FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
CONTACT ARRANGEMENT FOR
SWITCHGEARS;
LARSEN & TOUBRO LIMITED, A COMPANY INCORPORATED UNDER THE COMPANIES ACT, 1956, WHOSE ADDRESS IS L&T HOUSE, BALLARD ESTATE, MUMBAI - 400 001, MAHARASHTRA, INDIA
THE FOLLOWING SPECIFICATION
PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF INVENTION
The invention relates to switchgears and more particularly to contact arrangement for switchgears.
BACKGROUND OF THE INVENTION
The combination of equipment within the switchgear enclosure allows them to interrupt fault currents of thousands of amps. A circuit breaker (within a switchgear enclosure) is the primary component that interrupts fault currents. Electrical contact and contact arrangements are well known in switchgears.
US Patent 4550972 provides a cylindrical contact arrangement using sockets. It illustrates the use of inwardly formed spherical bosses within the socket to engage with the contact pin. The cylindrical contact arrangement provides sequential engagement of the bosses.
Another US Patent 3317881 provides an improved electrical contact having means to create contact pressure between the pin and socket. The invention uses a semi-elliptical spring to induce force after ingress.
In yet another US Patent 5932841 means to strengthen electrical contact between two axially connecting members is presented. The patent employs a spring to energize the contacting elongation of the two members towards each other.
However, all of the contact arrangements mentioned above and contact arrangements in general use contact assemblies comprising of several elements, which have complex shapes and thus difficult manufacturing processes.

In view of the above, there is a need of a simplified contact arrangement for switchgears which can overcome the shortcomings associated with above Patent prior arts. SUMMARY OF THE INVENTION
Accordingly, the present invention provides a contact arrangement for switchgears comprising at least one tubular female member at a first terminal; at least one tubular male member at a second terminal, the male member having atleast one slit at an open end of the tubular male member, the slit contracting when the tubular male member ingresses into the tubular female member; and at least one elastic element between the male and the female member, the elastic element providing an opposing force to the ingress of the male member into the female member.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Fig. 1 shows an isometric view of a contact arrangement in accordance with an embodiment of the present invention.
Fig. 2 shows a cross sectional view of the contact arrangement in accordance with an embodiment of the present invention.
Fig. 3 shows an exploded view of a pair of tubular members including a male member and a female member of the contact arrangement in accordance with an embodiment of the present invention.

Fig. 4a shows an isometric view of a pair of male and female member of the contact arrangement in accordance with an embodiment of the present invention.
Fig. 4b shows a cross sectional view of the pair of male and female member of the contact arrangement in accordance with an embodiment of the present invention.
Fig. 4c shows an exploded view of the pair of male and female member along with a spring of the contact arrangement in accordance with an embodiment of the present invention.
Fig. 5 shows a cross-sectional view of the female member in accordance with an embodiment of the present invention.
Fig. 6a shows an isomeric view of the male member in accordance with an embodiment of the present invention.
Fig. 6b shows a cross-sectional view of male member in accordance with an embodiment of the present invention.
Fig. 7a shows a trend of insertion force in Newton against the travel of the male member with respect to the female member in accordance with an embodiment of the present invention.
Fig. 7b shows a trend of resistance of the capsule in milli-Ohms against the travel of male member with respect to female member in mm in accordance with an embodiment of the present invention.
DESCRIPTION OF THE INVENTION
Various embodiments of the invention provide a contact arrangement for switchgears comprising at least one tubular female member at a first terminal; at least one tubular male member at a second terminal, the male member having atleast one slit at an open end of the tubular male member, the slit contracting when the tubular male member ingresses into the tubular female member; and at least one elastic element between the male and the female

member, the elastic element providing an opposing force to the ingress of the male member into the female member.
Figs. 1, 2 and 3 show contact arrangement 100 for switchgears in accordance with an embodiment of the invention. In accordance with an embodiment of the invention, contact arrangement 100 includes a tubular male member 130 and a tubular female member 140.
Male member 130 is electrically coupled to a second terminal 110 and female member 140 is electrically coupled to a first terminal 120.Tubular male member 130 has a slit 132 at an open end of male member 130 (as shown in Fig. 6a and 6b). Tubular female member 140 receives male member 130.
In an embodiment of the invention, tubular female member 140 stressfully receives male member 130 as shown in Fig 4b.
In an embodiment, length of slit 132 is 70-90% (greater than or equal to the overlapping length of the male and female parts) of length of male member 130. Slit 132 provides for the flexing of male member 130 on ingress into female member 140 as slit 132 contracts when male member 130 ingresses into female member 140.
In an embodiment, contact arrangement 100 includes a spring 150. Spring 150 is provided between inner face 134 of male member 130 and an inner face 144 of female member 140 as shown in 4b. Meanwhile, during ingress, spring 150 is compressed between the inner faces (134, 144) of the two contacts, and tends to push the two away from each other. This creates the required axial contact force between terminals 110 and 120 and the members 130, and 140.

In an embodiment, as an example female member 140 has a conical frustum 142 that enables face of the open end of male member 130 to slide over frustum 142 as shown in Fig. 5. Face 134 of member 130 slides over frustum 142 creating point contacts between the two members (130, 140) during this motion. Slit 132 contracts/diminishes with further ingress of member 130 in member 140. Owing to elasticity, member 130 tries to retain its original shape, hence an internal stress is created in the member 130, creating the required contact force.
In an embodiment, spring 150 is compressed between the inner faces of male and female members (130, 140) during ingress, spring 150 pushes pair of members (130, 140) away from each other thereby creating the required axial contact force between pair of terminals (110, 120) and pair of members (130, 140). Spring 150 provides a force against contraction of slit 132 of male member 130.
In an embodiment, male member 130 and female member 140 of contact arrangement 100 are conducting members.
It may be apparent to a person skilled in the art, force created between the two members (130, 140), and that created between the members (130, 140) and the terminals (110, 120) are a function of the relative ingress of the members (130, 140).
Fig 3 shows an exploded view of arrangement 100 with terminal 110 and terminal 120. Relative motion of terminal 110 and terminal 120 towards each other pushes male member 130 and female member 140 towards each other which compresses spring 150 and also member 130 enters female member 140.

Fig 5 shows conical frustum 142 in female member 140 in accordance with an embodiment of the invention. Male member 130 experiences deflection at face 134 owing to a reduction in diameter of female member 140 and the gap of the slit 132 decreases at the face 134 of member 130 post ingress into the conical frustum 142 of member 130.
Fig 6b shows the cross-sectional view of male member 130, showing slit 132. An internal stress is created within male member 130, which presses member 130 against the inner surface of the conical frustum 142. This provides for the contact pressure between the current carrying elements member 130 and member 140. The spring 150 presses member 130 against terminal 110 and member 140 against terminal 120.
Fig 7a shows the trend in the contact force between member 130 and member 140 from the beginning of the interface with the conical frustum 142 to the end of it.
Fig 7b shows the trend of the insertion force required to ingress member 130 into member 140 from the beginning to the end of interface with the conical frustum 142.
In an embodiment, and referring to fig 7b, the present invention shows the trend of the resistance offered by capsule arrangement 100 against the travel of member 130 with respect to member 140. When terminal 110 and terminal 120 moves away from each other, spring 150 tries to reach its free length and pushes member 130 away from member 140 which brings member 130 back to its original position.

The invention provides for a small and viable current carrying path between two terminals using a single elastic element. The elements used in this invention have simple geometry and are easy to manufacture, or are readily available.
In an advantageous aspect, the present invention provides telescopic mating current carrying elements that can be used in plurality to achieve branching of current. The present invention uses elastic elements between the two current carrying elements and the contact force achieved between each mating pairs follows the same trend as the distance between the terminals.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

We Claim:
1. A contact arrangement for switchgears, the contact arrangement comprising:
at least one tubular female member at a first terminal;
at least one tubular male member at a second terminal, the male member having atleast one slit at an open end of the tubular male member, the slit contracting when the tubular male member ingresses into the tubular female member; and
at least one elastic element between the male and the female member, the elastic element providing an opposing force to the ingress of the male member into the female member.
2. The contact arrangement as in claim 1, wherein the elastic element is a spring.