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 capacitor voltage transformer
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai - 400 030,
Maharashtra, India, an Indian Company
INVENTOR
Shirke Kishor Shantaram, S 1 Division, Crompton Greaves Ltd, A3, MIDC, Ambad_,Nashik, Maharashtra, India, an Indian national
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 a capacitor voltage transformer.
BACKGROUND OF THE INVENTION
Capacitor voltage transformers are used in power systems to step down high voltage signals and to provide low voltage signals for measurement or for operation of protective relays. A capacitor voltage transformer comprises an electromagnetic unit and a capacitor vertically disposed and mounted on the electromagnetic unit and electrically connected to the electromagnetic unit. The capacitor comprises a plurality of stacks of capacitor elements stacked one above another and located in a tubular porcelain insulator having convolutes along the outer circumference thereof. The porcelain insulator is supported on a base at the bottom thereof and has a top plate fitted at the top thereof. A bellows is disposed in the porcelain insulator at the top thereof and fitted to the top plate. Except the bottom stack, all the other stacks are supported on and isolated from one another by insulator material shield plates having aligning slots at one ends thereof. The stacks of capacitor elements including the shield plates are guided on two pairs of insulator material guide rods in guide notches provided in the capacitor elements and shield plates and held against the guide rods. One pair of guide rods are vertically disposed on the base at one side of the stacks and the other pair of guide rods are vertically disposed on the base at the opposite side of the stacks. The bottom stack is supported on an aluminium bottom support plate which is fixed to one pair of guide rods at one side thereof. The opposite side of the support plate simply abuts against the other pair of guide rods. An insulator material aligning rod is inserted in the

aligning slots in the shield plates and vertically disposed on the base. One pair of guide rods are fixed to the base with a stainless steel angle bracket. One limb of the angle bracket is fixed to the base and the other limb of the angle bracket is fixed to the one pair of guide rods.
Capacitor voltage transformers are installed with the capacitor in the vertical position. Transportation of capacitor voltage transformer is generally carried out with the capacitor in the vertical position. Because of the restriction on height in transportation, capacitor voltage transformers with heights beyond the prescribed heights cannot be transported. Therefore, capacitor voltage transformers beyond certain voltage rating and capacitance cannot be transported. As a result, the voltage rating and capacitance of the capacitor voltage transformers to be transported and installed at distant places away from the place of manufacture are limited in that the height and size of the capacitor increase with increase in voltage rating and capacitance of the capacitor voltage transformer. The higher the voltage rating and capacitance of the capacitor voltage transformer, the taller the capacitor and the larger the size of the capacitor.
Capacitor voltage transformers cannot be transported with the capacitor in the tilted down and horizontal position in that on tilting the capacitor, the stacks of capacitor elements of the capacitor also will tilt and misalign as there is a significant clearance between the shield plates and the inner circumference of the porcelain insulator. The bellows will also tilt and misalign as there is a substantial clearance between the outer circumference of the bellows and the inner circumference of the porcelain insulator. Further, the bottom support plate is fitted only to two porcelain guide rods at one side thereof. Therefore, the unsupported side of the bottom support plate will sag down, especially when the stacks of capacitor elements are heavier. The bottom

support plate also can misalign and cause misalignment of the stacks of the capacitor elements if the capacitor is tilted down.
OBJECTS OF THE INVENTION
An object of the invention is to provide a capacitor voltage transformer which can be tilted down without disturbing the position of the stacks of the capacitor elements and bellows and can be transported in the horizontal position.
Another object of the invention is to provide a capacitor voltage transformer which prevents the stacks of capacitor elements from sagging down in the vertical position of the capacitor and misalignment of the bottom support plate and stacks of capacitor elements if the capacitor is tilted down.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a capacitor voltage transformer comprising a capacitor having a plurality of stacks of capacitor elements stacked one above another and located in a tubular porcelain insulator having convolutes along the outer circumference thereof, the porcelain insulator being supported on a base at the bottom thereof and having a top plate fitted at the top thereof and a bellows disposed in the porcelain insulator at the top thereof and fixed to the top plate, the stacks of capacitor elements being insulated from one another and supported on insulator material shield plates, the stacks with the shield plates being guided on

two pairs of insulator material guide rods in guide notches provided in the shield plates and held against the guide rods, one pair of guide rods being vertically disposed on the base at one side of the stacks and the other pair of guide rods being vertically disposed on the base at opposite side of the stacks, an insulator material aligning rod inserted in aligning slots in the shield plates and vertically disposed on the base, the bottom shield plate being supported on a metallic bottom support plate fitted to one pair of guide rods at one side thereof, the lower ends of one pair of guide rods being fixed to one limb of a L-shaped metallic support bracket which one limb extends upwardly and supports the unsupported opposite side of the support plate, the other limb of the L-shaped support bracket being fixed to the base, each of the shield plates comprising a pair of lobes projecting outwardly from a pair of opposite sides thereof, the outer ends of the lobes being profiled to match with the inner circumference of the porcelain insulator and the bellows comprising a rim at the bottom thereof matching with the inner circumference of the porcelain insulator and having open slots for circulation of oil therethrough.
The following is a details description of the invention with reference to the accompanying drawings, in which:
Fig 1 is a cut section isometric view of the capacitor of a capacitor voltage transformer according to an embodiment of the invention.
Fig 2 is a cut section isometric view of the bottom portion of the capacitor of Fig I;
Fig 3 is an elevation of the bellows of the capacitor of Fig 1 fixed to the top plate thereof;

Fig 4 is a plan view of an insulator shield plate of the capacitor of Fig I; and
Fig 5 is a plan view of a capacitor element of the capacitor of Fig 1.
The capacitor 1 of a capacitor voltage transformer (not shown) a illustrated in figures 1 to 5 of the accompanying drawings comprises a plurality of stacks 2 of capacitor elements 3 stacked on arranged one above another and located in a tubular porcelain insulator 4 having convolutes 5 along the outer circumference thereof. The porcelain insulator is supported on a base 6 at the bottom thereof and has a top plate 7 fitted at the top thereof. 8 is a bellows disposed in the porcelain insulator at the top thereof and fixed to the top plate. The stacks of capacitor elements are insulated from one another and supported on insulator material shield plates 8a. The stacks with the shield plates are guided on two pairs of insulator materia! guide rods 9a and 9b and 10a and 10b in guide notches 11 provided in the shield plates. One pair of guide rods 9a and 9b are vertically disposed on the base at one side of the stacks and the other pair of guide rods 10a and 10b are vertically disposed on the base at opposite side of the stacks. 13 is an insulator material aligning rod inserted in aligning slots 14 in the shield plates and vertically disposed on the base. The bottom shield plate is supported on a metallic bottom support plate 15 fixed to a pair of guide rods of 9a and 9b at one side thereof. The lower ends of one pair of guide rods 9a, 9b are fixed to one limb 16 of a L-shaped metallic bracket 17 which limb 16 extends upwardly and supports the unsupported and unfixed opposite side of the support plate. The other limb 18 of the L-shaped bracket is fixed to the base. Each of the shield plates comprises a pair of lobes 19, 19 projecting outwardly from a pair of opposite sides thereof. The outer ends of the lobes are profiled to match with the inner circumference of the porcelain insulator. The bellows comprises

a rim 20 at the bottom thereof matching with the inner circumference of the insulator and having open slots 21 for circulation of oil therethrough. Preferably, the guide rods and aligning rods are made of bakelite, L-shaped bracket is made of steel, bottom support plate is made of aluminium, shield plate and rim are made of press board and bellows is made of stainless steel.
According to the invention the outer ends of the lobes of the shield plates are closely matched with the inner circumference of the porcelain insulator. The outer circumference of the rim at the bottom of the bellows is also closely matched with the inner circumference of the porcelain insulator. Therefore, the stacks of capacitor elements and bellows are properly held place in the porcelain insulator in close contact therewith and the stacks and bellows remain in position even when the capacitor is tilted down and held in the horizontal position. As a result, the capacitor voltage transformer can be transported with the capacitor in the horizontal position and the voltage rating and the capacitance of the capacitor voltage transformer can be increased. The invention thus eliminates the height constraint on transportation of capacitor voltage transformers and allows to have capacitor voltage transformers of higher voltage ratings and capacitance. As the bottom support plate is supported on the guide rods at one side thereof and also on the one limb of the L-shaped bracket at the opposite thereof, there are no chances for the stacks of capacitor elements to sag down and misalign either in the vertical position or tilted down or horizontal position of the capacitor especially when the stacks of capacitor elements are heavy.
It is understood that the configuration and construction of the rim at the bottom of the bellows and the open slots therein and the shield plate and the support bracket can vary to give the same functionality variations in the construction and configuration of the rim, shield plate and support

bracket which are obvious to a person skilled in the art, are to be construed and understood to be within the scope of the invention.

We claim:
1. A capacitor voltage transformer comprising a capacitor having a plurality of stacks of capacitor elements stacked one above another and located in a tubular porcelain insulator having convolutes along the outer circumference thereof, the porcelain insulator being supported on a base at the bottom thereof and having a top plate fitted at the top thereof and a bellows disposed in the porcelain insulator at the top thereof and fixed to the top plate, the stacks of capacitor elements being insulated from one another and supported on insulator material shield plates, the stacks with the shield plates being guided on two pairs of insulator material guide rods in guide notches provided in the shield plates and held against the guide rods, one pair of guide rods being vertically disposed on the base at one side of the stacks and the other pair of guide rods being vertically disposed on the base at opposite side of the stacks, an insulator material aligning rod inserted in aligning slots in the shield plates and vertically disposed on the base, the bottom shield plate being supported on a metallic bottom support plate fitted to one pair of guide rods at one side thereof, the lower ends of one pair of guide rods being fixed to one limb of a L-shaped metallic support bracket which one limb extends upwardly and supports the unsupported opposite side of the support plate, the other limb of the L-shaped support bracket being fixed to the base, each of the shield plates comprising a pair of lobes projecting outwardly from a pair of opposite sides thereof, the outer ends of the lobes being profiled to match with the inner circumference of the porcelain insulator and the bellows comprising a rim at the bottom thereof matching with the inner circumference of the porcelain insulator and having open slots for circulation of oil therethrough.

2. The capacitor voltage transformer as claimed in claim 1, wherein the guide rods and
aligning rods are made of bakelite, L-shaped bracket is made of steel, bottom support plate is made of aluminium, shield plates and rim are made of press board and bellows is made of stainless steel.