Isolated current transformer with convenient heat dissipation

Abstract

The utility model discloses an isolation current transformer convenient for heat dissipation, including shell and apron, two groups of baffle are fixedly connected with equidistance in the shell, and the baffle divides three groups of holding cavity in the shell cavity, and a plurality of current transformers are installed in the holding cavity, the inside wall of apron is installed with circuit board, and the circuit board is electrically connected with a plurality of current transformers, the utility model omits auxiliary assembly and heat dissipation component to improve the space in the shell to facilitate the electronic device arrangement on the circuit board, makes its arrangement be relatively loose, and it is convenient for heat dissipation, in addition, install the circuit board on the inside wall of apron, and the front end of apron is provided with the heat dissipation fin of interval arrangement along the width direction, and the transistor on the circuit board is arranged at one end close to the heat dissipation fin, after assembling, the transistor is attached with the inside wall of heat dissipation fin, and the heat of transistor is conducted to the heat dissipation fin fast, and the contact area with air is increased, and the heat dissipation capacity is improved.

Description

Technical Field

[0001] This utility model relates to a transformer, and more particularly to an isolation current transformer. Background Technology

[0002] Patent document CN222637012U discloses a three-phase isolation current transformer, including a housing and a connecting plate. Two sets of partitions are fixedly connected at equal intervals inside the housing, and three sets of current transformers are fixedly installed inside the partitions. An auxiliary component is arranged on the outside of the current transformer, and a heat dissipation component is arranged inside the housing. The auxiliary component includes a connecting ring, a heat pipe, and fins. The heat dissipation component includes a mounting plate and a cooling fan. When the current transformer is operating, it generates heat, which is transferred through the connecting ring and the heat pipe to the fins for heat dissipation. The cooling fan is activated, and the fan rotation generates airflow to cool the fins.

[0003] However, in practical applications, the heat generated by the magnetic core and coil of the current transformer is not very large. The main source of heat is the circuit board electrically connected to the current transformer. The circuit board usually has multiple transistors such as field-effect transistors or power amplifiers. During circuit operation, these transistors generate a lot of heat. Although the above technical solution can solve the heat dissipation problem, the assembly structure of its auxiliary components and heat dissipation components is relatively complex and the production cost is high. Moreover, the auxiliary components occupy most of the space inside the casing, and the size of the circuit board can only be made very small. On the one hand, the electronic components are densely arranged, making heat dissipation difficult. On the other hand, other functions may be sacrificed, resulting in a relatively simple function. Utility Model Content

[0004] To overcome the shortcomings of the existing technology, this utility model provides an isolated current transformer that facilitates heat dissipation.

[0005] The technical solution adopted by this utility model to solve its technical problem is:

[0006] An isolated current transformer with convenient heat dissipation includes a housing and a cover plate fixedly connected to one side of the housing. Two sets of partitions are fixedly connected at equal intervals inside the housing, dividing the inner cavity of the housing into three placement chambers. Several current transformers are installed in the placement chambers. A circuit board is installed on the inner wall of the cover plate, and the circuit board is electrically connected to the several current transformers. The front end of the cover plate is provided with heat dissipation fins arranged at intervals along the width direction. Transistors on the circuit board are located at one end close to the heat dissipation fins. After assembly, the transistors are attached to the inner wall of the heat dissipation fins.

[0007] Thermal adhesive is applied to the portion of the transistor that contacts the heat sink fins.

[0008] The circuit board includes a power board and a main control board. The power board is fixedly installed on the inner side wall of the cover plate. The main control board is electrically connected to the power board through a connection terminal. After assembly, the power board and the main control board are perpendicular to each other.

[0009] The power board includes a power module, an inductor connection module, and a feedback module. The main control board includes an amplifier circuit and a switch trigger circuit. The input terminal of the inductor connection module is connected to several current transformers, and the output terminal is connected to the amplifier circuit. The output terminal of the amplifier circuit is divided into two paths: one path is connected to the input terminal of the feedback module, and the other path is connected to the input terminal of the switch trigger circuit. The output terminal of the switch trigger circuit is connected to the input terminal of the feedback module.

[0010] The power supply module includes power supply terminals CON5 and CON4 for external connection. Power supply terminals CON5 and CON4 are connected to the input terminals of rectifier bridge BD1 through fuses F1 and F2, respectively. The output terminals of rectifier bridge BD1 are divided into two paths, one connected to linear regulator U9 and the other connected to linear regulator U8. The output terminals of linear regulator U9 and linear regulator U8 provide operating voltages for the inductor connection module, feedback module, amplifier circuit and switching trigger circuit, respectively.

[0011] The inductor connection module includes a connection terminal CON2 connected to a current transformer. The neutral wire N of several current transformers is grounded through diode D9 and capacitor C23. The live wire L of several current transformers is connected to the input terminal of the amplifier circuit through fuse F3, resistor R9 and capacitor C3. The live wire L and neutral wire N of several current transformers are respectively connected to a thyristor Q1. A TVS diode Z3 is connected between the first and second pins of the thyristor Q1. A resistor R13 is connected in series with the first pin of the thyristor Q1, and a resistor R14 is connected in series with the third pin of the thyristor Q1.

[0012] The feedback module includes a power amplifier U3. The input terminal of the power amplifier U3 is connected to the output terminal of the amplifier circuit. The second pin of the power amplifier U3 is connected to the live wire L of several current transformers. The fourth pin of the power amplifier U3 is connected to the second pin of the relay RLY1. The first and fifth pins of the relay RLY1 are connected to the live wire L and neutral wire N of several current transformers, respectively. The third pin of the relay RLY1 is connected to the output terminal of the switch trigger circuit through a transistor Q2. The fourth pin of the relay RLY1 is connected to the output terminal of the power supply module through a resistor R44.

[0013] The feedback module also includes optocouplers P01-P05. The second pins of optocouplers P02-P04 are connected to LEDs LED1-LED3 respectively. The negative terminal of LED3 is connected to the output terminal of the switch trigger circuit. The first pins of optocouplers P02-P04 are connected to the fourth pins of optocouplers P01 and P05 respectively through resistors R34, R37 and R40. The third pin of optocoupler P01 is connected to the switch trigger circuit through the reset button SW1. The third pins of optocouplers P02-P04, the second pin of optocoupler P01 and the second pin of optocoupler P05 are connected to the external control terminal CON3 respectively.

[0014] The amplification circuit includes operational amplifiers U1 and U2. The input terminal of operational amplifier U1 is divided into two paths: one path is connected to the live wire L of several current transformers, and the other path is connected to the output terminal of operational amplifier U1. The output terminal of operational amplifier U1 is connected to the input terminal of operational amplifier U2 through resistor R4. The input terminal of operational amplifier U2 is connected to the output terminal of operational amplifier U2 through resistors R5 and R6 and capacitor C2. The output terminal of operational amplifier U2 is connected to the switch trigger circuit. Operational amplifiers U4, U5, and U6 are connected between the output terminal of operational amplifier U2 and the switch trigger circuit.

[0015] The switch trigger circuit includes a trigger U7. The 8th pin of the trigger U7 is connected to the output of the operational amplifier U5 through a transistor Q3. The 12th pin of the trigger U7 is connected to the light-emitting diode LED3. The 13th pin of the trigger U7 is connected to the relay RLY1 through a transistor Q2. The 11th pin of the trigger U7 is connected to the output of the operational amplifier U6.

[0016] The beneficial effects of this utility model are: this utility model omits auxiliary components and heat dissipation components, thereby increasing the space inside the casing to facilitate the arrangement of electronic components on the circuit board, making the arrangement more loose and convenient for heat dissipation; in addition, the circuit board is mounted on the inner side wall of the cover plate, and the front end of the cover plate is provided with heat dissipation fins arranged at intervals along the width direction. The transistors on the circuit board are located at the end close to the heat dissipation fins. After assembly, the transistors are in contact with the inner side wall of the heat dissipation fins, allowing the heat generated by the transistors to be quickly conducted to the heat dissipation fins, increasing the contact area with the air and improving the heat dissipation capacity. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] Figure 1 This is a schematic diagram of the structure of this utility model.

[0019] Figure 2 This is a schematic diagram of the outer shell.

[0020] Figure 3 This is a structural diagram of the cover plate.

[0021] Figure 4 This is the circuit schematic of the power module.

[0022] Figure 5 This is the circuit schematic of the inductor connection module.

[0023] Figure 6 This is a circuit schematic of part of the feedback module.

[0024] Figure 7 This is a circuit diagram of part of the external terminal block.

[0025] Figure 8 This is the schematic diagram of an amplifier circuit.

[0026] Figure 9 This is the schematic diagram of a switch trigger circuit. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features of the present utility model can be combined with each other.

[0028] It should be understood that these descriptions are merely exemplary and not intended to limit the scope of this invention.

[0029] The following describes some embodiments of the present invention with reference to the accompanying drawings.

[0030] Reference Figures 1 to 3An isolated current transformer with convenient heat dissipation includes a housing 1 and a cover plate 2 fixedly connected to one side of the housing 1. Specifically, the housing 1 and the cover plate 2 are fixedly connected by screws. Two sets of partitions 3 are fixedly connected at equal intervals inside the housing 1, and the partitions 3 divide the inner cavity of the housing 1 into three sets of placement chambers 11. Several current transformers 4 are installed in the placement chambers 11. A circuit board is installed on the inner side wall of the cover plate 2. The circuit board is electrically connected to the several current transformers 4. The front end of the cover plate 2 is provided with heat dissipation fins 21 arranged at intervals along the width direction. A transistor 5 on the circuit board is located at one end close to the heat dissipation fins 21. After assembly, the transistor 5 is attached to the inner side wall of the heat dissipation fins 21. The transistor 5 is a power amplifier U3. In this utility model, compared with the prior art, auxiliary components and heat dissipation components are omitted, simplifying the overall assembly structure, thereby increasing the space inside the housing, increasing the area available for the circuit board, and making it easier to arrange electronic components when designing the circuit board, making the arrangement loose and facilitating heat dissipation of electronic components. In addition, the transistor is attached to the inner wall of the heat sink fin, so that the heat generated by the transistor can be quickly conducted to the heat sink fin. Specifically, thermal paste, such as thermal grease, is applied to the part where the transistor 5 contacts the heat sink fin 21, so that the heat sink fin 21 contacts the air to achieve the heat dissipation function.

[0031] In this embodiment, the transistor is a power amplifier U3. The head of the power amplifier U3 has a round hole, which can be fixedly connected to the heat sink fin 21 with screws.

[0032] The circuit board includes a power board 61 and a main control board 62. The power board 61 is fixedly installed on the inner side wall of the cover plate 2. The main control board 62 is electrically connected to the power board 61 through a connection terminal. After assembly, the power board 61 and the main control board 62 are perpendicular to each other. Due to the increased space inside the housing, the circuit board can be assembled separately as the power board 61 and the main control board 62, which allows for more efficient arrangement of electronic components. Moreover, if the power board 61 or the main control board 62 is damaged, it can be replaced separately, which facilitates later maintenance.

[0033] Reference Figures 4 to 9 The power board 61 includes a power module, an inductor connection module, and a feedback module. The main control board 62 includes an amplifier circuit and a switch trigger circuit. The input terminal of the inductor connection module is connected to several current transformers 4, and the output terminal is connected to the amplifier circuit. The output terminal of the amplifier circuit is divided into two paths: one path is connected to the input terminal of the feedback module, and the other path is connected to the input terminal of the switch trigger circuit. The output terminal of the switch trigger circuit is connected to the input terminal of the feedback module.

[0034] The power module includes power supply terminals CON5 and CON4 for external connection. Power supply terminals CON5 and CON4 are connected to the input terminals of rectifier bridge BD1 via fuses F1 and F2, respectively. The output terminal of rectifier bridge BD1 is divided into two paths: one connected to linear regulator U9 and the other to linear regulator U8. The output terminals of linear regulators U9 and U8 provide operating voltage to the inductor connection module, feedback module, amplifier circuit, and switch trigger circuit, respectively. Capacitors C30, C31, C19, C18, C26, and C28 are connected to the output terminal of rectifier bridge BD1 for filtering. In this embodiment, the external device for the current transformer, such as an AC 12V power supply, is first installed and connected to power supply terminals CON5 and CON4. After rectification by rectifier bridge BD1, the AC power enters linear regulators U9 and U8 for voltage regulation, and finally, it is output to the entire circuit to provide operating voltage.

[0035] The outer casing has three sets of placement cavities 11, and three current transformers 4 are installed in each of the three sets of placement cavities 11. Figures 5 to 7 In one embodiment, the current transformer 4 is connected to three current transformers 4. This embodiment can also be used to connect to other current transformers 4. Specifically, the inductor connection module includes a connection terminal CON2 connected to the three current transformers 4. The neutral wire N of several current transformers 4 is grounded through diode D9 and capacitor C23. The live wire L of several current transformers 4 is connected to the input terminal of the amplifier circuit through fuse F3, resistor R9 and capacitor C3. The live wire L and neutral wire N of several current transformers 4 are respectively connected to a thyristor Q1. A TVS diode Z3 is connected between the first and second pins of the thyristor Q1. A resistor R13 is connected in series with the first pin of the thyristor Q1, and a resistor R14 is connected in series with the third pin of the thyristor Q1. In this embodiment, the signal from the current transformer is transmitted to the amplifier circuit and amplified. Additionally, when the current transformer 4 is operating, it generates an induced electromotive force and an induced current. The live wire L of the current transformer 4 is connected to pin 1 of the thyristor Q1, and then connected to pin 3 through resistors R13 and R14. The voltage level at pin 3 reaches the high level required to turn on the thyristor Q1, thus starting the thyristor Q1 and forming a closed circuit between the live wire L and the neutral wire N, ensuring normal circuit operation. When the trigger signal disappears, the thyristor Q1 automatically turns off, cutting off current transmission and enabling flexible start / stop control of the circuit.

[0036] The feedback module includes a power amplifier U3. The input of power amplifier U3 is connected to the output of an amplification circuit. Pin 2 of power amplifier U3 is connected to the live wire L of several current transformers 4. Pin 4 of power amplifier U3 is connected to pin 2 of relay RLY1. Pins 1 and 5 of relay RLY1 are connected to the live wire L and neutral wire N of several current transformers 4, respectively. Pin 3 of relay RLY1 is connected to the output of a switching trigger circuit via transistor Q2. Pin 4 of relay RLY1 is connected to the output of a power module via resistor R44, supplying power to the relay. When the signal is normal, the base of transistor Q2 has a high level, turning on transistor Q2. Pins 1 and 2 of relay RLY1 close, connecting to the output OUT pin of power amplifier U3, providing compensation current to the current transformers. Additionally, pin 2 of power amplifier U3 is connected to a sampling resistor R11. The sampled current is fed back to pin 2 of power amplifier U3 for processing, and then amplified to compensate the secondary winding.

[0037] The feedback module also includes optocouplers P01-P05. The second pins of optocouplers P02-P04 are connected to LEDs LED1-LED3 respectively. The negative terminal of LED3 is connected to the output terminal of the switch trigger circuit. The first pins of optocouplers P02-P04 are connected to the fourth pins of optocouplers P01 and P05 respectively through resistors R34, R37 and R40. The third pin of optocoupler P01 is connected to the switch trigger circuit through the reset button SW1. The third pins of optocouplers P02-P04, the second pin of optocoupler P01 and the second pin of optocoupler P05 are connected to the external control terminal CON3 respectively. In this embodiment, optocouplers P02-P04 cooperate with LEDs LED1-LED3, where LEDs LED1-LED3 are used to indicate the operating status of the three sets of current transformers 4, respectively. The reset button SW1 can reset the circuit. The control terminal CON3 is used for external operation of the current transformers 4 by the user, such as... Figure 7 The labels P1, P2, and P3 indicate the control circuits of the three current transformers 4. When the first circuit is controlled, the signal from P1 is transmitted to the light-emitting diode LED3 through the optocoupler P04. The light-emitting diode LED3 lights up, indicating that the current transformer 4 is working normally.

[0038] The amplification circuit includes operational amplifiers U1 and U2. The input terminal of operational amplifier U1 is divided into two paths: one path is connected to the live wire L of several current transformers 4, and the other path is connected to the output terminal of operational amplifier U1. The output terminal of operational amplifier U1 is connected to the input terminal of operational amplifier U2 through resistor R4. The input terminal of operational amplifier U2 is connected to the output terminal of operational amplifier U2 through resistors R5 and R6 and capacitor C2. The output terminal of operational amplifier U2 is connected to the switch trigger circuit. Operational amplifiers U4, U5, and U6 are connected between the output terminal of operational amplifier U2 and the switch trigger circuit. The input and output terminals of the operational amplifier U1 are connected by resistors R2 and R3, which can increase the amplifier's amplification factor, amplifying the input voltage by 10 times. A phase compensation network consisting of capacitor C1 and resistor R5 is provided between operational amplifiers U1 and U2 to eliminate self-oscillation under high-frequency signals and ensure the stability of the amplifier circuit. In this embodiment, the weak voltage signal input from the inductor connection module is amplified to an amplitude that can be recognized by subsequent circuits.

[0039] The switch trigger circuit includes a trigger U7. The 8th pin of the trigger U7 is connected to the output of the operational amplifier U5 through a transistor Q3. The 12th pin of the trigger U7 is connected to the light-emitting diode LED3. The 13th pin of the trigger U7 is connected to the relay RLY1 through a transistor Q2. The 11th pin of the trigger U7 is connected to the output of the operational amplifier U6.

[0040] Working principle: First, install the external equipment for the current transformers and connect it to an AC 12V power supply to power the circuit board. The primary three-phase power lines are routed through the three current transformers. The secondary side is connected to the energy meter. The three-phase power supply is set to the desired test current, such as 0.1A-1A-20A-100A. At this time, the current flows through the center of the current transformer, generating excitation voltage and current. This is sampled by the sampling resistor and fed back to the power amplifier U3 and the amplification circuit for current amplification and compensation on the secondary side. Another output is to pins 3 and 6 of the operational amplifier U4. Pins 3 and 6 are compared with a ±10V reference voltage. When the input voltage is between 10V and -10V, the operational amplifier U4 outputs a low level; when the input voltage is greater than 10V or less than -10V, the operational amplifier U4 outputs a high level. The LED3 light-emitting diode is off, indicating that the circuit is in a protection state.

[0041] In this invention, the term "multiple" refers to two or more items unless otherwise expressly defined. The term "and / or" as used herein includes any and all combinations of one or more of the related listed items. The terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "linking" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0042] It should be noted that when a component is referred to as being "assembled on," "mounted on," "fixed to," or "set on" another component, it can be directly on the other component or there may be an intermediate component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0043] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0044] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A heat-dissipating isolation current transformer, comprising a housing (1) and a cover plate (2) fixedly connected to one side of the housing (1), wherein two sets of partitions (3) are fixedly connected at equal intervals inside the housing (1), the partitions (3) dividing the inner cavity of the housing (1) into three sets of placement chambers (11), wherein a plurality of current transformers (4) are installed in the placement chambers (11); characterized in that A circuit board is installed on the inner wall of the cover plate (2). The circuit board is electrically connected to several current transformers (4). The front end of the cover plate (2) is provided with heat dissipation fins (21) arranged at intervals along the width direction. The transistor (5) on the circuit board is located at one end close to the heat dissipation fins (21). After assembly, the transistor (5) is attached to the inner wall of the heat dissipation fins (21).

2. The heat-dissipating isolation current transformer according to claim 1, characterized in that... Thermal adhesive is applied to the part of the transistor (5) that contacts the heat sink fin (21).

3. The heat-dissipating isolation current transformer according to claim 1, characterized in that... The circuit board includes a power board (61) and a main control board (62). The power board (61) is fixedly installed on the inner side wall of the cover plate (2). The main control board (62) is electrically connected to the power board (61) through a connection terminal. After assembly, the power board (61) and the main control board (62) are perpendicular to each other.

4. The heat-dissipating isolation current transformer according to claim 3, characterized in that... The power board (61) includes a power module, an inductor connection module and a feedback module. The main control board (62) includes an amplifier circuit and a switch trigger circuit. The input terminal of the inductor connection module is connected to several current transformers (4), and the output terminal is connected to the amplifier circuit. The output terminal of the amplifier circuit is divided into two paths, one path is connected to the input terminal of the feedback module and the other path is connected to the input terminal of the switch trigger circuit. The output terminal of the switch trigger circuit is connected to the input terminal of the feedback module.

5. The heat-dissipating isolation current transformer according to claim 4, characterized in that... The power supply module includes power supply terminals CON5 and CON4 for external connection. Power supply terminals CON5 and CON4 are connected to the input terminals of rectifier bridge BD1 through fuses F1 and F2, respectively. The output terminals of rectifier bridge BD1 are divided into two paths, one connected to linear regulator U9 and the other connected to linear regulator U8. The output terminals of linear regulator U9 and linear regulator U8 provide operating voltages for the inductor connection module, feedback module, amplifier circuit and switching trigger circuit, respectively.

6. The heat-dissipating isolation current transformer according to claim 4, characterized in that... The inductor connection module includes a connection terminal CON2 connected to the current transformer (4). The neutral line N of several current transformers (4) is grounded through diode D9 and capacitor C23. The live line L of several current transformers (4) is connected to the input terminal of the amplifier circuit through fuse F3, resistor R9 and capacitor C3. The live line L and neutral line N of several current transformers (4) are respectively connected to the thyristor Q1. A TVS diode Z3 is connected between the first and second pins of the thyristor Q1. A resistor R13 is connected in series with the first pin of the thyristor Q1. A resistor R14 is connected in series with the third pin of the thyristor Q1.

7. The heat-dissipating isolation current transformer according to claim 4, characterized in that... The feedback module includes a power amplifier U3. The input terminal of the power amplifier U3 is connected to the output terminal of the amplifier circuit. The second pin of the power amplifier U3 is connected to the live wire L of several current transformers (4). The fourth pin of the power amplifier U3 is connected to the second pin of the relay RLY1. The first and fifth pins of the relay RLY1 are connected to the live wire L and neutral wire N of several current transformers (4), respectively. The third pin of the relay RLY1 is connected to the output terminal of the switch trigger circuit through the transistor Q2. The fourth pin of the relay RLY1 is connected to the output terminal of the power supply module through the resistor R44.

8. The heat-dissipating isolation current transformer according to claim 7, characterized in that... The feedback module also includes optocouplers P01-P05. The second pins of optocouplers P02-P04 are connected to LEDs LED1-LED3 respectively. The negative terminal of LED3 is connected to the output terminal of the switch trigger circuit. The first pins of optocouplers P02-P04 are connected to the fourth pins of optocouplers P01 and P05 respectively through resistors R34, R37 and R40. The third pin of optocoupler P01 is connected to the switch trigger circuit through the reset button SW1. The third pins of optocouplers P02-P04, the second pin of optocoupler P01 and the second pin of optocoupler P05 are connected to the external control terminal CON3 respectively.

9. The heat-dissipating isolation current transformer according to claim 4, characterized in that... The amplifier circuit includes operational amplifier U1 and operational amplifier U2. The input terminal of operational amplifier U1 is divided into two paths. One path is connected to the live wire L of several current transformers (4), and the other path is connected to the output terminal of operational amplifier U1. The output terminal of operational amplifier U1 is connected to the input terminal of operational amplifier U2 through resistor R4. The input terminal of operational amplifier U2 is connected to the output terminal of operational amplifier U2 through resistor R5, resistor R6 and capacitor C2. The output terminal of operational amplifier U2 is connected to the switch trigger circuit. Operational amplifiers U4, U5 and U6 are connected between the output terminal of operational amplifier U2 and the switch trigger circuit.

10. The heat-dissipating isolation current transformer according to claim 4, characterized in that... The switch trigger circuit includes a trigger U7. The 8th pin of the trigger U7 is connected to the output of the operational amplifier U5 through a transistor Q3. The 12th pin of the trigger U7 is connected to the light-emitting diode LED3. The 13th pin of the trigger U7 is connected to the relay RLY1 through a transistor Q2. The 11th pin of the trigger U7 is connected to the output of the operational amplifier U6.

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