F O R M 2

THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)

1. Title of the invention: A THERMOPLASTIC COMPONENT FOR SWITCHGEARS AND A METHOD OF MANUFACTURING THERMOPLASTIC COMPONENTS

2. Applicant(s):

(a) NAME : LARSEN & TOUBRO LIMITED
(b) NATIONALITY : An Indian Company
(c) ADDRESS : L & T House, Ballard Estate, Mumbai 400 001,
State of Maharashtra, India

3. PREAMBLE TO THE DESCRIPTION

The following specification particularly describes the invention and the manner in which it is to be performed:

A) TECHNICAL FIELD

The present invention generally relates to switchgears and particularly to cross linked thermoplastic components in switchgears. More particularly the present invention relates to a method of manufacturing cross linked thermoplastic components.

B) BACK GROUND OF THE INVENTION

Contactors, Circuit breakers, Switches and Switchboards are mechanical switching devices capable of making, carrying and breaking currents under normal circuit conditions and also making, carrying for a specified time and breaking currents under specified abnormal conditions. A contactor / circuit breaker / switch / switchboard basically consist of a pair of separable contacts and an interrupting medium. The function of the contacts is to conduct the electrical current when the breaker is closed and to withstand the arcs while interrupting. Generally the electrical contacts have a stationary part and a moving part. By bringing the moving contact to touch the stationary contact, an electric current flows and the circuit is closed. By driving the moving contact away from the stationary contact, an electric arc is developed and by quenching the electrical arc, the flow of electrical current is stopped and the circuit is opened.

In the current scenario, the one or more thermoplastic components may be melted or deformed, when exposed to extreme temperature and pressure conditions. The one or more thermoset components formed are not flexible in design for assembly features and the material used in the process may not be environmental friendly. Further in the existing technique, thermoplastics material with brominated flame retardant meeting UL94 FR V-0 may not be good for environment due to the presence of halogens.

Hence there is a need for a cross linked thermoplastic components and a method for manufacture of cross linked thermoplastic components using a thermoplastic material and an external radiation source.

The above mentioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.

C) OBJECT OF THE PRESENT INVENTION

The primary object of the present invention is to provide a cross linked thermoplastic component for switch gear devices to avoid melting during an application of normal operating pressure and at normal operating temperature.

Another object of the present invention is to develop a method for manufacturing thermoplastic components for switch gears.

Yet another object of the present invention is to develop a thermoplastic component in which one or more components are cross linked in less time thereby improving the production rate of components.

Yet another object of the present invention is to develop a thermoplastic component manufacturing method in which no thermoset material or component is used inside the molding process thereby avoiding the sticking of the components inside a mold reducing the rejection rate and time consumed for removal of stuck material.

Yet another object of the present invention is to develop a thermoplastic component manufacturing method for cross linking the thermoplastic components to provide a higher mechanical strength to avoid brittle failure during operation.

Yet another object of the present invention is to develop a thermoplastic component manufacturing method for cross linking components to enable a user to manufacture components of complex shapes or design.

These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.

D) SUMMARY OF THE INVENTION

The various embodiments of the present invention are to provide a thermoplastic component for switchgears comprising a thermoplastic material. The thermoplastic material is a cross linked thermoplastic polymer material to a preset level to avoid melting during an application of normal operating pressure and at normal operating temperature.

The various embodiments of the present invention provide a method for manufacturing thermoplastic components for switch gears. The method includes molding a thermoplastic component to a preset level using a thermal injection molding process and placing the molded thermoplastic component in a carton. The method further includes passing the carton through an irradiation chamber to provide an exposure to an electromagnetic radiation for cross linking one or more thermoplastic components.

According to one embodiment of the present invention, the thermoplastic material is molded and cross-linked by chemically cross linking one or more thermoplastic polymer materials to a preset level by exposure to irradiation to avoid melting. The one or more thermo plastic polymer materials include polyamide, polyethylene and a polypropylene.
According to one embodiment of the present invention, the thermoplastic component is a coil former, a contact bridge and a bus bar support, drive shaft, trip plate, housing, arc chamber, operating levers, arc liners.
According to one embodiment of the present invention, the carton is passed through the irradiation chamber and irradiated with an external radiation source. The external irradiation source is a gamma radiation source.
The thermoplastic component is molded using a thermoplastic material. The thermoplastic material is a cross linked thermoplastic polymer material. The cross linked thermoplastic material is obtained by chemically cross linking thermoplastic polymer materials. The thermoplastic polymer material includes a polyamide, polyethylene and a polypropylene.

According to one embodiment of the present invention, the carton is passed through the irradiation chamber for a preset number of times to determine a level of cross-linking of the thermoplastic component. The preset number of time of passing the carton through the irradiation chamber is selected based on a shape and a size of the thermoplastic component. The molded thermoplastic component with various shapes and sizes are packed in the carton to expose the thermoplastic components to obtain a cross linked thermoplastic component.

According to one embodiment of the present invention, the molded thermoplastic component is cross linked to avoid any dimensional distortion to the thermoplastic component.

These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.

E) BRIEF DESCRIPTION OF THE DRAWINGS

The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiments and the accompanying drawings in which:

FIG. 1 illustrates a process of cross linking thermoplastic components in an irradiation cell, according to one embodiment of the present invention.

FIG. 2 illustrates a top side perspective view of a coil in switchgears, according to one embodiment of the present invention.

FIG.3 illustrates a top side perspective view of a contact bridge in switchgears, according to one embodiment of the present invention.

FIG.4 illustrates a top side perspective view of a bus bar support in switchgears, according to one embodiment of the present invention.

Although the specific features of the present invention are shown in some drawings and not in others, this is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.

F) DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, a reference is made to the accompanying drawings that form a part hereof and in which the specific embodiments that may be practiced is shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.

The various embodiments of the present invention are to provide a thermoplastic component for switchgears comprising a thermoplastic material. The thermoplastic material is a cross linked thermoplastic polymer material to a preset level to avoid melting during an application of normal operating pressure and at normal operating temperature.

The various embodiments of the present invention provide a method for manufacturing thermoplastic components for switch gears. The method includes molding a thermoplastic component to a preset level using a thermal injection molding process and placing the molded thermoplastic component in a carton. The method further includes passing the carton through an irradiation chamber to provide an exposure to an electromagnetic radiation for cross linking one or more thermoplastic components.

According to one embodiment of the present invention, the thermoplastic material is molded and cross-linked by chemically cross linking one or more thermoplastic polymer materials to a preset level by exposure to irradiation to avoid melting. The one or more thermo plastic polymer materials include polyethylene and a polypropylene.

According to one embodiment of the present invention, the thermoplastic component is a coil former, a contact bridge, a bus bar support, a drive shaft, a trip plate, housings, an arc chamber, operating levers and arc liners.

According to one embodiment of the present invention, the carton is passed through the irradiation chamber and irradiated with an external radiation source. The external irradiation source is a gamma radiation source or electron beam radiation source.

According to one embodiment of the present invention, the thermoset component is molded using a thermoplastic material. The thermoplastic material is a cross linked thermoplastic polymer material. The cross linked thermoplastic material is obtained by chemically cross linking thermoplastic polymer material. The thermoplastic polymer material includes a polyamide, polyethylene and a polypropylene.

According to one embodiment of the present invention, the carton filled with cross linkable thermoplastic components is passed through the irradiation chamber for a preset number of times to determine a level of cross-linking of the thermoplastic component. The preset number of time of passing the carton through the irradiation chamber is selected based on a shape and a size of the thermoplastic component. The molded thermoplastic component with various shapes and sizes are packed in the carton to expose the thermoplastic components to obtain a cross linked thermoplastic component.

According to one embodiment of the present invention, the molded thermoplastic component is cross linked to avoid any dimensional distortion to the thermoplastic component.

FIG. 1 illustrates a process of cross linking thermoplastic components in an irradiation cell, according to one embodiment of the present invention. With respect to the FIG.1, one or more components are molded in a cross-linkable thermoplastic material using the thermoplastic molding process. The components molded are packed in a plurality of paper corrugated cartons and passed through the radiations such as gamma irradiation or electron beam irradiation source for preset number of times based on a shape and a size of the component. After each passage of the carton through the radiation source 102, the carton is marked for the number of passes and once the predetermined passes are completed then the components are said to have achieved the required level of cross-linking. The cross linked thermoplastic components are then sent for a final product assembly.
A high energy radiation produces ionization and excitation in the cross-linkable thermoplastic material. The thermoplastic material is a cross linked thermoplastic polymer material to a preset level to avoid melting during an application of normal operating pressure and at normal operating temperature. An example of cross linked thermoplastic material includes but is not limited to polyamide, polyethylene and a polypropylene. The thermoplastic material is molded and cross-linked by chemically cross linking one or more thermoplastic polymer materials to a preset level by exposure to irradiation to avoid melting. The one or more thermo plastic polymer materials include but are not limited to a polyamide, a polyethylene and a polypropylene.
The one or more thermo plastic polymer materials undergo dissociation, abstraction and addition reactions during an exposure to radiations and attain a chemical stability. The stabilizations in turn results into chemical cross-linking of thermoplastic components. The level of cross-linking is measured using a Differential Scanning Calorimeter (DSC) and the reduction in melting energy indicates the cross linked density of a component.
The method for manufacturing thermoplastic components for switch gears includes molding a thermoplastic component to a preset level using a thermal injection molding process. Further the method includes placing the molded thermoplastic component in a carton. The method also includes passing the carton through an irradiation chamber to provide an exposure to an electromagnetic radiation for cross linking one or more thermoplastic components. The carton is passed through the irradiation chamber for a preset number of times to determine a level of cross-linking of the thermoplastic component.

The preset number of times of passing the carton through the irradiation chamber is selected based on a shape and a size of the thermoplastic component. Further the molded thermoplastic component is cross linked to avoid any dimensional distortion to the thermoplastic component. Further the molded thermoplastic component with various shapes and sizes are packed in the carton to expose the thermoplastic components to obtain a cross linked thermoplastic component.

After achieving the desired level of cross-linking, the thermoplastic components are tested in various conditions such as a mechanical testing, an electrical testing, Flammability and a Thermal characterization testing. Further on satisfactory performance in the above conditions, the components are assembled for product testing such as a Mechanical Endurance Testing and Electrical Endurance Testing.

FIG. 2 illustrates a top side perspective view of a coil in switchgears, according to one embodiment of the present invention. With respect to the FIG.2, the coil includes a screw and a washer 206 for connecting the coil with one or more metal terminals 202 for supplying current or terminating current. The one or more metal terminals 202 are also used for connecting an enameled copper wire 208 to the coil. A cross-linked coil former 204 is used to provide an insulation base for winding the enameled copper wire 208 and supporting the one or more metal terminals 202. The enameled copper wire 208 is wound around the cross linked coil former 204 to create magnetic effect on the current supply. Further both ends of the enabled copper wire 208 are connected to the one or more metal terminals 202. At the other end of the metal terminals 202, the screw and washer 206 are located for supplying current or terminating current when a product is assembled with connection to an external electric circuit.

FIG.3 illustrates a top side perspective view of a contact bridge in switchgears, according to one embodiment of the present invention. With respect to the FIG.3, the top side perspective view includes one or more metal contacts 304 for making or breaking the current supply with a moving contact and a fixed contact on bridge movement. A cross-linked bridge 302 is used to provide an insulation base for the one or more metal terminals 202. On the metal terminals 202, the metal contacts 304 are placed at both the ends that form the moving contact on the bridge movement. The metal contacts 304 provide the current supply or terminate the current supply to the cross linked bridge 302.

FIG.4 illustrates a top side perspective view of a bus bar support in switchgears, according to one embodiment of the present invention. With respect to the FIG.4, the bus bar support includes a locator 402 for locating or positioning bus-bar support in a switchboard panel. There are two projected locators 402 at both the ends of the bus-bar Support which are used for locating or positioning bus-bar support in the switchboard panel. A cross linked bus bar support 404 is used for holding one or more metal bus-bars that provide a current supply in the switchboard panel. The cross linked bus bar support 404 provides a mechanical support and an electrical insulation to the current carrying parts. The bus bar support includes a channel or slot 406 through which the one or more metal bus-bars are passed. The bus bar supports also includes one or more cavities 408 for maintaining a uniform wall thickness on the bus-bar support to avoid any molding defects such as sink marks.

G) ADVANTAGES OF THE INVENTION

The various advantages of the present invention is that the one or more components are cross linked in less time using the process due to which there is a faster production of components, as compared to thermoset materials. Further no thermoset material or component is used inside the molding process, due to which sticking inside the mold is avoided and hence reduces the rejection rate and time consumed for removal of stuck material. The process employed in the present invention for cross linking the thermoplastic components provides a higher mechanical strength and avoids brittle failure during operation. Further the process employed for cross linking components in the present invention provides a possibility to make complex shapes or design for the components.

Although the invention is described with various specific embodiments, it will be obvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of the claims.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the present invention described herein and all the statements of the scope of the invention which as a matter of language might be said to fall there between.

WE CLAIM:

1. A thermoplastic component for switchgears comprising:
a thermoplastic material;
Wherein the thermoplastic material is a cross linked thermoplastic polymer material to a preset level to avoid melting during an application of normal operating pressure and at normal operating temperature.
2. The component according to claim 1, wherein the thermoplastic material is molded and cross-linked by chemically cross linking one or more thermoplastic polymer materials to a preset level by exposure to irradiation to avoid melting.
3. The component according to claim 1, wherein the one or more thermo plastic polymer materials include polyamide, polyethylene and a polypropylene.
4. The component according to claim 1, wherein the thermoplastic component is a coil former.
5. The component according to claim 1, wherein the thermoplastic component is a contact bridge.
6. The component according to claim 1, wherein the thermoplastic component is a bus bar support.
7. The component according to claim 1, wherein the thermoplastic component is a drive shaft.
8. The component according to claim 1, wherein the thermoplastic component is a trip plate.
9. The component according to claim 1, wherein the thermoplastic component is a housing.
10. The component according to claim 1, wherein the thermoplastic component is an arc chamber.
11. The component according to claim 1, wherein the thermoplastic component is an operating lever.
12. The component according to claim 1, wherein the thermoplastic component is an arc liner.
13. A method of manufacture of thermoplastic components for switch gears, the method comprising:
molding a thermoplastic component to a preset level using a thermal injection molding process;
placing the molded thermoplastic component in a carton; and
passing the carton through an irradiation chamber to provide an exposure to an electromagnetic radiation for cross linking one or more thermoplastic components.
14. The method according to claim 13, wherein the carton is passed through the irradiation chamber and irradiated with an external radiation source.
15. The method according to claim 13, wherein the external irradiation source is a gamma radiation source or electron beam radiation source.
16. The method according to claim 13, wherein the thermoset or thermoplastic component is molded using a cross linkable thermoplastic material.
17. The method according to claim 13, wherein the thermoplastic material is a cross linked thermoplastic polymer material.
18. The method according to claim 13, wherein the cross linked thermoplastic material is obtained by chemically cross linking thermoplastic polymer materials.
19. The method according to claim 13, wherein the thermoplastic polymer material includes a polyamide, a polyethylene and a polypropylene.
20. The method according to claim 13, wherein the carton is passed through the irradiation chamber for a preset number of times to determine a level of cross-linking of the thermoplastic component.
21. The method according to claim 13, wherein the preset number of time of passing the carton through the irradiation chamber is selected based on a shape and a size of the thermoplastic component.
22. The method according to claim 13, wherein the molded thermoplastic component is cross linked to avoid any dimensional distortion to the thermoplastic component.
23. The method according to claim 13, wherein the molded thermoplastic component with various shapes and sizes are packed in the carton to expose the thermoplastic components to obtain a cross linked thermoplastic component.
24. The method according to claim 13, wherein the thermoplastic component is a coil former.
25. The method according to claim 13, wherein the thermoplastic component is a contact bridge.
26. The method according to claim 13, wherein the thermoplastic component is a bus bar support.
27. The method according to claim 13, wherein the thermoplastic component is a drive shaft.
28. The method according to claim 13, wherein the thermoplastic component is a trip plate.
29. The method according to claim 13, wherein the thermoplastic component is housing.
30. The method according to claim 13, wherein the thermoplastic component is an arc chamber.
31. The method according to claim 13, wherein the thermoplastic component is an operating lever.
32. The method according to claim 13, wherein the thermoplastic component is an arc liner.