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: TRANSMISSION SHAFT FOR MOVING CONTACT IN LOW VOLTAGE SWITCHGEAR

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:

FIELD OF THE INVENTION

The present invention relates a low voltage switch gear. More particularly, the present invention relates to different electrical pole in switching devices those are positively interlocked with each other to form a transmission shaft without using any extra coupling component such that all the poles will be closed and opened simultaneously.

BACKGROUND AND THE PRIOR ART OF THE INVENTION

The current invention is used in switches which are required to isolate load from supply. So that load side will be completely de-energized to carry out any maintenance activity. Such switches are combination of number of electrical poles driven by a mechanism. In such switches it is necessary to Make and break all the poles simultaneously to avoid any damage to the load.

In conventional system poles are connected together by means of single rigid rod, which increases complexity in housing cover design also it is difficult to maintain adequate creepage distance and to give positive barriers to restrict internal gases which may cause internal flashover. In this conventional system it is difficult to assemble number of poles and carry out maintenance of specific electrical pole.

So for the ease of assembly, ease of maintenance and choice to connect number of poles; switch should be modular constructed that is number of poles connected together to form a switch. These all poles should be positively coupled together for simultaneous making and breaking.

US6960731 discloses a separate actuating module which is provided to couple adjacent poles. This additional coupler causes radial play between adjacent pole, which will result into asynchronous opening and closing of poles; which may lead to electrical failure. Extra component increases cost of the product which directly hampers customer. So the challenge was to design a contact support (rotor) which will form a transmission shaft without increasing number of components and which will ensure simultaneous ON/OFF operation.

US6960731 discloses different poles in circuit breaker that are interlocked to form a shaft. The adjacent contact supporting shafts have been coupled with each other by a separate actuating module. All the teeth are on actuating module and receptacles are on contact supporting shaft forming a Male-Female joint. The actuating module is connected to mechanism which drives contact supporting shaft to make and break switch.

US5479143 discloses different poles which are connected together in multipole circuit breaker. In this invention they are using metal coupler to interlock different poles.

US6084489 discloses a circuit breaker rotary contact assembly locking system. it shows how moving contacts are made in contact with stationary contacts and how they are break from stationary contacts, and how contacts of different poles are connected together. This invention uses Elongated pins to connect moving contact of all poles to form a drive shaft to make switch ON and OFF.

The disadvantages of the above mentioned prior art is that elongated pins are used to couple different poles that is extra coupler is used to couple the adjacent poles. Further the use extra metal insert to connect different poles. Further case extra actuating module is used to couple two adjacent poles. The Male features are on coupler and all female features are on contact supporting shaft which is cumbersome and complex. Further there is no adjustable pole pitch is offered. The radial play between interlocking features of end surfaces are observed in the prior art. The additional component to interlock adjacent rotor enhances radial play. Different rotor assembly does not suit different size of termination lug/links and hence different current rating cannot be easily offered.

Thus there is a need to provide an arrangement for moving contact in low voltage switchgear that can be configured with different electrical pole in switch to positively interlock with each other and form a transmission shaft without using any extra coupling component.

OBJECTS OF THE INVENTION

A basic object of the present invention is to overcome the drawbacks/disadvantages of the prior art.

One of the main objects of the invention lies in providing a modular construction switch.

Another object of the present invention is to provide a single integrated rotor to avoid radial play between interlocking features of end surfaces.

Yet another object of the present invention is to provide a switch where no additional component to interlock adjacent rotor is required avoiding radial play.

Yet another object of the present invention is to provide a rotor with male and female feature on both end surfaces.

Yet another object of the present invention is to provide same rotor assembly to suit different size of termination lug/links and hence different current rating can be easily offered.

Yet another object of the present invention is to provide positive interlocking of two poles.

Yet another object of the present invention is to provide transmission shaft with minimum number of components.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided an electric pole assembly for use in switching devices, said assembly comprising
a cassette means comprising a pair of identical housing;
a rotor assembly secured inside said housing, said assembly comprising :
a pair of moving contact means adapted to make said switch device on and off ;
a fixed contact;
a rotor means substantially holding said moving contact means;
a cladding means substantially having a C-shaped modular profile operatively connected with said moving contact means;
an energy storing element operatively connected with said moving contact means;
a projection means substantially projecting from said rotor ;
a cavity means substantially located on said rotor adapted to engage with said projection of another rotor for interlocking.
wherein said projection and said cavity means are substantially located on one end surface side A of said rotor, projection means and cavity means are substantially located on the opposite end surface side B of said rotor;
wherein side B is about 180 ˚ opposite to side A.

According to another aspect of the present invention there is provided a transmission shaft arrangement, said arrangement comprising :
plurality of cassette means , said each cassette comprising a pair of identical housing ;
plurality of electric pole assemblies;
said each assembly comprising:
a rotor assembly secured inside said housing, said assembly comprising :
a pair of moving contact means ;
a fixed contact;
a rotor means substantially holding said moving contact means;
a magnetic cladding means substantially having a C-shaped modular profile operatively connected with said moving contact means;
an energy storing element operatively connected with said moving contact means;
a projection substantially projecting from said rotor ;
a cavity substantially located on said rotor adapted to engage with said projection of another rotor for interlocking
wherein said projection and said cavity means are substantially located on one end surface side A of said rotor, projection means and cavity means are substantially located on the opposite end surface side B of said rotor;
wherein said projection and cavity of side B is 180 ˚ opposite to projection and cavity of side A;
wherein said transmission shaft arrangement is defined by engaging each electric pole assembly with one another adapted for simultaneous on/off operation;
wherein said mechanical transmission shaft arrangement is defined by engaging male feature of one rotor assembly with female feature of another rotor assembly such that Male feature and female feature of one rotor assembly engages with Female feature and male feature of adjacent rotor assembly.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING

Figure 1 illustrates Rotor Assembly.
Figure 2 illustrates Side A of rotor.
Figure 3 illustrates Side B of rotor.
Figure 4 illustrates Male-female feature of rotor.
Figure 5 illustrates Interlocking of rotor forming a transmission shaft.
Figure 6 illustrates Rotors separation is increased keeping adequate Male and female feature engagement for torque transmission taking care of different pole pitch.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWING

Following are the components used in the present invention:-
Rotor (1) - Is a plastic component which holds pair of moving contact, magnetic cladding and leaf spring
Moving contact (2) – Is a copper component which makes and breaks with terminals (Connected to supply and load) to Make switch ON and OFF respectively.
Magnetic cladding(3) : Is a C shape steel component used for enhancing the electrodynamic forces generated due to specific profile & arrangement of moving and fixed contacts.
Leaf spring (4) – Is a steel component which gives pressure to contacts
Male Feature (5) – Is a feature from rotor which engages with female feature of another rotor for interlocking of poles
Female Feature (6) – Is a feature from rotor which engages with male feature of another rotor for interlocking
Side A (7) – One end surface of rotor which have Male and Female feature
Side B (8) - Another end surface of rotor which have male and female part exactly 180 degree opposite to Side A

The working is explained with reference to the figures 1-6.

Switch is combination of mechanism and number of poles connected side by side. One mechanism drives all the poles simultaneously. All poles should be mechanically interlocked with each other for simultaneous ON/OFF operation. All poles are interlocked with each other through single integrated rotor of each cassette.

Rotors from adjacent pole engage with each other through Male and Female feature shown in Figure.1. Male and female feature of Side A in Figure.2 is 180 degree opposite to Male and Female feature of side B shown in Figure.3.

Figure 4 shows, after keeping poles side by side for assembly Male feature of one rotor comes in front of female feature of another rotor and vice versa. Thus Male, female feature of one rotor assembly engages with Female, male feature of adjacent rotor assembly respectively shown in Figure. 5 to form a transmission shaft of a switch, which can be drive through mechanism having identical male and female feature.

As rotor is a single moulded component there is no radial play between Male and female feature of both end surfaces (Side A and Side B) of same rotor. Due to interlocking features and absence of extra connecting component all poles can be simultaneously positively operated.

When same switch is to be used for application where different terminal pitch is needed to terminate different sizes of cables/links, the normal practice is to add another coupler to increase/decrease distance between two cassettes and hence the terminal pitch. But this has been taken care by giving more depth to female feature to accommodate more length of male feature that would have been necessary for adequate engagement between male and female feature in required extreme conditions. So again avoiding extra coupler helped to regain positive interlock even in case of different pole pith using same rotor assembly.

So because of adjustable pole pitch, Manufacturer gets benefit to offer same switch for different current rating which require different termination capacities and hence different pole pitch.

Following are the terminologies used in the present invention:-
Switch: Is an assembly of mechanism and contact system which isolates supply from load.
Cassette: Assembly of two identical housing which holds rotor assembly, terminal from supply and load side.
Mechanism: that operates rotor assembly to make switch ON/OFF.
Pole: Every cassette forms a single pole
Termination pitch: Distance between termination hole of adjacent pole.
Pole pitch: Distance between contact surface adjacent poles.

Advantages:
Modular construction switch

Single integrated rotor to avoid radial play between interlocking features of end surfaces

No additional component to interlock adjacent rotor avoiding radial play

Male and Female feature on both end surfaces

Same rotor assembly to suit different size of termination lug/links and hence different current rating can be easily offered

Positive Interlocking of two poles

Transmission shaft with minimum number of components

The invention has been described in a preferred form only and many variations may be made in the invention which will still be comprised within its spirit. The invention is not limited to the details cited above. The structure thus conceived is susceptible of numerous modifications and variations, all the details may furthermore be replaced with elements having technical equivalence. In practice the materials and dimensions may be any according to the requirements, which will still be comprised within its true spirit.

WE CLAIM:

1. An electric pole assembly for use in switching devices, said assembly comprising
a cassette means comprising a pair of identical housing;
a rotor assembly secured inside said housing, said assembly comprising :
a pair of moving contact means adapted to make said switch device on and off ;
a fixed contact;
a rotor means substantially holding said moving contact means;
a cladding means substantially having a C-shaped modular profile operatively connected with said moving contact means;
an energy storing element operatively connected with said moving contact means;
a projection means substantially projecting from said rotor ;
a cavity means substantially located on said rotor adapted to engage with said projection of another rotor for interlocking.
wherein said projection and said cavity means are substantially located on one end surface side A of said rotor, projection means and cavity means are substantially located on the opposite end surface side B of said rotor;
wherein side B is about 180 ˚ opposite to side A.

2. Assembly as claimed in claim 1 wherein said rotor means is a plastic component.

3. Assembly as claimed in claim 2 wherein said rotor means is adapted to hold pair of moving contact means; magnetic cladding and energy storing element.

4. Assembly as claimed in claims 1 and 3 wherein said cladding means is magnetic in nature.

5. Assembly as claimed in claim 4 wherein said cladding is a steel component.

6. Assembly as claimed in claim 1 wherein said projection means is a male projection /feature adapted to engage with said cavity means.

7. Assembly as claimed in claim 1 wherein said cavity means is a female cavity /feature adapted to be engaged with said projection means.

8. Assembly as claimed in claim 1 wherein said cladding is adapted for enhancing electrodynamic forces.

9. Assembly as claimed in claim 1 wherein said energy storing element is a spring means adapted to provide pressure to contacts.

10. Assembly as claimed in any of the preceding claims wherein said female feature is having more depth to accommodate more length of male feature adapted for adequate engagement between male and female feature in extreme conditions.

11. Assembly as claimed in any of the preceding claims wherein said male projections are identical to said female cavities.

12. A transmission shaft arrangement, said arrangement comprising :
plurality of cassette means , said each cassette comprising a pair of identical housing ;
plurality of electric pole assemblies;
said each assembly comprising:
a rotor assembly secured inside said housing, said assembly comprising :
a pair of moving contact means ;
a fixed contact;
a rotor means substantially holding said moving contact means;
a magnetic cladding means substantially having a C-shaped modular profile operatively connected with said moving contact means ;
an energy storing element operatively connected with said moving contact means;
a projection substantially projecting from said rotor ;
a cavity substantially located on said rotor adapted to engage with said projection of another rotor for interlocking
wherein said projection means and cavity means are substantially located on one end surface side A of said rotor, projection and cavity means are substantially located on the opposite end surface side B of said rotor;
wherein said projection and cavity of side B is 180 ˚ opposite to projection and cavity of side A;
wherein said transmission shaft arrangement is defined by engaging each electric pole assembly with one another adapted for simultaneous on/off operation;
wherein said mechanical transmission shaft arrangement is defined by engaging male feature of one rotor assembly with female feature of another rotor assembly such that Male feature and female feature of one rotor assembly engages with Female feature and male feature of adjacent rotor assembly.

13. Arrangement as claimed in claim 12 wherein said rotor means is a plastic component.

14. Arrangement as claimed in claim 13 wherein said rotor means is adapted to hold pair of moving contact means; magnetic cladding and energy storing element.

15. Arrangement as claimed in claims 12 and 14 wherein said cladding means is magnetic in nature.

16. Arrangement as claimed in claim 15 wherein said cladding is a steel component.

17. Arrangement as claimed in claim 12 wherein said projection means is a male projection /feature adapted to engage with said cavity means.

18. Arrangement as claimed in claim 12 wherein said cavity means is a female cavity /feature adapted to engage with said projection means.

19. Arrangement as claimed in claim 12 wherein said cladding is adapted for enhancing electrodynamic forces.

20. Arrangement as claimed in claim 12 wherein said wherein said energy storing element is a spring means adapted to provide pressure to contacts.

21. Arrangement as claimed in any of the preceding claims wherein said female feature is having more depth to accommodate more length of male feature adapted for adequate engagement between male and female feature in extreme conditions.

22. Arrangement as claimed in any of the preceding claims wherein said male projections are identical to said female cavities.

23. An electric pole assembly in a switch as herein substantially described and illustrated with reference to the accompanying drawings.

24. A transmission shaft arrangement as herein substantially described and illustrated with reference to the accompanying drawings.