EP2879146A1

EP2879146A1 - A linkage for actuating a disconnector switch blade for synchronising a sbs with disconnector switch of rmu

Info

Publication number: EP2879146A1
Application number: EP14306844.3A
Authority: EP
Inventors: Sanjay D. Gogawale
Original assignee: Schneider Electric Industries SAS
Current assignee: Schneider Electric Industries SAS
Priority date: 2013-11-29
Filing date: 2014-11-20
Publication date: 2015-06-03
Also published as: CN104681346A; CN104681346B; IN2013KO01351A

Abstract

The present invention discloses a linkage for actuating a disconnector switch blade in order to integrate a Shunt Breaking System (SBS) in existing disconnector switch of Ring Main Unit (RMU) which fulfills synchronization requirement of the SBS with the disconnector switch. The linkage includes a plurality of follower links connected to an offset link disposed over a drive shaft, a drive link for transferring mechanism energy to the plurality of follower links through a sliding pin joint which is directly pivoted to the offset link for ensuring the synchronization within the disconnector switch and the SBS, wherein the linkage enlarges the stroke of the disconnector switch blade during switch open and switch closed operations and maintains the stroke same as the disconnector switch mechanism during switch earth operation. The offset link is fixed over the drive shaft at offset distance from centre of the drive shaft to provide enlarged stroke of the disconnector switch blade in switch closed and switch open operations.

Description

FIELD OF THE INVENTION

The present invention generally relates to linkage design (transmission mechanism) which serves as an actuating device for disconnector switch blade. In particular, the present invention relates to linkage design in order to integrate a SBS (Shunt Breaking System) in existing disconnector switch of Ring Main Unit (RMU), which fulfills synchronization requirement of the SBS-Shunt Breaking System that is incorporated in designated disconnector switch.

BACKGROUND OF THE INVENTION

A power supply line of an electric load, to be controlled, is conventionally provided with at least one switchgear device. Typically, a switchgear device comprises pairs of contacts for each phase movable with respect to one another to switch the load. Actuation of the contacts can be performed in different manners. In particular, for certain high-power switchgear devices (generally for more than 600 A) that are used for example for safety purposes as line incomer, a high electrodynamic strength is required and the contacts are driven by a lever system coupled to a rotary spindle. Further, the rotary spindle is itself actuated by a tumbler mechanism.
Normally during switching operation small arcing takes place till blades rotates to a Transient Recovery Voltage (TRV) distance. Insulating media such as SF6 are widely used in switchgear to extinguish this arcing. As a green initiative the breaking of the current is achieved inside the vacuum interrupter instead of in the insulating media. To adopt this changes existing disconnector switch presently used in RMU is required to be integrated with the Shunt Breaking System. The base design of the SBS is covered under the patent EP2182536 and EP2479769 .
The moving contact of disconnector switch gets required energy from mechanism through intermediate linkages comprising rotary drive shaft and coupler. The existing four bar linkage design transfers the energy and stroke to moving blades offered by tumbler mechanism. The fixed stroke of the mechanism presently used in RMU is having stroke of 40 deg whereas SBS is designed for 50 deg stroke requirement.
Integration of SBS into existing disconnector switch requires design change of existing four bar linkage. This leads to major change in fix position and increase in dimensions of coupler links. This in-turn changes the linkage angles and results in considerable rise in energy requirement of the drive mechanism.
In view of the above discussion, it may be realized that there exists a need to provide kinematic adaptations in order to drive the new SBS with the existing disconnector switch mechanism and mechanical chains of RMU.

SUMMARY OF THE INVENTION

The main object of the present invention is to provide linkage design in order to integrate SBS in existing disconnector switch of RMU, which may fulfill synchronization requirement of the SBS-Shunt Breaking System which is incorporated in designated disconnector switch.
Another object of the present invention is to provide linkage design in order to integrate SBS in existing disconnector switch of RMU, which provides solution to reuse existing mechanism by delivering enlarged output stroke which is suitable to operate SBS.
Another object of the present invention is to provide linkage design in order to integrate SBS in existing disconnector switch of RMU, which may fulfill Critical to Quality (CTQ) requirement of SBS such as TRV position, minimum speed and Vacuum Interrupter (VI) opening.
Another object of the present invention is to provide linkage design in order to integrate SBS in existing disconnector switch of RMU, which guaranties the instantaneous position achieved by moving blade of disconnector switch with desired speed requirement.
Another object of the present invention is to provide linkage design in order to integrate SBS in existing disconnector switch of RMU, which is simple in construction and assures accurate functioning.
In order to achieve the above mentioned objects, the present invention discloses a linkage for actuating a disconnector switch blade in order to integrate a Shunt Breaking System (SBS) in existing disconnector switch of Ring Main Unit (RMU) which fulfill synchronization requirement of the SBS that is incorporated in said disconnector switch. The linkage includes a plurality of follower links connected to an offset link disposed over a drive shaft, a drive link for transferring mechanism energy to the plurality of follower links through a sliding pin joint which is directly pivoted to the offset link for ensuring the synchronization within disconnector switch and SBS, wherein the linkage enlarges the stroke of the disconnector switch blade during switch open and switch closed operations and maintains the stroke same as disconnector switch mechanism during switch earth operation.
In one embodiment, the offset link is fixed over drive shaft at offset from centre of drive shaft to provide enlarged stroke of the disconnector switch blade in switch closed and switch open operations.
In one embodiment, the driving link includes slot and is used to drive the linkage formed by the off-set link along with the disconnector switch blade of the disconnector switch.
In one embodiment, the off-set link is configured to regulate the speed of the disconnector switch blade by guiding the pivot pin in the slot of the driver link.
In one embodiment, the linkage is configured to maximize speed of the disconnector switch blade during switch open and switch closed operations.
It is to be understood that both the foregoing general description and the following detailed description of the present embodiments of the invention are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention and together with the description serve to explain the principles and operation of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and other advantages of the invention will be better understood and will become more apparent by referring to the exemplary embodiments of the invention, as illustrated in the accompanying drawings, wherein

FIG. 1 schematically illustrates linkage design including an offset link fixed over drive shaft at offset distance from centre of drive shaft to provide enlarged stroke of blade in switch close and switch open operation in accordance with one embodiment of the present invention;
FIG. 2 illustrates a drive link connected to rotating drive shaft modified with slot feature in accordance with an embodiment of the present invention;
FIG. 3 illustrates the offset link formed by making slot with fixed radius which is placed at offset distance away from drive shaft centre and placed as stationary part over rotating drive shaft in accordance with one embodiment of the present invention;
FIG. 4 - 6 schematically illustrate the close, open and earth positions respectively in accordance with one embodiment of the present invention;
FIG. 7-9 illustrate the close, open and earth positions respectively in accordance with one embodiment of the present invention; and
FIG. 10-11 show the output recorded in travel and speed graphs for particular positions and dimensions of the linkages according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made to the exemplary embodiments of the invention, as illustrated in the accompanying drawings. Where ever possible same numerals will be used to refer to the same or like parts.
Disclosed herein is a linkage design in order to integrate SBS in existing disconnector switch of RMU which fulfill synchronization requirement of the SBS-Shunt Breaking System that is incorporated in the disconnector switch.
This is achieved by forming a 4 bars linkage with an additional offset link placed over drive shaft. A drive link transfers mechanism energy to 4 bars linkage through a sliding pin joint which is directly pivoted to the offset link. The offset link regulates the speed of moving blade by guiding the pivot pin in the slot of the drive link. The optimized linkage design ensures the desired synchronization between the disconnector switch and the SBS.
The drive mechanism operates the disconnector switch rotary shaft with fix stroke during switch open, switch close and switch earth operations. The present linkage design enlarges the stroke of the moving blade during switch opening and switch closing operations and it also keeps the maximum speed of moving contacts. However during the switch earth operation, it maintains the stroke same as the mechanism.
FIG. 1 schematically illustrates such a linkage design 100 including an offset links 104 fixed over drive shaft at offset distance from centre of drive shaft to provide enlarged stroke of blade in switch close and switch open operation in accordance with one embodiment of the present invention.
A driving link 102 is connected to rotating drive shaft 202 as shown in FIG.2. The driving link 102 includes slot and is used to drive four bar linkage formed by off-set link 104 along with moving contact of the disconnector switch.
The fifth additional link (the offset link) 104 is fixed at off-set distance from centre of the drive shaft 202 and it is pivoted at extreme end of slot away from centre of shaft while in closed position. The offset link 104 is formed by making slot with fixed radius as shown in FIG. 3 which is placed at offset distance away from drive shaft centre and placed as stationary part over rotating drive shaft.
Input for the drive link 102 is received from tumbler mechanism which is designed for 40 degree stroke. The linkage design rotates moving contacts of disconnector switch faster in initial stage in order to reach TRV position faster. Further, the linkage design ensures motion transfer to SBS fulfills the synchronization criteria of CTQ phase such as TRV distance, minimum Vacuum interrupter (VI) opening speed and total VI opening. The moving blade enters in CTQ phase after travelling around 30 - 35% of stroke and it lasts till 90% of stroke. The duration of moving contact in CTQ phase is about 35 - 40%. The mean velocity of moving blade in CTQ phase is at least thrice as high as in initial phase.
FIG. 4 - 6 and FIG. 7 - 9 illustrate the close, open and earth positions respectively in accordance with one embodiment of the present invention. When the drive shaft rotates through 40 degree, the pivoted pin of the offset link 404 slides in slot and converts the output stroke into 50 degree.
The drive mechanism energy transferred to moving contact through four bar linkage decides the resultant speed and position of the moving contacts. The off-set location and angles formed by linkages governs the speed of the moving contacts. This may be optimized with the help of theoretical simulation performed by pro-mechanism. The output of simulation recorded in travel and speed graphs are analyzed and accordingly position and dimensions of the linkages are finalized. FIG. 10-11 show the output recorded in travel and speed graphs for particular positions and dimensions of the linkages according to one embodiment of the present invention.
Further, the drive link (406, 708), off-set link (404, 706), coupler (402, 704), follower link/ moving contact (410, 702) are designed based on available space in the RMU.
The sliding pin joint reduces wear and friction losses which results in higher accuracy and reliability. The off-set link in form of off-centre radial slot around drive shaft is simple in construction and assures accurate functioning of the linkage design. Further, the offset link forms parallelogram in four bar linkage which helps in efficient torque/movement transmission to moving contacts.
Alternate option to achieve desired results is also possible by placing the offset link with follower link/moving contacts of disconnector switch. A slot can be made in follower link and pivoted with off-set link through sliding pin joint. As follower link/ moving contact is a current carrying element these parts need to be built in non-conductive resin parts. The off-set link build in resin parts may also give benefit of improved dielectric distances between phase to phase and phase to earth.
It is to be understood by a person of ordinary skill in the art that various modifications and variations may be made without departing from the scope and spirit of the present invention. Therefore, it is intended that the present invention covers such modifications and variations provided they come within the ambit of the appended claims and their equivalents.

Claims

A linkage for actuating a disconnector switch blade in order to integrate a Shunt Breaking System (SBS) in existing disconnector switch of Ring Main Unit (RMU) which fulfills synchronization requirement of the SBS that is incorporated in said disconnector switch, the linkage comprising:
a plurality of follower links connected to an offset link which is disposed over a drive shaft;

a drive link for transferring mechanism energy to the plurality of follower links through a sliding pin joint which is directly pivoted to the offset link for ensuring the synchronization within the disconnector switch and the SBS,

wherein the linkage enlarges the stroke of the disconnector switch blade during switch open and switch closed operations and maintains the stroke same as the disconnector switch mechanism during switch earth operation.
The linkage for actuating a disconnector switch blade as claimed in claim1, wherein the offset link is fixed over the drive shaft at offset distance from centre of the drive shaft to provide enlarged stroke of blade in the switch closed and the switch open operations.
The linkage for actuating a disconnector switch blade as claimed in claim1 or 2, wherein the driving link comprises slot and is used to drive the linkage formed by the off-set link along with the switch disconnector blade of the disconnector switch.
The linkage for actuating a disconnector switch blade as claimed in claim 3, wherein the off-set link is configured to regulate the speed of the disconnector switch blade by guiding the pivot pin in the slot of the driver link.
The linkage for actuating a disconnector switch blade as claimed in any of the preceding claims, configured to maximize speed of the disconnector switch blade during switch open and switch closed operations.