Secondary open circuit protection device for current transformer

Abstract

The utility model relates to a secondary open circuit protection device for a current transformer, which is characterized in that an insulating mounting seat is arranged in a secondary junction box, one side of the insulating mounting seat is provided with a trigger mounting hole, the other side of the insulating mounting seat is provided with a grounding element, and the grounding trigger element is supported by a spring and arranged in the corresponding trigger mounting hole in a floating manner; the grounding trigger element is correspondingly connected with a protected secondary terminal through a line, a limiting slot is formed in the insulating mounting seat, a limiting piece is arranged in the limiting slot, when the current transformer works normally, the grounding trigger element is limited through the limiting piece, a spacing distance is formed between the grounding trigger element and the grounding element, and when the secondary side of the current transformer is open-circuited, the grounding trigger element is closed. Local high-temperature melting of the limiting piece does not limit displacement of the grounding trigger element any more, and the grounding trigger element makes contact with the grounding element. The grounding protection device can be arranged in a secondary junction box, and when the secondary side of the current transformer is open-circuited, the grounding trigger element can reliably trigger to move and reliably contact with the grounding element to realize the purpose of grounding protection.

Description

Technical Field

[0001] This utility model relates to the field of current transformers, specifically a secondary open-circuit protection device for current transformers. Background Technology

[0002] A current transformer is a device that converts a large current in a power system into a smaller current through the principle of electromagnetic induction. The primary winding of a current transformer is connected in series in the power system, while the secondary winding is connected to the required measuring instruments, meters, or relay protection and automatic control devices through an external circuit. The secondary circuit of a current transformer must be connected to a load or directly short-circuited. If an open circuit occurs in the secondary circuit during normal operation of the current transformer, the magnetomotive force generated by the primary current is entirely used for excitation, causing the magnetic flux density of the iron core to increase sharply and reach saturation. This can easily generate a large open-circuit voltage at the secondary open circuit point, thereby endangering the safety of the product and maintenance personnel.

[0003] Currently, most open-circuit protection devices for current transformers are independent devices consisting of mechanical or electrical circuits placed in external cabinets. These devices suffer from high costs, inconvenient maintenance, and the need for additional space. For example, patent CN107785870B discloses a current transformer and its secondary open-circuit protection device, which includes a current transformer body, an open-circuit detection module, and a short-circuit protection module, both located outside the current transformer body. Another example is patent CN211183391U, which discloses an open-circuit protection device for current transformers. This device includes a mounting base, a current transformer body, and a connecting plate. The current transformer body includes a rectangular shell at the bottom and a line connection metal plate located above the rectangular shell. This device protects the line connection metal plate by using a fixing plate, an arc-shaped protective cover, a rotating shaft, and a magnetic block, thereby improving product safety performance. Utility Model Content

[0004] The purpose of this utility model is to provide a secondary open-circuit protection device for a current transformer, which can be installed in the secondary junction box, and when an open circuit occurs on the secondary side of the current transformer, the grounding trigger element can be reliably triggered to move and reliably contact the grounding element to realize the grounding state of the protected secondary terminal.

[0005] The objective of this utility model is achieved through the following technical solution:

[0006] A secondary open-circuit protection device for a current transformer includes an insulating mounting base, a grounding trigger element, a grounding element, and a limiting plate. The insulating mounting base is disposed in a secondary junction box, with a trigger mounting hole on one side and a grounding element on the other side. The grounding trigger element is floatingly disposed in the corresponding trigger mounting hole by a spring support, and is connected to the protected secondary terminal in the secondary junction box via a lead wire. The insulating mounting base has a limiting slot, and a limiting plate is disposed in the limiting slot. When the current transformer is working normally, the grounding trigger element is limited by the corresponding limiting plate and forms a gap distance with the corresponding grounding element. When an open circuit occurs on the secondary side of the current transformer, the limiting plate partially melts at high temperature and no longer limits the displacement of the grounding trigger element, and the grounding trigger element comes into contact with the corresponding grounding element.

[0007] The grounding trigger element is provided with a limiting protrusion, and the outer end of the trigger mounting hole is provided with a spring limiting stop. One side of the limiting protrusion cooperates with the corresponding limiting piece for limiting, and the other side is provided with a spring between it and the spring limiting stop. The spring is fitted onto the grounding trigger element.

[0008] The insulating mounting base has a trigger groove on the side away from the grounding trigger element, and the groove wall of the trigger groove has multiple sets of grounding mounting holes. The grounding element is installed in the corresponding set of grounding mounting holes. The number of trigger mounting holes on the other side of the insulating mounting base is the same as the number of sets of grounding mounting holes.

[0009] The limiting slot is perpendicular to the axial direction of the grounding trigger element, and the overall length of the limiting slot is greater than the overall length of each group of grounding mounting holes.

[0010] The grounding trigger element is set perpendicular to the grounding element.

[0011] The limiting plate is provided with a limiting through hole, and the trigger end of the grounding trigger element located inside the insulating mounting base passes through the limiting through hole, and the end face of the trigger end is spherical.

[0012] The insulating mounting base is elongated in shape and is located inside the secondary junction box on one side and mounted on the secondary junction board inside the secondary junction box.

[0013] The grounding trigger element is located on the outside of the insulating mounting base, and its connection end is connected to the protected secondary terminal in the secondary junction box via a line.

[0014] The advantages and positive effects of this utility model are as follows:

[0015] 1. This utility model utilizes a spring-loaded floating support to place the grounding trigger element in the corresponding trigger mounting hole, and uses a limiting plate in the limiting slot to limit the displacement of the grounding trigger element when the current transformer is working normally, so that it does not come into contact with the grounding element. However, when the secondary side of the current transformer is open-circuited, causing the limiting plate to melt locally at high temperature and unable to limit the displacement of the grounding trigger element, the grounding trigger element can reliably move under the action of the spring and reliably come into contact with the grounding element, thereby realizing the grounding state of the protected secondary terminal.

[0016] 2. The insulating mounting base of this utility model has multiple trigger mounting holes on one side for accommodating grounding trigger elements, and a trigger groove on the other side. The groove wall of the trigger groove has multiple sets of grounding mounting holes. At the same time, the insulating mounting base also has a limiting slot with a total length greater than the total length of each set of grounding mounting holes for installing a limiting piece that limits the displacement of the grounding trigger element. In this way, this utility model can flexibly select the number and position of the grounding trigger element and the grounding element according to actual needs. At the same time, the limiting slot has sufficient length for the limiting piece to move in the slot, which also facilitates the installation of the limiting piece and the grounding trigger element.

[0017] 3. The present invention is long and narrow in shape, with a compact structure that does not occupy too much installation space. During installation, the present invention can be placed inside one side of the secondary junction box without affecting the normal wiring of the secondary junction box.

[0018] 4. The limiting plate of this utility model is provided with a limiting through hole, and the trigger end of the grounding trigger element located inside the insulating mounting base passes through the limiting through hole and the end face is spherical. This makes it convenient for the trigger end to automatically slide into the limiting through hole under the action of the spring during installation, which can improve the installation efficiency. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of this utility model.

[0020] Figure 2 This is a schematic diagram of the working state of this utility model. Figure 1 ,

[0021] Figure 3 for Figure 2 AA view in

[0022] Figure 4 This is a schematic diagram of the working state of this utility model. Figure 2 ,

[0023] Figure 5 for Figure 4 BB view in

[0024] Figure 6 This is a schematic diagram of the installation state of this utility model in a secondary junction box.

[0025] Among them, 1 is a grounding trigger element, 101 is a limiting protrusion, 102 is a spring, 103 is a trigger end, 104 is a connection end, 2 is a grounding element, 3 is an insulating mounting base, 301 is a trigger groove, 302 is a limiting slot, 303 is a grounding mounting hole, 304 is a spring limiting stop, 305 is a trigger mounting hole, 4 is a limiting piece, 5 is a protected secondary terminal, and 6 is a grounding terminal. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings.

[0027] like Figures 1-6 As shown, this utility model includes an insulating mounting base 3, a grounding trigger element 1, a grounding element 2, and a limiting piece 4, wherein... Figure 1 and Figure 3 As shown, the insulating mounting base 3 has a trigger mounting hole 305 on one side, and the grounding trigger element 1 is floatingly mounted in the corresponding trigger mounting hole 305 by means of a spring 102. The insulating mounting base 3 has a grounding element 2 on the other side, and the grounding element 2 is perpendicular to the grounding trigger element 1. The insulating mounting base 3 has a limiting slot 302 in the middle, and the limiting slot 302 has a limiting piece 4 that limits the displacement of the grounding trigger element 1. Figure 6 As shown, the insulating mounting base 3 is located in the secondary junction box, and the grounding trigger element 1 is connected at its connecting end 104 outside the insulating mounting base 3 via a lead wire to the protected secondary terminal 5 inside the secondary junction box. The grounding element 2 is connected to the grounding terminal 6 via a line. Figure 3 and Figure 5 As shown, when an open circuit occurs on the secondary side of the current transformer, the open circuit voltage exceeds the withstand voltage of the limit plate 4 and is broken down. This causes the limit plate 4 to melt locally at high temperature and can no longer limit the displacement of the grounding trigger element 1. The grounding trigger element 1 is displaced under the action of the spring 102, and the trigger end 103 of the grounding trigger element 1 located inside the insulating mounting base 3 contacts the corresponding grounding element 2, thereby forming a ground short circuit state of the protected secondary terminal 5 of the current transformer, achieving the protection purpose.

[0028] like Figure 3 and Figure 5 As shown, in this embodiment, the grounding trigger element 1 is provided with a limiting protrusion 101, and the outer end of the trigger mounting hole 305 is provided with a spring limiting stop 304. One side of the limiting protrusion 101 cooperates with the corresponding limiting piece 4 for limiting, and the other side is provided with a spring 102 between it and the spring limiting stop 304. The spring 102 is fitted on the grounding trigger element 1.

[0029] like Figure 1As shown, in this embodiment, the insulating mounting base 3 has a trigger groove 301 on the side away from the grounding trigger element 1, and the groove wall of the trigger groove 301 is provided with multiple sets of grounding mounting holes 303. The grounding element 2 is installed in the corresponding set of grounding mounting holes 303. At the same time, the trigger groove 301 also provides space for the grounding trigger element 1 to move. The number of trigger mounting holes 305 on the other side of the insulating mounting base 3 is the same as the number of sets of grounding mounting holes 303. In this way, the present invention can flexibly select the number and installation position of the grounding trigger element 1 and the grounding element 2 according to actual needs.

[0030] like Figures 1-3 As shown, the limiting slot 302 is perpendicular to the axial direction of the grounding trigger element 1, and the overall length of the limiting slot 302 is greater than the overall length of each group of grounding mounting holes 303. In this way, the present invention can set an appropriate number of limiting pieces 4 in the limiting slot 302 according to the number and position of the grounding trigger element 1 and the grounding element 2. At the same time, the limiting slot 302 has sufficient length to allow the limiting pieces 4 to move in the slot, which also facilitates the cooperation and installation of the limiting pieces 4 and the grounding trigger element 1.

[0031] like Figure 3 As shown, in this embodiment, the limiting plate 4 is provided with a limiting through hole. The trigger end 103 of the grounding trigger element 1, located inside the insulating mounting base 3, passes through the limiting through hole, and the end face of the trigger end 103 is spherical. This facilitates the automatic sliding of the trigger end 103 into the limiting through hole under the action of the spring 102 during installation, thereby improving installation efficiency. Furthermore, when an open circuit occurs on the secondary side of the current transformer, the open circuit voltage exceeds the withstand voltage of the limiting plate 4 and is broken down. At this time, the limiting plate 4 partially melts at high temperature, causing the diameter of the limiting through hole to expand, thus failing to limit the displacement of the grounding trigger element 1, and consequently causing the grounding trigger element 1 to move.

[0032] The insulating mounting base 3 is made of high-temperature resistant insulating material to isolate the electrical connection between the grounding trigger element 1 and the grounding element 2. This ensures that the grounding trigger element 1 will only move and contact the grounding element 2 to achieve electrical connection when an open circuit occurs on the secondary side of the current transformer, causing the limiting plate 4 to partially melt at high temperature and fail to limit the displacement of the grounding trigger element 1. Simultaneously, the high-temperature resistant insulating material is not affected by the melting of the limiting plate 4, allowing the insulating mounting base 3 to be reused. In this embodiment, the high-temperature resistant insulating material can be made of materials such as epoxy glass cloth, which is a well-known technology in the art.

[0033] In this embodiment, as Figure 6 As shown, the insulating mounting base 3 is generally elongated and installed on the secondary terminal board inside the secondary junction box, and the insulating mounting base 3 is located on one side inside the secondary junction box.

[0034] In this embodiment, the grounding trigger element 1 can be in the shape of a shaft, and the grounding element 2 can be a grounding bolt, which can be threaded onto a set of grounding mounting holes 303 on the groove wall of the triggering groove 301.

[0035] The working principle of this utility model is as follows:

[0036] When this utility model is working normally, such as Figures 2-3 and Figure 6 As shown, the connection end 104 of the grounding trigger element 1 located outside the insulating mounting base 3 is connected to the corresponding protected secondary terminal 5 inside the secondary junction box via a line, thereby obtaining an electrical signal. Simultaneously, the trigger end 103 of the grounding trigger element 1 located inside the insulating mounting base 3 is displaced by the limiting piece 4 and the limiting protrusion 101, thus maintaining a distance from the corresponding grounding element 2 to prevent contact. When an open circuit occurs on the secondary side of the current transformer, such as... Figures 4-5 As shown, when the open-circuit voltage exceeds the withstand voltage of the limit plate 4, it breaks down. This causes the limit plate 4 to melt locally at high temperature and can no longer limit the displacement of the grounding trigger element 1. The grounding trigger element 1 moves under the action of the spring 102 and the trigger end 103 contacts the corresponding grounding element 2 to achieve electrical connection, thereby forming a grounding short circuit state of the protected secondary terminal 5 of the current transformer, achieving the protection purpose.

[0037] Other examples Figure 6 As shown, the present invention is long and narrow in shape, with a compact structure that does not occupy too much installation space. During installation, the insulating mounting base 3 only needs to be placed on one side inside the secondary junction box, without affecting the normal wiring of the secondary junction board. During maintenance and replacement, it is only necessary to pull the grounding trigger element 1 away from the limiting piece 4, and then pull the limiting piece 4 out of the limiting slot 301 for replacement. The operation is simple and convenient.

Claims

1. A secondary open-circuit protection device for a current transformer, characterized in that: The device includes an insulating mounting base (3), a grounding trigger element (1), a grounding element (2), and a limiting piece (4). The insulating mounting base (3) is located in the secondary junction box. One side of the insulating mounting base (3) is provided with a trigger mounting hole (305), and the other side is provided with a grounding element (2). The grounding trigger element (1) is supported by a spring (102) and floats in the corresponding trigger mounting hole (305). The grounding trigger element (1) is connected to the protected secondary terminal (5) in the secondary junction box via a lead wire. The insulating mounting base (3) is provided with a limiting slot (302), and the limiting slot (302) is provided with a limiting piece (4). When the current transformer is working normally, the grounding trigger element (1) is limited by the corresponding limiting piece (4) and forms a gap between it and the corresponding grounding element (2). When the secondary side of the current transformer is open-circuited, the limiting piece (4) melts locally at high temperature and no longer limits the displacement of the grounding trigger element (1). The grounding trigger element (1) comes into contact with the corresponding grounding element (2).

2. The secondary open-circuit protection device for current transformers according to claim 1, characterized in that: The grounding trigger element (1) is provided with a limiting protrusion (101), and the outer end of the trigger mounting hole (305) is provided with a spring limiting stop (304). One side of the limiting protrusion (101) cooperates with the corresponding limiting piece (4) for limiting, and the other side is provided with a spring (102) between it and the spring limiting stop (304). The spring (102) is fitted on the grounding trigger element (1).

3. The secondary open-circuit protection device for current transformers according to claim 1, characterized in that: The insulating mounting base (3) has a trigger groove (301) on the side away from the grounding trigger element (1), and the wall of the trigger groove (301) has multiple sets of grounding mounting holes (303). The grounding element (2) is installed in the corresponding set of grounding mounting holes (303). The number of trigger mounting holes (305) on the other side of the insulating mounting base (3) is the same as the number of sets of grounding mounting holes (303).

4. The secondary open-circuit protection device for current transformers according to claim 3, characterized in that: The limiting slot (302) is perpendicular to the axial direction of the grounding trigger element (1), and the overall length of the limiting slot (302) is greater than the overall length of each group of grounding mounting holes (303).

5. The secondary open-circuit protection device for current transformers according to claim 1 or 3, characterized in that: The grounding trigger element (1) is set perpendicular to the grounding element (2).

6. The secondary open-circuit protection device for current transformers according to claim 1, characterized in that: The limiting plate (4) is provided with a limiting through hole. The trigger end (103) of the grounding trigger element (1) located inside the insulating mounting base (3) passes through the limiting through hole, and the end face of the trigger end (103) is spherical.

7. The secondary open-circuit protection device for current transformers according to claim 1, characterized in that: The insulating mounting base (3) is generally long and narrow, and is located inside the secondary junction box on one side and installed on the secondary junction board inside the secondary junction box.

8. The secondary open-circuit protection device for current transformers according to claim 1, characterized in that: The grounding trigger element (1) is connected at its connection end (104) outside the insulating mounting base (3) to the protected secondary terminal (5) in the secondary junction box via a line.

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