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
Method and apparatus for batchwise vulcanization of the rubber insulation of electrical windings


APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR
Moudghil Ashish Saurabh, Crompton Greaves Limited, Engineering, M7 Division, Mandideep, Madhya Pradesh, India, an Indian National
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 method and apparatus for batchwise vulcanization of the rubber insulation of electrical windings.
BACKGROUND OF THE INVENTION
The rubber insulation of electrical windings of rotary electrical machines like alternators or motors is vulcanized in order to improve the mechanical properties of the insulation. Vulcanization is usually carried out batchwise in a vulcanization chamber at an air pressure of 5 to 6 bars and at 170 to 180°C. Each batch operation comprises the steps of loading the rubber insulated electrical winding to be vulcanized in the vulcanization chamber, filing the vulcanization chamber with compressed air to the required pressure of 5 to 6 bars and heating the electrical winding by injecting current to develop the required temperature of 170 to 1 S0°C. On completion of one batch, the vulcanization chamber is completely emptied of the used compressed air by releasing the air into the atmosphere and freshly compressed air is filled in the vulcanization chamber for the next batch of operation. Because of the exhaustion of the entire used compressed air and use of entire amount of freshly compressed air for each batch of operation, electric power required for producing the compressed air increases and time required for compression of the air also increases. As a result of all this, power consumption, production time and cost are increased and productivity and production efficiency are reduced.

OBJECTS OF THE INVENTION
An object of the invention is to provide a method for batchwise vulcanization of the
rubber insulation of electrical winding, which method reduces power consumption and
cost.
Another object of the invention is to provide a method for batchwise vulcanization of the rubber insulation of electrical winding, which method reduces production time and increases productivity and production efficiency.
Another object of the invention is to provide an apparatus for batchwise vulcanization of the rubber insulation of electrical winding, which apparatus reduces power consumption and cost.
Another object of the invention is to provide an apparatus for batch wise vulcanization of the rubber insulation rubber insulation of electrical winding, which apparatus reduces production time and increases productivity and production efficiency.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a method for batchwise vulcanization of the rubber insulation of an electrical winding, the method comprising carrying out vulcanization of the rubber insulation of the electrical winding with compressed air at a pressure of 5 to 6 bars and at 170 - 180°C, wherein the compressed air comprises one

part of compressed air used in the previous batch and the remaining part of freshly compressed air.
According to the invention there is also provided an apparatus for batch wise vulcanization of rubber insulation of an electrical winding, the apparatus comprising a vulcanization chamber provided with a 2 way 2 position exhaust valve and a used air storage chamber, the vulcanization chamber and storage chamber being connected to each other and to an air compressor through a 4 way 3 position direction control valve.
The following is a detailed description of the invention with reference to the accompanying drawings, in which :
Fig 1 is a schematic view of the apparatus for batch wise vulcanization of the rubber insulation of an electrical winding according to an embodiment of the invention;
Fig 2 is a schematic view of the 4 way 3 position direction control valve of the apparatus of Fig 1; and
Fig 3 is a schematic view of the 2 way 2 position exhaust valve of the apparatus of Fig 1.
The apparatus 1 as illustrated in Figs 1 to 3 of the accompanying drawings comprises a vulcanization chamber 2 provided with a 2 way 2 position exhaust valve 3. 4 is a used compressed air storage chamber. Both the vulcanization chamber and storage chamber

are connected to each other and to an air compressor 5 through a 4 way 3 position direction control valve 6. The interconnecting pipes are marked 7, 8 and 9. The four ports of the valve 6 are marked 10a, 10b, 10c and lOd. The 3 positions of valve 6 are as shown in Fig 2. In position A of valve 6, the compressor and vulcanization chamber are interconnected. In position B of valve 6, the valve is closed and non-functional. In position C of valve 6, vulcanization chamber and storage tank are interconnected. The two ports of the valve 3 are marked 1 la and 1 lb. The 2 positions of valve 3 are as shown in Fig 3. In position D of valve 3, the valve is connected to the atmosphere. In position E of valve 3, the valve is closed and non-operational. A batch wise operation of the apparatus is carried out as follows:
In the first batch or cycle of operation, a rubber insulated electrical winding (not shown) to be vulcanized is loaded into the vulcanization chamber. The exhaust valve 3 of the vulcanization chamber is closed as shown at E in Fig 3. The compressor is connected to the vulcanization chamber by operating the direction control valve as shown in position A in Fig 3 and the vulcanization chamber is filled with freshly compressed air to a pressure of 5 - 6 bars. A current is injected to the electrical winding in the vulcanization chamber to develop a temperature of 170 to 180°C and vulcanization is carried out. On completion of vulcanization, current to the electrical winding is cut off and a predetermined volume of the used compressed air is transferred into the storage chamber by connecting the vulcanization chamber and the storage chamber by operating the direction control valve 6 as shown in position C in Fig 2. On completion of transfer of the used air, valve 6 is closed as shown in position B in Fig 2. The remaining amount of

compressed air in the vulcanization chamber is exhausted by opening valve 3 to the atmosphere as shown in position D in Fig 3. The vulcanized electrical winding is unloaded from the vulcanization chamber. In the next cycle of vulcanization, another rubber insulated electrical winding (not shown) to be vulcanized is loaded into the vulcanization chamber. The exhaust valve is closed as shown in position E in Fig 3 and used compressed air in the storage chamber is transferred into the vulcanization chamber by connecting the storage chamber and the vulcanization chamber by operating the valve 6 as shown in position C in Fig 2. Following this, the air compressor and vulcanization chamber are connected by operating the valve 6 to be in position A as shown in Fig 3 and the partly filled vulcanization chamber is filled with freshly compressed air to the required pressure of 5 to 6 bars. Valve 6 is closed by shifting it to position B as shown in Fig 3 and current is injected into the electrical winding to develop the required temperature and vulcanisation is carried out. On completion of vulcanization, current supply to the electrical winding is discontinued and the vulcanization chamber is connected to the storage chamber by operating the valve 6 to position C in Fig 2 and part of the used compressed air is transferred into the storage chamber. Valve 6 is closed as shown in position B in Fig 2 and exhaust valve is opened to the atmosphere as shown in position D in Fig 3. After exhaustion of the remaining air in the vulcanization chamber, the vulcanized electrical winding is unloaded from the vulcanization chamber. In the third cycle of operation used air in the storage chamber is reused along with freshly compressed air and vulcanization is carried out as described earlier. Each subsequent cycle of vulcanization is thus carried out with a predetermined volume of the compressed air used in a previous cycle and a predetermined volume of

freshly compressed air. According to the invention because of the use of a predetermined volume of used air in each batch or cycle of vulcanization from previous cycle or batch of operation in combination with a predetermined volume of freshly compressed air, there is considerable saving in time and power required for compression of the air in each cycle of operation. There is thus saving in overall power consumption. Production time and cost are reduced. Productivity and production efficiency are increased.
Comparative vulcanization studies were carried out as per the method of the invention and conventional method and the results were as shown in the following Table :

Table

The above Table clearly illustrates the advantages of the invention. The Table also clearly shows that by increasing the capacity of the storage chamber increased amounts of used air can be stored and reused to further improve the efficiency of the apparatus and the method of the invention.

We claim:
1. A method for batchwise vulcanization of the rubber insulation of an electrical winding, the method comprising carrying out vulcanization of the rubber insulation of the electrical winding with compressed air at a pressure of 5 to 6 bars and at 170 - 180°C, wherein the compressed air comprises one part of compressed air used in the previous batch and the remaining part of freshly compressed air.
2. An apparatus for batch wise vulcanization of rubber insulation of an electrical winding, the apparatus comprising a vulcanization chamber provided with a 2 way 2 position exhaust valve and a used air storage chamber, the vulcanization chamber and storage chamber being connected to each other and to an air compressor through a 4 way 3 position direction control valve.
Dated this 4th day of March 2009