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
Operating mechanism for combined operation of disconnector and earthing switches of a
Gas Insulated Switchgear
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli. Mumbai 400 030,
Maharashtra, India, an Indian Company
INVENTOR
Arun Tom Mathew of Analytics Lab, Global R&D, Crompton Greaves Ltd., Kanjur
Marg, Mumbai 400042, Maharashtra, 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
The present invention relates to an operating mechanism for combined operation of Disconnector and Earthing switches of a Gas Insulated Switchgear.
BACKGROUND OF THE INVENTION
A Gas Insulated Switchgear (GIS) comprises a plurality of electrical components and includes gas as primary insulating medium typically at high voltages. In the GIS, an electric component is typically connected to a power supply via a disconnector switch and to the ground through an earthing switch. Both the disconnector and earthing switches are interrupters, each of which comprises a fixed contact and a movable contact linearly movable relative to the fixed contact. Under normal operating conditions, the disconnector switch of an electric component is closed and the earthing switch is opened. However, when the circuit breaker or the Busbars need to be isolated for testing/maintenance, the disconnector switches need to be opened and earthing switches closed. Thus, both the disconnector and earthing switches operate in conjunction in a GIS.
Conventionally, many operating mechanisms exist which comprises a common actuating means for operating the disconnector and earthing switches. However, existing operating mechanisms are complex in nature and include a large number of components makes it complex and increases the probability of malfunctioning. Further, due to large number of components, the operating mechanism occupies a significant space in the housing of the GIS.

Hence, there is a need for an operating mechanism for actuating the pair of interrupters disposed in the GIS, which is simple, employ less number of components, having ease of maintenance, cost effective and enables a user to have precise control over the operation of the interrupters/switches.
DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION
Various embodiments of the present invention provide an operating mechanism for combined operation of a disconnector switch and an earthing switch of a Gas Insulated Switchgear (GIS). The disconnector and earthing switches are disposed along a common axis and each comprises a fixed contact and a movable contact. The operating mechanism comprises a rotary shaft disposed substantially perpendicular to the common axis of motion of the movable contacts; a first disc and a second disc fixedly positioned adjacent to each other on the rotary shaft and rotatable therewith; and a first crank member disposed adjacent to the first disc and a second crank member disposed adjacent to the second disc over the rotary shaft, each of the first and second crank members having a circular portion with a central opening for receiving the rotary shaft and an upper arm portion for connecting to a movable contact, and being rotatable with respective adjacent disc between an initial angular position and a final angular position for facilitating linear motion of respective movable contact between an open and a closed position, wherein when the first crank member is at corresponding initial angular position, the second crank member is at corresponding final angular position, and vice versa.

Preferably, the first disc comprises a pin fixedly disposed on an inner surface facing the first crank member, and the first crank member comprising a pair of stopper pins disposed at either sides of the pin on an inner surface facing the first disc, such that when the pin reaches a stopper pin on rotation of the first disc, it forces the first crank member to rotate along with the first disc towards corresponding initial/final angular position.
Preferably, circular portion of the second crank member extend between two L-shaped end portions.
Preferably, the second disc comprises two pins fixed disposed at two angularly spaced apart positions on an outer surface facing the second crank member, such that when a pin reaches an L-shaped end portion on rotation of the second disc, it engages into the L-shaped end portion and forces the second crank member to rotate along with the second disc towards corresponding initial/final angular position.
Preferably, each of first and second crank members is pivotally mounted on a circular supporting member positioned over the rotary shaft.
Preferably, the rotary shaft is rotated by half a revolution to change from disconnector closed position to earthing closed position, and vice versa.
Various embodiments of the present invention provide a Gas Insulated Switchgear (GIS) which comprises a disconnector switch and an earthing switch disposed along a common axis and each comprising a fixed contact and a movable contact; and an

operating mechanism for combined operation of the disconnector and earthing switches. The operating mechanism comprises a rotary shaft disposed substantially perpendicular to the common axis of motion of the movable contacts; a first disc and a second disc fixedly positioned adjacent to each other on the rotary shaft and rotatable therewith; and a first crank member disposed adjacent to the first disc and a second crank member disposed adjacent to the second disc over the rotary shaft, each of the first and second crank members having a circular portion with a central opening for receiving the rotary shaft and an upper arm portion for connecting to a movable contact, and being rotatable with respective adjacent disc between an initial angular position and a final angular position for facilitating linear motion of respective movable contact between an open and a closed position, wherein when the first crank member is at corresponding initial angular position, the second crank member is at corresponding final angular position, and vice versa.
These and other aspects, features and advantages of the invention will be better understood with reference to the following detailed description, accompanying drawings and appended claims, in which,
Fig. 1 is a perspective view of a portion of a Gas insulated Switchgear (GIS) containing an operating mechanism for combined operation of a pair of switches disposed therein in accordance with various embodiments of the present invention;
Fig.2 is an exploded view of the operating mechanism in accordance with an embodiment of the present invention;

Fig.3 illustrates the operating mechanism enabling one switch to be opened and another switch to be closed in accordance with an embodiment of the present invention;
Fig.4 illustrates the operating mechanism enabling both the switches to be opened in accordance with an embodiment of the present invention; and
Fig.5 illustrates the operating mechanism enabling the one switch to be closed and the another switch to be opened in accordance with an embodiment of the present invention.
Fig. 1 is a perspective view of a portion of a Gas insulated Switchgear (GIS) 100 illustrating a housing 1 which encloses a disconnector switch 2, an earthing switch 3, and an operating mechanism 10 for combined operation of the disconnector and earthing switches 2 and 3. Preferably, the GIS is of high voltage of the range of 245kv and the disconnector and earthing switches 2 and 3 are encapsulated in the housing 1 containing SF6 gas.
The disconnector switch 2 comprises a first movable contact 4 and a first fixed contact (not shown in the figure) fixedly disposable at disconnector side 5 of the housing 1 for engaging with the first movable contact 4. The first movable contact 4 is linearly movable with respect to the first fixed contact and is coupled to the operating mechanism 10. Further, the first movable contact 4 is housed in a contact housing 8 fixed to the main housing I.
Similarly, the earthing switch 3 comprises a second movable contact 6 (not shown in the figure) and a second fixed contact (not shown in the figure) fixedly disposed at

earthing side 7 of the housing 1 for engaging with the second movable contact 6. The second movable contact 6 is linearly movable with respect to the second fixed contact and is coupled to the operating mechanism 10. The second movable contact 6 is housed in a contact housing 9 fixed to the main housing 1.
Preferably, the disconnector switch 2 and earthing switch 3 are identical in shape, size and construction and are disposed along a common axis.
The operating mechanism 10 is configured to actuate the first and second movable contacts 4 and 6 to either move towards or away from each other along a common axis for enabling opening and closing of respective switches.
Referring to Fig.2, the operating mechanism 10 composes a rotary shaft 20 disposed substantially perpendicular to the common axis of motion of the movable contacts 4 and 6. The operating mechanism 10 further comprises a first disc 21 and a second disc 23 fixedly positioned adjacent to each other on the shaft 20 and rotatable along with the shaft 20.
Adjacent to the first disc 21, there is provided a first crank member, 25 disposed over the shaft 20. The first crank member 25 is not directly attached and rotatable with the shaft 20 and may be pivotally mounted on a circular supporting member such as a bushing concentric to the rotary shaft 20 and fixed to the contact housing 8.

The first crank member 25 has a circular portion 24 with a central opening (not shown in the figure) for receiving the rotary shaft 20 and an upper arm portion 26 for connecting to the first movable contact 4.
Further, adjacent to the second disc 23, there is provided a second crank member 27 disposed over the shaft 20. The second crank member 27 is not directly attached and rotatable with the shaft 20 and may be pivotally mounted on a circular supporting member 28 such as a bushing concentric to the rotary shaft 20 and fixed to the contact housing 9.
The second crank member 27 has a circular portion 29 with a central opening 30 for receiving the rotary shaft 20 and an upper arm portion 31 for connecting to the second movable contact 6. Further, the circular portion 29 extends between two L-shaped end portions 32 and 33(not shown in the figure).
As illustrated in the figure, the first disc 21 comprises a pin 34 fixedly disposed on an inner surface facing the first crank member 25. Further, the first crank member 25 comprise a pair of stopper pins 35 and 36 disposed at either sides of the pin 34 on an inner surface facing the first disc 21. The pin 34 moves towards the stopper pin 35 on clockwise rotation of the first disc 21, whereas the pin 34 moves towards the stopper pin 36 on anticlockwise rotation of the first disc 21.
The second disc 23 comprises two pins 37 and 38 (not shown in the figure) fixedly disposed at two angularly spaced apart positions on an outer surface facing the second crank member 27. The pin 37 is engageable in the L-shaped portion 32 on

clockwise rotation of the second disc 23. Similarly, on the other side, the pin 38 is engageable in the L-shaped portion 33 on anticlockwise rotation of the second disc 23.
Operationally, when the shaft 20 rotates in clockwise direction, both the discs 21 and 23 rotate freely in the clockwise direction. The pin 34 on the disc 21 moves towards the stopper pin 35 and forces the first crank member 25 to rotate along with. When the first crank member 25 rotates in clockwise direction, it pulls the first movable contact 4 away from respective fixed contact and leads to opening of the disconnector switch 2. Concurrently, the pin 37 of the second disc 23 moves towards the L-shaped portion 32 and engages itself therein, and thus forces the second crank member 27 to rotate along with the second disc 23. When the second crank member 27 rotates clockwise, it pushes the movable contact 6 towards respective fixed contact and leads to closing of the earthing switch 3.
Similarly, when the shaft 20 rotates in anticlockwise direction, both the discs 21 and 23 rotate freely in the anticlockwise direction. The pin 34 on the disc 21 moves towards the stopper pin 36 and forces the first crank member 25 to rotate along with the first disc 21. When the first crank member 25 rotates in anticlockwise direction, it pushes the first movable contact 4 towards respective fixed contact and leads to closing of the disconnector switch 2. Concurrently, the pin 38 of the second disc 23 moves towards the L-shaped portion 33 and engages itself therein, and forces the second crank member 27 to rotate along with the second disc 23. When the second crank member 27 rotates anticlockwise, it pulls the movable contact 6 away from respective fixed contact and leads to opening of the earthing switch 3.

Thus, each of the first crank member 25 and second crank member 27 are rotatable with respective adjacent disc between an initial angular position and a final angular position for facilitating linear motion of respective movable contact between an open and a closed position. It may be noted that when the first crank member 25 is at corresponding initial angular position, the second crank member 27 is at corresponding final angular position, and vice versa.
The pins 34, 37 and 38 and stoppers 35 and 36 are configured and positioned such that by rotating the shaft 20 only by half a revolution in clock as well as anticlockwise directions, it is possible to change from disconnector closed/earthing open to earthing closed/disconnector open and vice versa.
Fig.3 illustrates the operating mechanism 10 when the disconnector switch 2 is closed and the earthing switch 3 is opened. The first crank member 25 is disposed at its final angular position for keeping the disconnector switch 2 closed, whereas the second crank member 27 is disposed at its initial angular position for keeping the earthing switch 3 opened.
In order to change from disconnector closed to earting closed position, the rotary shaft 20 may be rotated in clockwise direction. When the rotary shaft 20 is rotated in clockwise direction by quarter of a revolution, the pin 34 may reach the stopper pin 35 and pulls the movable contact 6 away from respective fixed contact. In the meantime, the pin 37 reaches the L-shaped portion 32. The second crank member 27 starts rotating in clockwise direction only after the pin 37 reaches the L-shaped portion 32. An

intermediate position when the movable contact 4 is partially pulled away from respective fixed contact, and the pin 37 is on the way to reach the L-shaped portion 32 is illustrated in Fig.4.
From position illustrated in Fig.4, the rotary shaft 20 may be further rotated clockwise by a quarter of revolution to enable the pin 37 to rotate the second crank member 27 towards its final angular position and pushes the movable contact 6 towards respective fixed contact. Concurrently, the first crank member 25 rotates clockwise towards its initial angular position where the movable contact 4 is completely pulled away from respective fixed contact
Fig.5 illustrates the operating mechanism 10 when the first crank member 25 is disposed at its initial angular position for keeping the movable contact 4 in open position, whereas the second crank member 27 is disposed at its final angular position for keeping the movable contact 6 in closed position.
Various embodiments of the present invention provide an operating mechanism for combined operation of disconnector and earthing switches of a Gas Insulated Switchgear (GIS). The proposed control mechanism is very simple, includes significantly less number of components, reduces the space of the enclosure and reduces the time required for operating the pair of interrupters. The rotary shaft needs to be rotated by only half a revolution to change from disconnector closed position to earthing closed position, and vice versa.

It will be appreciated by a person skilled in the art that the operating mechanism may be used in any system where two electric switches are required to be operated together. Several other applications of the control mechanism other than Gas Insulated Switchgear are possible and should be considered within the scope of the present invention.
Although the invention has been described with reference to a specific embodiment, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiment, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the scope of the invention as defined in the appended claims.

We claim:
1. An operating mechanism for combined operation of a disconnector switch and an
earthing switch of a Gas Insulated Switchgear (GIS), the disconnector and earthing
switches are disposed along a common axis and each comprising a fixed contact and a
movable contact, the operating mechanism comprising:
a rotary shaft disposed substantially perpendicular to the common axis of motion of the movable contacts;
a first disc and a second disc fixedly positioned adjacent to each other on the rotary shaft and rotatable therewith; and
a first crank member disposed adjacent to the first disc and a second crank member disposed adjacent to the second disc over the rotary shaft, each of the first and second crank members having a circular portion with a central opening for receiving the rotary shaft and an upper arm portion for connecting to a movable contact, and being rotatable with respective adjacent disc between an initial angular position and a final angular position for facilitating linear motion of respective movable contact between an open and a closed position, wherein when the first crank member is at corresponding initial angular position, the second crank member is at corresponding final angular position, and vice versa.
2. The operating mechanism as claimed in claim 1, wherein the first disc comprises
a pin fixedly disposed on an inner surface facing the first crank member, and the first

crank member comprising a pair of stopper pins disposed at either sides of the pin on an inner surface facing the first disc, such that when the pin reaches a stopper pin on rotation of the first disc, it forces the first crank member to rotate along with the first disc towards corresponding initial/final angular position.
3. The operating mechanism as claimed in claim 1, wherein circular portion of the second crank member extend between two L-shaped end portions.
4. The operating mechanism as claimed in claim 3, wherein the second disc comprises two pins fixed disposed at two angularly spaced apart positions on an outer surface facing the second crank member, such that when a pin reaches an L-shaped end portion on rotation of the second disc, it engages into the L-shaped end portion and forces the second crank member to rotate along with the second disc towards corresponding initial/final angular position.

4. The operating mechanism as claimed in claim 1, wherein each of first and second crank members is pivotally mounted on a circular supporting member positioned over the rotary shaft.
5. The operating mechanism as claimed in claim 1, wherein the rotary shaft is rotated by half a revolution to change from disconnector closed position to earthing closed position, and vice versa.
6. A Gas Insulated Switchgear (GIS) comprising:
a disconnector switch and an earthing switch disposed along a common axis and each comprising a fixed contact and a movable contact; and

an operating mechanism for combined operation of the disconnector and earthing switches, the operating mechanism comprising:
a rotary shaft disposed substantially perpendicular to the common axis of motion of the movable contacts;
a first disc and a second disc fixedly positioned adjacent to each other on the rotary shaft and rotatable therewith; and
a first crank member disposed adjacent to the first disc and a second crank member disposed adjacent to the second disc over the rotary shaft, each of the first and second crank members having a circular portion with a central opening for receiving the rotary shaft and an upper arm portion for connecting to a movable contact, and being rotatable with respective adjacent disc between an initial angular position and a final angular position for facilitating linear motion of respective movable contact between an open and a closed position, wherein when the first crank member is at corresponding initial angular position, the second crank member ts at corresponding final angular position, and vice versa.
7. The GIS as claimed in claim 6, wherein the first disc comprises a pin fixedly
disposed on an inner surface facing the first crank member, and the first crank member comprising a pair of stopper pins disposed at either sides of the pin on an inner surface facing the first disc, such that when the pin reaches a stopper pin on rotation of the first disc, it forces the first crank member to rotate along with the first disc towards corresponding initial/final angular position.

8. The GIS as claimed in claim 6, wherein circular portion of the second crank member have two L-shaped end portions.
9. The GIS as claimed in claim 8, wherein the second disc comprises two pins fixed disposed at two angularly spaced apart positions on an outer surface facing the second crank member, such that when a pin reaches an L-shaped end portion on rotation of the second disc, it engages into the L-shaped end portion and forces the second crank member to rotate along with the second disc towards corresponding initial/final angular position.