Non-linear double motion circuit breaker, switchgear including the same and method for disconnecting the same

Abstract

The present invention relates to a dual motion circuit breaker (10) comprising a primary movable contact (25) and a secondary movable contact (55) slidably mounted in a primary retainer (20) and a secondary retainer (50), wherein the primary movable contact (25) comprises a tulip (26) and a contact cylinder (28) attached to the tulip (26), and the secondary movable contact (55) comprises a pin (56) for engaging the tulip (26) but does not comprise a corresponding contact for engaging the contact cylinder (28). The circuit breaker (10) also has a non-linear coupling mechanism (80) with a pin-slot mechanism (83) and a fixed dielectric shield (66) provided on the secondary retainer (50). During disconnection, the coupling mechanism (80) is preferably arranged to cause the pin (56) to move to a greater extent than the tulip (26) in proportion to the maximum travel of the pin (56) and the tulip (26), thereby quickly bringing the pin tip (56A) into the fixed dielectric shield (66), after which the tulip (26) moves to a greater extent than the pin (56). The circuit breaker (10) is cheaper, 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 motion circuit breaker with a non-linear motion coupling mechanism. The present invention also relates to a method of tripping a circuit breaker. Background Art

[0002] Nonlinear dual motion high voltage (HV) circuit breakers are well known. US9543081 B2 discloses such a circuit breaker. The circuit breaker includes two movable contacts that move in opposite directions to interrupt the circuit. The primary movable contact includes a tulip, a nozzle, and a contact cylinder attached together, while the secondary movable contact includes a pin attached together and a corresponding contact cylinder). The nonlinear motion coupling mechanism 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 can interrupt the circuit.

[0003] However, moving the various components of the circuit breaker consumes a lot of energy because they are heavy and require sufficient acceleration and speed to cut off. In addition, the circuit breaker has many moving parts, which makes the circuit breaker generally more prone to mechanical failure. Finally, the circuit breaker is expensive because certain components such as the contact cylinder and the counter contact cylinder must be coated with silver to have the required hardness and conductivity in order to ensure proper functioning.

[0004] Therefore, there is clearly a need for circuit breakers that can operate faster, more reliably and also less expensively. Summary of the invention

[0005] The present invention relates to a nonlinear dual motion circuit breaker, which comprises a primary movable contact and a secondary movable contact respectively slidably mounted in a primary retainer and a secondary retainer, wherein the primary movable contact comprises a tulip-shaped piece and a contact cylinder attached to the tulip-shaped piece, and the secondary movable contact comprises a pin with a pin tip, the circuit breaker further comprises a coupling mechanism, the coupling mechanism is arranged to allow the secondary movable contact to perform nonlinear movement in a direction opposite to the movement of the primary movable contact, wherein the secondary retainer has a fixed dielectric shield at the end opposite to the primary retainer, and wherein the secondary movable contact does not include a corresponding contact for engaging the contact cylinder.

[0006] The present invention also relates to a method for cutting off a nonlinear dual-motion circuit breaker, the method comprising: slidingly mounting a primary movable contact and a secondary movable contact in a primary retainer and a secondary retainer respectively; providing the primary movable contact with a tulip-shaped piece and an attached contact cylinder, and providing the secondary movable contact with a pin having a pin tip; providing a connecting mechanism that allows the secondary movable contact to move nonlinearly in a direction opposite to the movement of the primary movable contact; and retracting the pin from the primary movable contact until the pin tip is located in a fixed dielectric shielding piece provided at the end of the secondary retainer opposite to the primary retainer without moving the corresponding contact for engaging the contact cylinder.

[0007] Preferred features of the invention are defined in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The invention will be better understood upon reading the following detailed description and non-limiting examples and upon studying the accompanying drawings, in which:

[0009] Figure 1 A cross-sectional view of a circuit breaker according to a preferred embodiment of the present invention is shown, the circuit breaker being in a closed position,

[0010] Figure 2 showing a cross-sectional view of the same circuit breaker in the open position,

[0011] Figure 3 showing a close up cross-sectional view of the same circuit breaker, in particular showing its coupling mechanism at a mid-position of the circuit breaker, and

[0012] Figure 4 A graph comparing the travel of the secondary movable contact (y-axis) relative to the travel of the primary movable contact (x-axis) is shown.

[0013] In all of these drawings, the same reference symbols can designate the same or similar elements. In addition, the various parts shown in the drawings are not necessarily shown according to a uniform scale in order to make the drawings easier to read. DETAILED DESCRIPTION

[0014] Figure 1A circuit breaker 10 according to a preferred embodiment of the present invention is shown, in particular, details of the two movable contacts 25, 55 of the circuit breaker and its coupling mechanism 80 when the circuit breaker 10 is in a closed position are shown. The circuit breaker 10 includes 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 the 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 a self-blast type and is also part of a switchgear 100.

[0015] The primary movable contact 25 includes a tulip 26, a nozzle 27, and a contact cylinder 28, which are attached together and arranged to move as a single unit. The primary movable contact 25 is shown extending out of the primary retainer 20 when the circuit breaker 10 is in the closed position. However, as shown in Figure 2 As can be seen in FIG. 1 , the primary movable contact 25 can be moved back into the primary holder 20 . Figure 2 The circuit breaker 10 is shown in the open position.

[0016] At the same time, the secondary movable contact 55 includes a pin 56. When the circuit breaker 10 is in the closed position, the secondary movable contact 55 is shown extending out of the secondary retainer 50, engaging with the primary movable contact 25. More precisely, the pin 56 extends through the nozzle 27 of the primary movable contact 25 and engages with its tulip 26. Figure 2 As can be seen in FIG. 1 , the secondary movable contact 55 can be moved back into the secondary holder 20 . Figure 2 The circuit breaker 10 is shown in the open position.

[0017] However, unlike the prior art, we observe that the secondary movable contact 55 does not include a corresponding contact cylinder attached to the pin 56. This is an important aspect of the present invention. Since there is no corresponding contact (cylinder or other) attached to the pin, the coupling mechanism 80 does not have to move the combined mass of the pin 56 and the corresponding contact. Instead, the coupling mechanism 80 only has to move the much lighter pin 56. This critically reduces the weight of the secondary movable contact 55, and therefore, the energy required to operate the circuit breaker 10 is also reduced. The absence of a corresponding contact that needs to be moved on the circuit breaker 10 means that disconnection can be achieved quickly.

[0018] The secondary holder 50 includes a bridge 60 for slidably supporting the pin 56. The bridge 60 has a sleeve 61 in which the pin 56 is located to slide along the main axis. In this embodiment, the secondary movable contact 55 has a maximum stroke of about one third of the maximum stroke of the primary movable contact 25. The bridge 60 is ideally equipped with a spoke 62 that supports the sleeve 61 so that the sleeve 61 is held centrally in the secondary holder 50. The sleeve 61 of the bridge 60 has a contact point 63 on its interior that allows current to flow between the secondary holder 50 and the pin 56. Instead of the contact point, a flexible connection extending from the secondary holder 50 to the pin 56 can be provided to allow current to flow.

[0019] The circuit breaker 10 also includes dielectric shields 36, 66 on the primary retainer 20 and the secondary retainer 50. The dielectric shields 36, 66 are fixed at opposite ends of the primary retainer 20 and the secondary retainer 50, effectively surrounding the primary movable contact 25 and the secondary movable contact 55 and thus also effectively surrounding the main axis. These dielectric shields 36, 66 are designed to improve the dielectric resistance and reduce the possibility of flash-over during operation of the circuit breaker 10. Although the corresponding contact cylinder of the prior art also acts as a dielectric shield for the pin, this function is now provided for the pin 56 by the dielectric shield 66 on the secondary retainer 50.

[0020] Since there is no corresponding 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 20. When in the closed position, the contact cylinder 28 of the primary movable contact 25 engages the fixed dielectric shield 66 of the secondary holder 50. The inner circumference of the fixed dielectric shield 36, 66 is provided with contact points 37, 67 to improve electrical continuity with the contact cylinder 28. When the contact cylinder 28 is in the open position, the contact cylinder 28 is substantially located within the fixed dielectric shield 36, which helps prevent flashover. Similarly, for the pin 56, when the circuit breaker 10 is in the open position, the pin tip 56A will be located within the fixed dielectric shield 66 of the secondary holder 50, which helps prevent flashover.

[0021] Another novel aspect of the present invention is the kinematics of the primary movable contact 25 and the secondary movable contact 55, which brings us to the interesting feature of the present invention, namely the coupling mechanism 80. The coupling mechanism 80 of the circuit breaker 10 includes a driving lever 81 and a driven lever 91. Both levers 81, 91 are mounted on pivots 82, 92 attached to the secondary retainer 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 movable contact 25 by a driving rod 88. The driving rod 88 extends between the spokes 62 of the bridge that holds the pin 56. At the same time, the driven lever 91 is connected to the pin 56 / secondary movable contact 55 by a driven rod 98.

[0022] The driving lever 81 and the driven lever 91 are connected together by a pin and slot connection 83. The driving lever 81 has two legs, one leg is attached to the driving rod 88, and the other leg includes a follower pin 84. At the same time, the driven lever 91 also has two legs, one leg is attached to the driven rod 98, and the other leg includes a slot 94. The pin and slot connection 83 allows the movement of the driving lever 81 to control the movement of the driven lever 91, and is substantially located between the pivot 82 of the driving lever 81 and the pivot 92 of the driven lever 91, and can be moved from one side of the imaginary line connecting the pivot 82 of the lever 81 and the pivot 92 of the lever 91 to the opposite side. The rotation of the driving lever 81 and the driven lever 91 is generally opposite to each other, however, this does not apply to the full range of their movement.

[0023] The slot 94 has a short section 95 located closer to the pivot 92 of the follower lever 91 and an adjacent long section 96 located farther away. The short section 95 is straight, while the long section 96 is curved, having the same radius as the follower pin 84 from its pivot 82. The curvature of the long section 96 of the slot 94 is generally inverted with the curved trajectory of the follower pin 84 when located on one side of an imaginary line between the pivots 82 and 92, and corresponds to the curved trajectory of the follower pin 84 when located on the other side.

[0024] The linkage mechanism 80 is arranged so that during the initial stages of severance, rotation of the drive lever 81 acts significantly on the driven lever 91, causing the driven lever 91 to rotate relatively rapidly, causing the pin tip 56A to retract into the fixed dielectric shield 66. During this stage, the pin 56 is actually retracted to a greater extent than the tulip 26 in proportion to the maximum travel of the pin 56 and the tulip 26, thereby reaching or very nearly reaching the end of its travel, whereas the tulip 26 is only about halfway through its travel.

[0025] However, during the later stages of disconnection, the driving lever 81 does not function or functions to a very small extent to rotate the driven lever 91. Therefore, during this stage, the pin 56 moves very little or not at all and remains within the fixed dielectric shield 66, causing the tulip 26 to be retracted to a greater extent than the pin 56 in proportion to its maximum travel. We will note that the total mass of the movable contacts is reduced to the mass of the primary movable contact 25 only, which means that the energy for disconnection of the circuit breaker is completely used to move the primary movable contact 25.

[0026] Thus, shutoff of the circuit breaker 10 can be viewed as having a first stage between the closed position and an intermediate position in which the pin tip 56A is located within the fixed dielectric shield 66 and has stopped retracting, and a second stage between the intermediate position and the open position. Figure 3 The link mechanism 80 is shown at an intermediate position of the circuit breaker 10 .

[0027] This operation of the connecting mechanism 80 is partially achieved by a pin-and-slot connector 83 between the levers 81 and 91, and the pin-and-slot connector 83 is configured so that between the closed position and the intermediate position, the rotation of the drive lever 81 causes the follower pin 84 to move in the slot 94, so that the follower pin 84 causes the driven lever 91 to rotate significantly, while between the intermediate position and the disconnected position, the follower pin 84 moves in the slot 94, so that the follower pin 84 does not rotate the driven lever 91 or causes the driven lever 91 to rotate to a very small extent.

[0028] Furthermore, the pin-and-slot mechanism 83 is configured such that on one side of the imaginary line, the follower pin 84 moves in one direction in the slot 94 , and on the other side of the imaginary line, the follower pin 84 moves in the opposite direction in the slot 94 .

[0029] For the avoidance of doubt, it is stated herein that the tulip 26 typically moves faster than the pin 56 throughout the operation of the circuit breaker 10. However, the pin 56 moves to a greater extent than the tulip 26 in proportion to the maximum travel of the pin 56 and the tulip 26. In other words, the pin 56 achieves its maximum travel more quickly than the tulip 26.

[0030] To facilitate understanding of the present invention, reference will be made to a circuit breaker 10. Figure 1-3 and a graph showing the travel of the pin 56 (y-axis) relative to the travel of the tulip 26 (x-axis) Figure 4 Instead, the tripping of the circuit breaker 10 from the closed position to the open position will be briefly discussed.

[0031] The circuit breaker 10 is initially located as Figure 1, and with current flowing through the circuit breaker 10. During disconnection, a force is applied to the primary movable contact 25 to move the primary movable contact 25 away from the secondary movable contact 55. The movement of the primary movable contact 25 in one direction is transformed into a non-linear movement of the secondary movable contact 55 in the opposite direction. More specifically, the primary movable contact 25 will pull the drive rod 88, which in turn will cause the drive lever 81 to rotate around its pivot 82 (counterclockwise in this view). The drive lever 81 then acts on the driven lever 91 through the pin-slot mechanism 83, causing the driven lever 91 to rotate around its pivot 92 (clockwise in this view).

[0032] The follower pin 84 initially travels along the long section 96 of the slot (inverting the curved path of the follower pin 84 in its current position) and into the short section 95 of the slot 94. Due to the position and shape of the slot 94 relative to the follower pin 84, the pin 56 is retracted from the initial shearing and is also retracted to a greater extent than the tulip 26 in proportion to the maximum travel of the pin 56 and the tulip 26.

[0033] The retraction of the pin 56 and tulip 26 continues at substantially the same rate as above with the rotation of the drive lever 81. The follower pin 84 remains traveling in the slot 94 until the follower pin 84 reaches an imaginary line between the pivots 82, 92 (and the point at which it is closest to the pivot 92 of the follower lever 91), where the follower pin 84 then begins to move in the opposite direction along the slot 94. The pin 56 is now at three quarters of its maximum travel. The retraction of the pin 56 and tulip 26 continues until the follower pin 84 leaves the short straight section 95 of the slot 94 and begins to travel in the long curved section 96. This can be stated as the intermediate position of the circuit breaker 10. For the sake of completeness, it will be mentioned that it takes about a few milliseconds for the pin 56 to reach this position.

[0034] Figure 3 The position of the pin 56 and also the position of the coupling mechanism 80 are shown in an intermediate position of the circuit breaker 10. However, from this point on, the rotational movement of the drive lever 81 has little or no effect on the movement of the pin. This is because the follower lever 91 in its current position is positioned so that the long section 96 of the slot 94 corresponds to the curved trajectory of the follower pin 84. As a result, the tulip 26 continues to retract, while the pin 56 is retracted to a little or not at all, wherein the pin tip 56A remains within the fixed dielectric shield 66, i.e. substantially between the front and rear parts of the (annular) fixed dielectric shield 66.

[0035] The relatively short travel of the pin 56 compared to those of known circuit breakers helps ensure that the pin 56 is quickly retracted into the fixed dielectric shield 66, so that the pin 56 and the fixed dielectric shield 66 together reduce any dielectric risk and prevent dielectric flashover. Once the pin 56 is substantially at its maximum travel, only the tulip 26 continues to move toward its maximum travel. This then completes the cut-off, Figure 2 Since the secondary movable contact 55 has a pin 56 but no corresponding contact, the circuit breaker 10 of the present invention can therefore be regarded as having a simplified double movement. For reconnection of the circuit breaker 10, the skilled person will understand that essentially the opposite of the above occurs.

[0036] The circuit breaker 10 of the present invention represents a significant improvement over the prior art because it allows disconnection to occur quickly while using less energy. By omitting a component, namely a corresponding contact, the lighter pin 56 can be moved more easily and more 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 produce and cheaper to operate because the circuit breaker 10 consumes less energy.

[0037] In addition, the pin-slot connection 83 of the link mechanism 80 is configured to allow the pin 56 to be retracted from the beginning of the cut and quickly retract the pin tip 56A into a safe position to secure the dielectric shield 66, thereby significantly reducing dielectric risks and flashovers. The shortened travel of the pin 56 is also advantageous because it means that the pin 56 needs to be moved to a lesser extent to be located in the required position.

[0038] This allows the cut to occur much more quickly and with less energy and movement involved than in the prior art.While the skilled person would put more effort into achieving faster cuts, the present invention proposes a new and innovative way to achieve this.

[0039] Although the secondary movable contact is described as comprising a tulip (for receiving a pin), this may not always be the case and should therefore be understood in the broader sense of a pin receiver. Although the main embodiments discuss the invention in the context of a double motion HV circuit breaker using self-explosion technology in a switchgear, the invention is not limited thereby and it will be apparent that the invention will be applicable to various types of switchgear, whether or not they employ self-explosion technology.

[0040] Since the tulip is part of the primary movable part and the pin is part of the secondary movable part, for reasons of simplicity the primary movable contact and the secondary movable contact may sometimes have been referred to simply as tulip and pin, respectively.

Claims

1. A non-linear dual motion circuit breaker (10), comprising a primary movable contact (25) and a secondary movable contact (55) slidably mounted in a primary retainer (20) and a secondary retainer (50), respectively, wherein: The primary movable contact (25) comprises a tulip (26) and a contact cylinder (28) attached to the tulip (26), and the secondary movable contact (55) comprises a pin (56) having a pin tip (56A), the circuit breaker (10) further comprising a coupling mechanism (80) arranged to allow non-linear movement of the secondary movable contact (55) in a direction opposite to the movement of the primary movable contact (25), characterized in that the secondary retainer (50) has a fixed dielectric shield (66) at an end opposite to the primary retainer (20), and characterized in that the secondary movable contact (55) does not include a corresponding contact member for engaging the contact cylinder (28), and the connecting mechanism (80) includes a pivot drive lever (81), a drive rod (88) extending from the pivot drive lever (81) to the primary movable contact member (25), a pivot follower lever (91) and a follower rod (98) extending from the pivot follower lever (91) to the secondary movable contact member (55), the pivot drive lever (81) and the pivot follower lever (91) are connected to each other by a pin-slot connecting member (83), a follower pin (84) is provided on the pivot drive lever (81), and a slot (94) is provided on the pivot follower lever (91).

2. The nonlinear dual motion circuit breaker according to claim 1, characterized in that: The pin-slot connection (83) is configured such that during disconnection, rotation of the pivot drive lever (81) acts to rotate the pivot follower lever (91) so that the pin (56) is retracted from the closed position to an intermediate position of the circuit breaker (10) wherein the pin tip (56A) is located within the fixed dielectric shield (66), and rotation of the pivot drive lever (81) acts so as not to rotate the pivot follower lever from the intermediate position to an open position of the circuit breaker (10) such that the pin tip (56A) is maintained within the fixed dielectric shield (66), wherein the pin (56) moves from the closed position to the intermediate position to a greater extent than the primary movable contact (25) in proportion to the maximum travel of the pin (56) and the primary movable contact (25), and the primary movable contact (25) moves from the intermediate position to the open position of the circuit breaker (10) to a greater extent than the pin (56).

3. The nonlinear dual motion circuit breaker according to claim 2, characterized in that: The groove (94) has a straight short section (95) and a curved long section (96).

4. The nonlinear dual motion circuit breaker according to claim 3, characterized in that: The curvature of the long section (96) corresponds to the curved path of the follower pin (84).

5. The non-linear dual motion circuit breaker according to any one of claims 2 to 4, characterized in that: The pin-and-slot connection (83) is configured to allow the pin (56) to move from the start of the cut.

6. The non-linear dual motion circuit breaker according to any one of claims 2 to 4, characterized in that: The pin-slot connection (83) is configured so that during cut-off, the pin (56) stops moving midway through the stroke of the primary movable contact (25).

7. The non-linear dual-motion circuit breaker according to any one of claims 2 to 4, characterized in that: The pin-and-slot connection (83) is configured such that during cutting, the follower pin (84) moves in the slot (94) first in one direction and then in the opposite direction.

8. The non-linear dual motion circuit breaker according to any one of claims 2 to 4, characterized in that: The pin (56) has a stroke which is one third of the stroke of the primary movable contact (25).

9. The non-linear dual-motion circuit breaker according to any one of claims 2 to 4, characterized in that: The secondary retainer (50) has a bridge (60) having a sleeve (61) and a spoke (62) for supporting the sleeve (61), and the pin (56) is slidably located in the sleeve (61).

10. The non-linear dual motion circuit breaker according to any one of claims 2 to 4, characterized in that: The contact cylinder (28) is arranged to engage the secondary retainer (50).

11. A switchgear (100) comprising the non-linear dual-motion circuit breaker (10) according to any one of claims 2-10.

12. A method for tripping a nonlinear dual motion circuit breaker, comprising: A primary movable contact (25) and a secondary movable contact (55) are slidably mounted in a primary retainer (20) and a secondary retainer (50) respectively; the primary movable contact (25) is provided with a tulip-shaped piece (26) and an attached contact cylinder (28), and the secondary movable contact (55) is provided with a pin (56) having a pin tip (56A); a connecting mechanism (80) is provided to allow the secondary movable contact (55) to move non-linearly in a direction opposite to the movement of the primary movable contact (25), characterized in that the method of cutting off includes retracting the pin (56) from the primary movable contact (25) without moving a corresponding contact for engaging the contact cylinder (28) until the pin (56) is retracted. The tip (56A) is located in a fixed dielectric shield (66) provided at the end of the secondary retainer (50) opposite to the primary retainer (20), and the connecting mechanism (80) is provided with a pivot drive lever (81), a drive rod (88) is connected from the pivot drive lever (81) to the primary movable contact (25), a pivot follower lever (91) is provided, and a follower rod (98) is connected from the pivot follower lever (91) to the secondary movable contact (55), and the pivot drive lever (81) and the pivot follower lever (91) are connected by a pin-slot connection (83) by providing a follower pin (84) on the pivot drive lever (81) and a slot (94) on the pivot follower lever (91).

13. The method according to claim 12, further characterized in that: The pivot drive lever (81) is rotated to rotate the pivot follower lever (91) so that the pin (56) is retracted from the closed position, thereby moving to a greater extent than the primary movable contact (25) in proportion to the maximum travel of the pin (56) and the primary movable contact (25), until the circuit breaker (10) is in an intermediate position wherein the pin (56) is located within the fixed dielectric shield (66), and without rotating the pivot follower lever (91), the pivot drive lever (81) is rotated so that the pin tip (56A) is maintained within the fixed dielectric shield (66) and the primary movable contact (25) is retracted, thereby moving to a greater extent than the pin (56) until the circuit breaker (10) reaches the open position.

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