Fuse comprising overvoltage triggering device

Abstract

The present invention relates to a fuse comprising: a fuse tube forming an enclosed space that can be arranged in a pressurized tank, the pressure of the pressurized tank being maintained higher than the pressure within the enclosed space of the fuse tube; a fuse cover sealing an opening in the fuse tube to the enclosed space, the fuse cover comprising a striker configured to move in the fuse cover in the event of a fuse trigger, a fuse cover housing accommodating the striker, a passage through the fuse cover, and a housing housing accommodating the striker and the passage through the fuse cover, the invention relates to a fuse tube comprising a channel connecting an enclosed space in the fuse tube and an environment outside the fuse tube, and an overvoltage trigger device arranged in the channel or at an opening of the channel to at least partially block the channel, the overpressure trigger device is configured to transition from a first state to a second state in response to an overpressure in the enclosed space of the fuse tube caused by a leak between the enclosed space of the fuse tube and the pressurized canister.

Description

Technical Field

[0001] The present invention relates to an electrical fuse. Background Art

[0002] Electrical fuses for medium and high voltage switchgear are typically installed in a fuse panel. The fuse includes a fuse tube and a fuse cap mounted on the fuse tube, and the fuse cap forms a sealed environment at atmospheric pressure. The fuse tube extends to the rear of the fuse panel and into an overpressure tank that contains a dielectric gas medium for dielectric isolation between the fuse phases.

[0003] Leakage from the overpressure tank to the sealed fuse tube creates a force on the fuse cap, which can cause injury to an operator when removing the cap. Summary of the Invention

[0004] In view of the above and other disadvantages of the prior art, an object of the present invention is to provide an electrical fuse that at least partially alleviates the disadvantages of the prior art.

[0005] According to a first aspect of the present invention, there is provided a fuse, which includes: a fuse tube that forms a closed space that can be arranged in a pressurized tank, the pressurized tank being maintained at a pressure higher than the pressure inside the closed space of the fuse tube; a fuse cap that seals an opening in the fuse tube leading to the closed space, the fuse cap including: a striker configured to move in the fuse cap in the event of a fuse trigger; a fuse cap housing that houses the striker; a passage through the fuse cap that communicates the closed space in the fuse tube and the external environment of the fuse tube, and an overpressure trigger device arranged in the passage or at the passage opening to at least partially block the passage, the overpressure trigger device being configured to transition from a first state to a second state in response to an overpressure inside the closed space of the fuse tube due to a leak between the closed space of the fuse tube and the pressurized tank.

[0006] The present invention is at least partially based on the implementation of forming a passage through the fuse cap. This passage allows the release of pressure from the closed space of the fuse tube. The passage also enables the overpressure trigger device to operate between two states, which changes the configuration structure of the passage, or its ability to release pressure through or in the passage. Thus, the passage itself can allow gas to pass through the passage, and the overpressure trigger device is configured to change the ability of the passage to transmit gas.

[0007] The pressure inside the closed space of the fuse tube can be close to atmospheric pressure.

[0008] The fuse tube can have a main opening where the fuse cover is arranged. The main components of the fuse mechanism (such as the striker) are located in the cover. The striker is arranged to move forward in the case of the fuse being triggered due to an electrical fault, that is, away from the enclosed space of the fuse tube, and cause the current to be interrupted in its phase.

[0009] According to at least one embodiment, a channel can be located in the striker. Thus, the striker can include a channel extending along its longitudinal axis. The striker passes through the fuse cover housing, so it is an advantageous position for a channel that should extend to allow the release of pressure from the enclosed space of the fuse tube.

[0010] According to at least one embodiment, a channel can be located within the fuse cover housing. The fuse cover housing includes a block of material and is a suitable location for the channel. In particular, the channel can accommodate other devices.

[0011] According to at least one embodiment, the overpressure triggering device can be a bursting element, which is configured to keep the channel at least partially blocked in a first state and burst in a second state to release the overpressure within the enclosed space of the fuse tube. Advantageously, when the pressure within the enclosed space of the fuse tube becomes too high, the bursting element ruptures, thereby releasing the pressure to the surrounding atmosphere through the channel.

[0012] According to at least one embodiment, the bursting element is configured to maintain the channel completely blocked in the first state.

[0013] The bursting element can be part of the striker, for example, made as an integral piece and integrated with the striker. For example, the channel can be made not to pass completely through the striker, leaving a disk at the end of the channel. This can be achieved by not drilling a channel hole through the entire length of the striker. In this case, the material of the bursting element is the same as that of the striker, preferably metal. The bursting element can be disk-shaped, and its diameter can be selected in the range of about 1 mm to about 10 mm, and the thickness can be selected in the range of about 0.1 mm to 2 mm.

[0014] Alternatively, the bursting element can be a separate component, which can be metal or preferably plastic, and is assembled in the channel by some means of sealing the channel. For example, a washer can be used to seal the channel, or the bursting element can be press-fitted or glued in the channel. The size of the bursting element can be selected in the range of about 1 mm to about 10 mm, and the thickness can be selected in the range of about 0.1 mm to 2 mm. The shape of the bursting element depends on the shape of the opening on the channel, and basic shapes such as circular, square, triangular, disk, etc. are suitable.

[0015] According to at least one embodiment, the bursting element can be arranged at the internal opening of the channel facing the fuse tube enclosed space. In other words, the channel can include an internal opening, i.e., an opening located within the fuse tube, and an external opening located on the opposite side of the fuse cap outside the fuse tube (e.g., in the surrounding atmosphere outside the fuse tube). Preferably, in order to protect the bursting element, the bursting element is arranged at the internal opening.

[0016] The bursting element can be a bursting disc, i.e., a disc-shaped bursting element.

[0017] According to at least one embodiment, the overpressure triggering device can include a piston arranged in a piston volume space in the channel, and a pin connected to the piston, wherein the transition is that the pin moves in the channel in response to overpressure. The piston volume space can be formed as a part of the channel. The piston can move along the channel in the piston volume space. In particular, in the case of overpressure occurring in the fuse tube, the overpressure inside the fuse tube presses the piston towards the external opening of the channel. The pin is attached to the piston or forms an integral part with the piston, so the pin also moves in the channel. The pin is preferably formed such that the free end of the pin points towards the external opening of the channel. The opposite end of the pin is the fixed end at or on the piston.

[0018] According to at least one embodiment, the pin can at least partially move out of the channel to provide an indication of overpressure outside the fuse tube. Therefore, in response to the piston moving due to overpressure, the pin can protrude from the external opening of the channel. This provides an indication to the operator that there is overpressure inside the fuse tube. In addition, the movement of the piston provides a certain amount of pressure relief.

[0019] According to at least one embodiment, the overpressure triggering device can further include a spring that biases the piston in the channel towards the internal opening of the channel facing the enclosed space in the fuse tube. Therefore, once there is a certain amount of overpressure in the fuse tube, the piston will move and compress the spring. Thus, the spring force is overcome by the force from the overpressure in the fuse tube. In the absence of the said certain amount of overpressure, the piston remains in its initial position and the pin does not protrude outwards from the channel. The spring can be customized according to the allowable overpressure. Towards the internal opening here means the upstream of the channel where the internal opening is located. The downstream of the channel is the direction of the external opening facing the external environment.

[0020] According to at least one embodiment, the piston volume space is wider than the adjacent part of the channel. In other words, the piston volume space can be a separate chamber in the channel for receiving the piston.

[0021] According to at least one embodiment, the piston can move from a rear position in the piston volume space to a front position in response to overpressure, and a sealing member is arranged in the piston volume space to at least partially seal the channel when the piston is in the front position. Sealing the piston volume space prevents the pressure in the piston volume space from completely disappearing and the spring from pushing the piston back and the pin back into the channel. However, a small amount of pressure release can be allowed through the seal.

[0022] According to at least one embodiment, the sealing member can be annular and can be arranged on a shoulder in the piston volume space around a narrower portion of the channel, and when the piston is in the front position, the piston applies a force along the entire circumference of the annular sealing member. In one example, the sealing member can be an O-ring.

[0023] In another embodiment, the sealing member is attached to the piston.

[0024] According to at least one embodiment, the overpressure trigger device can be part of a firing pin that includes a piston located at the rear end portion of the firing pin and a sealing member that seals the piston to the side wall of the piston volume space, where the piston and the firing pin move forward in the fuse cap in response to overpressure in the enclosed space of the fuse tube. Advantageously, the firing pin has multiple uses, namely electrical fuse triggering, pressure release, and overpressure indication.

[0025] According to at least one embodiment, the fuse can include at least one pressure relief chamber that is connected to the piston volume space through a side channel in the fuse cap housing. The pressure relief chamber allows gas to escape into the chamber to allow the firing pin including the piston to move forward in response to overpressure behind the piston of the firing pin.

[0026] Other features and advantages of the present invention will become apparent when studying the appended claims and the following description. Those skilled in the art will recognize that different features of the present invention can be combined to create embodiments other than those described below without departing from the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] These and other aspects of the present invention will now be described in more detail with reference to the drawings showing exemplary embodiments of the present invention, in which:

[0028] Figure 1 An exemplary electrical fuse according to an embodiment of the present invention is shown;

[0029] Figure 2A An exemplary fuse cap according to an embodiment of the present invention is shown;

[0030] Figure 2B is Figure 2A an enlarged view of the fuse cap in;

[0031] Figure 3A shows an exemplary fuse cover according to an embodiment of the present invention;

[0032] Figure 3B is Figure 3A an enlarged view of the fuse cover in [reference], where the overvoltage triggering device is in the first state;

[0033] Figure 3C is Figure 3A an enlarged view of the fuse cover in [reference], where the overvoltage triggering device is in the second state; and

[0034] Figure 4 shows an exemplary fuse cover according to an embodiment of the present invention. Detailed Description

[0035] In this detailed description, various embodiments of the present invention are described herein with reference to specific implementation manners. When describing the embodiments, specific terms are used for clarity. However, the present invention is not intended to be limited to the specific terms selected. Although specific exemplary embodiments are discussed, it should be understood that this is for illustrative purposes only. Those skilled in the relevant art will recognize that other components and configurations can be used without departing from the scope of the present invention.

[0036] Figure 1 is a cross-section of the electrical fuse 100. The electrical fuse 100 includes a fuse tube 102 that forms a closed space 104. The fuse tube 102 is arranged in a fuse panel 106, and multiple electrical fuses can be arranged in the fuse panel 106. The fuse panel is part of a pressurized tank 108 that encloses a volume space 110, and the pressure in the volume space 110 is maintained higher than the pressure in the closed space 104 of the fuse tube. In one example, the pressure in the closed space 104 of the fuse tube is close to atmospheric pressure.

[0037] The electrical fuse 100 further includes a fuse cover 112 that seals an opening 114 leading to the closed space 104 in the fuse tube 102. That is, the fuse tube 102 is a sealed closed space 104, preferably having atmospheric pressure. One end of the fuse tube 102 is sealed by a cap 103.

[0038] The electrical fuse 100 includes a striker 116 that is received within and longitudinally passes through a fuse cover housing 113. The striker 116 is movable along a longitudinal axis 130. When the fuse 100 is actuated or triggered - i.e., "blown" - the striker 116 pops forward along the longitudinal axis 130, away from the fuse tube 102 in the forward direction 118 along the longitudinal axis 13. The forward movement of the striker 116 causes actuation of a rod 120 that is coupled to a mechanism 122, thereby interrupting the current in the electrical phase of the fuse 100.

[0039] The can 108 is pressurized with gas to ensure dielectric tolerance between different phases in the fuse panel. Typical applications are so-called gas-insulated switchgear (GIS) in the voltage range from 5 kV to 50 kV, such as 12 kV, 24 kV, 36 kV or 40.5 kV.

[0040] The gas used as dielectric medium can be air, dry air, N 2 , CO 2 or a mixture of two or three of N 2 , O 2 and CO 2 In an exemplary embodiment, the dielectric medium is a mixture of air, fluoroketone and / or AirPlus.

[0041] It is desirable to increase the pressure difference between the can volume space 110 and the fuse tube enclosed space 104, especially when switching to more environmentally friendly gases that require higher pressures to achieve sufficient insulation between the phases. However, higher pressures are also associated with a higher risk of leakage between the overpressure can 108 and the sealed fuse tube 102. For example, if a leak occurs, the overpressure will create a force on the fuse cover 112, which has the potential to harm the operator removing the fuse cover 112. Embodiments of the present disclosure are directed to reducing the risk of potentially harmful conditions due to leakage between the overpressure can 108 and the sealed fuse tube 102.

[0042] Figure 2A and Figure 2B The close-up views in

[0043] show an exemplary fuse cover 200 of an electrical fuse according to an embodiment. The fuse cover 200 includes a striker 116 that passes through the fuse cover 200, from the interior to the external environment 126.

[0044] AsFigure 2B As shown more clearly in the close-up view in [description of the figure], an overvoltage triggering device implemented as a burst element (here in the form of a bursting disc 204) is arranged in the channel 202, or more specifically at the opening 206 of the channel 202. The opening 206 is an internal opening of the channel 202 facing the enclosed space 104 of the fuse tube 102.

[0045] The bursting disc 204 is arranged to at least partially block the channel 202, or in some embodiments completely block the channel 202, such that in a first state where the bursting disc is intact, a certain pressure difference is allowed to exist between the enclosed space 104 of the fuse tube 102 and the external environment 126. The external environment 126 can be at atmospheric pressure. Preferably, the bursting disc 204 completely blocks the channel to ensure a dielectric barrier towards the operator side at the external environment 126. The bursting disc is preferably rounded or circular, i.e., disc-shaped. The bursting disc 204 can be made as part of the firing pin, i.e., integrally formed with the firing pin, or the bursting disc is a separate component inserted into the channel 202.

[0046] However, due to a possible leak between the enclosed space 104 of the fuse tube 102 and the pressurized tank 108, the pressure in the enclosed space 104 of the fuse tube 102 may become excessive, causing the bursting disc 204 to rupture. The rupture of the bursting disc 204 is a transition to a second state. When the bursting disc 204 ruptures, a fluid connection is formed between the enclosed space 104 of the fuse tube 102 and the external environment 126 through the channel 202, thereby providing a pressure relief path such that the pressure in the enclosed space 104 equals the pressure of the external environment 126.

[0047] In other words, the bursting disc 204 is designed and sized to maintain the channel 202 at least partially blocked in the first state when the pressure difference between the enclosed space 104 and the external environment 126 is below a certain predetermined threshold, and to burst in the second state to release the overpressure in the enclosed space 104 of the fuse tube 102.

[0048] Figure 3A An exemplary fuse cap 300 of an electrical fuse according to one embodiment is shown. The fuse cap 300 includes a firing pin 116 that passes through the fuse cap 300 from the interior 104 to the external environment 126.

[0049] The fuse cap 300 further includes a fuse cap housing 113 that houses the firing pin 116.

[0050] In this embodiment, the passage 304 through the fuse cover 300 passes through the fuse cover housing 113 to connect the enclosed space 104 in the fuse tube 102 with the environment 126 outside the fuse tube 102. The passage includes a first opening, such as an inlet 306 for pressure release that faces and is in fluid connection with the enclosed space 104 in the fuse tube 102, and a second opening, such as an outlet 308 that faces the external environment 126.

[0051] In this embodiment, the overpressure triggering device 310 is arranged in the passage 304 to at least partially block the passage 304.

[0052] Go to Figure 3B , which is a close-up view of the passage 304 in the fuse cover housing 113. The overpressure triggering device 310 includes a piston 312 that is arranged in a piston volume space 314 in the passage 304. In addition, a pin 316 is connected to the piston 312. The pin 316 and the piston 312 can be made as a single device, for example, formed as an integral piece.

[0053] The piston volume space 314 forms a wider part of the passage 304 to accommodate the piston 312. The width or diameter of the piston 312 is smaller than the width or diameter of the piston volume space 314, but larger than the width or diameter of the adjacent parts 304a, b of the passage 304. In other words, the piston 312 cannot escape from the piston volume space 314.

[0054] The overpressure triggering device 310 further includes a spring 318 that biases the piston 312 in the passage 304 towards the opening 306 in the passage 304 that faces the enclosed space 104 in the fuse tube 102. The spring 318 is arranged concentrically with the pin 316 and is radially outside the pin 316. That is, the pin passes through the central hole of the axial spring 318.

[0055] The transition of the overpressure triggering device 310 from the first state to the second state is that the piston 312 and the pin 316 move in the passage 304 in response to overpressure that appears in the enclosed space 104 of the fuse tube 102 due to a leak between the enclosed space 104 of the fuse tube and the pressure tank 108.

[0056] Figure 3B The overpressure device 310 in its first state is shown, in which the piston 312 is in the rear position and is held in the rear position by the spring 318, thus preventing the piston from moving forward towards the front opening 308 of the passage 304.

[0057] Figure 3CShows the overvoltage device 310 in its second state, in which the piston 312 is in the front position. The overpressure in the fuse tube enclosed space 104 connected to the opening 306 forces the piston 312 to move forward in the piston volume space 314. The piston 312 has compressed the spring 318. That is, the force exerted by the overpressure on the rear side 312a of the piston exceeds the spring force of the spring 318. This causes the pin 316 to move at least partially out of the channel 304 to provide an indication of overpressure outside the fuse tube 102. Here, "at least partially" means that only a part 316a of the pin 316 protrudes outward through the opening 308 of the channel 304. The movement of the piston 312 provides a partial pressure release from the inside of the fuse tube enclosed space 104.

[0058] The protrusion of the pin 316 from the channel 304 into the external environment can indicate to the user the presence of overpressure inside the fuse tube enclosed space 104. Therefore, the user should be cautious when removing the fuse cover 300.

[0059] The sealing member 320 is arranged in the piston volume space 314 to at least partially seal the channel 304 when the piston 312 is in the front position. Under the influence of the overpressure in the fuse tube enclosed space 104, the piston 312 presses against the sealing member 320. Therefore, there is also overpressure in the piston volume space 314 behind the piston 312 (i.e., the part of the volume space 314 facing the rear side 312a of the piston 312). Therefore, the piston 312 moves in the piston volume space 314 from Figure 3B the rear position in Figure 3C to the front position in

[0060] Once in the front position, the piston 312 and the sealing member 320 at least partially seal the channel 304. This causes the piston 312 to remain in the front position and the pin 316 to remain protruding outward through the opening 308, and the spring 318 does not push the piston 312 back in the piston volume space 314.

[0061] In other possible embodiments, the sealing member 320 is attached to the piston 312 to seal between the piston and the wall 321 of the piston volume space 314.

[0062] Figure 4Shows an exemplary fuse cover 400 of an electrical fuse according to one embodiment. The fuse cover 400 includes a firing pin 416 that passes through the fuse cover 400 from the interior 104 through a channel 401 in the fuse cover housing 428 to the external environment 126. The channel 401 has an opening 403.

[0063] The firing pin 416 includes an overpressure triggering device in the form of a piston 418 located at the rear end portion 420 of the firing pin 416. The piston 418 is located near the internal opening 403 of the channel 401 facing the fuse tube enclosed space 104. In addition, a sealing member 422 (such as a washer) is arranged in a groove of the piston 418 to seal against the side wall 424 of the piston volume space 426. The piston volume space 426 is located at the rear end of the fuse cover housing 428. The rear side 418a of the piston 418 faces the fuse tube enclosed space 104, while the front side 418b of the piston 418 faces the opposite direction.

[0064] If a leak occurs between the fuse tube 102 and the overpressure tank 108, the overpressure exerts a force on the rear side 418a of the piston 418, which acts as an overpressure triggering device, thereby pushing the piston 418 and further pushing the firing pin 416 forward 118 in the fuse cover 400 towards the external environment 126. The movement of the firing pin 416 triggers the mechanism 122, thereby cutting off the current in the fuse electrical phase.

[0065] To ensure a low pressure in the piston volume space 426 in front of the piston 418 (i.e., the part of the piston volume space 426 facing the front side 418b of the piston 418), the fuse cover 400 includes at least one pressure relief chamber 430 that is connected to the piston volume space 426 through a side channel 432 in the fuse cover housing 428.

[0066] Thus, when the piston 418 is pushed forward towards the external environment 126 by the overpressure in the volume space 104 of the fuse tube 102, the gas in the piston volume space 426 can escape through the side channel 432 into the pressure relief chamber 430. This prevents the pressure in the piston volume space 426 in front of the piston 418 facing the side 418b from becoming too high and preventing further movement of the piston 418.

[0067] Although the invention has been described with reference to specific exemplary embodiments, many different variations, modifications, etc. will become apparent to those skilled in the art.

[0068] In addition, those skilled in the art can understand and implement variations of the disclosed embodiments by studying the drawings, the disclosure, and the appended claims when practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used advantageously.

Claims

1. A fuse (100), comprising: A fuse tube (102) forming a closed space (104) that can be arranged in a pressurized tank (108), the pressure of the pressurized tank (108) being maintained higher than the pressure in the closed space (104) of the fuse tube (102), A fuse cover (112, 200, 300, 400) seals an opening (114) in the fuse tube (102) leading to the closed space (104), the fuse cover (112, 200, 300, 400) comprising: a striker (116) configured to move in the fuse cover (112, 200, 300, 400) when the fuse is triggered, a fuse cover housing (113, 428) which accommodates the striker (116), a passage (202, 304, 401) passing through the fuse cover (112, 200, 300, 400) connecting the enclosed space (104) in the fuse tube (102) and the environment (126) outside the fuse tube (102), wherein the passage (202) is located in the striker (116), and An overpressure triggering device (204, 310, 418) is arranged in the passage (202, 304, 401) or at an opening (206, 403) of the passage (202, 304, 401) to at least partially block the passage (202, 304, 401), the overpressure triggering device (204, 310, 418) being configured to change from a first state to a second state in response to an overpressure in the enclosed space (104) of the fuse tube (102) caused by a leakage between the enclosed space (104) of the fuse tube and the pressurized tank (102).

2. The fuse (100) according to claim 1, wherein: The overpressure triggering device is a bursting element (204) which is configured to keep the passage at least partially blocked in the first state and to burst in the second state to release the overpressure in the fuse tube enclosure.

3. The fuse according to claim 2, wherein: The burst element is configured to keep the passageway fully blocked in the first state.

4. The fuse (100) according to any one of claims 2 and 3, wherein: The bursting element (204) is arranged at an inner opening (206) of the passage (202), and the opening (206) faces the closed space (104) of the fuse tube (102).

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