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 coil locking assembly for transformer
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTORS
Deepak Kamble and Anirudha Bharnuke, Crompton Greaves Ltd, Kanjur Marg, Mumbai. 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 present invention relates to a modified coil locking assembly for transformer.
BACKGROUND OF THE INVENTION
A transformer is an essential electronic component for voltage regulation into required voltages for various kinds of electric appliances. Transformers are generally classified as core type and shell type depending upon the manner in which the windings are wound around a magnetic core. The present invention relates to the construction of the core type transformer and a locking mechanism to retain the alignment of the windings with the magnetic core element. The core elements are available generally in the form of E shape and U shape elements and are formed with laminated metal sheets.
The construction of a core type transformer essentially includes a first former being placed around a core limb/leg portion of the E or U shaped element around which a primary winding is wound and a second former being placed concentric to the first former around which a secondary winding is wound. The complete core and winding assembly is placed inside a metal enclosure. The electrical wire connections to the primary winding and the secondary winding are brought out of the meta! enclosure. The primary winding receives an input ac voltage from a power source and the secondary winding receives electrical energy by mutual induction from the primary winding and delivers a stepped up or a stepped down voltage to a load. The construction of the core type transformer generally includes the primary winding

being wound on a primary former and a secondary winding wound on a secondary former. The secondary winding wounded over a secondary former is concentrically placed over the primary winding wound over the primary former. The primary and secondary formers are generally cylindrical in shape. It is important to retain the axial alignment of the windings against the core as it affects the amount of magnetic flux linkage that gets induced into the winding which in turn affects the rated voltage output of the transformer. As known generally, the primary windings stay in radial alignment with a core limb of the core type transformer, however the secondary former (and therefore the secondary winding) is subjected to some radial miss-alignments that are mostly caused due to jerks, shakes and vibration during transportation and installation and re-location of the transformers. The miss-alignments of the former against the core strains the electrical wire connections made to the primary winding and secondary winding and can lead to malfunctioning of the transformer.
As can be understood by a person of average skill in the art there is a need for restricting the axial (radial) alignment of the secondary former with respect to the core so that the transformer performs without malfunctioning and according to the designed rated parameters.
OBJECTS OF THE INVENTION
An object of the invention is to provide for a locking mechanism to retain the axial positioning of secondary former with respect to the core limb.

DETAILED DESCRIPTION OF THE INVENTION
In accordance with the invention, disclosed herein is a locking mechanism to retain the axial positioning of secondary winding with respect to the core limb. The secondary winding is mounted on a secondary former. Generally, since the secondary winding is firmly wounded on the secondary former, it is sufficient to arrest any relative movement of the secondary former to retain the axial positioning of the secondary winding with respect to the core limb.
According to an invention, a coil is locking assembly in a transformer to retain the radial alignment of a secondary former with respect to a core limb, the coil locking assembly comprising of a pair of flanges defining semi circular inner edges and having projected portions along the semi-circular inner edges that can be engaged within a pair of notches provided in the secondary former, and the pair of flanges firmly secured to the core limb by means of a plurality of nut and bolt arrangements.
These and other aspects, features and advantages of the invention will be better understood with reference to the following detailed description, accompanying drawings and appended claims in which
Figure 1 illustrates an exploded view of a core type transformer and illustrates the assembly of components according to the present invention.
Figure 2 illustrates a perspective view of the core type transformer with a detachable limb according to the present invention.

Figure 3-4 illustrates the manner in which the semicircular flange and a cylindrical hollow secondary former is mounted in the core type transformer according to the present invention.
Figure 5-6 illustrate perspective views of the core type transformer according to the invention.
In the figures the multiple instances of components that intend similar constriction and function are represented by the same numerical.
Figure .1 illustrates an exploded view of all the components that essentially comprise of a core type transformer. A core type transformer is shown comprising of a rectangular magnetic core 6, primary winding wound on a primary former 5, a cylindrical hollow secondary former 4, a secondary winding 3, a first and second pair flanges represented as '2', a first and second pair of longitudinal brackets represented as ' I'.
The magnetic core 6 is assembled out of laminated metallic sheets to form the rectangular shaped core as illustrated. Further as commonly known, the magnetic core 6 can be assembled and dissembled of the core limbs that form the length and breadth of the magnetic core 6. In figure 1, the core 6 is shown being formed of four core limbs represented by limb. At least one limb is detachable from the core 6 to allow for insertion of the primary and secondary windings on to a core limb. In Figure I, the limb 8 of core 1 is capable of being disassembled and allows the insertion of the components as mentioned above on to the core

limb 7 of core 6. The primary former 5 has a diametrical dimension that allows for a firm insertion over core limb 7. Secondary former 4 is wound around the primary winding wound over primary former 5. The diametrical dimension secondary former 7 is so chosen, so as, to have a coaxially tight alignment between the primary winding disposed over primary former 5. However, the coaxial alignment between the secondary former 7 and the primary winding tends to get disturbed due to shakes and vibrations during transportation of the transformer. According to the present invention, the axial alignment position of the secondary former 7 by fastening it with the flanges 2. It may be noted here that the flanges 2 may additionally function as high voltage shields between a primary and secondary windings that are generally used in a transformer to attenuate electrical noise and transients that can affect the performance of electrical loads and peripherals. The flanges 2 are shown having a protruding lug 9 along its semi-circular edge and the secondary former 4 is shown having a notch 10. The flanges 2 and the secondary former 4 are latched in to a position as a result of the protruding lug 9 getting inserted in to notch 10. Further the flange 2 is retained against the core limb of the core 6 by using longitudinal brackets 11. The brackets 11 are tightly fastened to the core limb of core 6 and the flanges 2 by using nuts and bolts as shown in Figure I. The arrangement between the flange 2 and secondary former 4 prevents any relative radial movement of the secondary former 4 with respect to the core limb 6.
Figure 2 illustrates a perspective view of the core type transformer with a detachable limb according to the present invention. The core limb 8 is shown detachable in isolation from the core I. The primary winding over the primary former 5 is inserted on the core limb 7.The secondary former 4 is coaxially received above the primary former 5. The secondary winding

3 is wound over the secondary former 4. The manner in which core limb 8 is fixed back to the core 1 is better illustrated in the following description of Figure 3 and Figure 4.
In Figure 3.the flanges 2 is shown placed against the secondary former in manner such that the protruding lug 9 is received within the notch 10 in the secondary former 4. Flange 2 is shown having holes along its length and longitudinal brackets 11 have a set of holes along two of its perpendicular edges. The brackets 11 can be aligned with the flange 2 with the set of holes along one edge and the other set of holes aligned with the holes provided on the core limb 8. The bracket 11 can be fastened to the flange 2 and the core limb 8 using nut and bolt arrangement as commonly known. To add more clarity to the Figure 3, the encircled portion 12 in Figure 3 is shown enlarged in Figure 4 to show the protruding lug 9 being received within the notch 10 provided in the secondary former 4.
As will be easily appreciated by an ordinary skilled person, the secondary former 4 is firmly positioned with respect to the core limb 8 because the notch 10 and the protruding lug 9 arrest any axial rotation.
Figure 5 represents a perspective view of the transformer to clearly illustrate the arrangement of the longitudinal brackets 11 that is firmly secured with the flanges 2 and the core limb 8 using nut and bolt arrangement along both edges. As can be seen in the figure there are two pairs of longitudinal brackets 11 and two pairs of flanges 2 to firmly secure the core limb at either sides.

It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Thus it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

We Claim:
I. A coil locking assembly in a core type transformer to retain the radial alignment between a
core limb of the transformer and a secondary winding, the coil locking assembly comprising
of:
a cylindrical hollow secondary former that is receivable on the core limb, the secondary
winding being firmly mounted over the secondary former, the cylindrical hollow secondary
former having atleast two notches along the top and bottom circular edges,
a pair of flanges at each end of the core limb, the flanges defining semi circular inner edges
and having at least one protruding lug portion along each semi-circular inner edge that can be
in a firm engagement with the notch provided on the circular edge of the secondary former
such that the engagement substantially prevents any relative radial movement between the
secondary former and the flanges, and
a pair of longitudinal brackets at each end of the core limb that are securely attached to the
core limb and the flanges by a plurality of nut and bolts.