TECHNICAI. FIELD
the subject matter described herein, in general, relates to an apparatus and method for impregnating resin in relation to its use for impregnating windings / electrical wires of an electrical machinery, and in particular, relates to use of electromagnetic heat for impregnation of resin.
BACKGROUND
Wires, conductors, metal parts and other electrical machinery or parts thereof often need to be impregnated with a resin. One such requirement is seen in electrical machinery, wherein stator, armature wires, and other copper wires are impregnated with a resin.
The windings of the electrical machine are customarily impregnated by saturation. The function of such an impregnation is to induce mechanical strengthening of the winding so that the winding is able to absorb mechanical and electromechanical forces. Further, impregnation also protects against harml\il external influences, such as, deposition of dust particles, collector abrasion, humidity, salts and solvents. Further it contributes to improve the electrical insulation. This also contributes to a prolonged life of the electrical machinery and also improves its perlbrmance. The impregnation of these windings, or the coating/of other electrical and/or electronic components, is usually done by using resins which after curing forms thcrmosets.
Conventionally impregnation process involves use of vacuum to impregnate the resin and use of oven to cure the resin by heating. The transfer of heat in such cases is by convection and effected from outside air to the coil. Thereafter the

principle of conduction is utilized to transfer the heat from the coil to the resin. The above mentioned conventional heating process has many disadvantages such as, more energy consumption, extremely high process cycle time of about 45 minutes and the like.
Therefore, in the context of aforesaid, there is a need to provide an apparatus for heating and curing of resin impregnated on electrical machinery, and that the apparatus has substantially less energy consumption and less process cycle time thereby achieving cost effectiveness in the production of electrical machinery. SUMMARY
Ihe subject matter described herein is directed to an apparatus and method for impregnating electrical machinery with a resin. The present subject matter proposes an apparatus and method that utilizes electromagnetic heat for impregnating electrical machinery with the resin thereby consuming lesser power and a short process cycle time.
In accordance with at least one embodiment of the present subject matter, an apparatus, which includes one or more holding structures, rotatably holds the electrical machinery for impregnating it with a resin. The apparatus also includes one or more power supply units, one or more electromagnetic coils and a resin trickling unit. The electromagnetic coil is electrically connected to the power supply unit so as to generate an electromagnetic heat when a current is passed through it. Further, the electromagnetic coil protrudes out of the power supply unit to form a loop. The electrical machinery is placed in a close proximity of the electromagnetic coil such that the looped electromagnetic coil defines a periphery around the electrical machinery. Thus the electromagnetic heat generated from the electromagnetic coil heats the electrical machinery as well. Inirthermore, the holding structure is operably connected to one or

more motors so as to rotate the electrical machinery while a resin is being trickled so as to evenly spread it on the electrical machinery.
According to another embodiment of the present subject matter, the electrical machinery includes a stator core with windings and the electromagnetic coil includes water cooled copper induction coil.
According to yet another embodiment of the present subject matter, the resin trickling device includes a pump, a reservoir to store resin and a resin trickling nozzle. The resin trickling device is configured to trickle the resin onto the electrical machinery at a pre determined rate and volume.
According to yet another embodiment of the present subject matter, the electrical machinery is placed at a distance of preferably 10-12 mm from the electromagnetic coil, fhe holding structure rotates the electrical machinery at about 10-15 rpm while the resin is being trickled onto the electrical machinery so as to evenly spread the resin.
According to another aspect of the present mentioned subject matter, a method for impregnrating the electrical machinery with resin includes the steps of providing one or more electromagnetic coils and placing the electrical machinery in close proximity of the electromagnetic coils. An electromagnetic coil generates heat when an electric current is passed through it, consequently heating the electrical machinery. Subsequently, the electrical machinery is preheated to a temperature just below the gelling temperature of the resin, fhe final steps of the method includes contacting the resin with the electrical machinery by way of the resin trickling device and further

heating the electrical machinery to a temperature equal to or more than the curing temperature of the resin.
These and other features, aspects, and advantages of the present subject matter will become better understood with reference to the following description and appended claims. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS
The above and other features, aspects and advantages of the subject matter will be better understood with regard to the following description, appended claims, and accompanying drawings where;
Fig.l illustrates a schematic representation of an apparatus for impregnating a stator core containing windings according to one embodiment of the present subject matter.
Fig 2 illustrates a method for impregnating the stator core containing windings by means of a flowchart.
DETAILED DESCRIPTION
fo overcome the aforementioned needs, according to an embodiment of the present subject matter, an apparatus and method for impregnating a stator core containing windings with a resin is illustrated herein.

In accordance with at least one embodiment of the present subject matter, an apparatus for impregnating the stator core includes one or more induction coils and one or more power supply units. The induction coil protrudes out of the power supply unit to form a loop. The stator core is placed within this loop, preferably at a distance of 10-12 mm from the induction coil, such that the looped induction coil defines a periphery around the stator core. When an electric current is passed through the induction coil, induction heat is generated which in turn heats the stator core. The apparatus further includes one or more holding structures and a resin trickling device. The holding structure is connected to a motor so as to rotatably hold the stator core. The holding structure rotates the stator core preferably at about 10-15 rpm while resin is being trickled onto the windings of the stator by the resin trickling device.
According to another aspect of the present subject matter, a method for impregnrating the electrical machinery with resin includes the steps of providing one or more induction coil and placing the stator core in close proximity of the induction coil, fhe induction coil generates induction heat when an electric current is passed through it, consequently heating the stator core. Subsequently, the stator core is preheated to a temperature just below the gelling temperature of the resin to be impregnated. The final steps of the method includes contacting the resin with the windings of the stator core by way of the resin trickling device and ilirther heating the stator core to a temperature equal to or more than the curing temperature of the resin.
Fig.l illustrates a schematic representation of an apparatus 100 for impregnating stator cores 105 containing windings according to one embodiment of the present subject matter. The apparatus 100 comprises of three holding structures 110, a

power supply unit 115, a water circulated copper induction coil 120, and a resin trickling device. The induction coil 120 protrudes out of the power supply 115 unit to form a loop. The stator cores 105 are placed in close proximity of the induction coil 120, for example at a distance of about 10-12 mm, such thai the looped induction coil 120 defines a periphery around the stator cores 105. When a current is passed through the induction coil 120 by the power supply unit 115, induction heat is generated which in turn heats the stator cores 105.
liach holding structure 110 holds a stator core 105 and is operably connected to a motor 125 so as to rotate the stator cores 105. When the resin is being trickled onto the windings of the stator cores 105, the holding structure 110 rotates the stator cores, for example at about 10-15 rpm, so as to evenly spread the resin. Further, the resin trickling device comprises of a pump 130, a reservoir 135 to store resin and a resin trickling nozzle 140. The pump 100 sucks the resin stored in the reservoir 135 and trickles onto the stator cores via the trickling nozzle 140. The resin trickling device is configured to trickle the resin onto the stator cores 105 at a pre determined rate and volume. The power supply unit 115 generates power, for example 5 kW power at a frequency of 25 kHz, to supply current to the induction coil 120. The resin used according to the present mentioned embodiment is a Polysterimide/Epoxy and a hardener with a gelling temperature of 80 to 100 degree Celsius and a curing temperature of preferably 130 to 170 degree Celsius. I'he entire process of impregnating the stator cores containing windings with the resin can be completed in about 700-1000 seconds. In other embodiments, other resins known in the art can also be used, and the process may take slightly more or less time than that mentioned above.

Fig 2 illustrates a method for impregnating the stator core containing windings by means of a flowchart 200.
At block 205, the first step of the method is to provide an induction coil so as to generate induction heat when connected to a high frequency power supply unit. Preferably, the induction coil is a water circulated copper coil connected to a power supply unit which generates 5kW power at a frequency of 25kHz.
Al block 210, the second step is to place the stator core containing windings within close proximity of the induction coil. The induction coil forms a loop around the stator cores so as to remain at a distance of about 10-12 mm from the stator core.
At block 215, the third step includes preheating the stator cores to a temperature just below the gelling temperature of the resin to be impregnated.
At block 220, the fourth step of the method is to contact the resin with the windings of the stator core, f he resin is trickled onto the windings of the stator core by means of a resin trickling device for a period of approximately 60-90 seconds. The stator core is rotated at about 10-15 rpm when the resin is being trickled onto the windings of the stator core so as to evenly spread the resin.
At block 225, the final step of the method is to further heat the stator core to a temperature equal to or more than the curing temperature of the resin. For a Polysterimide/Epoxy resin and a hardener with gelling temperature of about 80 to 100 degree Celsius and a curing temperature of 130 to 170 degree Celsius, the stator core is heated for a period of about 500-700 seconds. The entire process of impregnating the

resin is completed within 700-1000 seconds. There is also a reduction in energy consumption of about 50% by way of the method described.
Although the subject matter has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are possible. As such, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiment contained therein.

We claim:
1. An apparatus 100 for impregnating an electrical machinery with a resin, said apparatus comprising:
one or more holding structures 110 configured to hold said electrical
machinery 105 wherein said holding structure 110 is adapted to rotate said
electrical machinery 105 by way of a one or more motors 125;
one or more power supply units 115;
one or more electromagnetic coils 120 electrically connected to said power
supply unit 115 so as to generate an electromagnetic heat while a current is
passed through said electromagnetic coil 120 by said power supply unit 115;
and
a resin trickling device for trickling said resin onto said electrical machinery
105;
wherein,
said electromagnetic coil 120 protrudes out of said power supply unit 115 so as to form a loop such that said looped electromagnetic coil 120 defines a periphery around said electrical machinery 105 such that said electromagnetic heat generated by said electromagnetic coil 120 heats said electrical machinery 105.
2. The apparatus 100 as claimed in claim 1, wherein said electrical machinery 105 includes a stalor core having windings.
3. The apparatus 100 as claimed in claim 1, wherein said electromagnetic coil 120 is an induction coil.

4. 'J^he apparatus 100 as claimed in claim 1, wherein said holding structure 110 is operably connected to a motor 125 so as to rotate said electrical machinery 105.
5. The apparatus 100 as claimed in claim I, wherein said electrical machinery 105 is rotated while said resin is being trickled so as to evenly spread said resin onto said electrical machinery 105.
6. The apparatus 100 as claimed in claim 1, wherein said resin trickling device comprises of a pump 130, a reservoir 135 for storing said resin, and a trickling nozzle 140.
7. The apparatus 100 as claimed in claim 6, wherein said trickling nozzle 140 is adapted to trickle said rein onto said electrical machinery 105 at a pre-determined rate and a pre-determined volume.
8. A method for curing of resin onto an electrical machinery 105, said method comprising:
providing one or more electromagnetic coil 120 to generate an
electromagnetic heat wherein said electromagnetic coil 120 is energized by a
one or more power supply unit 115;
placing said electrical machinery 105 in close proximity of said
electromagnetic coil 120;
clectromagnetically preheating said electrical machinery 105 to a temperature
just below a gelling temperature of said resin to be cured;
spreading said resin with said electrical machinery 105 by one or more resin
trickling device; and

cleclromagnetically heating said electrical machinery 105 to a temperature equal to or more than a curing temperature of said resin.
9. I'he method as claimed in claim 8, wherein said electrical machinery 105 is
placed at a distance of 10-12 mm from said electromagnetic coil 120.
10. The method as claimed in claim 8, wherein said electrical machinery 105 is
placed in close proximity of said electromagnetic coil 120 by way of a one or
more holding structures 110 wherein said electrical machinery 105 is rotatably
held onto said holding structure 110.
11. The method as claimed in claim 8, wherein said electrical machinery 105 is
rotated while resin is trickled onto said electrical machinery 105 so as to evenly
spread said resin.