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
Control mechanism for 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, 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 a control mechanism for a Gas insulated Switchgear. More specifically, the present invention relates to a control mechanism for actuating movable contacts of a pair of interrupters disposed in the GIS.
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 control mechanisms exist which comprises a common actuating means for operating the disconnector and earthing switches. However, existing control 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 control mechanism occupies a significant space in the housing of the GIS.

Hence, there is a need for a control 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 a control mechanism for a Gas Insulated Switchgear (GIS), the GIS comprising a pair of interrupters orthogonally disposed with respect to each other in a housing, each of the interrupters comprising a fixed contact and a movable contact linearly movable relative to the fixed contact, the control mechanism disposed in the housing for actuating linear motion of the movable contacts and comprising a rotary shaft disposed substantially perpendicular to the axes of motion of the movable contacts and intermittently rotatable by an intermittent drive mechanism disposed outside the housing; a pair of levers fixedly positioned on the rotary shaft in a spaced apart relationship and rotatable with the rotary shaft, each of the levers having a first arm portion and a second arm portion disposed substantially perpendicular to each other, the first arm portions being disposed in proximity to a first movable contact of the movable contacts and the second arm portions being disposed in proximity to a second movable contact of the movable contacts; and a first pair of links connecting the first movable contact to the second arm portions and a second pair of links connecting the second movable contact to the first arm portions, the first and second pair of links being movable on rotation of the levers for pushing first movable contact towards respective

fixed contact and pulling second movable contact away from respective fixed contact, and vice versa.
Preferably, the rotary shaft is disposed at intersection of respective axes of linear motion of the movable contacts.
Preferably, the control mechanism comprises a pair of stoppers fixedly disposed around the rotary shaft at two angularly spaced apart end positions for preventing rotation of the pair of levers beyond said end positions.
Preferably, when either of the first and second arm portions of the levers reach at an end position, one interrupter is closed and another interrupter is opened.
Preferably, the intermittent drive mechanism enables the rotary shaft to start and stop at the two angularly spaced apart end positions and an intermediate position therebetween.
Preferably, the intermittent drive mechanism comprises a Geneva drive mechanism.

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.l is a perspective view of a portion of a Gas insulated Switchgear (GIS) containing a control mechanism for actuating movable contacts of a pair of interrupters disposed therein in accordance with various embodiments of the present invention;
Fig.2 is an exploded view of the control mechanism in accordance with an embodiment of the present invention;
Fig. 3 is a back side view of the GIS illustrating an intermittent drive mechanism for rotating a rotary shaft of the control mechanism in accordance with an embodiment of the present invention;
Fig.4 is front cross-sectional view of the GIS illustrating the control mechanism disposed in a first position for enabling one interrupter to be opened and another interrupter to be closed in accordance with an embodiment of the present invention;
Fig.5 is front cross-sectional view of the GIS illustrating the control mechanism disposed in an intermediate position for enabling both the interrupters to be opened in accordance with an embodiment of the present invention; and
Fig.6 is front cross-sectional view of the GIS illustrating the control mechanism disposed in a second position for enabling the one interrupter to be closed and the another interrupter to be opened in accordance with an embodiment of the present invention.

Fig.l is a perspective view of a portion of a Gas insulated Switchgear (GIS) 100 illustrating a housing 1 which encloses a pair of interrupters 2 and 3 and a control mechanism 4 for operating the same. Preferably, the interrupters 2 and 3 are disposed orthogonally with respect to each other.
The pair of interrupters comprises a first interrupter 2 and a second interrupter 3. The first interrupter 2 comprises a first fixed contact 5 and a first movable contact 6 linearly movable relative to the fixed contact 5. The second interrupter 3 comprises a second fixed contact 7 and a second movable contact 8 linearly movable relative to the fixed contact 7. The fixed contacts 5 and 7 are fixedly disposed in the housing 1, whereas the movable contacts 6 and 8 are coupled to the control mechanism 4. Preferably, the first and second interrupters 2 and 3 are identical in shape, size and construction.
The movable contacts 6 and 8 linearly move either towards or away from respective fixed contacts 5 and 7 for enabling opening and closing of respective interrupters. The respective axes of linear motion of the movable contacts 6 and 8 are perpendicular to each other. The control mechanism 4 actuates the movable contacts 6 and 8 to move together along perpendicular axes.
Preferably, the first interrupter 2 is an earthing switch coupled to the ground and the second interrupter 3 is a disconnector switch coupled to the power supply. An electric component (not shown) may be disposed in the housing, and may be connected to the power supply via the second interrupter 3 and to the ground via the first interrupter 2. Thus, at any time, one interrupter has to be closed and other to be opened for turning on/off the electric component. The interrupters 2 and 3 may be operated manually or

automatically together for connecting/disconnecting an electric component to ground/power supply.
Referring to Fig.2, the control mechanism 4 comprises a rotary shaft 20, a pair of levers 21 and 22, a first pair of links 23 and 24, a second pair of links 25 and 26, and a pair of stoppers 27 and 28.
The rotary shaft 20 is disposed substantially perpendicular to the axes of motion of the movable contacts 6 and 8. Preferably, the rotary shaft 20 is disposed at intersection of respective axes of linear motion of the movable contacts 6 and 8. The rotary shaft 20 is intermittently rotatable in both clockwise and anticlockwise directions by an intermittent drive mechanism disposed outside the housing 1.
The levers 21 and 22 are fixedly positioned on the rotary shaft 20 in a spaced apart relationship with each other and rotatable with the rotary shaft 20. The levers 21 and 22 may be fixedly or integrally attached to the rotatable shaft 20. Preferably, the levers 21 and 22 are identical. The lever 21 has a first arm portion 29 and a second arm portion 30 disposed substantially perpendicular to each other. The lever 22 has a first arm portion 31 and a second arm portion 32 disposed substantially perpendicular to each other. It may be noted that the first arm portions 29 and 31 are disposed in proximity to the first movable contact 6 and the second arm portions 30 and 32 are disposed in proximity to the second movable contact 8.
The first pair of links 23 and 24 connect the first movable contact 6 to the second arm portions 30 and 32, whereas, the second pair of links 25 and 26 connect the second movable contact 8 to the first arm portions 29 and 31. Examples of a link, include, but are not limited to, coupling rods, cranks, etc.

Preferably, the links 23 and 24 are disposed parallel to each other. Each of the links 23 and 24 extend between two ends, where, one end of each of the links 23 and 24 is attached to an outer surface of a second arm portion (30, 32) through an attaching means such as a pin, bolt, nut etc. For example, one end of the link 23 is pivotally attached to an outer surface of the second arm portion 30 and one end of the link 24 is pivotally attached to an outer surface of the second arm portion 32. The other ends of the links 23 and 24 are fixedly attached to two diametrically opposite ends of the movable contact 6.
Similarly, the links 25 and 26 are disposed parallel to each other. Each of the links 25 and 26 extend between two ends, where, one end of each of the links 25 and 26 is pivotally attached to an inner surface of a first arm portion (29, 31) through an attaching means. For example, one end of the link 25 is pivotally attached to an inner surface of the first arm portion 29 and one end of the link 26 is pivotally attached to an inner surface of the first arm portion 31. The other ends of the links 25 and 26 are fixedly attached to two diametrically opposite ends of the movable contact 8.
The links 23 and 24 are attached to outer surfaces of the second arm portions, whereas the links 25 and 26 are attached to inner surfaces of the first arm portions. Such an arrangement facilitates better balance and stability in the system and prevents clashing of links with each other.
Operationally, the links 23, 24, 25 and 26 are movable on rotation of the rotary shaft 20 for pushing one movable contact towards respective fixed contact and pulling other movable contact away from respective fixed contact. For example, when the rotary shaft 20 and the levers 21 and 22 rotate anticlockwise, the links 23 and 24 push the

movable contact 6 towards the fixed contact 5 and links 25 and 26 pulls the movable contact 8 away from the fixed contact 7. Similarly, when the rotary shaft 20 and the levers 21 and 22 rotate clockwise, the links 23 and 24 pull the movable contact 6 away from the fixed contact 5 and links 25 and 26 push the movable contact 8 toward the fixed contact 7. Thus, on rotation of the single rotary shaft 20, both the movable contacts 6 and 8 are linearly movable relative to their respective fixed contacts.
The stoppers 27 and 28 are fixedly disposed around the rotary shaft 20 at two angularly spaced apart end positions for preventing rotation of the levers 21 and 22 beyond said end positions. Preferably, the stoppers 27 and 28 are angularly spaced apart by an angle of .130 (approx). When the arm portions of the levers 21 and 22 are adjacent to an end position, then, one of the interrupter is closed, and another interrupter is opened. For example, when the second arm portions 30 and 32 reach a first end position at the stopper 28, the interrupter 2 is opened and the interrupter 3 is closed. Similarly, when the first arm portions 29 and 31 reach a second end position at the stopper 27, the interrupter 2 is closed and the interrupter 3 is opened. The rotary shaft 20 intermittently rotates between the first and second end positions for facilitating opening and closing of the interrupters 2 and 3.
Fig. 3 illustrates an intermittent drive mechanism fixedly disposed outside the housing 1 for intermittently rotating the rotary shaft 20. The intermittent drive mechanism comprises an actuating wheel 31 and a Geneva drive mechanism 32. The Geneva drive mechanism 32 is a well-known mechanism in the art primarily used for providing indexed motion to rotary devices. The Geneva drive mechanism 32 is connected to the rotary shaft 20 and provides intermittent motion thereto. The Geneva drive mechanism 32

facilitates the rotary shaft 20 to start and stop after rotating for a pre-defined angle, also referred to as indexing angle.
Referring to Figs.2 and 3, the levers 21 and 22 can only rotate to and fro between the stoppers 27 and 28, i.e. first and second end positions, therefore, the rotary shaft 20 can also rotate only between said end positions. When the first and second end positions are spaced apart by 130 (approx) and angle of indexing is 65°, then the rotary shaft 20 may start at the first end position, rotate for 65° to attain an intermediate position, then again rotate for 65 and stop at second end position, and vice versa. The number of intermediate positions may vary depending on the angle of indexing of the rotary shaft 20. It will also be appreciated by a person skilled in the art that several other intermittent drive mechanism may be used in the various embodiments of the present invention and be considered within the scope of the present invention.
Referring to Fig.4, the second arm portions 30 and 32 of the levers 21, 22 are disposed adjacent to the stopper 28, i.e. at first end position, and the interrupter 3 is closed and the interrupter 2 is opened. When the interrupters 2 and 3 are earthing and disconnector switches of an electric component, then in such position, the electric component may be connected to a power supply. When the electric component needs to be disconnected from the power supply due to fault or testing purposes, then the rotary shaft 20 is required to be rotated anticlockwise by an intermittent mechanism disposed outside the housing 1.
The rotary shaft 20 is rotated anticlockwise by a quarter of revolution and is disposed in an intermediate/neutral position (as shown in Fig.5), where both the first arm portions 29, 31 and the second arm portions 30, 32 are disposed slightly far away from

the stoppers 27 and 28. During rotation of the rotary shaft 20 in anticlockwise direction, the movable contact 8 is moved away from the fixed contact 7 and the movable contact 6 is moved towards the fixed contact 5. It may be noted that the length of the links 23-26, speed of rotation of the rotary shaft 20, angle of indexing of the rotary shaft 20 is determined based on the required stroke of the interrupters 2 and 3.
The rotary shaft 20 is rotated further by a quarter of revolution and is disposed in a position (as shown in Fig.6), where the first arm portions 29 and 31 are disposed adjacent to the stopper 27, i.e. at second end position, and the interrupter 2 is closed and the interrupter 3 is opened. During rotation of the rotary shaft 20 in anticlockwise direction, the movable contact 8 is moved further away from the fixed contact 7 and the movable contact 6 is moved towards the fixed contact 5 to establish an electric connection therein. In such position, the electric component is completely disconnected from the power supply and connected to the ground.
When the electric component is required to be connected to the power supply and disconnected from the ground, the rotary shaft 20 may be rotated in clockwise direction from the second end position to the first end position for achieving the desired objective. Thus, by intermittently rotating the shaft 20 twice, the state of an electric component can be changed.
Various embodiments of the present invention provide a control mechanism for operating a pair of interrupters which may be disposed in a high voltage switching device such as a Gas Insulated Switchgear (GIS). The proposed control mechanism is very simple, includes significantly less number of components, and reduces the time required for operating the pair of interrupters. The feature of intermittent rotation of the rotary

shaft provides to a user, a good control over the rotation of the shaft, thus enabling precise control over the opening and closing of the interrupters.
It will be appreciated by a person skilled in the art that the control mechanism 4 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. A control mechanism for a Gas Insulated Switchgear (GIS), the GIS comprising a pair of interrupters orthogonally disposed with respect to each other in a housing, each of the interrupters comprising a fixed contact and a movable contact linearly movable relative to the fixed contact, the control mechanism disposed in the housing for actuating linear motion of the movable contacts and comprising:
a rotary shaft disposed substantially perpendicular to the axes of motion of the movable contacts and intermittently rotatable by an intermittent drive mechanism disposed outside the housing;
a pair of levers fixedly positioned on the rotary shaft in a spaced apart relationship and rotatable with the rotary shaft, each of the levers having a first arm portion and a second arm portion disposed substantially perpendicular to each other, the first arm portions being disposed in proximity to a first movable contact of the movable contacts and the second arm portions being disposed in proximity to a second movable contact of the movable contacts; and
a first pair of links connecting the first movable contact to the second arm
portions and a second pair of links connecting the second movable contact to the first
arm portions, the first and second pair of links being movable on rotation of the
levers for pushing first movable contact towards respective fixed contact and pulling
second movable contact away from respective fixed contact, and vice versa.
2. The control mechanism as claimed in claim 1, wherein the rotary shaft is disposed
at intersection of respective axes of linear motion of the movable contacts.

3. The control mechanism as claimed in claim 1, which comprises a pair of stoppers
fixedly disposed around the rotary shaft at two angularly spaced apart end positions for
preventing rotation of the pair of levers beyond said end positions.
4. The control mechanism as claimed in claim 3, wherein when either of the first and
second arm portions of the levers reach at an end position, one interrupter is closed and
another interrupter is opened.
5. The control mechanism as claimed in claim 3, wherein the intermittent drive mechanism enables the rotary shaft to start and stop at the two angularly spaced apart end positions and an intermediate position therebetween,
6. The control mechanism as claimed in claim 5, wherein the intermittent drive mechanism comprises a Geneva drive mechanism.
7. A Gas Insulated Switchgear (GIS) comprising:
a pair of interrupters orthogonally disposed with respect to each other in a housing, each of the interrupters comprising a fixed contact and a movable contact linearly movable relative to the fixed contact; and
a control mechanism disposed in the housing for actuating linear motion of the movable contacts, the control mechanism comprising:
a rotary shaft disposed substantially perpendicular to the axes of motion of the movable contacts and intermittently rotatable by an intermittent drive mechanism disposed outside the housing;
a pair of levers fixedly positioned on the rotary shaft in a spaced apart relationship and rotatable with the rotary shaft, each of the levers having a first arm portion and a second arm portion disposed substantially perpendicular to each other,

the first arm portions being disposed in proximity to a first movable contact of the movable contacts and the second arm portions being disposed in proximity to a second movable contact of the movable contacts; and
a first pair of links connecting the first movable contact to the second arm portions and a second pair of links connecting the second movable contact to the first arm portions, the first and second pair of links being movable on rotation of the levers for pushing first movable contact towards respective fixed contact and pulling second movable contact away from respective fixed contact, and vice versa.