WO2013030846A2

WO2013030846A2 - A control mechanism for a switchgear equipment

Info

Publication number: WO2013030846A2
Application number: PCT/IN2011/000855
Authority: WO
Inventors: Mitrik ZSOLT; Arun Tom MATHEW
Original assignee: Crompton Greaves Limited,
Priority date: 2011-09-02
Filing date: 2011-12-14
Publication date: 2013-03-07
Also published as: WO2013030846A3

Abstract

A control mechanism for a switchgear equipment, said equipment including at least a conductor located in a downward facing cantilever manner to form a stationary contact of a disconnector switch or a disconnector mechanism and at least a conductor in an upward facing manner to form a stationary contact of an earthing switch or an earthing mechanism, for obtaining the states of disconnection, neutral, and earthing in said switchgear equipment, said mechanism comprises: cylindrical moving contact with an angularly displaceable shaft at its operative distal end with angular displacement of said shaft being about its operative proximal pivot point, said shaft adapted to be engaged with a slot of a slotted disc such that linear displacement of said cylindrical moving contact causes corresponding angular displacement of said shaft to achieve said disconnection state and further angular displacement of said engaged disc to achieve said neutral state; and blade-type moving contact adapted to be angularly displaced about its operative proximal pivot point on said disc such that angular displacement of said disc causes corresponding angular displacement of said blade-type moving contact to achieve said earthing state.

Description

TITLE OF THE INVENTION

A control mechanism for a switchgear equipment

This application claims priority from Indian Patent Application No. 2441/MUM/2011 filed on 2^nd September 2011.

FIELD OF THE INVENTION:

This invention relates to the field of mechanical assemblies and mechanical engineering. Particularly, this invention relates to switchgear equipment.

More particularly, this invention relates to a control mechanism for obtaining the states of disconnection, neutral, and earthing in a switchgear equipment.

BACKGROUND OF THE INVENTION:

The term 'switchgear', used in association with the electric power system, or grid, refers to the combination of electrical disconnects, fuses and/or circuit breakers used to isolate electrical equipment. Switchgear is used both to de-energize equipment to allow work to be done and to clear faults.

An effective form of switchgear is gas insulated switchgear (GIS). In a GIS, there is a plurality of electrical components where the conductors and contacts are insulated by pressurized sulfur hexafluoride gas (SF6). overload or short circuit. Its basic function is to interrupt continuity upon detection of a fault condition to immediately discontinue electrical flow. The circuit breaker must react to fault condition; in low-voltage circuit breakers this is usually done within the breaker enclosure. Circuit breakers for large currents or high voltages are usually arranged with pilot devices to sense a fault current and to operate the trip opening mechanism. The trip coil that releases the latch is usually energized by a separate battery, although some high-voltage circuit breakers are self-contained with current transformers, protection relays, and an internal control power source.

Once a fault is detected, contacts within the circuit breaker must open to interrupt the circuit; some mechanically-stored energy (using something such as springs or compressed air) contained within the breaker is used to separate the contacts. Small circuit breakers may be manually operated; larger units have coils to trip the mechanism, and electric motors to restore energy to the springs.

A trip coil is a type of solenoid in which the moving armature opens a circuit breaker or other protective device when the coil current exceeds a predetermined value. A closing coil is adapted to shut the circuit breaker completely.

In its working mode, if a power surge occurs in the electrical system, the breaker will trip. This means that a breaker that was in the "on" position will flip to the "off position and shut down the electrical power leading from that breaker. Essentially, a circuit breaker is a safety device. When a circuit breaker is tripped, it may prevent a fire from starting on an overloaded circuit; it can also prevent the destruction of the device that is drawing the electricity.

In switchgear components and equipment, a disconnector or isolator switch is used to make sure that an electrical circuit can be completely de-energised for service or maintenance. 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.

Prior art mechanisms include an arrangement wherein there is provided a first position of contacts such that disconnecting can be achieved, a second position of contacts such that earthing can be achieved, and a third position of contacts, intermittently positioned between the first position and the second position, in order to achieve a neutral condition.

This arrangement, operation, and actuation of contacts form a control mechanism.

There is a need for a system which exercises precise control to obtain fast and distinct switching between the states of 1 ) disconnecting; 2) earthing; and 3) neutral.

OBJECTS OF THE INVENTION:

An object of the invention is to provide a mechanism which provides precise actuation of contacts to achieve the states of 1 ) disconnecting; 2) earthing; and 3) neutral.

Another object of the invention is to provide a mechanism which provides distinct actuation of contacts to achieve the states of 1 ) disconnecting; 2) earthing; and 3) neutral.

Yet another object of the invention is to provide a mechanism which provides relatively faster actuation of contacts to achieve the states of 1 ) disconnecting; 2) earthing; and 3) neutral. SUMMARY OF THE INVENTION:

According to this invention, there is provided a control mechanism for a switchgear equipment, said equipment including at least a conductor located in a downward facing cantilever manner to form a stationary contact of a disconnector switch or a disconnector mechanism and at least a conductor in an upward facing manner to form a stationary contact of an earthing switch or an earthing mechanism, for obtaining the states of disconnection, neutral, and earthing in said switchgear equipment, said mechanism comprises:

a. cylindrical moving contact with an angularly displaceable shaft at its operative distal end with angular displacement of said shaft being about its operative proximal pivot point, said shaft adapted to be engaged with a slot of a slotted disc such that linear displacement of said cylindrical moving contact causes corresponding angular displacement of said shaft to achieve said disconnection state and further angular displacement of said engaged disc to achieve said neutral state; and

b. blade-type moving contact adapted to be angularly displaced about its operative proximal pivot point on said disc such that angular displacement of said disc causes corresponding angular displacement of said blade-type moving contact to achieve said earthing state.

Typically, said cylindrical moving contact is a cylindrical moving disconnecting contact with a first conducting end at its operative proximal end adapted to mate with a conductor located in a downward facing cantilever manner and a shaft at a second end from an operative distal end extending therethrough, said cylindrical disconnecting moving contact adapted to move linearly along its axis and said shaft adapted to be angularly displaced about its pivoting point with respect to the cylindrical disconnecting moving contact in a single pre-defined plane and further adapted to provide forward thrusting action in synchronism with said linear movement of said cylindrical contact. Typically, said slotted disc includes a first planar side and a second planar side adapted to receive said shaft along said first planar side of said disc and an orthogonal stub at the end of said shaft adapted to move in said slot of said disc, and further adapted to rotate said disc.

Typically, said slotted disc includes a first planar side and a second planar side and said blade- type moving contact is a blade-type moving earthing contact placed at a second planar side of said disc, with the movement of said blade being an angularly displaced movement about its first pivoting proximal end, said blade including a slot of pre-defined curvature and shape such that as said disc rotates, a stub extending from said disc moves within said slot of the blade-type moving contact and further rotation of said disc results in a thrusting force of said disc stub on said slot end in said blade-type moving contact for moving said blade-type contact towards said conductor in said upward manner which receives the faces of the blade-type moving contact.

Typically, the first end of the elongate cylinder is a conductor face which mates with a conductor stationary face of the disconnector switch to actuate a disconnector mode.

Typically, said second end of the elongate cylinder is a split end with a pinned shaft extending there-between such that there is an angular uni-planar play and provides a forward thrusting action, simultaneously.

Typically, said elongate cylinder is a linearly moving contact adapted to move linearly in an operative upward and an operative downward manner along the axis of the cylinder.

Typically, said shaft is a bent shaft.

Typically, said slot in the disc is a semicircular slot.

Typically, said mechanism includes a contoured housing which permits the entire play from disconnecting to earthing with the intermittent neutral position, and back of said mechanism. According to this invention, there is also provided a method of achieving the states of disconnection, neutral, and earthing in said switchgear equipment, using a control mechanism for a switchgear equipment, said equipment including at least a conductor located in a downward facing cantilever manner to form a stationary contact of a disconnector switch or a disconnector mechanism and at least a conductor in an upward facing manner to form a stationary contact of an earthing switch or an earthing mechanism, said method comprises the steps of:

i. linearly displacing a cylindrical moving contact in an operative upward direction in order to make contact with said conductor located in a downward facing manner in order to obtain said disconnection state and further linearly displacing a cylindrical moving contact in an operative downward direction in order to break contact with said conductor located in a downward facing manner;

ii. angularly displacing an extendable shaft, in correspondence with said linear displacement of said cylindrical moving contact, from an operative distal end of said cylindrical moving contact with the operative distal end of said shaft moving in a guided manner in a slot of a disc in order to achieve said neutral state and further extending a forward thrust to angularly displace said disc; and

iii. angularly displacing a blade-type moving contact about its operative proximal pivot point on said disc such that angular displacement of said disc causes corresponding angular displacement of said blade-type moving contact to achieve said earthing state.

Typically, said step of linear displacement of said cylindrical moving contact and subsequent angular displacement of said extended shaft in said slot of said slotted disc results in moving of the mechanism from the disconnecting mode to the neutral mode.

Typically, said step of angular displacement of said disc and said blade-type moving contact results in moving of the mechanism from the disconnecting mode to the neutral mode. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:

The invention will now be described in relation to the accompanying drawings, in which:

Figure 1 illustrates a schematic view of a switchgear equipment with the control mechanism for obtaining the states of disconnection, neutral, and earthing in the switchgear equipment;

Figure 2 illustrates a front view of the control mechanism; and

Figures 3 and 4 illustrate a back view of the control mechanism.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:

According to this invention, there is provided a control mechanism for a switchgear equipment.

Figure 1 illustrates a schematic view of a switchgear equipment with the control mechanism for obtaining the states of disconnection, neutral, and earthing in the switchgear equipment.

Figure 2 illustrates a front view of the control mechanism

Figures 3 and 4 illustrate a back view of the control mechanism.

There are a plurality of conductors (3 conductors for a 3 -phase supply) ( 10) located in a downward facing cantilever manner to form a stationary contact of a disconnector switch or a disconnector mechanism. There are also a plurality of conductors (3 conductors for a 3-phase supply) (20) in an upward facing manner to form a stationary contact of an earthing switch or an earthing mechanism. In accordance with an embodiment of this invention, there is provided an elongate cylinder (12) which forms the moving contact of the disconnector switch or disconnector mechanism. A first end (12a) of the elongate cylinder is the conductor face which mates with the conductor face (10) of the disconnector switch to actuate a disconnector mode. A second end (12b) of the elongate cylinder is a split end with a pinned shaft (14) extending there-between such that there is an angular uni-planar play and provides a forward thrusting action, simultaneously. This elongate cylinder (12) is a linearly moving contact adapted to move linearly in an operative upward and an operative downward manner along the axis of the cylinder. While this moving contact travels operative upwards, it makes contact with a conducting face (10) of the stationary contact where its operative upward travel is halted and the disconnector mode is actuated. This moving contact (12) travels operative downwards in two phases; in its first phase of movement it achieves a 'neutral mode and in its second phase of movement, it enables further components of the control mechanism and helps to actuate an earthing mode. The shaft (14) is preferably a bent shaft.

In accordance with another embodiment of this invention, there is provided a slotted disc (16). The slot (18) in the disc (16) is a semicircular slot. The shaft (14) is placed along a first planar side of the disc (16). It includes an orthogonal stub (19) which moves in the slot (18) of the disc (16). While the moving contact (12) and the extended shaft (14) move about the slot (18) from its first end to the second end, it results in moving from the disconnecting mode to the neutral mode.

Further thrust of the extended shaft results (14) in rotation of the disc (16) about its axis.

In accordance with yet another embodiment of this invention, there is provided a blade-type moving contact (22). This is the earthing moving contact. The blade is placed at a second planar side of the disc (opposite of the first planar side) (16). The movement of the blade (22) is about its first pivoting end. The blade (22) includes a slot (24) of pre-defined curvature and shape such that as the disc (16) rotates, a stub (25) extending from the disc (16) moves within the slot (24) of the blade-type moving contact (22). Further rotation of the disc (16) results in thrusting force of the disc stub (25) on the slot (24) end in the blade-type moving contact (22) and for moving the blade-type contact (22) towards a conductor face (20) for earthing switch which receives the faces of the blade-type moving contact (22).

In accordance with still another embodiment of this invention, the mechanism of the cylinder - shaft - disc - (earthing moving) contact is located in a contoured housing which permits the entire play from disconnecting to earthing with the intermittent neutral position, and back.

For each phase of the power supply, a mechanism of cylinder - shaft - disc - (earthing moving) contact is provided. Thus, in its totality, a combination of three such mechanism form the entire system, each mechanism co-operating with an individual conductor face (per phase) for disconnecting and another individual earthing face (per phase) for earthing.

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.

Claims

We claim,

1. A control mechanism for a switchgear equipment, said equipment including at least a conductor located in a downward facing cantilever manner to form a stationary contact of a disconnector switch or a disconnector mechanism and at least a conductor in an upward facing manner to form a stationary contact of an earthing switch or an earthing mechanism, for obtaining the states of disconnection, neutral, and earthing in said switchgear equipment, said mechanism comprising:

2. A mechanism as claimed in claim 1 wherein, said cylindrical moving contact is a cylindrical moving disconnecting contact with a first conducting end at its operative proximal end adapted to mate with a conductor located in a downward facing cantilever manner and a shaft at a second end from an operative distal end extending therethrough, said cylindrical disconnecting moving contact adapted to move linearly along its axis and said shaft adapted to be angularly displaced about its pivoting point with respect to the cylindrical disconnecting moving contact in a single pre-defined plane and further adapted to provide forward thrusting action in synchronism with said linear movement of said cylindrical contact.

3. A mechanism as claimed in claim 1 wherein, said slotted disc includes a first planar side and a second planar side adapted to receive said shaft along said first planar side of said disc and an orthogonal stub at the end of said shaft adapted to move in said slot of said disc, and further adapted to rotate said disc.

4. A mechanism as claimed in claim 1 wherein, said slotted disc includes a first planar side and a second planar side and said blade-type moving contact is a blade-type moving earthing contact placed at a second planar side of said disc, with the movement of said blade being an angularly displaced movement about its first pivoting proximal end, said blade including a slot of pre-defined curvature and shape such that as said disc rotates, a stub extending from said disc moves within said slot of the blade-type moving contact and further rotation of said disc results in a thrusting force of said disc stub on said slot end in said blade-type moving contact for moving said blade-type contact towards said conductor in said upward manner which receives the faces of the blade-type moving contact.

5. A mechanism as claimed in claim 1 wherein, the first end of the elongate cylinder is a conductor face which mates with a conductor stationary face of the disconnector switch to actuate a disconnector mode.

6. A mechanism as claimed in claim 1 wherein, said second end of the elongate cylinder is a split end with a pinned shaft extending there-between such that there is an angular uni- planar play and provides a forward thrusting action, simultaneously.

7. A mechanism as claimed in claim 1 wherein, said elongate cylinder is a linearly moving contact adapted to move linearly in an operative upward and an operative downward manner along the axis of the cylinder.

8. A mechanism as claimed in claim 1 wherein, said shaft is a bent shaft.

9. A mechanism as claimed in claim 1 wherein, said slot in the disc is a semicircular slot.

10. A mechanism as claimed in claim 1 wherein, said mechanism includes a contoured housing which permits the entire play from disconnecting to earthing with the intermittent neutral position, and back of said mechanism.

1 1 . A method of achieving the states of disconnection, neutral, and earthing in said switchgear equipment, using a control mechanism for a switchgear equipment, said equipment including at least a conductor located in a downward facing cantilever manner to form a stationary contact of a disconnector switch or a disconnector mechanism and at least a conductor in an upward facing manner to form a stationary contact of an earthing switch or an earthing mechanism, said method comprising the steps of:

ii. angularly displacing an extendable shaft, in correspondence with said linear displacement of said cylindrical moving contact, from an operative distal end of said cylindrical moving contact with the operative distal end of said shaft moving in a guided manner in a slot of a disc in order to achieve said neutral state and further

. extending a forward thrust to angularly displace said disc; and

12. A method as claimed in claim 1 1 wherein, said step of linear displacement of said cylindrical moving contact and subsequent angular displacement of said extended shaft in said slot of said slotted disc results in moving of the mechanism from the disconnecting mode to the neutral mode.

13. A method as claimed in claim 1 1 wherein, said step of angular displacement of said disc and said blade-type moving contact results in moving of the mechanism from the disconnecting mode to the neutral mode.