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 mobile fixture for assembling a current transformer
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai - 400 030, Maharashtra, India, an Indian Company
INVENTORS
Gosavi Shripad and Gokhale Prakash, both of Crompton Greaves Limited, Switchgear, A-3, MIDC, Ambad, Nasik, 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
This invention relates to a mobile fixture for assembling a current transformer
BACKGROUND OF THE INVENTION
A current transformer includes a torroidal wound core located within a non-magnetic material transformer shell. Usually the shell is two pieces construction and is made of aluminum. After locating the torroidal wound core in the bottom half of the shell, the bottom half of shell is closed with the top half of the shell and the shell halves are assembled together. The transformer is assembled generally at several assembly stations spread out at different locations. Firstly, the torroidal wound core is located within the bottom half shell and the bottom half shell is closed with the top half shell and the shell halves are clamped together at the shell assembly station. The shell is manually carried to the electrical testing station to check the electrical parameters of the wound core. After testing, the shell is manually carried to the welding station where the shell halves are welded together at the contact surfaces thereof. A bushing pipe support block is welded onto the shell. The shell is manually carried to the grinding station where the welded areas of the shell are ground and smoothened. The shell is again manually taken to the electrical testing station to check the electrical parameters of the wound core. Thereafter a bushing pipe is assembled on the support block. All the above operations are carried at different locations which are spread out and in order to carry out these operations, the shell is manually carried from station to station. This requires increased man power and is inconvenient and cumbersome to carry out. It is also time consuming and causes operator fatigue. As a result of all this, productivity is reduced. In order to weld the support block the shell has to be tilted in the vertical plane. Tilting of the shell in the vertical plane and holding it tilted in the vertical plane is very inconvenient and cumbersome to carry out. Being very heavy, manual handling of the shell can also lead to accidents. While shifting

the shell from station to station and lifting and tilting the shell there are possibilities of dislocation of the core within the shell. As a result, the transformer may not give the rated performance.
OBJECTS OF THE INVENTION
An object of the invention is to provide a mobile fixture for assembling a current
transformer, which fixture reduces man power requirement and renders assembly of the
current transformer easy and convenient so as to reduce assembly time and increase
productivity.
Another object of the invention is to provide a mobile fixture for assembling a current transformer, which fixture reduces operator fatigue for assembly of the transformer and prevents accidents.
Another object of the invention is to provide a mobile fixture for assembling a current transformer, which fixture prevents core dislocation during assembly of the transformer and ensures rated performance of the transformer.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a mobile fixture for assembling a current transformer, the fixture comprising a mobile carriage, a swivel cum rotary support mounted on the mobile carriage and adapted to swivel in the horizontal plane and rotate in the vertical plane and support and clamp a transformer shell, drive means to swivel and rotate the swivel cum rotary support, arrestor means for arresting the rotary motion of the swivel

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cum rotary support, locator means for locating the transformer shell on the swivel cum rotary support, guide means for guiding the transformer shell on the swivel cum rotary support and clamping means for clamping the transformer shell on the swivel cum rotary support.
The following is a detailed description of the invention with reference to the accompanying drawings, in which :
Figs 1 and 2 are isometric views of the mobile fixture for assembling a current transformer according to an embodiment of the invention;
Figs 3 and 4 are opposite side views of the mobile fixture of Figs 1 and 2;
Fig 5 is a longitudinal crosssectional view of the mobile fixture of Figs 1 and 2;
Fig 6 is an isometric view of the mobile fixture of Figs 1 and 2 with a transformer shell mounted thereon;
Fig 7 is an isometric view of the mobile fixture for assembling a current transformer according to another embodiment of the invention; and
Fig 8 is a bottom view of the rotary disc of the mobile fixture of Fig 7.
The mobile fixture 1 for assembling a current transformer as illustrated in Figs 1 to 6 of the accompanying drawings comprises a mobile carriage 2 having a base frame 3 provided
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with castor wheels 4 and a pair of spaced apart upstanding support members 5a, 5b and a handle bar 6 fitted to support member 5a. 7 is a swivel cum rotary support comprising a C-shaped member 8 having a bottom portion 9 and a pair of upwardly extending end portions 10a, 10b. End portions 10a, 10b are provided with shaft extensions 1 la and 1 lb protruding out from the outer surfaces thereof, respectively. The shaft extensions are co-axial and are rotatably supported in the upstanding support members 5a and 5b using bearings 12a and 12b, respectively. 13 is a horizontally disposed rotary disc mounted on a vertical shaft 14 rotatably held in the bottom portion 9 of the C-shaped member 8 at the center thereof using bearings 15a, 15b. 16 is a gear mounted on shaft extension 1 la. 17 is a right angled gear box mounted on the upstanding support member 5a. 18 is a pinion mounted on the output shaft 19 of the gear box in mesh with the gear 16. 20 is a handle mounted on the input shaft 21 of the gear box 17. 22 is vertically disposed lever hinged (hinge marked 23) on the bottom portion 9 of C-shaped member 8 and adapted to engage and disengage a plurality of open slots 24 provided at the circumference of the rotary disc 13 in radially spaced apart relationship. A plurality of upright projections 25 are provided at the upper surface of the rotary disc. 26 is a crossmember mounted on the rotary disc. The distal ends of the limbs of the crossmember are provided with raised portions 27 adapted to abut the outer surface of the bottom half shell 28 of a transformer located on the upright projections 25 and the crossmember 26. A plurality of upright guide rods 29 are provided on the rotary disc. 30 is a clamping nut engaged at the correspondingly threaded (threaded upper end marked 31) upper end of the vertical shaft 14.
During assembly of a current transformer, the clamping nut 30 is removed from the upper end 31 of the vertical shaft 14 and the bottom half shell 28 of the transformer is located on the upright projections 25 provided at the upper surface of the rotary disc 13 and the
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crossmember 26 mounted on the rotary disc with the raised portions 27 at the distal ends of
the limbs of the crossmember adapted to abut the outer surface of the bottom half shell of
the transformer and hold the bottom half shell of the transformer in position. While
locating the bottom half shell of the transformer on the upper surface of the rotary disc, the
bottom half shell of the transformer is guided over the upright guide rods 29 on the rotary
disc. The rotary movement of the bottom half shell of the transformer on the rotary disc is
prevented by engaging the vertically disposed lever 22 in one of the open slots 24 provided
at the circumference of the rotary disc. The top half shell 32 of the transformer is located
against the bottom half shell of the transformer and the transformer shell halves are
clamped together against the rotary disc by locating a crossshaped clamp 33 located against
the upper surface of Che top half shell of the transformer ond tightening the damping nut 30
at the upper end 31 of the vertical shaft 14 against the cross shaped clamp 34. The
transformer shell is then wheeled to the various stations of assembly on the mobile fixture.
During welding of the contact surfaces of the transformer shell at the welding station, the
transformer shell is rotated manually with the vertical shaft. Similarly for grinding and
smoothening of the welded areas of transformer shell at the grinding station, rotation of the
transformer shell is carried out with the vertical shaft manually. Tilting of the transformer
shell to weld a bushing pipe support block (not shown) at the welding station is carried out
by operating the handle 20. On rotating the handle in the clockwise direction, the pinion 18
rotates in the anticlockwise direction and the gear 16 rotates in the clockwise direction. As
a result, the C-shaped member 8 along with the transformer shell tilts in the vertical plane
with the shaft extensions 11a, 1 lb so as to facilitate welcling of the bush pipe support block
onto the shell. The transformer shell and C-shaped support member are brought back to
the original position by rotating the handle in the anticlockwise direction. The handle bar 6
provides a hand grip to move the mobile fixture from blace to place. In the embodiment
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illustrated in Figs 7 and 8 of the accompanying drawings the rotating and tilting movements of the transformer shell have been motorized. 34 is a reversible electric motor mounted on the base frame with the help of a bracket 35 and the shaft 36 of the motor 34 is coupled to the input shaft 21 of the gear box 17. The transformer shell is tilted up and down by operating the reversible electric motor 34 and rotating the shaft 36 thereof, in clockwise and anticlockwise directions. 37 is an electric motor mounted on the rotary disc 13 and having a pinion 38 mounted on the shaft 39 thereof. The pinion 38 is in mesh with a circular rack 40 provided at the bottom surface of the rotary disc. The rotary disc and the transformer shell mounted on the rotary disc are rotated by operating the electric motor 37. The pinion 38 and rack 40 arrangement facilitates rotational movement of the rotary disc and transformer shell on the mobile fixture.
According to the invention a current transformer can be assembled on the mobile fixture with the transformer shell mounted in position on the fixture. The shell mounted on the mobile fixture can be easily and conveniently transported from station to station to carry out the various operations of assembly. Rotation of the shell for welding and for grinding and smoothening of the welded areas and tilting of the shell for welding the support block can be easily carried out. As a result of all this, man power required for assembly of the transformer is reduced. Operator fatigue is reduced and time for assembly is reduced and productivity is increased. Accidents that may occur during shifting, lifting and tilting are prevented. Dislocation of the wound core within the shell during shifting, tilting and lifting is avoided and rated performance of the transformer is ensured.
The above embodiment is by way of example and should not be construed and interpreted to be limiting scope of the invention. Embodiments comprising several variations of the

invention without deviating from the scope of the invention are possible. The mobile carriage, swivel cum rotary support, drive means for the swivel cum rotary support, arrestor means, locator means, guide means and clamping means all can be of different configurations / constructions. The invention is basically in facilitating assembly of transformer shell on a mobile fixture which can be transported from station to station to carry out various operations of assembly easily and conveniently and within reduced time and with reduced effort and man power so as to achieve the objects and advantages as described in the specification. Embodiments comprising such variations of the invention which are obvious to those skilled in the art are to be construed and understood to be within the scope of the invention.

We claim:
1) A mobile fixture for assembling a current transformer, the fixture comprising a mobile carriage, a swivel cum rotary support mounted on the mobile carriage and adapted to swivel in the horizontal plane and rotate in the vertical plane and support and clamp a transformer shell, drive means to swivel and rotate the swivel cum rotary support, arrestor means for arresting the rotary motion of the swivel cum rotary support, locator means for locating the transformer shell on the swivel cum rotary support, guide means for guiding the transformer shell on the swivel cum rotary support and clamping means for clamping the transformer shell on the swivel cum rotary support.
2) The fixture as claimed in claim 1, wherein the mobile carriage comprises a base frame provided with castor wheels and a pair of spaced apart upstanding support members and a handle bar fitted to one of the support members, the swivel cum rotary support comprises a C-shaped member comprising a bottom portion and a pair of upwardly extending end portions, each of the end portions being provided with a shaft extension protruding out from the outer surface thereof, the shaft extensions being co-axial and rotatably supported in the upstanding support members, a horizontally disposed rotary disc mounted on a vertical shaft rotatably held in the bottom portion of the C-shaped member at the center thereof, the drive means comprises a gear mounted on one of the shaft extensions and a right angled gear box mounted on one of the upstanding support members corresponding to the said one shaft extension and a pinion mounted on the output shaft of the gear box in mesh with the said gear and a handle mounted on the input shaft of the gear box, the arrestor means comprises a vertically disposed lever hinged on the bottom portion of the C-shaped member and adapted to engage and disengage a plurality of open slots

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provided at the circumference of the rotary disc in radially spaced apart relationship, the locator means comprises a plurality of upright projections provided at the upper surface of the rotary disc and a cross member mounted on the rotary disc, the distal ends of the limbs of the cross member being provided with raised portions adapted to abut the outer surface of the bottom half shell of the transformer, the guide means comprises a plurality of upright guide rods provided on the rotary disc and the clamping means comprises a clamping nut adapted to be tightened on the correspondingly threaded upper end of the vertical shaft against a cross shaped clamp member located against the upper surface of the top half shell of the transformer.
3. The fixture as claimed in claim 1, wherein the mobile carriage comprises a base frame provided with caster wheels and a pair of spaced apart upstanding support members and a handle bar fitted to one of the support members, the swivel cum rotary support comprises a C-shaped member comprising a bottom portion and a pair of upwardly extending end portions, each of the end portions being provided with a shaft extension protruding out from the outer surface thereof, the shaft extensions being co-axial and rotatably supported in the upstanding support members, a horizontally disposed rotary disc mounted on a vertical shaft rotatably held in the bottom portion of the C-shaped member at the center thereof, the drive means comprises a gear mounted on one of the shaft extensions and a right angled gear box mounted on one of the upstanding support members corresponding to the said one shaft extension and a first pinion mounted on the output shaft of the gear box in mesh with the said gear and a reversible electric motor mounted on the base frame with its shaft coupled to the input shaft of the gear box, an electric motor mounted on the bottom portion of the C-shaped member and having a second pinion mounted on the shaft thereof adapted to mesh with a circular rack provided at the bottom
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surface of the rotary disc, the arrestor means comprises a vertically disposed lever hinged on the bottom portion of the C-shaped member and adapted to engage and disengage a plurality of open slots provided at the circumference of the rotary disc in radially spaced apart relationship, the locator means comprises a plurality of upright projections provided at the upper surface of the rotary disc and a cross member mounted on the rotary disc, the distal ends of the limbs of the cross member being provided with raised portions adapted to abut the outer surface of the bottom half shell of the transformer, the guide means comprises a plurality of upright guide rods provided on the rotary disc and the clamping means comprises a nut adapted to be tightened on the Correspondingly threaded upper end of the shaft against a cross shaped clamp member located against the upper surface of the top half shell of the transformer.
Dated this 30th day of March 2009

(Jose M A) of Khaitan & Co
Crompton Greaves Limited By their Agent & Attorney