables enclosed therein. A lighting arrester 9 is mounted on top of the cable box 6. A winding cable 2 originating from the core coil assembly is branched into a first 10 and a second cable 11 in the transformer tank 1 for connection to the over head and underground cables respectively. The first cable 10 extends through the HV turret 3 and the HV oil to air bushing 4 to terminate as oil to air HV terminal 12 which is connected to the overhead cable. The second cable 11 extends through the HV oil to oil bushing 7 into the cable sealing terminal end 8 for connection with the underground cable terminal.
Fig 2 is cross sectional view of the high voltage power transformer in the testing mode. For testing the transformer for the overhead cable connection, the cable box 6 as shown in Fig 1 is not mounted to the HV disconnecting chamber 5. Consequently, the free end of second cable 11 remains non-insulated in the HV disconnecting chamber 5. A stress cap 13 is mounted on the non-insulated terminal of the second cable 11 in the HV disconnecting chamber 5. The free end of the HV disconnecting chamber 5 remains sealed.
According to the invention, the cable box is rendered redundant for testing the transformer for the overhead cable connection thereby reducing the overall testing time of the transformer which otherwise would have been substantially more owing to the complex and time consuming process of mounting the cable box to the HV disconnecting
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chamber of the transformer. Also the space occupied by the transformer during the above testing is substantially less owing to the absence of cable box.
The shapes of the oil to air bushing and the cable box may vary. The method of electrical connections within the cable box may vary.
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 spirit or scope of the invention as defined.
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We claim:
1. A dual distribution high voltage power transformer comprising a core coil assembly mounted in a transformer tank filled with transformer oil, the transformer further comprising of an oil to air high voltage terminal assembly and an oil to oil high voltage terminal assembly, wherein the oil to air high voltage assembly comprising of a high voltage turret mounted on the transformer tank and an oil to air bushing mounted on the turret; the oil to oil high voltage terminal assembly comprising of a high voltage disconnecting chamber mounted to a wall of the transformer tank, a cable box mounted to the high voltage disconnecting chamber and an oil to oil high voltage bushing enclosed partially within the high voltage disconnecting chamber and the cable box, further a winding cable of the core coil assembly is branched within the transformer tank, each branch being extended through the to the oil to air and oil to oil bushings for outputting power to an over head and underground cable respectively.
2. The dual distribution high voltage power transformer as claimed in claim 1, wherein a lightning arrester is mounted on top of the cable box.
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3. The dual distribution high voltage power transformer as claimed in claim 1,
wherein the cable box is an elbow shaped oil filled cylindrical structure.
Dated this 30th day of March 2009.

(Ivan Bernard Fuller) of Khaitan & Co
Crompton Greaves Limited By their Agent & Attorney