A simplified nonlinear double action circuit breaker.

Abstract

The present invention relates to a double-action circuit breaker (10) having primary and secondary movable contacts (25, 55) slidably mounted within primary and secondary holders (20, 50), the primary movable contact (25) having a tulip (26) and a contacting cylinder (28) attached thereto, and the secondary movable contact (55) having a pin (56) for engaging the tulip (26) but no mating contact for engaging the contacting cylinder (28). The circuit breaker (10) also has a nonlinear linkage (80) having a pin-slot mechanism (83) and a fixed dielectric shield (66) mounted on the secondary holder (50). During disconnection, the linkage 80 is preferably arranged to move the pin 56 more than the tulip 26 in proportion to their maximum stroke, thereby quickly retracting the pin tip 56A into the fixed dielectric shield 66 and then moving the tulip 26 more than the pin 56. This circuit breaker 10 is less expensive, lighter, and can be disconnected more quickly.

Description

[Technical field]

[0001] The present invention relates to the field of high voltage circuit breakers for switchgear. More particularly, the present invention relates to a simplified double action circuit breaker having a non-linear action linkage. The present invention also relates to a method for disconnecting a circuit breaker. [Background technology]

[0002] Nonlinear double action high voltage (HV) circuit breakers are known. US Patent No. 9543081 discloses such a circuit breaker. It comprises two movable contacts that move in opposite directions to interrupt a circuit. The primary movable contact comprises a tulip, a nozzle and a contacting cylinder mounted together, and the secondary movable contact comprises a pin and a mating contacting cylinder mounted together. A nonlinear action linkage converts the movement of the primary movable contact in one direction into a nonlinear movement of the secondary movable contact in the opposite direction. In this way, the circuit breaker is able to interrupt a circuit.

[0003] However, moving the various components of the circuit breaker consumes a lot of energy since they are heavy and require sufficient acceleration and speed to trip. Moreover, the circuit breaker has many moving parts, which generally makes it susceptible to mechanical failure. Finally, it is also expensive since certain components such as the contact cylinder and the mating contact cylinder must be coated with silver to have the necessary hardness and conductivity to ensure proper functioning.

[0004] Thus, there is a clear need for a circuit breaker that is faster acting, more reliable, and less expensive. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US Patent Publication No. 2018 / 182578 Summary of the Invention

[0006] The present invention relates to a non-linear double action circuit breaker comprising a primary movable contact and a secondary movable contact slidably mounted in a primary holder and a secondary holder respectively, the primary movable contact comprising a tulip and a contacting cylinder attached thereto, the secondary movable contact comprising a pin having a pin tip, the circuit breaker further comprising a linkage arranged to permit non-linear movement of the secondary movable contact in a direction opposite to the movement of the primary movable contact, the secondary holder having a fixed dielectric shield at an end opposite to the primary holder, and the secondary movable contact does not have a mating contact for engaging the contacting cylinder.

[0007] The present invention also relates to a method of disconnecting a non-linear double action circuit breaker, comprising the steps of slidably mounting a primary and a secondary moving contact in a primary holder and a secondary holder, respectively; providing the primary moving contact with a tulip and an attached contacting cylinder; providing the secondary moving contact with a pin having a pin tip; providing a linkage allowing non-linear movement of the secondary moving contact in a direction opposite to the movement of the primary moving contact; and retracting the pin from the primary moving contact without moving the mating contact to engage the contacting cylinder until the pin tip is within a fixed dielectric shield provided at the end of the secondary holder opposite the primary holder.

[0008] Preferred features of the invention are defined in the accompanying claims.

[0009] The invention will be better understood on reading the following detailed description and non-limiting examples and on examining the drawings, in which: [Brief description of the drawings]

[0010] [Figure 1]1 is a cross-sectional view of a circuit breaker in accordance with a preferred embodiment of the present invention, the circuit breaker being in a closed position; [Diagram 2] FIG. 2 is a cross-sectional view of the same circuit breaker in an open position. [Diagram 3] 2 is an enlarged cross-sectional view of the same circuit breaker, particularly showing its coupling mechanism in an intermediate position of the circuit breaker; FIG. [Figure 4] 1 shows a graph comparing the stroke of the secondary movable contact stroke (y-axis) with the stroke of the primary movable contact (x-axis). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] In all these figures, the same reference signs may designate the same or similar elements. Moreover, the various parts shown in the figures are not necessarily shown according to a uniform scale in order to make the figures more readable.

[0012] 1 shows a circuit breaker 10 according to a preferred embodiment of the present invention, particularly showing the two movable contacts 25, 55 of the circuit breaker together with details of its coupling mechanism 80, the circuit breaker being in a closed position. The circuit breaker 10 comprises a primary (contact) holder 20 and a secondary (contact) holder 50 in which the primary movable contact 25 and the secondary movable contact 55 are slidably mounted, respectively. The coupling mechanism 80 converts the movement of the primary movable contact 25 in one direction along a main axis into a non-linear movement of the secondary movable contact 55 in the opposite direction along the main axis. In this preferred embodiment, the circuit breaker 10 is of the auto-blast type and is also part of a switchgear 100.

[0013] The primary movable contact 25 includes a tulip 26, a nozzle 27, and a contacting cylinder 28 attached together and arranged to move as a single unit. The primary movable contact 25 is shown extending from the primary holder 20 when the circuit breaker 10 is in the closed position. However, the primary movable contact 25 can retract into the primary holder 20 as seen in FIG. 2, which shows the circuit breaker 10 in the open position.

[0014] The secondary movable contact 55, on the other hand, comprises a pin 56. The secondary movable contact 55 is shown extending from the secondary holder 50 and engaging with the primary movable contact 25 when the circuit breaker 10 is in the closed position. More precisely, the pin 56 extends through the nozzle 27 of the primary movable contact 25 and engages with its tulip 26. The secondary movable contact 55 can move back into the secondary holder 50, as can be seen in Figure 2, which shows the circuit breaker 10 in the open position.

[0015] However, unlike the prior art, it will be observed that the secondary movable contact 55 does not include a mating contact cylinder attached to the pin 56. This is an important aspect of the present invention. Because there is no mating contact (such as a cylinder) attached to the pin, the linkage 80 does not need to move the combined mass of the pin 56 and mating contact. Rather, it only needs to move the pin 56, which is much lighter. This significantly reduces the weight of the secondary movable contact 55, and therefore the energy required to operate the circuit breaker 10. The absence of a mating contact on the circuit breaker 10 that needs to be moved means that disconnection can be achieved quickly.

[0016] The secondary holder 50 comprises a bridge 60 for slidably supporting the pin 56. The bridge 60 has a sleeve 61 in which the pin 56 sits for sliding along a main axis. In this embodiment, the maximum stroke of the secondary movable contact 55 is about one third of the maximum stroke of the primary movable contact 25. The bridge 60 is ideally equipped with spokes 62 that support the sleeve 61 so that it is held centrally in the secondary holder 50. The sleeve 61 of the bridge 60 has contact points 63 therein that allow current to flow between the secondary holder 50 and the pin 56. Instead of contact points, a flexible connection may be provided that extends from the secondary holder 50 to the pin 56, allowing current to flow.

[0017] The circuit breaker 10 also includes dielectric shields 36, 66 on the primary and secondary holders 20, 50. The dielectric shields 36, 66 are fixed to opposite ends of the primary and secondary holders 20, 50 and effectively surround the primary and secondary moving contacts 25, 55, and therefore also the shaft. These dielectric shields 36, 66 are designed to improve dielectric resistance and reduce the likelihood of flashover during operation of the circuit breaker 10. While the mating contact cylinders of the prior art also functioned as dielectric shields for the pins, this function is now provided for the pins 56 by the dielectric shield 66 on the secondary holder 50.

[0018] Due to the absence of a mating contact on the secondary movable contact 55, the contact cylinder 28 of the circuit breaker 10 of the present invention is arranged to directly engage the secondary holder 50. When in the closed position, the contact cylinder 28 of the primary movable contact 25 engages with the fixed dielectric shield 66 of the secondary holder 50. The fixed dielectric shields 36, 66 are provided with contact points 37, 67 on their inner circumferences to improve electrical continuity with the contact cylinder 28. When the contact cylinder 28 is in the open position, it is essentially located within the fixed dielectric shield 36, which helps to prevent flashover. Similarly, with respect to the pin 56, when the circuit breaker 10 is in the open position, the pin tip 56A is located within the fixed dielectric shield 66 of the secondary holder 50, which helps to prevent flashover.

[0019] Another novel aspect of the present invention is the kinematics of the primary moving contact 25 and the secondary moving contact 55, which results in an interesting feature of the present invention, namely the linkage 80. The linkage 80 of the circuit breaker 10 comprises a driving lever 81 and a driven lever 91. Both levers 81, 91 are mounted on pivots 82, 92 attached to the secondary holder 50. The axes of these pivots 82, 92 are parallel and perpendicular to the main axis, i.e. the direction of movement of the pin 56 and the tulip 26. The driving lever 81 is connected to the tulip 26 / primary moving contact 25 by a driving rod 88. This driving rod 88 extends between the spokes 62 of the bridge that holds the pin 56. The driven lever 91, on the other hand, is connected to the pin 56 / secondary moving contact 55 by a driven rod 98.

[0020] The driving lever 81 and the driven lever 91 are connected to each other by a pin and slot connection 83. The driving lever 81 has two legs, one attached to the driving rod 88 and the other with a follower pin 84, while the driven lever 91 also has two legs, one attached to the driven rod 98 and the other with a slot 94. This pin and slot connection 83 allows the movement of the driving lever 81 to control the movement of the driven lever 91, which is essentially located between the pivot 82 of the driving lever 81 and the pivot 92 of the driven lever 91 and can move from one side to the other of a notional line connecting the pivots 82, 92 of the levers 81, 91. The rotations of the driving lever 81 and the driven lever 91 are generally opposite to each other, although this does not apply to the full range of movement of the levers.

[0021] The slot 94 has a short section 95 located closer to the pivot 92 of the driven lever 91 and an adjacent long section 96 located further away. The short section 95 is straight and the long section 96 is curved and has the same radius from its pivot 82 as the follower pin 84. The curvature of the long section 96 of the slot 94 is approximately reversed relative to the curved path of the follower pin 84 when on one side of a notional line between the pivots 82, 92, but corresponds to the curved path of the follower pin 84 when on the other side.

[0022] Linkage 80 is positioned so that, during the initial stage of cutting, rotation of drive lever 81 substantially acts on driven lever 91, rotating it fairly rapidly and causing pin tip 56A to retract into stationary dielectric shield 66. Pin 56 is actually pulled out more than tulip 26 in proportion to its maximum stroke during this stage, and is at or nearly at the end of its stroke, while tulip 26 is only about halfway through its stroke.

[0023] However, in the later stages of disconnection, the driving lever 81 does not or barely acts to rotate the driven lever 91. As a result, the pin 56 has little or no movement during this stage and is always maintained within the fixed dielectric shield 66, so that the tulip 26 is withdrawn relative to the pin 56 in proportion to its maximum stroke. Note that the total mass of the moving contacts is reduced to only the total mass of the primary moving contact 25, which means that the energy for disconnecting the circuit breaker is entirely directed towards the movement of the primary moving contact 25.

[0024] Thus, disconnection of the circuit breaker 10 can be considered to have a first stage between a closed position and an intermediate position, where the pin tip 56A is within the fixed dielectric shield 66 and stops retracting, and a second stage between the intermediate position and an open position. Figure 3 shows the coupling mechanism 80 in the intermediate position of the circuit breaker 10.

[0025] This operation of the linkage 80 is achieved in part by a pin and slot connection 83 between the levers 81, 91, which is configured such that between the closed and intermediate positions, rotation of the drive lever 81 causes the follower pin 84 to move within the slot 94 such that it substantially rotates the driven lever 91, while between the intermediate and open positions, the follower pin 84 moves within the slot 94 such that it does not rotate, or barely rotates, the driven lever 91.

[0026] Additionally, the pin slot mechanism 83 is configured such that on one side of the notional line, the follower pin 84 moves within the slot 94 in one direction, and on the other side of the notional line, the follower pin 84 moves within the slot 94 in the opposite direction.

[0027] For the avoidance of doubt, it is stated herein that during operation of the circuit breaker 10, the tulip 26 typically moves faster than the pin 56. However, in proportion to their maximum stroke, the pin 56 moves more than the tulip 26. In other words, the pin 56 achieves its maximum stroke faster than the tulip 26.

[0028] To facilitate an understanding of the invention, a brief description of switching the circuit breaker 10 from a closed position to an open position will now be given with reference to Figures 1 to 3 which show the circuit breaker 10, and Figure 4 which shows a graph of the stroke of the pin 56 (y-axis) against the stroke of the tulip 26 (x-axis).

[0029] The circuit breaker 10 is initially in a closed position as shown in Figure 1 with current flowing through the circuit breaker 10. During disconnection, a force is applied to the primary movable contact 25 to move it away from the secondary movable contact 55. The movement of the primary movable contact 25 in one direction is translated into a non-linear movement of the secondary movable contact 55 in the opposite direction. More specifically, the primary movable contact 25 pulls on the drive rod 88 which in turn rotates the drive lever 81 about its pivot 82 (counterclockwise in this view). The drive lever 81 then acts on the driven lever 91 via a pin and slot mechanism 83 to rotate the driven lever 91 about its pivot 92 (clockwise in this view).

[0030] Follower pin 84 moves first along long portion 96 of the slot (which is now reversed relative to the curved trajectory of follower pin 84) and into short portion 95 of slot 94. Due to the location and shape of slot 94 relative to follower pin 84, pin 56 retracts sooner from the start of the cut and also retracts more than tulip 26 in proportion to their maximum stroke.

[0031] The retraction of pin 56 and tulip 26 continues at essentially the same speed as above with rotation of drive lever 81. Follower pin 84 continues to move in slot 94 until it reaches the notional line between pivots 82, 92 (and the closest point of driven lever 91 to pivot 92) and then begins to move in the opposite direction along slot 94. Pin 56 is now at three-quarters of its maximum stroke. Retraction of pin 56 and tulip 26 continues until follower pin 84 leaves short straight section 95 of slot 94 and begins to move in long curved section 96. This may be referred to as the intermediate position of circuit breaker 10. For completeness, it is noted that it takes about a few milliseconds for pin 56 to reach this position.

[0032] 3 shows the position of pin 56, and the position of linkage 80, in the intermediate position of circuit breaker 10. However, from this point onwards, the rotational movement of drive lever 81 has little or no effect on the movement of the pin, because the follower lever 91 in its current position is positioned such that the long portion 96 of slot 94 corresponds to the curved trajectory of follower pin 84. As a result, while tulip 26 continues to retract, pin 56 does little or no retraction, and pin tip 56A remains within the fixed dielectric shield 66, i.e., generally between the front and rear of the (annular) fixed dielectric shield 66.

[0033] The relatively short stroke of the pin 56 compared to that of known circuit breakers helps ensure that the pin retracts quickly into the fixed dielectric shield 66, so that the pin 56 and the fixed dielectric shield 66 together reduce dielectric risk and prevent dielectric flashover. Once the pin 56 is essentially at its maximum stroke, only the tulip 26 continues to move toward its maximum stroke. This then completes the disconnection of the circuit breaker 10, which is the open position shown in FIG. 2. The circuit breaker 10 of the present invention can therefore be considered to have a simplified double action since the secondary movable contact 55 has a pin 56 but no mating contact. For reconnection of the circuit breaker 10, one skilled in the art will appreciate that essentially the reverse is done.

[0034] The circuit breaker 10 of the present invention represents a significant improvement over the prior art because it allows for faster disconnection while using less energy. By eliminating a component, the mating contact, the lighter pin 56 can move more easily and quickly while consuming less energy. The reduced part count of the secondary movable contact 55 also means that the circuit breaker 10 is cheaper to manufacture and cheaper to operate because it consumes less energy.

[0035] Additionally, the pin slot connection 83 of the linkage 80 is configured to allow the pin 56 to begin retracting from the onset of disconnection, quickly retracting the pin tip 56A into the safety of the fixed dielectric shield 66, significantly reducing dielectric risk and flashover. The shortened stroke of the pin 56 is also advantageous as it means the pin 56 requires less travel to get to the required position.

[0036] In contrast to the prior art, this allows cutting to occur more quickly and with less energy and movement. While those skilled in the art would put in more energy to achieve faster cutting, the present invention presents a new and inventive way to achieve this.

[0037] Although the secondary movable contact is described as including a tulip (for receiving a pin), this is not always the case and should therefore be understood in the broader sense of a pin receiver. Although the main embodiment discusses the invention in the context of a double action HV circuit breaker using self-blasting technology in switchgear, it will be apparent that the invention should not be so limited and is applicable to various types of switchgear and whether or not they use self-blasting technology.

[0038] Where the tulip is part of the primary moving member and the pin is part of the secondary moving member, for simplicity the primary and secondary moving contacts may be referred to simply as the tulip and pin, respectively. [Explanation of symbols]

[0039] 10. Circuit Breakers 20 Primary Holder 25 Primary moving contact 26 Tulips 27 Nozzle 28 Contact Cylinder 36 Fixed Dielectric Shield 37 contact points 50 Secondary Holder 55 Secondary Movable Contact 56 pin 56A Pin Tip 60 Bridge 61 Sleeve 62 spokes 63 contact points 66 Fixed Dielectric Shield 67 contact points 80 Connection mechanism 81 Drive lever 82 Pivot 83 Pin slot connection, pin slot mechanism 84 Follower pin 88 Drive Rod 91 Follower lever 92 Pivot 94 Slots 95 Short section, short straight section 96 Long section, long curved section 98 Follower rod 100 Switchgear

Claims

1. A non-linear double action circuit breaker (10) comprising a primary movable contact (25) and a secondary movable contact (55) slidably mounted in a primary holder (20) and a secondary holder (50), respectively, said primary movable contact (25) comprising a tulip (26) and a contacting cylinder (28) attached thereto, said secondary movable contact (55) comprising a pin (56) having a pin tip (56A), said circuit breaker (10) further comprising a linkage (80) arranged to permit non-linear movement of said secondary movable contact (55) in a direction opposite to the movement of said primary movable contact (25), said linkage (80) comprising a pivoting drive lever (81) and a pivoting spring (82) for connecting said primary movable contact (25) to said secondary movable contact (55). a drive rod (88) extending from a contact (25) to the secondary movable contact (55), a pivoting follower lever (91) and a follower rod (98) extending therefrom to the secondary movable contact (55), the drive lever (81) and the follower lever (91) being connected to each other via a pin and slot connection (83), a follower pin (84) is provided in the drive lever (81) and a slot (94) is provided in the follower lever (91), the secondary holder (50) has a fixed dielectric shield (66) at an end facing the primary holder (20), and the secondary movable contact (55) does not have a mating contact for engaging with the contact cylinder (28).

2. A non-linear double action circuit breaker (10) comprising a primary movable contact (25) and a secondary movable contact (55) slidably mounted within a primary holder (20) and a secondary holder (50), respectively, the primary movable contact (25) comprising a tulip (26) and a contacting cylinder (28) attached thereto, the secondary movable contact (55) comprising a pin (56) having a pin tip (56A), the circuit breaker (10) further comprising a linkage (80) arranged to permit non-linear movement of the secondary movable contact (55) in a direction opposite to the movement of the primary movable contact (25), the secondary holder (50) having a fixed dielectric shield (66) at an end facing the primary holder (20), and the secondary movable contact (55) does not have a mating contact for engaging with the contacting cylinder (28), 1. A non-linear double action circuit breaker (10), wherein the coupling mechanism (80) comprises a pivoting drive lever (81) and a drive rod (88) extending therefrom to the primary movable contact (25), and a pivoting follower lever (91) and a follower rod (98) extending therefrom to the secondary movable contact (55), the drive lever (81) and the follower lever (91) being connected to each other via a pin and slot connection (83), a follower pin (84) being provided in the drive lever (81) and a slot (94) being provided in the follower lever (91).

3. 3. The circuit breaker (10) of claim 2, wherein the pin and slot connection (83) is configured such that during disconnection, rotation of the drive lever (81) acts to rotate the driven lever (91) so that the pin (56) retracts from a closed position to an intermediate position of the circuit breaker (10) in which the pin tip (56A) is within the fixed dielectric shield (66) and rotation of the drive lever (81) acts not to rotate the driven lever (91) from the intermediate position of the circuit breaker (10) to an open position, thereby maintaining the pin tip (56A) within the fixed dielectric shield (66), wherein the pin (56) moves more than the primary movable contact (25) from the closed position to the intermediate position in proportion to their maximum strokes and the primary movable contact (25) moves more than the pin (56) of the circuit breaker (10) from the intermediate position to the open position.

4. The circuit breaker (10) of claim 3, wherein the slot (94) has a straight short portion (95) and a curved long portion (96).

5. The circuit breaker (10) of claim 4, wherein the curvature of the elongated portion (96) corresponds to a curved trajectory of the follower pin (84).

6. 6. The circuit breaker (10) of any one of claims 3 to 5, wherein the pin and slot connection (83) is configured such that the pin (56) moves from the onset of disconnection.

7. 7. The circuit breaker (10) according to claim 3, wherein the pin and slot connection (83) is configured such that, during disconnection, the pin (56) stops moving midway through a stroke of the primary movable contact (25).

8. 8. The circuit breaker (10) of claim 3, wherein the pin and slot connection (83) is configured such that, during disconnection, the follower pin (84) moves first in one direction within the slot (94) and then in the opposite direction.

9. 9. The circuit breaker (10) according to any one of the preceding claims, characterized in that the stroke of the pin (56) is 1 / 3 of the stroke of the primary movable contact (25).

10. A non-linear double action circuit breaker (10) comprising a primary movable contact (25) and a secondary movable contact (55) slidably mounted within a primary holder (20) and a secondary holder (50), respectively, the primary movable contact (25) comprising a tulip (26) and a contacting cylinder (28) attached thereto, the secondary movable contact (55) comprising a pin (56) having a pin tip (56A), the circuit breaker (10) further comprising a linkage (80) arranged to permit non-linear movement of the secondary movable contact (55) in a direction opposite to the movement of the primary movable contact (25), the secondary holder (50) having a fixed dielectric shield (66) at an end facing the primary holder (20), and the secondary movable contact (55) does not have a mating contact for engaging the contacting cylinder (28), The secondary holder (50) comprises a bridge (60) having a sleeve (61) in which the pin (56) is slidably positioned, and spokes (62) for supporting the sleeve (61).

11. 11. The circuit breaker (10) according to any one of the preceding claims, characterized in that the contact cylinder (28) is arranged to engage with the secondary holder (50).

12. A switchgear (100) comprising a circuit breaker (10) according to any one of claims 1 to 11.

13. A method of disconnecting a non-linear double action circuit breaker (10), comprising the steps of slidably mounting a primary moving contact (25) and a secondary moving contact (55) in a primary holder (20) and a secondary holder (50), respectively; providing the primary moving contact (25) with a tulip (26) and an attached contact cylinder (28); providing the secondary moving contact (55) with a pin (56) having a pin tip (56A); and providing a linkage (80) enabling non-linear movement of the secondary moving contact (55) in a direction opposite to the movement of the primary moving contact (25), wherein the disconnecting method includes the step of retracting the pin (56) from the primary moving contact (25) until the pin tip (56A) is within a fixed dielectric shield (66) provided at an end of the secondary holder (50) facing the primary holder (20); the method further characterized by providing a pivoting drive lever (81) in said linkage (80) and connecting a drive rod (88) therefrom to said primary movable contact (25); providing a pivoting follower lever (91) and connecting a follower rod (98) therefrom to said secondary movable contact (55); and connecting said drive lever (81) and said follower lever (91) via a pin and slot connection (83) by providing a follower pin (84) in said drive lever (81) and a slot (94) in said follower lever (91).

14. 14. The method of claim 13, further characterized by: rotating the driving lever (81) to rotate the driven lever (91) so that the pin (56) retracts from a closed position and moves more than the primary moving contact (25) in proportion to their maximum stroke to an intermediate position of the circuit breaker (10) where the pin (56) is within the fixed dielectric shield (66); and rotating the driving lever (81) without rotating the driven lever (91) so that the pin tip (56A) remains within the fixed dielectric shield (66) and the primary moving contact (25) retracts and moves more than the pin (56) until the circuit breaker (10) reaches an open position.

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