Center turn and twist mechanism of a switchgear

Abstract

A switchgear having a turn and twist mechanism. The switchgear has a contact system for electrical current conduction and bus transfer switching. The contact system has a fixed contact assembly and a movable contact assembly. The turn and twist mechanism drives the movable contact assembly for engagement/disengagement of the movable contacts with the fixed contacts. The turn and twist mechanism comprises a cylindrical pipe and a driving assembly. The driving assembly comprises a driving base, a floating carrier and a driving pin arrangement, for driving the cylindrical pipe for the engagement/disengagement. The driving base drives the floating carrier for turning the cylindrical pipe about a first axis, and drives the driving pin arrangement for twisting the cylindrical pipe about a second axis.

Claims

1. A switchgear having a turn and twist mechanism for electrical connection and disconnection, the switchgear comprising a contact system for electrical current conduction and bus transfer switching, the contact system comprising a fixed contact assembly and a movable contact assembly, wherein the turn and twist mechanism drives the movable contact assembly for one of engagement and disengagement of one or more movable contacts with one or more corresponding fixed contacts, the turn and twist mechanism comprising: a cylindrical pipe of the movable contact assembly, for turning about a first axis and twisting about a second axis, for one of engagement and disengagement of the one or more movable contacts with the one or more corresponding fixed contacts of the contact system; and a driving assembly comprising a driving base, a floating carrier, and a driving pin arrangement, wherein the driving assembly is mechanically coupled with the cylindrical pipe, wherein the driving base is mounted for rotating about the first axis, wherein during a first stage of rotation, the driving base drives the floating carrier for turning the cylindrical pipe about the first axis, and during a second stage of rotation, the driving base drives the driving pin arrangement for twisting the cylindrical pipe about the second axis, wherein the floating carrier is mounted on the driving base and mechanically coupled with the movement of the driving base such that during the first stage of rotation the floating carrier rotates about the first axis in response to the rotation of the driving base, and in turn rotates the cylindrical pipe about the first axis, wherein the floating carrier comprises two parallel plates having circular openings for supporting the cylindrical pipe such that centers of the circular openings are positioned on the second axis, wherein the driving pin arrangement comprising three pins, wherein two pins are two parallel pins mounted on the driving base, and a third pin is attached with the cylindrical pipe, such that the third pin is mechanically coupled to the movement of the two parallel pins mounted on the driving base, wherein during the second stage of rotation, the rotation of the driving base causes the two parallel pins to move the third pin for rotating the cylindrical pipe about the second axis, and wherein during engagement for electrical current conduction, the driving base drives the floating carrier to turn the cylindrical pipe about the first axis during the first stage of rotation to bring the movable contact assembly proximal to the fixed contact assembly, and the driving base drives the driving pin arrangement to twist the cylindrical pipe about the second axis during the second stage of rotation for engagement of the one or more movable contacts with the one or more corresponding fixed contacts.

2. The switchgear of claim 1, wherein the driving base comprises one or more slots for limiting the rotation of the driving base during the second stage of rotation.

3. The switchgear of claim 1, wherein the third pin of the driving pin arrangement is perpendicular to the two parallel pins mounted on the driving base.

4. The switchgear of claim 1, wherein the third pin is attached with the cylindrical pipe using a collar assembly, wherein the collar assembly comprises a circular opening for connection between the collar assembly and the cylindrical pipe, and wherein the collar assembly comprises an opening for mounting of the third pin parallel to the longitudinal axis of the cylindrical pipe.

5. The switchgear of claim 1, wherein the driving base and the floating carrier are connected with two springs, wherein one end of each spring is connected with the driving base and the other end is connected with the floating carrier.

6. The switchgear of claim 1, wherein the driving base is mounted on a driving mechanism and comprises two protrusions provided on edges.

7. The switchgear of claim 6, wherein each plate of the floating carrier comprises a protrusion about an edge of the plate, wherein two springs connect the driving base with the floating carrier, wherein one end of each spring is connected with a protrusion of the driving base and the other end is connected with a corresponding protrusion of the floating carrier.

8. The switchgear of claim 1, wherein the switchgear is a double side break disconnector.

9. The switchgear of claim 1, wherein during disengagement, the driving base drives the driving pin arrangement to twist the cylindrical pipe about the second axis, and thereafter drives the floating carrier to turn the cylindrical pipe about the first axis.

10. A method in a switchgear having a turn and twist mechanism for electrical connection and disconnection, the switchgear comprising a contact system for electrical current conduction and bus transfer switching, the contact system comprising a fixed contact assembly and a movable contact assembly, wherein the turn and twist mechanism drives the movable contact assembly for one of engagement and disengagement of one or more movable contacts with one or more corresponding fixed contacts, the method comprising: rotating a driving base of a driving assembly of the switchgear about a first axis in a first direction to engage the one or more movable contacts with the one or more corresponding fixed contacts, the driving assembly comprising the driving base, a floating carrier, and a driving pin arrangement, wherein the driving assembly is mechanically coupled with a cylindrical pipe of the movable contact assembly, the cylindrical pipe for turning about the first axis and twisting about a second axis, for one of engagement and disengagement of the one or more movable contacts with the one or more corresponding fixed contacts of the contact system, wherein during a first stage of rotation in the first direction, the driving base drives the floating carrier for turning the cylindrical pipe about the first axis, and during a second stage of rotation, the driving base drives the driving pin arrangement for twisting the cylindrical pipe about the second axis, wherein the floating carrier is mounted on the driving base and mechanically coupled with the rotation of the driving base such that during the first stage of rotation, the floating carrier rotates about the first axis in response to the rotation of the driving base, and in turn rotates the cylindrical pipe about the first axis, wherein the floating carrier comprises two parallel plates having circular openings for supporting the cylindrical pipe such that centers of the circular openings are positioned on the second axis, wherein the driving pin arrangement comprising three pins, wherein two pins are two parallel pins mounted on the driving base, and a third pin is attached with the cylindrical pipe, such that the third pin is mechanically coupled to movement of the two parallel pins mounted on the driving base, wherein during the second stage of rotation, the rotation of the driving base causes the two parallel pins to move the third pin for rotating the cylindrical pipe about the second axis; responsive to rotating the driving base in the first direction, the driving base drives the floating carrier to turn the cylindrical pipe about the first axis during the first stage of rotation to bring the movable contact assembly proximal to the fixed contact assembly, and the driving base drives the driving pin arrangement to twist the cylindrical pipe about the second axis during the second stage of rotation for engagement of the one or more movable contacts with the one or more corresponding fixed contacts; and rotating the driving base of the driving assembly of the switchgear about the first axis in a second direction to disengage the one or more movable contacts with the one or more corresponding fixed contacts, wherein responsive to rotating the driving base about the first axis in the second direction, the driving base drives the driving pin arrangement to twist the cylindrical pipe about the second axis, and thereafter drives the floating carrier to turn the cylindrical pipe about the first axis to move the movable contact assembly away from the fixed contact assembly.

11. The method of claim 10, further comprising limiting the rotation of the driving base during the second stage of rotation.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The subject matter of the invention will be explained in more detail in the following text with reference to exemplary embodiments which are illustrated in attached drawings in which:

(2) FIGS. 1A and 1B show perspective views of a switchgear having a turn and twist mechanism, in accordance with an embodiment of the invention;

(3) FIGS. 2A and 2B shows a perspective view of a fixed contact assembly of the switchgear, in accordance with an embodiment of the invention;

(4) FIGS. 3, 4 and 5 show perspective views of a movable contact assembly of the switchgear, in accordance with an embodiment of the invention;

(5) FIG. 6 shows a perspective view of the turn and twist mechanism, in accordance with an embodiment of the invention;

(6) FIG. 7 shows a sectional view of the turn and twist mechanism, in accordance with the embodiment of the invention;

(7) FIGS. 8A to 9B show perspective views of the turn and twist mechanism before and after twisting, in accordance with an embodiment of the invention; and

(8) FIGS. 10-13 show different side views during engagement of the movable and fixed contact assemblies during switching, in accordance with an embodiment.

DETAILED DESCRIPTION

(9) The present invention provides a switchgear with a turn and twist mechanism. The switchgear of the invention has a contact system having contacts for bus transfer switching. FIGS. 1A and 1B show an embodiment wherein the switchgear is a disconnector (100). In accordance with the embodiment, the disconnecter is a double side break disconnector. In FIG. 1A, the disconnector is in an open position, from which it can turn to a position for closing as shown in FIG. 1B. In the embodiment of FIGS. 1A and 1B, the disconnector has two fixed contacts (102a, 102b) and two movable contacts (104a, 104b).

(10) FIGS. 2A and 2B show shows a fixed contact assembly of the switchgear, in accordance with an embodiment of the invention. As shown, the fixed contact assembly has a fixed main contact (primary contact) and a fixed arcing contact (also referred herein as auxiliary contact). The main and arcing contacts are attached with a casting as shown in FIGS. 2A and 2B. In the embodiment, the main contact comprises a first set (202a) and a second set (202b) of main contact fingers. As shown, each set can have multiple contact fingers that are of similar size and shape, and are positioned in parallel to each other. In the embodiment of FIGS. 2A and 2B, each contact finger is L-shaped and attached with the plate at one end (214a, 214b) as shown such that the contact fingers in the corresponding set are parallel to each other. The number of contact fingers in each set can be determined based on the rating of the switchgear.

(11) The arcing contact (204) is a contact finger for bus transfer switching. In accordance with the embodiment, the arcing contact is proximal to the first set of contact fingers (202a). Further, the arcing contact is positioned slightly lower than the first set of contact fingers for corresponding engagement with a movable arcing contact.

(12) In accordance with the embodiment shown in FIGS. 2A and 2B, the arcing contact is substantially flat, with a first portion (206) of the contact being parallel to the main contact fingers, and a second portion (208) of the contact being at an angle to the first portion. It will be apparent that the contact finger is bent at a line, making the two flat surfaces at an angle to each other. The arcing contact has a contacting element (210) on the second portion, for engaging with a movable arcing contact. Thus, the arcing contact acts as a leaf spring and a current carrying system. In the embodiment shown in FIGS. 2A and 2B, the fixed contact assembly also comprises a mechanical stopper (212). In accordance with some embodiments, the stopper is for stopping the turning movement of the movable contact assembly.

(13) FIGS. 3, 4 and 5 show a movable contact assembly of the switchgear, in accordance with an embodiment of the invention. The movable contact assembly comprises a current path pipe (302) and an end piece (304). As shown, the current path pipe is a cylindrical pipe and the end piece is a rectangular block. Further as shown, dimensions (length, breadth) of the rectangular block are less than diameter of the cylindrical pipe. Here, the rectangular block is attached with the cylindrical pipe at an end. In accordance with the embodiment, as highlighted in FIG. 5, the rectangular block is attached (e.g. welded) at the end of the cylindrical pipe with a flange (306) of the rectangular block.

(14) The movable contact assembly comprises a movable main contact (308) and the movable arcing contact (310). The movable main contact can be a single contact or a contact with two or more contacting elements. In the embodiment of FIGS. 3 and 4, the main contact (or primary contact) comprises two u-shaped contacting elements (312a, 312b) provided on the rectangular block as shown. Further, as shown, the movable arcing contact is provided at the end of the cylindrical pipe. Here, the arcing contact is provided on a portion (312) about the periphery (peripheral portion) of the cylindrical pipe.

(15) As shown in FIGS. 3 and 4, the movable arcing contact is positioned such that a portion of the movable arcing contact protrudes at the portion of about the periphery of the cylinder. Further as shown, the movable arcing contact is attached with the cylindrical pipe, at a portion of the movable arcing contact that is within the periphery of the cylindrical pipe. The movable arcing contact is provided such that at the end of the turning movement of the movable contact assembly, initially the arcing contacts (of fixed/movable contact assembly) engage, after which commutation happens, in which the arcing contacts gradually disengage and the primary contacts engage.

(16) The movable contact assembly can rotate about two axes. Referring to FIG. 1, the cylindrical pipe can rotate or turn (106a, 106b) about a first axis (AA′), and twist (108a, 108b) about a second axis (BB′). As shown in FIG. 1, the first axis is a vertical axis (e.g. axis of the insulator), about which the cylindrical pipe can rotate to move the movable contact assembly (or assemblies) to bring the movable contacts proximal to the fixed contacts. Further, as shown, the second axis is a horizontal axis (e.g. the axis of the cylindrical pipe), about which the pipe can rotate (or twist) to move the movable contact assembly (or assemblies) relative to the fixed contact assembly (or assemblies).

(17) Referring to FIG. 6, which shows the turn and twist mechanism of the present invention, in accordance with an embodiment. As shown, the turn and twist mechanism comprises the cylindrical pipe (302), and a driving assembly. The driving assembly comprises a driving base (604), a floating carrier (606), and a driving pin arrangement (608). As shown in FIG. 7, the driving base can be mounted for rotation about the first axis. For example, the driving base can be mounted on an insulator as shown in FIG. 7. The driving base may be welded as a single piece having a plate for mounting on the insulator. Thus, the driving base can be rotated by the driving insulator about the axis of the driving insulator (i.e. first axis AA′).

(18) The floating carrier is connected with the driving base. As shown, the floating carrier comprises two parallel plates (610a, 610b) having circular openings for supporting the cylindrical pipe during the turning and twisting. Here, the circular openings are such that the current path pipe can fit into the circular openings. For instance, the openings can have a diameter of about the cylindrical pipe, and the centers of the openings can be positioned about the second axis (BB′).

(19) The movement of the floating carrier can accordingly move the current path pipe. In accordance with the embodiment of FIGS. 6-9B, the floating carrier is mounted on the driving base. The mounting can be done with one or more bushes or spacers (704a, 704b, 704c), to have relative movement between the driving base and the floating carrier. As shown in FIG. 8B, slots (802a, 802b) are provided in the driving base to lock relative motion between the floating carrier and the driving base. In accordance with the embodiment, the support spacers (706a, 706b) move inside the slots of the driving base during operation.

(20) In accordance with the embodiment, as shown in FIG. 9B, two extension springs (912a, 912b) are used in the turn and twist mechanism. One end of each spring is mounted on the driving base and one end is mounted on the floating carrier. Protrusions can be provided on the driving base (804a, 804b) and the floating carrier (806a, 806b) for connecting the springs. As there is a relative motion between the floating carrier and the driving base, this motion is locked with the use of extension springs. In the first stage rotation shown in FIGS. 8A and 8B (before twisting), components of the turn and twist mechanism including the current path (cylindrical pipe) will move together with the rotating insulator. Once the current path reaches to its limit position, it will come in contact with the physical stopper (212) provided in the fixed contact housing.

(21) The remaining motion of the driving base is used in twisting the current path from the driving base. The twisting motion is enabled with the driving pin arrangement. As shown in FIGS. 8A-9B, the driving pin arrangement comprising three pins. Two pins (808a, 808b) of the driving pin arrangement are mounted on the driving base and one pin (810) is attached with the cylindrical pipe. In the embodiment shown, the two pins mounted on the driving base are parallel to each other and the pins are mounted perpendicularly on the driving base. Further, the third pin is perpendicular to the two parallel pins mounted on the driving base. As shown, the third pin is attached with the cylindrical pipe using a collar assembly (812). The collar assembly has a circular opening for connection between the collar assembly and the cylindrical pipe. Further, the collar assembly has an opening for mounting of the third pin parallel to the longitudinal axis of the cylindrical pipe.

(22) Thus, once the twisting movement begins, the turn and twist mechanism is in a position shown in FIGS. 8A and 8B. Here, relative movement between the floating carrier and the driving base will happen. In this stage, the driving base rotates and drives the driving pin arrangement. This rotation is limited by the slots (802a, 802b). As shown, during rotation the driving base rotates from a position shown in FIGS. 8A and 8B to a position shown in FIGS. 9A and 9B. The two parallel pins in turn move the third pin, which twists the current path pipe and closes the switchgear. In the embodiment shown, the extension spring gets elongated. The elongated spring helps in quickly untwisting the current path during opening. So, it can be seen that spring plays important role in closing and opening of the switchgear.

(23) The following describes the position of the contacts during switching, in accordance with an embodiment. Turing the movable contact assembly results in the movable contact assembly to come to a position as shown in FIG. 10. During closing, the current path enters the fixed contact assembly at an angle (e.g. around 50° w.r.t vertical). The angle of current path is set in such way that sufficient clearance is maintained between the primary contacts to prevent arcing between the primary contacts during closing.

(24) The current path pipe turns till the pipe touches the stopper. FIG. 11 shows the position of the contacts just before twisting. Thus, when the current path further moves inside the fixed contact, the arcing contacts first touch each other and arcing occurs only between the arcing contacts.

(25) FIG. 12 shows the position of the contacts during commutation. When the current path touches the stopper (212, FIG. 2), it starts twisting. During this stage, the arcing contacts are gradually disengaging and the primary contacts are gradually engaging. The contacts are designed in such a way that there is sufficient overlap of contacts for smooth switching of current from arcing contacts to primary contacts.

(26) FIG. 13 shows the position of the contacts in full close condition. When the current path fully twists, the switchgear comes to full close condition. In an embodiment, the current path twists by 50° for the switchgear to come to a full close condition. In the full close condition, the arcing contacts completely disengage and the primary contacts engage completely as shown. In this position, the rated current flows only from the primary contacts.

(27) The turn and twist mechanism of the present invention provides for greater twisting, which allows for adding the auxiliary (or bus transfer) contacts. The mechanism of the present invention provides for greater twisting of the current path as compared to the prior art twisting mechanisms. The pin arrangement helps in achieving twisting of about 50 degrees. This assists in having good amount of clearance between the fixed and movable contacts before twisting, which allows for adding auxiliary contact for bus transfer. Here, even if there is slightly misalignment in the current path and fixed contact at the end of the turning motion, the main contacts do not touch as there is sufficient clearance. The supports (bushes, spacers) connecting the floating carrier and the driving bush provide extra stability and prevent accidental over-twisting. They also provide for ease of assembly of the center turn and twist mechanism.