CN218160043U - Excitation protector for two-way or multi-way circuit breaking - Google Patents

Abstract

The invention relates to the field of electric power and new energy automobiles, and particularly provides a two-way or multi-way circuit breaking excitation protection device which comprises an excitation source, a piston structure and at least two conductors arranged at intervals, wherein at least one end of each conductor is not connected with each other; the impact end of the piston structure is provided with a cutting end corresponding to each conductor, and each conductor and each cutting end of the piston structure are arranged side by side or in a staggered manner; when the excitation source receives the trigger signal to act, the piston structure can simultaneously break or break all conductors according to time sequence. The invention realizes the rapid cut-off protection of a multi-load circuit or a multi-branch circuit, and forms a physical fracture between each load or branch circuit, thereby avoiding the mutual interference or damage caused by the continuous reverse current or interference current between the loads or the branch circuits.

Description

Excitation protector for two-way or multi-way circuit breaking

Technical Field

The invention relates to the field of power control and electric automobiles, in particular to an excitation protection device with a two-way or multi-way circuit breaking function.

Background

Two types of current circuit protection devices exist, thermal fusion fusing and mechanical disconnection. The traditional thermal fuse realizes protection by fusing and disconnecting a circuit through a melt, and has the defects of high power consumption (large heat productivity), larger volume and weight, limited current impact resistance, long breaking time, uncontrolled breaking process and the like.

The application range of mechanically disconnected protection devices is gradually expanded at present. The general structure composition is as follows: the electronic ignition device acts to release high-pressure gas to drive the piston to displace, and the piston disconnects the conductive busbar (conductive plate) to disconnect a circuit, so that circuit protection is realized. The protection device for mechanical disconnection has the characteristics of high corresponding speed, high breaking capacity and the like.

In order to meet the requirements of various circuits, a protection device with multiple excitation sources, disclosed in chinese patent ZL2021225928293, realizes multiple circuit protection in one device through multiple groups of excitation sources (electronic ignition devices), pistons and conductive plates. Although multiple circuit protection can be implemented in one device, it has certain drawbacks: because the influence time of the plurality of excitation sources and the corresponding pistons always has precedence, the disconnection of a multi-path circuit at the same time cannot be ensured; when the circuit needs to be disconnected in sequence, a plurality of groups of external trigger signal circuits need to be matched for realization.

In order to solve the above defects, chinese patent ZL2021225949001 discloses an excitation protection device with multi-path air pressure distribution, which realizes the requirements of simultaneous disconnection or successive disconnection through an excitation source (electronic ignition device), a plurality of groups of piston structures and a conductive plate and through different air paths. Although the control is relatively easy, the difficulty in manufacturing is relatively high, because the size of the gas circuit is difficult to control, the gas pressure entering each gas circuit cannot be ensured to be the same, and the piston cannot be ensured to move at the same speed, so that the control of simultaneously disconnecting the multiple groups of pistons and the corresponding conductive plates is difficult, and the simultaneous disconnection of multiple groups of circuits is realized. Similarly, when the sequential disconnection is required, the multi-path air pressure distribution is difficult to control and realize.

In the mechanical breaking protection device, the fracture is generally an air fracture, and the breaking capacity is poor, so in order to improve the breaking capacity, the breaking capacity is generally improved by connecting a melt in parallel on a conductive plate. For example, the excitation protection device for multi-path air pressure distribution disclosed in the above-mentioned chinese patent ZL2021225949001 improves the breaking capacity by connecting the melts in parallel. The parallel melt is also protected by mechanical disconnection. Since the housing for the parallel melt through which the piston passes generally matches the size of the cut end of the piston, it is necessary for the cut end of the piston to enter the channel to break the parallel melt. However, due to manufacturing and assembly differences, it is difficult to ensure that the cut-off end of the piston is aligned with the channel of the housing in which the parallel melts are located, and the cut-off end is just as large as the size of the housing, and this may cause failure of the operation. When the parallel connection melts are in a plurality of groups, the parallel connection melts can not be guaranteed.

Disclosure of Invention

The invention aims to provide an excitation protection device for two-way or multi-way circuit breaking, which can ensure that two-way or multi-way circuits are broken simultaneously or according to time sequence, and the circuits do not interfere with each other. Meanwhile, by changing the push plate structure of the parallel fuse, the possibility of action failure caused by manufacturing and assembling errors is solved, the disconnection of the fused mass in the parallel fuse is ensured, and the working reliability of the excitation protection device is improved.

In order to solve the technical problem, the technical scheme provided by the invention is a two-way or multi-way circuit breaking excitation protection device, which comprises an excitation source, a piston structure and conductors, wherein the conductors comprise at least two conductors arranged at intervals, and at least one end of each conductor is not connected with each other; the impact end of the piston structure is provided with a cutting end corresponding to each conductor, and each conductor and each cutting end of the piston structure are arranged side by side or in a staggered manner; the conductors corresponding to the cut ends of the piston structures are insulated; when the excitation source receives the trigger signal action, the piston structure can break off all the conductors simultaneously or in time sequence.

Preferably, one ends of at least two of the conductors are integrally connected.

Preferably, an insulating spacer is provided between the connection ends of the conductors.

Preferably, the impact end of the piston structure is provided with notches corresponding to the conductors at intervals, and the notches are the cut-off ends.

Preferably, a pre-fracture is arranged on each conductor, and the shape of the bottom of the notch of each cutting end of the piston structure is matched with the shape of the surface of the pre-fracture of each conductor.

Preferably, fuses are connected in parallel on the conductors, and melt assemblies which correspond to the conductors one by one and are connected with the conductors in parallel are arranged in the fuses in a penetrating mode; each melt component comprises at least one melt, and when each melt component comprises more than two melts, the more than two melts are connected in parallel with each other; the melt assemblies are respectively positioned in different arc extinguishing chambers, and the arc extinguishing chambers are filled with arc extinguishing medium.

Preferably, the fuse comprises a fuse housing, a cover plate and a plurality of channels penetrating through the fuse housing and the cover plate, at least two groups of the melt assemblies penetrate between the fuse housing and the cover plate, and the melt in each group of the melt assemblies penetrates through at least one channel; a melt cutter penetrates through each channel; a melt cutter pushing device is arranged between the melt cutter and the corresponding conductor; and after the piston structure is disconnected with each conductor, the melt cutter pushing device and each melt cutter can be pushed to disconnect the melt assembly corresponding to the conductor.

Preferably, a cavity matched with the shape of the impact end of the piston structure is arranged between the conductor and the melt cutter pushing device, and the melt cutter pushing device is positioned through the cavity and the melt cutter.

Preferably, one end of the melt cutter pushing device facing the conductor is arranged in the cavity, and an accommodating groove for accommodating the disconnected part of the conductor is arranged on the end face of one end of the melt cutter pushing device in the cavity.

Preferably, the melt cutter comprises a push block and a guide block, and the melt passing through each channel is clamped between the push block and the guide block.

Preferably, the cover plate is of a concave structure, and the melt cutter pushing device is located in the concave structure of the cover plate.

Preferably, a buffer device is arranged at the bottom of the fuse.

The invention utilizes the excitation source to push the piston structure with two or more cut-off ends, simultaneously cuts off two or more circuit branches connected by conductors, and is matched with two or more corresponding arc-extinguishing melt branches under necessary conditions, thereby realizing the rapid cut-off protection of a multi-load circuit or a multi-branch circuit, and forming a physical fracture between each load or branch circuit, thereby avoiding the mutual interference or damage caused by the continuous occurrence of reverse current or interference current between the loads or the branch circuits.

According to the fuse, the fuse cutter pushing device is additionally arranged between the fuse cutter and the conductor of the fuse through the parallel fuse, and when manufacturing or assembling errors exist, the piston structure can be ensured to drive the fuse cutter pushing device to act, disconnection of parallel fuses is ensured, and working reliability is improved; meanwhile, the impact force of the piston structure is uniformly dispersed to the melt cutter pushing device through the melt cutter pushing device, so that the melt cutter is uniformly stressed.

The invention also improves the product integration level, is more convenient for the wiring of the electric circuit and reduces the use cost of customers.

Drawings

Fig. 1 is a schematic perspective view of embodiment 1.

FIG. 2 is a schematic sectional view of example 1.

Fig. 3 is a schematic diagram of the two-conductor structure of embodiment 1.

Fig. 4 is a schematic view of the fuse structure of embodiment 1.

FIG. 5 is a schematic view of the melt assembly of example 1.

Fig. 6 is a schematic structural diagram of the piston of embodiment 1, wherein a diagram and B diagram are respectively schematic structural diagrams of the piston structure from different viewing angles.

Fig. 7 is a schematic diagram of the operation process in embodiment 1, in which fig. a shows a normal operation state, fig. B shows the operation process, and fig. C shows the operation end.

FIG. 8 is a schematic diagram of a conductor and fuse assembly and a fuse of example 2, wherein FIG. A is a schematic diagram of the conductor structure and FIG. B is a schematic diagram of the fuse assembly structure; and the diagram C is a structural schematic diagram of the fuse.

Fig. 9 is a schematic structural diagram of the excitation protection device of embodiment 2.

FIG. 10 is a schematic structural diagram of embodiment 3.

FIG. 11 is a schematic sectional view showing the structure of embodiment 3.

Fig. 12 is a schematic view of the structure of three conductors of embodiment 3.

Fig. 13 is a schematic view of the piston structure of embodiment 3.

Detailed Description

With respect to the above technical solutions, preferred embodiments are described in detail with reference to the drawings.

The positional relationship "front, back, left, right, upper, lower, top, bottom, etc" in the following embodiments is described only for the purpose of facilitating understanding of the positional relationship, and does not constitute a limitation of the positional relationship.

Example 1

The excitation protection device, see fig. 1 to 6, comprises a butted upper housing 10 and a lower housing 11. A first conductor 21 and a second conductor 22 are provided between the upper case 10 and the lower case 11. The first conductor 21 and the second conductor 22 are arranged at a distance. The two ends of the first conductor and the second conductor which are positioned outside the upper shell and the lower shell are respectively connecting ends which can be connected with an external circuit. An insulating spacer 23 is provided between the connection ends of the first and second conductors 21 and 22 located outside the upper and lower housings. Referring to fig. 3, the first conductor 21 and the second conductor 22 are respectively provided with a pre-fracture (211, 221), and weak points, such as V-shaped grooves in the present embodiment, or U-shaped grooves or other structures that reduce mechanical strength, are arranged on the upper and lower surfaces of both sides of the pre-fracture. Under the action of mechanical force, the conductor is easily disconnected from the pre-breaking position.

The upper casing 10 and the lower casing 11 are respectively provided with through holes, and a smaller cavity 48 and a larger cavity are sequentially arranged in the through holes of the lower casing 11 from top to bottom. The through hole of the upper shell 10 is step-shaped, an excitation source protective sleeve 12 is installed at the step at the upper part of the through hole, an excitation source 13 is installed in the excitation source protective sleeve 12, the excitation source 13 is fixed on the excitation source protective sleeve 12 through an upper protective cover 14, and meanwhile, the excitation source protective sleeve 12 is installed on the upper shell 10. The excitation source 13 is an electronic ignition device which can trigger ignition according to a received trigger signal, and high-pressure gas is released as a driving force.

The piston structure 30, see fig. 2 and 6, is mounted in the through hole of the upper housing 10 between the excitation source 13 and the first and second conductors 21, 22. The upper end edge of the piston structure 30 is provided with a limiting device 301, and the limiting device is clamped at the inclined plane of the through hole of the upper shell 10 to form position limitation. A sealing device 302 is disposed between the piston structure 30 and the through hole contact surface of the upper housing 10. The piston structure 30 is in sealing contact with the through hole contact surface of the upper housing 10, and may be implemented by an interference structure, or may be implemented by the sealing device of this embodiment.

The impact end of the piston structure 30 has two notches spaced apart to form two cut ends 303, and a sufficient insulation distance is maintained between the two cut ends 303. The smaller cavity 48 in the lower housing 11 is shaped to match the profile shape formed by the two cut-off ends of the piston structure 30. One cut end corresponds to one conductor, i.e., the pre-cut of the first conductor 21 corresponds to one cut end of the piston structure and the pre-cut of the second conductor 22 corresponds to the other cut end of the piston structure. The bottom of the notch of each cut-off end 303 is in the shape of a groove, which is matched with the shape of the upper surface of the pre-cut of the conductor. When the two cutting ends 303 of the piston structure 30 are located at the pre-cut positions of the two conductors, the pre-cut positions of the two conductors are insulated and isolated through two gaps which are arranged at intervals. After the conductors are cut, the two cut ends of the impact end of the piston structure carry the pre-cut openings of the two conductors into the cavity 48 of the lower housing.

A fuse 40 is connected in parallel below the first and second conductors 21 and 22, and referring to fig. 4, the fuse 40 is located in a cavity having a large through hole of the lower case 11, a buffer 50 is provided at the bottom of the fuse 40, and a bottom protective cover 15 closes the bottom of the lower case 11. Fuse 40, includes a fuse housing 41, a cover plate 42, and two sets of fuse elements (43, 44). The cover plate 42 is of a concave configuration, enclosing the fuse housing 41. The fuse element (43, 44) is inserted into the fuse housing 41 and the cover plate 42, respectively, and is located in different arc extinguishing chambers, and the arc extinguishing chambers are filled with arc extinguishing medium 49. Melt assembly 43 position corresponds to the position of first conductor 21 and melt assembly 44 position corresponds to the position of second conductor 22. The two ends of the fuse element assemblies (43, 44) are located outside the fuse housing 41, respectively, to facilitate connection in parallel with the first and second conductors. The resistance of the melting body components (43, 44) is far higher than that of the first conductor and the second conductor, so that the current can flow through the first conductor and the second conductor under the normal working state, and the current can flow through the melting body components (43, 44) connected in parallel with the first conductor and the second conductor only after the first conductor and the second conductor are disconnected.

Melt assembly 43 and melt assembly 44 may be identical in construction or may be different. Referring to fig. 5, the melt assembly 43 and the melt assembly 44 have the same structure, and are respectively connected in parallel with two melts, and both ends of the two melts are integrally connected. A pre-breaking opening (431, 441) is respectively arranged on the melts of the melt assembly. The fuse housing 41 and the cover plate 42 at the position of the pre-cut on the fuse assembly (43, 44) are provided with a channel 45 which penetrates through the upper and lower ends of the fuse housing 41 and the cover plate 42. The number of melts in parallel can also be different between the melt assembly 43 and the melt assembly 44 according to actual needs.

A group of melt cutters 46 are correspondingly arranged at each pre-fracture position of each melt assembly, namely one end of each melt cutter 46 penetrates through the channel 45, and the other end of each melt cutter is positioned above the cover plate 42. A melt cutter pushing device 47 is arranged above the melt cutter 46 and used for pushing the melt cutter 46 to disconnect the melt assembly. The melt cutter pushing device 47 is located in a concave configuration above the fuse cover plate 42. The upper end of the melt cutter pushing device 47 contacts the lower end of the smaller cavity 48 of the lower housing 11. One end of a cavity 48 of the lower shell 11, which is positioned on one side of the conductor, is clamped at a weak breaking position at two ends of the conductor pre-break, the upper end of the melt cutter pushing device 47 is positioned in the lower end of the cavity 48, and the upper end face of the melt cutter pushing device 47 forms an accommodating groove, wherein the shape of the accommodating groove is the same as the lower surface structure of the conductor pre-break.

The melt cutter 46 comprises a push block and a guide block which are arranged at the position of the pre-fracture of the melt, one end of the push block is positioned above the cover plate 42, the push block and the guide block are mutually matched to clamp the pre-fracture of the melt in the middle, and the contact surface between the fuse shell and the cover plate is limited by a limiting block arranged on the guide block. A melt cutter pusher 47 is located above the pusher.

Among the above-mentioned each part, upper and lower casing, piston structure, fuse-element cutter thrust unit, fuse-element cutter are all electrically insulating material.

The operation principle of the embodiment 1 is as follows:

when any circuit has fault current, the excitation source 13 receives a trigger signal to trigger ignition, releases high-pressure gas, drives the piston structure 30 to move after overcoming limit, two cutting ends of the piston structure respectively cut off pre-cuts on corresponding conductors and then enter the cavity 48 to continuously move and extrude to generate electric arcs, and because the piston cutting ends at the conductor cuts directly enter the cavity 48, an insulation and mutual noninterference state is actually formed between the first conductor and the second conductor cuts. When the first conductor and the second conductor are disconnected, most of the current flowing through the first conductor and the second conductor flows through the melt assembly connected in parallel with the first conductor and the second conductor, and the electric arc generated at the disconnected position of the first conductor and the second conductor is relatively small and is rapidly extinguished.

The piston cut end is in sealing contact or small gap contact with the cavity 48, the arc is extruded in the small cavity 48, and arc extinction is prolonged through extrusion. And as the piston structure continues to displace, the cut-off end of the piston structure brings the conductor cut-off part into contact with the melt cutter pushing device 47 to wrap the conductor cut-off part, and the piston structure continues to push the melt cutter pushing device 47 and the melt cutter 46 to displace together to cut off all melt in the melt assembly. After the melt assembly is disconnected, an arc generated after the melt assembly is disconnected is extinguished through the arc extinguishing medium.

Because the bottom of the fuse is provided with the buffer device, the impact force of the melt cutter after the melt is cut off can be buffered. Because the melt cutter pushing device 47 has a large area, even if the manufacturing and assembling errors occur, the cutting end of the piston structure can contact the melt cutter pushing device; meanwhile, the area of the area where the melt cutter is located is covered by the melt cutter pushing device, and the melt cutter pushing device can be guaranteed to push the melt cutter. Therefore, by adding the melt cutter pushing device, action failure possibly caused by manufacturing and assembling errors is avoided, and the working reliability is improved; meanwhile, the impact force of the piston structure is uniformly dispersed on the melt cutter pushing device, the melt cutter is guaranteed to bear uniform vertical downward pressure, and stable motion is more reliable when the multi-path arc-extinguishing melt structure is cut off.

Meanwhile, because only one excitation source and one piston structure are arranged, each cut-off end of the piston structure can ensure simultaneous action, and the possibility of inconsistent response speed due to a plurality of excitation sources or a plurality of pistons is avoided.

In this embodiment, the first conductor and the second conductor are arranged in the same horizontal direction, the two cutting ends of the piston structure are arranged in parallel, and the first conductor and the second conductor are cut simultaneously.

In practical application, the first conductor and the second conductor can be arranged in the same horizontal direction, the two cutting ends of the piston structure are arranged in a high-low mode, the two cutting ends of the piston structure are different in distance from the conductor, and the first conductor and the second conductor are disconnected according to time sequence.

The first conductor and the second conductor can also be arranged in a staggered mode, two cutting ends of the piston structure are arranged in a flush mode, the distance between the two cutting ends of the piston structure and the conductor is different, and the first conductor and the second conductor are disconnected according to time sequences.

The first conductor and the second conductor can also be arranged in a staggered mode, the two cutting ends of the piston structure are arranged in a high-low mode, and the first conductor and the second conductor are cut off simultaneously or in a time sequence mode.

All of the melts of the melt assembly may be broken off simultaneously or in a time sequence. When time-sharing disconnection is required, the disconnection can be realized by the following modes: the parallel melt pre-fracture surfaces in each melt assembly can be positioned on the same horizontal plane or arranged in a high-low mode; the length of the melt cutter can be different, and the melt cutter can be driven only by meeting the requirement of the displacement process of the melt cutter pushing device.

Compared with the prior art, the present embodiment has the advantages that:

in a double-circuit power supply system, an excitation source pushes a piston structure to simultaneously cut off two conductors, and the two conductors are continuously matched with two independent arc extinguishing assemblies to complete breaking, so that the control difficulty of a double-circuit system is reduced, the system wiring is simplified, and the cost is reduced.

In the two-way circuit which is mutually associated and synchronously and cooperatively works, instantaneous simultaneous disconnection of the circuit is realized, mutual interference between circuits or loads is avoided, and unnecessary property damage is prevented.

When two groups of circuits need to be cut off sequentially according to time sequence, the cutting off can be realized through a physical structure, and the protection is more reliable.

The excitation protection device in this embodiment may be used for two-way circuit protection. When three-way circuits, four-way circuits and the like are required to be protected simultaneously, the number of conductors can be increased according to requirements, for example, three conductors, four conductors and the like are required, the cutting ends of the corresponding pistons are correspondingly three, four and the like, and when necessary, three melt components, four melt components and the like can be correspondingly increased.

Example 2

The method is improved on the basis of the embodiment 1. Embodiment 2 is applied to a circuit node of a complex power circuit and provides breaking protection at the node. Referring to fig. 8, the conductor 60 has three connection ends, the larger of which is a common end 61 and the other two smaller connection ends (62, 63) are two branch ends. The fuse element 70 of the arc-extinguishing fuse 40a below the conductor 60 in parallel corresponds in structure thereto. The common end 71 of the melt assembly 70 is connected to the common end 61 of the conductor and the two branch ends (72, 73) of the melt assembly are connected to the corresponding branch ends (62, 63) of the conductor. The two branches of the melt assembly 70 are placed in different arc quenching chambers, respectively.

The physical form of the excitation protection device with three connection terminals, see fig. 9, provides an insulating spacer 23 between the two connection terminals (62, 63) located outside the housing. Other structures and principles are the same as those of embodiment 1. In this embodiment, both branches of the conductor need to be disconnected simultaneously.

The advantages of example 2 are: the method can be applied to key nodes of a complex power circuit, and can be used for carrying out quick disconnection protection on the nodes and forming insulation protection among the nodes. The protection circuit can be applied to simultaneous protection of a plurality of parallel loads of the same power supply, and when one of the parallel loads fails, all circuits can be quickly cut off, so that the loss is prevented from being enlarged. The wiring cost of the protection of the parallel circuit is reduced, and the integration level of the product is improved.

Example 3

On the basis of embodiment 1, the number of conductors is increased. The two independent conductors are increased to three, see fig. 10-13, a first conductor 21, a second conductor 22, a third conductor 24. In order to reduce the volume of the excitation protection device, the three conductors are arranged in a spatially offset manner, such as in a delta shape, an inverted triangle or other forms. In this example, a delta-shaped arrangement. Correspondingly, the cutting end of the piston structure 30a is also changed correspondingly, and has three cutting ends with three insulation intervals, the cutting end corresponding to the second conductor 22 arranged higher in the middle is arranged at a high position, and the cutting end corresponding to the first conductor 21 and the third conductor 24 arranged at two sides of the second conductor 22 in a staggered low position is arranged at a low position. And insulating isolation plates 23 are respectively arranged outside the excitation protection device shell and between the adjacent two conductor connecting ends.

The working principle is as follows:

when one circuit has fault current, the excitation source receives the trigger signal to act to drive the piston structure to overcome the displacement of the limiting structure, and simultaneously the first conductor, the second conductor and the third conductor are disconnected according to the time sequence or the distance between the disconnecting end of the piston structure and the conductors, and then the melt component connected with the first conductor, the second conductor and the third conductor in parallel is disconnected.

The embodiment can be applied to systems such as three-phase power supply or three-phase motors, and the like, and can be used for quickly disconnecting three power supply lines to form insulation and protect the three power supply lines. The cutter height difference protection circuit can be applied to three mutually-associated lines, and the disjunction protection is realized according to a certain time sequence by utilizing the cutter height difference. It can be extended to multi-channel power supply systems, which provide simultaneous protection from disconnection.

In the above embodiment, the number of the conductors is two or three, and according to actual needs, the number of the conductors may be multiple, and correspondingly, the number of the cut-off ends of the piston structure also needs to be correspondingly multiple. When the conductors are arranged in a plurality, one ends of two conductors can be integrally connected, and other conductors are independently arranged in parallel according to the actual circuit requirement; or grouping, one end of one group of conductors or a plurality of groups of conductors are connected integrally, and other conductors are independently arranged in parallel. Accordingly, the corresponding parallel melt components may vary depending on the conductor shape.

Claims (12)

1. A two-way or multi-way circuit breaking excitation protection device comprises an excitation source, a piston structure and conductors, and is characterized by comprising at least two conductors which are arranged at intervals, wherein at least one end of each conductor is not connected with each other; the impact end of the piston structure is provided with a cutting end corresponding to each conductor, and the cutting ends of each conductor and the piston structure are respectively arranged side by side or in a staggered manner; insulation is arranged between the conductors corresponding to the cutting ends of the piston structures; when the excitation source receives the action of the trigger signal, the piston structure can simultaneously disconnect or disconnect each conductor according to time sequence.

2. Excitation protection device according to claim 1, characterized in that at least two of said conductors are integrally connected at one end.

3. Excitation protection means according to claim 1, characterised in that an insulating spacer is provided between the connecting ends of the conductors.

4. The excitation protection device of claim 1 wherein the impact end of the piston structure is spaced apart by a gap corresponding to each of the conductors, the gap being the cut-off end.

5. The excitation protection device of claim 4 wherein a pre-break is provided in each of said conductors, and wherein the shape of the bottom of the gap at each cut end of said piston structure matches the shape of the pre-break surface of each of said conductors.

6. The excitation protection device according to any one of claims 1 to 5, wherein fuses are connected in parallel to the conductors, and fuse elements are arranged in the fuses in one-to-one correspondence with the conductors and in parallel to the conductors; each melt component comprises at least one melt, and when each melt component comprises more than two melts, the more than two melts are connected in parallel with each other; the melt assemblies are respectively positioned in different arc extinguishing chambers, and the arc extinguishing chambers are filled with arc extinguishing medium.

7. The excitation protection device of claim 6 wherein the fuse includes a fuse housing, a cover plate, and a plurality of passages through the fuse housing and the cover plate, at least two sets of the melt assemblies being disposed between the fuse housing and the cover plate, the melt in each set of the melt assemblies passing through at least one of the passages; a melt cutter penetrates through each channel; a melt cutter pushing device is arranged between the melt cutter and the corresponding conductor; the piston structure can push the melt cutter pushing device and the melt cutters to break the melt assemblies corresponding to the conductors after the conductors are broken.

8. The excitation protector of claim 7 wherein a cavity matching the shape of the impact end of the piston structure is provided between the conductor and the melt cutter pushing device, the melt cutter pushing device being positioned by the cavity and the melt cutter.

9. The excitation protector as claimed in claim 8 wherein the end of the melt cutter pushing means facing the conductor is disposed in the cavity and the end face of the melt cutter pushing means end in the cavity is provided with a receiving recess for receiving the break-away portion of the conductor.

10. The excitation protector of claim 7 wherein the melt cutter includes a push block and a guide block, the melt passing through each of the channels being sandwiched between the push block and the guide block.

11. The excitation guard of claim 7 wherein said cover plate is concave in configuration and said melt cutter pushing means is located in said concave configuration of said cover plate.

12. Excitation protection means according to claim 7, wherein a damping means is provided at the bottom of the fuse.

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