Current transformer with built-in open circuit prevention device

Abstract

The utility model relates to the technical field of transformers, in particular to a current transformer with a built-in open circuit prevention device, which comprises a primary winding and a secondary winding coupled with the primary winding, the epoxy resin layer wraps the primary winding and the secondary winding and is called as an insulating layer; the bottom of the insulating layer is also connected with a grounded metal plate which is called a grounding plate; the resistor is arranged in the insulating layer and is called as an open-circuit-preventing resistor, and the number of the open-circuit-preventing resistor is two; the open-circuit-preventing resistor comprises two wiring ends which are respectively called as a connecting end and a grounding end; the number of the secondary windings is two. A coil wire of the secondary winding is conductively connected with a connecting end of the open-circuit-preventing resistor, and a grounding end of the open-circuit-preventing resistor is conductively connected with the grounding plate; wiring terminals of the primary winding and the secondary winding are connected to the outer side of the insulating layer; and danger caused by overhigh induced voltage when the secondary winding is in an open circuit state is avoided.

Description

Technical Field

[0001] The present application relates to the technical field of transformers, and in particular to a current transformer. Background Art

[0002] A current transformer is a device consisting of an iron core and windings for measuring current. It is widely used in power systems. It is mainly used to measure current in high-voltage or high-current lines and convert it into a signal that can be safely measured in order to monitor and control the operating status of the power system.

[0003] However, if the secondary side terminals of the current transformer are not tightly connected, or if the secondary side of the current transformer is open due to other reasons, a large open-circuit voltage will be generated on the secondary side due to the principle of electromagnetic induction, causing the current transformer to overload and possibly damage the current transformer, which may easily cause dangers such as electric shock and fire. Utility Model Content

[0004] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract of the specification and the name of the utility model of this application to avoid blurring the purpose of this section, the abstract of the specification and the name of the utility model, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the above problems existing in the prior art, the present utility model is proposed.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A current transformer with a built-in open circuit prevention device includes a primary winding and a secondary winding coupled to the primary winding;

[0008] It also includes the epoxy resin layer that wraps the primary and secondary windings, called the insulation layer;

[0009] The bottom of the insulating layer is also connected to a grounded metal plate, called a grounding plate;

[0010] It also includes a resistor built into the insulation layer, called an anti-open circuit resistor, and two of the anti-open circuit resistors are provided;

[0011] The anti-open circuit resistor includes two terminals, namely a connection terminal and a ground terminal;

[0012] There are two secondary windings;

[0013] A coil conductor of a secondary winding is conductively connected to a connection end of an anti-open circuit resistor, and a grounding end of the anti-open circuit resistor is conductively connected to the ground plate;

[0014] The coil wire of another secondary winding is conductively connected to the connection end of another anti-open circuit resistor, and the grounding end of the other anti-open circuit resistor is conductively connected to the ground plate;

[0015] The connection terminals of the primary winding and the secondary winding are both connected and arranged outside the insulation layer.

[0016] The above design first sets an epoxy resin insulation layer that wraps the primary winding and the secondary winding. The insulation layer ensures the insulation performance and mechanical strength of the current transformer, and ensures that the current transformer can operate stably for a long time without being interfered with by the outside world. Secondly, an anti-open circuit resistor is connected to the secondary winding and conductively connected to the grounding plate. When the secondary winding is in an open circuit, the anti-open circuit resistor is connected to the coil wire of the secondary winding and grounded, which can provide enough charge to reduce the consumption of the electromotive force induced by the secondary winding, and avoid the danger caused by the induction of excessively high voltage at the secondary winding. Finally, by embedding the anti-open circuit resistor in the insulation layer and connecting the grounding end of the anti-open circuit resistor to the grounding plate, the current transformer connected to the anti-open circuit group is connected into a whole. The wiring is quick and simple, which avoids the wiring of the current transformer being too complicated to adapt to a small space, and is beneficial to the safe operation of the electrical appliance.

[0017] When the secondary winding of a current transformer is energized and connected to a device, if the connection becomes disconnected or in a high-resistance state, the secondary winding will induce high-voltage current, causing breakdown or other hazards. The present invention connects an anti-open-circuit resistor to the coil wires of all secondary windings of the current transformer, with the other end of the anti-open-circuit resistor grounded. This provides sufficient charge to the secondary winding coil when the device connected to the secondary winding is disconnected. The voltage induced by the secondary winding drives the charge in the ground into the entire coil of the secondary winding, preventing high-voltage current breakdown. Compared to connecting an anti-open-circuit resistor in parallel to the secondary winding terminal, this connection method can cause measurement signal inaccuracy due to the nonlinear value of the electrical energy continued to be consumed by the resistor. The present invention grounds the anti-open-circuit resistor connected to the secondary winding, and the electrical energy consumed by the anti-open-circuit resistor is consumed linearly, greatly improving measurement accuracy.

[0018] Preferably, the connection end and the grounding end of the anti-open circuit resistor are connected by a soft copper wire with a diameter of 1.0-2.0 mm. The 1.0-2.0 mm soft copper wire ensures that the anti-open circuit resistor can absorb enough charge to reduce the consumption of the electromotive force induced by the secondary winding.

[0019] Preferably, the anti-open-circuit resistor is wrapped with a semiconductor electrical tape; the anti-open-circuit resistor wrapped with the semiconductor electrical tape is attached to the bottom of the secondary winding at an angle of 42°-48°; to prevent the anti-open-circuit resistor from inducing the coil magnetic field of the secondary winding to generate current during operation, thereby affecting the accuracy of the current transformer measurement.

[0020] Preferably, the connection terminal of the anti-open circuit resistor is conductively connected to the coil wire at any position of the inner ring, outer ring and end face of the secondary winding; when the secondary winding is open, the connection terminal of the anti-open circuit resistor is connected to the coil wire of the secondary winding, and the charge provided by the anti-open circuit resistor can quickly balance the electromotive force generated by the secondary winding, thereby avoiding high charge breakdown.

[0021] Preferably, the grounding plate is made of an aluminum alloy plate; the grounding plate is also connected with bolts connecting the insulating layer and the grounding plate; by setting the grounding plate made of aluminum alloy, the conductivity and rust and radiation resistance of the grounding plate are guaranteed, and then the insulating layer and the grounding plate are fixed with bolts to ensure the stability of the grounding plate connection, thereby improving the safety of the current transformer.

[0022] The secondary winding terminal adopts a threaded mechanism terminal; the insulating layer is provided with a structure for mounting the secondary winding terminal, which is called a mounting seat; the mounting seat is embedded with a metal sleeve with threaded holes that is conductively connected to the two ends of the secondary winding coil wire; the metal sleeve is provided with a screw in threaded engagement; by providing the metal sleeve and the screw as the secondary winding terminal, the screw is screwed into the metal sleeve to fix the conductive wire, and the connection is stable, thereby preventing the danger caused by the secondary winding short circuit.

[0023] Preferably, a spring washer is provided on the screw rod of the screw, and the spring washer is arranged between the screw head and the metal sleeve; by providing the spring washer, the terminal will not loosen even when the current transformer is working, preventing the secondary winding from breaking and causing danger.

[0024] Preferably, the mounting base is detachably provided with a cover covering the secondary winding terminal. By providing the cover covering the secondary winding terminal, the secondary winding terminal is prevented from being dripped with liquid, causing corrosion and circuit breaking of the terminal, thereby preventing the secondary winding circuit breaking from causing danger. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without inventive work. Among them:

[0026] Figure 1 A schematic diagram of the internal structure of a current transformer with a built-in anti-open circuit device according to an embodiment of the present invention;

[0027] Figure 2 A schematic diagram of the internal structure of a current transformer with a built-in open circuit prevention device according to an embodiment of the present invention;

[0028] Figure 3 A schematic diagram of the structure of an anti-open circuit resistor with a built-in anti-open circuit device according to an embodiment of the present invention;

[0029] Figure 4 A schematic diagram of the bottom surface structure of a grounding plate with a built-in anti-open circuit device according to an embodiment of the present invention;

[0030] Figure 5 This is a schematic diagram of the overall appearance and structure of a built-in anti-open circuit device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more understandable, the specific implementation methods of the present invention are described in detail below with reference to the accompanying drawings.

[0032] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0033] Next, the present invention is described in detail with reference to schematic diagrams. For ease of illustration, cross-sectional views of device structures may be partially enlarged and not to scale when describing embodiments of the present invention. Furthermore, the schematic diagrams are merely illustrative and should not limit the scope of protection of the present invention. Furthermore, in actual production, three-dimensional dimensions, including length, width, and depth, should be included.

[0034] Furthermore, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it designate a separate or selective embodiment that is mutually exclusive with other embodiments.

[0035] Example 1

[0036] Reference Figures 1-4 , this embodiment provides a current transformer with a built-in anti-open circuit device.

[0037] A current transformer with a built-in anti-open circuit device includes a primary winding 1 and a secondary winding 2 coupled with the primary winding 1; it also includes an epoxy resin layer wrapping the primary winding 1 and the secondary winding 2, called an insulating layer 3; the bottom of the insulating layer 3 is also connected to a grounded metal plate, called a grounding plate 5; it also includes a resistor built into the insulating layer 3, called an anti-open circuit resistor 4, and there are two anti-open circuit resistors 4; the anti-open circuit resistor 4 includes two terminals, respectively called a connection terminal and a grounding terminal; there are two secondary windings 2; the coil wire of one secondary winding 2 is conductively connected to the connection terminal of the anti-open circuit resistor 4, and the grounding terminal of the anti-open circuit resistor 4 is conductively connected to the grounding plate 5; the coil wire of the other secondary winding 2 is conductively connected to the connection terminal of the other anti-open circuit resistor 4, and the grounding terminal of the other anti-open circuit resistor 4 is conductively connected to the grounding plate 5; the wiring terminals of the primary winding 1 and the secondary winding 2 are both connected and arranged on the outside of the insulating layer 3; the bottom of the insulating layer 3 is also The connection is provided with a plate made of metal material, which is called a grounding plate 5; first, an epoxy resin insulation layer 3 is provided to wrap the primary winding 1 and the secondary winding 2, and the insulation performance and mechanical strength of the current transformer are guaranteed by the insulation layer 3, so as to ensure the long-term stable operation of the current transformer without external interference. Secondly, an anti-open circuit resistor 4 is connected to the secondary winding 2 and conductively connected to the grounding plate 5 for grounding. When the secondary winding 2 is in an open circuit, the anti-open circuit resistor 4 is connected to the coil wire of the secondary winding 2 and grounded, which can provide enough charge to reduce the consumption of the electromotive force induced by the secondary winding 2, and avoid the danger caused by the excessively high voltage induced at the secondary winding 2. Finally, the anti-open circuit resistor 4 is built into the insulation layer 3, and the grounding end of the anti-open circuit resistor 4 is connected to the grounding plate 5, so that the current transformer connected to the anti-open circuit group is connected into a whole, and the wiring is quick and simple, which avoids the wiring of the current transformer being too complicated to adapt to a small space, and is beneficial to the safe operation of the electrical appliance.

[0038] When the secondary winding 2 of a current transformer is energized and connected to a device, if the connection is disconnected or in a high-resistance state, the secondary winding 2 will induce a high charge, causing breakdown or other dangers. The present invention connects an anti-open-circuit resistor 4 to the coil conductors of all the secondary windings 2 of the current transformer, with the other end of the anti-open-circuit resistor 4 grounded. When the device connected to the secondary winding 2 is disconnected, the charge induced by the secondary winding 2 drives the charge in the ground into the entire coil of the secondary winding 2, preventing high-charge breakdown. Compared to connecting the anti-open-circuit resistor 4 in parallel to the secondary winding 2 terminal, this connection method will cause measurement signal inaccuracy due to the nonlinear value of the electrical energy continued to be consumed by the resistor. The present invention grounds the anti-open-circuit resistor 4 connected to the secondary winding 2, and the electrical energy consumed by the anti-open-circuit resistor 4 is consumed linearly, greatly improving measurement accuracy.

[0039] The connection end and the grounding end of the anti-open circuit resistor 4 are connected by a soft copper wire with a diameter of 1.0-2.0 mm. The 1.0-2.0 mm soft copper wire ensures that the anti-open circuit resistor 4 is allowed to absorb enough charge to reduce the consumption of the electromotive force induced by the secondary winding 2.

[0040] The anti-open-circuit resistor 4 is wrapped with a semiconductor electrical tape; the anti-open-circuit resistor 4 wrapped with the semiconductor electrical tape is attached to the bottom of the secondary winding at an angle of 42°-48°; this prevents the anti-open-circuit resistor 4 from inducing the coil magnetic field of the secondary winding 2 to generate current during operation, thereby affecting the accuracy of the current transformer measurement.

[0041] The connection terminals of the anti-open-circuit resistor 4 are conductively connected to the coil wire at any position of the inner ring, outer ring and end face of the secondary winding; when the secondary winding 2 is open-circuited, the connection terminals of the anti-open-circuit resistor 4 are connected to the coil wire of the secondary winding. The charge provided by the anti-open-circuit resistor 4 can quickly balance the electromotive force generated by the secondary winding, avoiding high charge breakdown.

[0042] The grounding plate 5 is made of an aluminum alloy plate; the grounding plate 5 is also connected with bolts 6 connecting the insulating layer 3 and the grounding plate 5; by setting the grounding plate 5 made of aluminum alloy, the conductivity and rust and radiation resistance of the grounding plate 5 are guaranteed, and the insulating layer 3 and the grounding plate 5 are fixed with bolts 6 to ensure the stability of the connection of the grounding plate 5, thereby improving the safety of the current transformer.

[0043] During use, the coil wires of the two secondary windings 2 coupled with the primary winding 1 are respectively welded to the connection ends of the two anti-open circuit resistors 4, and the welding points are located at any position on the wire in the inner ring, outer ring and end face of the secondary winding. Then, the primary winding 1 and the secondary winding 2 connected with the anti-open circuit winding are placed in a mold and poured with a mixture of epoxy resin and curing agent. After the epoxy resin solidifies into an insulating layer 3, it is ensured that the grounding end of the anti-open circuit resistor 4, the primary winding 1 terminal and the secondary winding 2 terminal are all connected and arranged on the outside of the insulating layer 3. Then, the grounding plate 5 is connected to the bottom of the insulating layer 3 with bolts 6, and the grounding end of the anti-open circuit resistor 4 is welded to the grounding plate 5 to ensure that the current transformer connected to the anti-open circuit group is connected as a whole. The wiring is quick and simple, which is conducive to the safe operation of the electrical appliance and avoids the danger caused by the induction of excessively high voltage at the secondary winding 2.

[0044] Example 2

[0045] Reference Figure 1 and Figure 5 , which is the second embodiment of the present utility model, and this embodiment is based on the previous embodiment.

[0046] The connection terminals of the secondary winding 2 adopt a connection terminal with a threaded mechanism; a structure for mounting the connection terminals of the secondary winding 2 is provided on the insulating layer 3, which is called a mounting seat 7; a metal sleeve with threaded holes is embedded in the mounting seat 7 and is conductively connected to the two ends of the coil wire of the secondary winding 2; a screw 8 is provided in the metal sleeve in threaded engagement; by providing the metal sleeve and the screw 8 as the connection terminals of the secondary winding 2, the screw 8 is screwed into the metal sleeve to fix the conductive wire, and the connection is stable, thereby preventing the danger caused by the secondary winding 2 being broken.

[0047] A spring washer is provided on the screw rod of the screw 8, and the spring washer is provided between the head of the screw 8 and the metal sleeve; by providing the spring washer, the terminal will not loosen even when the current transformer is working, preventing the secondary winding 2 from breaking and causing danger.

[0048] The mounting base 7 is detachably provided with a cover 9 for covering the connecting terminals of the secondary winding 2. By providing the cover 9 for covering the connecting terminals of the secondary winding 2, it is ensured that the connecting terminals of the secondary winding 2 are not corroded and open-circuited due to liquid dripping onto them, thereby preventing the connecting terminals from being open-circuited and causing danger.

[0049] During use, when the current transformer is connected to the electrical equipment, open the cover 9 covering the secondary winding 2 terminal, unscrew the screw 8, put the conductive wire on the screw 8, then put on the spring washer and flat washer, screw the screw 8 into the metal sleeve, and the head of the screw 8 presses the conductive wire tightly so that the terminal will not loosen even during the operation of the current transformer, preventing the secondary winding 2 from being broken and causing danger. Then cover the mounting base 7 to prevent the secondary winding 2 from being dripped with liquid and causing corrosion and breaking of the terminal, preventing the secondary winding 2 from being broken and causing danger.

[0050] It is important to note that the configuration and arrangement of the present application, as illustrated in various exemplary embodiments, are illustrative only. Although only a few embodiments are described in detail in this disclosure, those reading this disclosure will readily appreciate that numerous modifications are possible without materially departing from the novel teachings and advantages of the subject matter described herein. For example, variations in the size, dimensions, structure, shape, and proportions of various components, as well as parameter values ​​such as temperature, pressure, mounting arrangements, use of materials, color, and orientation, are possible. For example, components shown as integrally formed may be constructed from multiple parts or components, the positions of components may be inverted or otherwise altered, and the nature, number, or position of discrete components may be modified or changed. Therefore, all such modifications are intended to be encompassed within the scope of this disclosure. The order or sequence of any process or method steps may be altered or reordered according to alternative embodiments. In the claims, any "means-plus-function" clause is intended to cover structures that perform the functions described herein, and not only structural equivalence but also structural equivalents. Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the exemplary embodiments without departing from the scope of this disclosure. Therefore, the invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0051] Furthermore, in order to provide a concise description of the exemplary embodiments, all features of the actual embodiment may not be described, i.e., those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention.

[0052] It should be understood that in the development of any actual embodiment, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but for those of ordinary skill having the benefit of this disclosure, the development effort will be a routine task of design, fabrication, and production without undue experimentation.

[0053] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, and all of these should be included in the scope of the claims of the present invention.

Claims

1. A current transformer with a built-in open circuit prevention device, comprising a primary winding and a secondary winding coupled to the primary winding, characterized in that: It also includes the epoxy resin layer that wraps the primary and secondary windings, called the insulation layer; The bottom of the insulating layer is also connected to a grounded metal plate, called a grounding plate; It also includes a resistor built into the insulation layer, called an anti-open circuit resistor, and two of the anti-open circuit resistors are provided; The anti-open circuit resistor includes two terminals, which are respectively called a connection terminal and a ground terminal; The secondary winding is provided with two; A coil conductor of a secondary winding is conductively connected to a connection end of an open circuit prevention resistor, and a grounding end of the open circuit prevention resistor is conductively connected to the grounding plate; The coil wire of another secondary winding is conductively connected to the connection end of another open circuit prevention resistor, and the grounding end of the other open circuit prevention resistor is conductively connected to the grounding plate; The connection terminals of the primary winding and the secondary winding are both connected and arranged outside the insulating layer.

2. The current transformer with a built-in open circuit prevention device according to claim 1, characterized in that: The connection end of the anti-open circuit resistor and the grounding end are connected by a soft copper wire with a diameter of 1.0-2.0 mm.

3. The current transformer with a built-in open circuit prevention device according to claim 2, characterized in that: The anti-open circuit resistor is wrapped with a semiconductor electrical tape; The anti-open circuit resistor wrapped with semiconductor electrical tape is attached to the bottom of the secondary winding at an angle of 42°-48°.

4. The current transformer with a built-in open circuit prevention device according to claim 3, characterized in that: The connection terminal of the open circuit prevention resistor is conductively connected to the coil wire at any position of the inner circle, the outer circle and the end surface of the secondary winding.

5. The current transformer with a built-in open circuit prevention device according to claim 4, characterized in that: The grounding plate is made of aluminum alloy; The grounding plate is also provided with bolts connecting the insulating layer and the grounding plate.

6. The current transformer with a built-in open circuit prevention device according to claim 1, characterized in that: The connection terminals of the secondary winding are connection terminals with a threaded mechanism; The insulating layer is provided with a structure for mounting the connection terminal of the secondary winding, which is called a mounting seat; The mounting seat is embedded with a metal sleeve with threaded holes that is conductively connected to both ends of the secondary winding coil wire; The metal sleeve is threadedly provided with a screw.

7. The current transformer with a built-in open circuit prevention device according to claim 6, characterized in that: A spring washer is sleeved on the screw rod of the screw, and the spring washer is arranged between the screw head and the metal sleeve.

8. The current transformer with a built-in open circuit prevention device according to claim 7, characterized in that: The mounting seat is detachably provided with a cover for covering the secondary winding connection terminal.

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