FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
AND
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION (See section 10 and rule 13)
TITLE OF THE INVENTION
A disconnector / earth switch of a switchgear equipment, and switchgear equipment, thereby
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR
Rajan Aravind, of Crompton Greaves Ltd, Bhaskara, Building No. 1, Global R&D, Kanjurmarg, Mumbai 400042, India; 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 the field of Gas Insulated Switchgear.
Particularly, this invention relates to a disconnector / earth switch of a switchgear equipment, and switchgear equipment, thereby.
BACKGROUND OF THE INVENTION:
A piece of switchgear may be a simple open-air isolator switch or it may be insulated by some other dielectric material. An effective although more costly form of switchgear is gas insulated switchgear (GIS), where the conductors and contacts are insulated by pressurized sulfur hexafluoride gas (SF6). A disconnector or isolator switch is used to make sure that an electrical circuit can be completely de-energized for service or maintenance.
Switches (Disconnector and earth switches) in GIS are formed of two contacts: fixed and moving. The current design has a single moving contact inside its housing. Lamellas are typically used to make the contact between the moving part and the housing. The distance between the housing and the fixed contact/enclosure is determined by the clearance required for the given pressure of SF6 (Hereafter, referred as clearance).
There is a need for switchgear equipment with reduced housing size.
OBJECTS OF THE INVENTION:
An object of the invention is to provide switchgear equipment housing with reduced length.

Another object of the invention is to provide an effective switch with reduced length.
SUMMARY OF THE INVENTION:
According to this invention, there is provided a disconnector / earth switch of a switchgear equipment, said disconnector / earth switch comprising:
at least a solid slider element adapted to be slidably ensconced within at least a hollow slider element, said solid slider element adapted to be slidably ensconced within a channel, said solid slider element adapted to slide out of said hollow slider up to a pre-determined first length in order to obtain an intermediate non-mating condition, and said hollow slider element adapted to slide out of said channel up to a pre-determined second length, for the solid slider element to be received by a receptacle in order to obtain a final closed condition.
Typically, said channel is a fixed channel.
Typically, said receptacle is a fixed receptacle.
Typically, said switch includes a chain of multiple hollow slider elements and a single solid slider element to form a telescopic assembly.
According to this invention, there is provided a switchgear equipment with a disconnector / earth switch, said switchgear equipment comprises;
a. conductor with a channel transversely located with respect to said shaft conductor; and

b. at least a solid slider element adapted to be slidably ensconced within at least a hollow slider element, said solid slider element adapted to be slidably ensconced within a channel, said solid slider element adapted to slide out of said hollow slider up to a pre-determined first length in order to obtain an intermediate non-mating condition, and said hollow slider element adapted to slide out of said channel up to a pre-determined second length, for the solid slider element to be received by a receptacle in order to obtain a final closed condition.
Typically, said channel includes linear slits (rails) along the inner wall of said channel.
Typically, said solid slider element includes a stub placed along the outer wall of the solid slider element, said stub slidable along linear slits (rails) along the inner wall of said hollow slider element.
Typically, said hollow slider element includes stop elements placed along linear slits (rails) along the inner wall of said hollow slider element to ensure that the solid slider element does not cross beyond said second pre-determined distance.
Typically, said hollow slider element includes a stub placed along the outer wall of the hollow slider element, said stub slidable along linear slits (rails) along the inner wall of said channel.
Typically, said channel includes stop elements placed along linear slits (rails) along the inner wall of said channel to ensure that the hollow slider element does not cross beyond said first pre-determined distance.
Typically, said solid slider element is a first moving contact.

Typically, said hollow slider element is a second moving contact,
Typically, said solid slider element is a plate / shaft which is co-axial with said hollow slider element and adapted to slide in and out of said hollow slider element.
Alternatively, , said equipment includes a chain pf a plurality of telescopically engaged hollow slider elements and a solid slider element.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 illustrates a cross-section view of the housing of the prior art showing disconnector of the prior art in its open configuration; and
Figure 2 illustrates a cross-section view of the housing of the prior art showing disconnector of the prior art in its closed configuration.
The invention will now be described in relation to the accompanying drawings, in
which:
Figure 3 illustrates a cross-section view of the housing showing disconnector in its
closed configuration;
Figure 4 illustrates a cross-section view of the housing showing disconnector in its intermediate configuration; and
Figure 5 illustrates a cross-section view of the housing showing disconnector in its open configuration.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 illustrates a cross-section view of the housing of the prior art showing disconnector of the prior art in its open configuration. Figure 2 illustrates a cross-section view of the housing of the prior art showing disconnector of the prior art in its closed configuration.
There is a enclosure (12) which includes a conductor (14). In the conductor (14), a mechanical slider switch (16) is provided which makes or breaks contact. The mechanical slider switch (16) includes a slider element (16a) which slides through a channel (16b) to mate with or slide partially into a receptacle (16c) located along the inner wall of the enclosure. The receptacle (16c) is a fixed contact. The slider element (16a) is a moving contact which slides between an open position (as shown in Figure 1 of the accompanying drawings) and a closed position (as shown in Figure 2 of the accompanying drawings).
In the open position, the moving contact (16a) is completely inside the channel (16b).
The moving contact (16a), in the closed position, is required to have a certain wipe in the fixed contact (16c).
Thus, the moving contact (16a) length is greater than the clearance (gap between the channel (16b) and receptacle (16c)).
Consequently, the housing (12) length is also greater than the clearance by the same length. This makes the length of the enclosure (12) large.

According to this invention, there is provided a disconnector / earth switch of a switchgear equipment. According to another embodiment of this invention, there is provided a switchgear equipment with a disconnector / earth switch of this invention.
Figure 3 illustrates a cross-section view of the housing showing disconnector in its closed configuration. Figure 4 illustrates a cross-section view of the housing showing disconnector in its intermediate configuration. Figure 5 illustrates a cross-section view of the housing showing disconnector in its open configuration
In accordance with an embodiment of this invention, there is provided an conductor (14) with a channel (18) similar to the prior art. The channel (18) dimensions may differ.
In accordance with another embodiment of this invention, there is provided a solid slider element (20) adapted to slide out of said hollow slider element (22) up to a pre-determined first distance. Advantageously, the sliding movement may be facilitated by means of linear slits (rails) along the inner wall of the solid slider element (22) which receives a stub placed along the outer wall of the solid slider element. There are stop elements placed along the linear slits to ensure that the solid slider element does not cross beyond the first pre-determined distance. The solid slider element (20) is the first moving contact.
In accordance with yet another embodiment of this invention, there is provided a hollow slider element (22) adapted to slide out of said channel (18). The hollow slider element (22) is co-axial with the solid slider element (20). It is adapted to slide in and out of the said channel (18). The hollow slider element (22) is adapted

to slide out of said channel (18) up to a pre-determined second distance. The second slider element (22) is the second moving contact. Advantageously, the sliding movement may be facilitated by means of linear slits (rails) along the inner wall of the channel (18) which receives a stub placed along the outer wall of the hollow slider element. There are stop elements placed along the linear slits to ensure that the hollow slider element does not cross beyond the second predetermined distance. The hollow slider element (22) is the second moving contact.
In accordance with still another embodiment of this invention, there is provided a receptacle (24) located along the inner wall of the enclosure. The receptacle (24) is a fixed contact. It receives the solid slider element (20) when it fully slides out and when the hollow slider element (22) has also fully slid out.
In its closed configuration (as shown in Figure 3 of the accompanying drawings), the solid slider element (20) is fully slid out of the hollow slider element (22) and the hollow slider element (22) is fully slid out of the channel (18). Thus, the solid slider element (20) mates with the receptacle (24).
In its intermediate configuration (as shown in Figure 4 of the accompanying drawings), the solid slider element (20) is fully placed (not slid out) within hollow slider element (22) and the solid slider element (22) is fully slid out of the channel (18). Thus, the solid slider element (20) does not mate with the receptacle (24).
In its open configuration (as shown in Figure 5 of the accompanying drawings), the solid slider element (20) is fully placed (not slid out) within the hollow slider

element (22) and the solid slider element (22) is fully placed (not slid out) within the channel (18). Thus, the solid slider element (20) does not mate with the receptacle (24).
Consequently, a chain of moving contacts can be established with an innermost solid moving contact and subsequent outer hollow moving contacts adapted to receive preceding moving contacts. A chain link of contacts can be established, depending upon the length to be traversed to reach the receptacle (24) from the conductor (14). The moving contacts are coaxially placed within the enclosure. The length of these individual contacts is much smaller than the clearance. Each contact is connected to the immediate outer one via lamellas.
For instance, if two the moving contact is split up into two: one hollow (22) and one solid (20), then each of them has to be little longer than half the clearance.
Consequently, the overall length (of the switch as well as the enclosure) is much smaller than the prior art.
While this detailed description has disclosed certain specific embodiments of the present invention for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We claim,
1. A disconnector / earth switch of a switchgear equipment, said disconnector /
earth switch comprising:
a. at least a solid slider element adapted to be slidably ensconced within at least a hollow slider element, said solid slider element adapted to be slidably ensconced within a channel, said solid slider element adapted to slide out of said hollow slider up to a pre-determined first length in order to obtain an intermediate non-mating condition, and said hollow slider element adapted to slide out of said channel up to a pre-determined second length, for the solid slider element to be received by a receptacle in order to obtain a final closed condition.
2. A disconnector / earth switch as claimed in claim 1 wherein, said channel is a fixed channel.
3. A disconnector / earth switch as claimed in claim 1 wherein, said receptacle is a fixed receptacle.
4. A disconnector / earth switch as claimed in claim 1 wherein, said switch includes a chain of multiple hollow slider elements and a single solid slider element to form a telescopic assembly.
5. A switchgear equipment with a disconnector / earth switch, said switchgear equipment comprising:

a. conductor with a channel transversely located with respect to said shaft
conductor; and
b. at least a solid slider element adapted to be slidably ensconced within at least
a hollow slider element, said solid slider element adapted to be slidably
ensconced within a channel, said solid slider element adapted to slide out of
said hollow slider up to a pre-determined first length in order to obtain an
intermediate non-mating condition, and said hollow slider element adapted
to slide out of said channel up to a pre-determined second length, for the
solid slider element to be received by a receptacle in order to obtain a final
closed condition.
6. A switchgear equipment as claimed in claim 5 wherein, said channel includes linear slits (rails) along the inner wall of said channel.
7. A switchgear equipment as claimed in claim 5 wherein, said solid slider element includes a stub placed along the outer wall of the solid slider element, said stub slidable along linear slits (rails) along the inner wall of said hollow slider element.
8. A switchgear equipment as claimed in claim 5 wherein, said hollow slider element includes stop elements placed along linear slits (rails) along the inner wall of said hollow slider element to ensure that the solid slider element does not cross beyond said second pre-determined distance.
9. A switchgear equipment as claimed in claim 5 wherein, said hollow slider element includes a stub placed along the outer wall of the hollow slider

element, said stub slidable along linear slits (rails) along the inner wall of said channel.
10.A switchgear equipment as claimed in claim 5 wherein, said channel includes stop elements placed along linear slits (rails) along the inner wall of said channel to ensure that the hollow slider element does not cross beyond said first pre-determined distance.
11 .A switchgear equipment as claimed in claim 5 wherein, said solid slider element is a first moving contact.
12.A switchgear equipment as claimed in claim 5 wherein, said hollow slider element is a second moving contact.
13.A switchgear equipment as claimed in claim 5 wherein, said solid slider element is a plate / shaft which is co-axial with said hollow slider element and adapted to slide in and out of said hollow slider element.
14.A switchgear equipment as claimed in claim 5 wherein, said equipment includes a chain of a plurality of telescopically engaged hollow slider elements and a solid slider element.