Residual-current circuit breaker

Abstract

The utility model discloses a residual-current circuit breaker, which comprises a zero-sequence mutual inductor TA, an amplitude limiting circuit, an impedance matching circuit, a voltage-multiplying integral energy storage circuit, a voltage detection circuit, a tripping circuit and an anti-surge circuit, the zero sequence mutual inductor TA sleeves the main line and is used for sensing leakage current; the voltage-multiplying integral energy storage circuit is used for carrying out voltage-multiplying superposition on the input voltage, providing a comparison signal for the voltage detection circuit and providing tripping energy for the tripping circuit; the voltage detection circuit is connected with the tripping circuit, and when the comparison signal reaches a set value of the voltage detection circuit, the voltage detection circuit conducts the tripping circuit to enable the tripping circuit to work; the anti-surge circuit is connected to the voltage-multiplying integral energy storage circuit, and when induced current generated by surge current is greater than a set value of the anti-surge circuit, the anti-surge circuit is conducted to limit voltage superposition of the voltage-multiplying integral energy storage circuit, so that a comparison signal is lower than a set value of the voltage detection circuit; the surge protection circuit has the characteristic of preventing a product from malfunctioning due to surge.

Description

Technical Field

[0001] This application relates to the field of low-voltage electrical equipment, specifically to a residual current circuit breaker. Background Technology

[0002] A residual current circuit breaker (RCCB) is a protective device to prevent electric shock accidents. Installed in the power grid, it disconnects the circuit or issues an alarm signal when the leakage current in the grid exceeds a set value, ensuring personal and electrical safety. The national standard GB / T16917.1, clause 9.19.2, verifies the performance under a 3000A surge current (8 / 20μs surge current test), requiring the RCCB to trip but not be damaged. However, in reality, large current surges can occur in applications with downstream large motors, large capacitors, or induced lightning strikes. Users often do not want the RCCB to trip and cause accidental power outages. Therefore, surge-resistant RCCBs that do not trip under this test have appeared on the market.

[0003] In order to withstand surges, the existing residual current circuit breaker has the same residual current protection circuit structure as described in documents such as CN116667280a and CN207251174U, which connects a bidirectional suppression diode D1 in parallel on the secondary side of the zero-sequence current transformer. Although it can play a certain voltage suppression function, this product is still prone to tripping when a surge current occurs.

[0004] Therefore, developing a residual current circuit breaker that will not trip falsely when a surge current occurs is a direction worth exploring. Summary of the Invention

[0005] In view of this, the purpose of this application is to overcome the shortcomings of the prior art and to provide a residual current circuit breaker that prevents the product from tripping accidentally due to surge.

[0006] This application provides: a residual current circuit breaker, comprising a zero-sequence current transformer (TA), a limiting circuit, an impedance matching circuit, a voltage multiplier integrated energy storage circuit, a voltage detection circuit, a tripping circuit, and a surge protection circuit; the zero-sequence current transformer (TA) is installed in the main line to sense leakage current; the limiting circuit and the impedance matching circuit are connected to the secondary side of the zero-sequence current transformer (TA), and limit and modulate the signal induced by the current transformer (TA) before outputting it to the voltage multiplier integrated energy storage circuit; the voltage multiplier integrated energy storage circuit is connected to the impedance matching circuit, the voltage detection circuit, and the tripping circuit; The voltage multiplier and integral energy storage circuit multiplies the input voltage, providing a comparison signal for the voltage detection circuit and tripping energy for the tripping circuit. The voltage detection circuit is connected to the tripping circuit. When the comparison signal reaches the set value of the voltage detection circuit, the voltage detection circuit activates the tripping circuit to make it work. The surge protection circuit is connected to the voltage multiplier and integral energy storage circuit. When an induced current is generated due to a surge current, the surge protection circuit activates to limit the voltage superposition of the voltage multiplier and integral energy storage circuit, thereby making the comparison signal lower than the set value of the voltage detection circuit.

[0007] In some embodiments of this application, the impedance matching circuit includes a capacitor C1 and a resistor R1, which are connected in parallel on the secondary side of the zero-sequence current transformer TA.

[0008] In some embodiments of this application, the impedance matching circuit includes a capacitor C1 connected in parallel on the secondary side of the zero-sequence current transformer TA.

[0009] In some embodiments of this application, the limiting circuit is a transient suppression diode D1, a discharge tube, or a varistor, which is connected in parallel on the secondary side of the zero-sequence current transformer TA.

[0010] In some embodiments of this application, the voltage multiplier energy storage circuit includes resistors R2 and R3, diodes D2 and D3, capacitors C2 and C3; the first terminal of resistor R2 is connected to the first terminal of capacitor C1, the second terminal of resistor R2 is connected to the anode of diode D2, and the cathode of diode D2 is connected to the first terminal of capacitor C2; the first terminal of resistor R3 is connected to the second terminal of capacitor C1, and the second terminal of resistor R3 is connected to the second terminal of capacitor C2 and the first terminal of capacitor C3; the second terminal of capacitor C3 is connected to the anode of diode D3, and the cathode of diode D3 is connected to the anode of diode D1; during the positive half-cycle of the leakage current, the signal induced by the current transformer TA charges capacitor C2, and during the negative half-cycle of the leakage current, the signal induced by the current transformer TA charges capacitor C3.

[0011] In some embodiments of this application, the surge protection circuit includes two first electronic switches, both of which are connected to the voltage multiplier energy storage circuit. After the first electronic switches are turned on, the charging of the voltage multiplier energy storage circuit is restricted. One of the first electronic switches is turned on when the induced current of the surge current occurs during the positive half-cycle, and the other first electronic switch is turned on when the induced current of the surge current occurs during the negative half-cycle.

[0012] In some embodiments of this application, the two first electronic switches are a PNP transistor and an NPN transistor, respectively.

[0013] In some embodiments of this application, the two first electronic switches are an N-channel MOSFET and a P-channel MOSFET, respectively.

[0014] In some embodiments of this application, the surge protection circuit includes transistors Q1 and Q2; the base of transistor Q1 is connected to the second terminal of capacitor C2 and the second terminal of resistor R3, respectively; the collector of transistor Q1 is connected to the first terminal of capacitor C2 and the negative terminal of diode D2, respectively; the emitter of transistor Q1 is connected to the second terminal of capacitor C1 and the first terminal of resistor R3, respectively; the base of transistor Q2 is connected to the first terminal of capacitor C3 and the second terminal of resistor R3, respectively; the emitter of transistor Q2 is connected to the first terminal of resistor R3 and the second terminal of capacitor C1, respectively; the collector of transistor Q2 is connected to the second terminal of capacitor C3 and the positive terminal of diode D3, respectively; when an induced surge current occurs during the positive half-cycle, transistor Q1 conducts to limit the charging of C2; when an induced surge current occurs during the negative half-cycle, transistor Q2 conducts to limit the charging of C3.

[0015] In some embodiments of this application, the voltage detection circuit includes a diode D4, a capacitor C4, and a voltage detector U1; the positive terminal of the diode D4 is connected to the voltage multiplier energy storage circuit, and the positive terminal of the diode D4 is connected to the first terminal of the capacitor C4 and the Vin pin of the voltage detector U1; the second terminal of the capacitor C4 is connected to the Vss pin of the voltage detector U1 and the drive tripping circuit, and the Vout pin of the voltage detector U1 is connected to the drive tripping circuit; during the positive and negative half-cycles of the leakage current, the signals induced by the current transformer TA charge C4 after passing through the voltage multiplier energy storage circuit, and the comparison signal is the voltage across the capacitor C4. When the voltage detector U1 detects that the comparison signal is greater than the detector set value, the voltage detector U1 outputs a signal to drive the tripping circuit.

[0016] In some embodiments of this application, the tripping circuit includes a second electronic switch and a trip coil KM. The control terminal of the second electronic switch is connected to the Vout pin of the voltage detector U1, and the second electronic switch is connected in series with the trip coil KM.

[0017] In some embodiments of this application, the second electronic switch is a MOSFET or a silicon controlled rectifier (SCR).

[0018] The advantages of this application compared to the prior art are:

[0019] First, by adding a voltage multiplier and integral energy storage circuit, the input voltage is multiplied and superimposed multiple times to meet the requirements. This reduces the requirements for the instrument transformer, reduces its size, and enables product miniaturization.

[0020] Secondly, the surge protection circuit is combined with the voltage multiplier energy storage circuit. By using the voltage superposition of the voltage multiplier energy storage circuit (when there is no surge current), the comparison signal reaches the set value of the voltage detection circuit, causing the trip circuit to conduct (that is, to achieve leakage trip). When a surge occurs (when there is an induced current of surge current), the conduction of the surge protection circuit limits the voltage superposition of the energy storage circuit, so that the comparison signal is lower than the set value of the voltage detection circuit, the trip circuit cannot conduct, and the circuit breaker will not malfunction due to surge current. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A circuit diagram of a residual current circuit breaker according to an embodiment of this application is shown;

[0023] Figure 2 A circuit diagram of yet another embodiment of the residual current circuit breaker according to this application is shown;

[0024] Figure 3 A circuit diagram of another embodiment of the residual current circuit breaker according to this application is shown. Detailed Implementation

[0025] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0026] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0028] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0029] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature. Example

[0030] like Figure 1-3 As shown, an embodiment of this application is a residual current circuit breaker, which includes a zero-sequence current transformer (TA), a limiting circuit 101, an impedance matching circuit 102, a voltage multiplier integral energy storage circuit 103, an anti-surge circuit 104, a voltage detection circuit 105, and a tripping circuit 106.

[0031] The zero-sequence current transformer (TA) is installed on the main line (the main line connected to the circuit breaker) to detect leakage current signals in the power grid; that is, it generates an induced current when leakage current exists in the main line. Of course, besides detecting leakage current signals, the induced current generated by the zero-sequence current transformer (TA) can also provide operating energy for the entire circuit.

[0032] The limiting circuit 101 is connected to the zero-sequence current transformer TA. In this embodiment, a transient voltage suppressor diode D1 is used, connected in parallel to the secondary side of the zero-sequence current transformer TA. That is, the two ends of the transient voltage suppressor diode D1 are connected to signal points a and b on the secondary side of the zero-sequence current transformer TA, respectively. In this way, the signal induced by the zero-sequence current transformer TA will be suppressed by the transient voltage suppressor diode D1, keeping the voltage within a suitable range to ensure that it will not damage the electronic components in the circuit. Of course, in addition to using the transient voltage suppressor diode D1, the limiting circuit 101 can also use a varistor or a discharge tube, which can also achieve the effect of suppressing large voltages.

[0033] Impedance matching circuit 102 is connected to the zero-sequence current transformer TA. In this embodiment, impedance matching circuit 102 uses capacitor C1 and resistor R1, and is also connected in parallel with limiting circuit 101. Specifically, capacitor C1 is connected in parallel with transient suppression diode D1, and resistor R1 is connected in parallel with capacitor C1. In this way, the signal on the secondary side of the zero-sequence current transformer TA can be modulated through impedance matching to ensure that a suitable output voltage is supplied to subsequent circuits. As an alternative, resistor R1 can also be omitted, such as... Figure 3 As shown.

[0034] The voltage multiplier energy storage circuit 103 is connected to the impedance matching circuit 102 and includes resistor R2, resistor R3, diode D2, diode D3, capacitor C2, and capacitor C3.

[0035] The first terminal of resistor R2 is connected to the first terminal of capacitor C1, the second terminal of resistor R2 is connected to the positive terminal of diode D2, and the negative terminal of diode D2 is connected to the first terminal of capacitor C2.

[0036] The first terminal of resistor R3 is connected to the second terminal of capacitor C1. The second terminal of resistor R3 is connected to the second terminal of capacitor C2 and the first terminal of capacitor C3. The second terminal of capacitor C3 is connected to the positive terminal of diode D3, and the negative terminal of diode D3 is connected to the positive terminal of diode D1.

[0037] The voltage detection circuit 105 is connected to the voltage multiplier energy storage circuit 103 and includes a diode D4, a capacitor C4, and a voltage detector U1.

[0038] The positive terminal of diode D4 is connected to the first terminal of capacitor C2. The positive terminal of diode D4 is also connected to the first terminal of capacitor C4 and the Vin pin of voltage detector U1. The second terminal of capacitor C4 is connected to the Vss pin of voltage detector U1 and the trip circuit 106. The Vout pin of voltage detector U1 is connected to the trip circuit 106.

[0039] The specific working principle of this voltage multiplier energy storage circuit 103 and voltage detection circuit 105 is as follows: The voltage multiplier energy storage circuit 103 can multiply the signal output by the zero-sequence current transformer (TA) and store energy to ensure sufficient energy in the drive trip unit. Assuming that during the positive half-cycle of the leakage current, when the signal at point a is high and the signal at point b is low, the signal returns to point b via resistor R2, diode D2, capacitor C2, and resistor R3 to charge capacitor C2. During the negative half-cycle of the leakage current, when the signal at point b is high and the signal at point a is low, the signal returns to point a via resistor R3, capacitor C3, diode D3, and resistor R2 to charge capacitor C3. Regardless of whether capacitor C2 is charged during the positive half-cycle or capacitor C3 is charged during the negative half-cycle, capacitor C4 in the voltage detection circuit 105 is also charged simultaneously, thus achieving multiple voltage multiplications. In other words, at this time, the U signal between signals e and f in the circuit is the sum of the voltages across capacitor C2 and C3, achieving a voltage multiplication function. The voltage across capacitor C4 is Uef minus the forward conduction voltage of diode D4. After several positive and negative half-cycles of leakage current charging, the voltage on capacitor C4 reaches the set value of the voltage detection circuit 105 (that is, the comparison signal reaches the set value). The voltage detector U1 outputs a signal to trigger the tripping circuit. The number of repeated charging cycles determines the leakage current delay time of the product, which can be set according to actual needs.

[0040] Here, as an alternative, R1 and C1 of the impedance matching circuit 102 can be moved after R2 of the voltage multiplier energy storage circuit 103 (e.g., Figure 2 As shown in the diagram, the circuit connection method at this time is:

[0041] The first terminal of resistor R2 is connected to transient voltage suppressor diode D1, and the second terminal of resistor R2 is connected to resistor R1, capacitor C1, and the positive terminal of diode D2. (The connection methods of other components are basically the same.) Figure 1 Similarly, except that transistors Q1 and Q2 are replaced with MOSFETs, the connection method will not be described again. In this way, R2 and C1 can form an L-type filter circuit to improve anti-interference capability.

[0042] The trip circuit 106 is connected to the voltage detection circuit 105 and the voltage multiplier energy storage circuit 103, and includes a MOSFET Q3 and a trip coil KM. The drain of the MOSFET Q3 is connected to the first terminal of the capacitor C2, the gate of the MOSFET Q3 is connected to the Vout pin of the voltage detector U1, the source of the MOSFET Q3 is connected to the first terminal of the trip coil KM, and the second terminal of the trip coil KM is connected to the second terminal of the capacitor C3.

[0043] In this tripping circuit 106, after the voltage across capacitor C4 has undergone several positive and negative half-cycles of leakage current charging, it reaches the set value of the voltage detection circuit 105. When this voltage reaches the set value, the voltage detector U1 outputs a signal, and the MOSFET Q3 turns on, energizing the trip coil KM and causing the circuit breaker to trip. Here, the MOSFET Q3 can also be considered a second electronic switch (referred to as the second electronic switch to distinguish it from the first electronic switch).

[0044] In addition to MOSFETs, the second electronic switch can also be a silicon controlled rectifier (SCR) or a SCR composed of transistors.

[0045] The surge protection circuit 104 is connected to the voltage multiplier energy storage circuit 103 and includes transistor Q1 (NPN type), transistor Q2 (PNP type) and resistor R3 (which shares the resistor R3 of the voltage multiplier energy storage circuit 103).

[0046] The base of transistor Q1 is connected to the second terminal of capacitor C2 and the second terminal of resistor R3, respectively. The collector of transistor Q1 is connected to the first terminal of capacitor C2 and the negative terminal of diode D2, respectively. The emitter of transistor Q1 is connected to the second terminal of capacitor C1 and the first terminal of resistor R3, respectively.

[0047] In this way, by using transistor Q1 and resistor R3, when the zero-sequence current transformer TA senses a relatively large positive half-cycle surge signal, the voltage at signal point a is higher than that at signal point b. The signal returns to signal point b through resistor R2, diode D2, capacitor C2, and resistor R3 to charge capacitor C2. A voltage Udc is formed across resistor R3 (the voltage at signal point d is higher than that at signal point c). When Udc is greater than a certain value, a base current is generated at the base of transistor Q1, and transistor Q1 conducts, limiting the rise of the voltage across capacitor C2. At this time, the voltage on capacitor C4 cannot reach the set value of voltage detection circuit 105 (that is, the comparison signal is lower than the set value), and the second electronic switch of tripping circuit 106 cannot be turned on, so the circuit breaker will not trip erroneously.

[0048] The base of transistor Q2 is connected to the first terminal of capacitor C3 and the second terminal of resistor R3. The emitter of transistor Q2 is connected to the first terminal of resistor R3 and the second terminal of capacitor C1. The collector of transistor Q2 is connected to the second terminal of capacitor C3 and the positive terminal of diode D3.

[0049] In this way, by using transistor Q2 and resistor R3, when the zero-sequence current transformer TA senses a relatively large negative half-cycle surge signal, the voltage at signal point b is higher than that at signal point a. The signal returns to signal point a through resistor R3, capacitor C3, diode D3, and resistor R2 to charge C3. A voltage Ucd is formed across resistor R3 (the voltage at signal point c is higher than that at signal point d). When Ucd is greater than a certain value, a base current is generated at the base of transistor Q2, and transistor Q2 conducts, limiting the rise of the voltage across capacitor C3. At this time, the voltage on capacitor C4 cannot reach the set value of voltage detection circuit 105 (that is, the comparison signal is lower than the set value), and the second electronic switch of trip circuit 106 cannot be turned on, so the circuit breaker will not trip erroneously.

[0050] In this way, by combining transistors Q1 and Q2, the circuit breaker can be prevented from tripping accidentally when surge current occurs, regardless of whether it is the positive or negative half-cycle.

[0051] Here, transistors Q1 and Q2 actually function as the first electronic switch (referred to as the first electronic switch to distinguish them from the second electronic switch). Besides transistors, MOSFETs can also be used instead, such as... Figure 2 , 3 As shown.

[0052] In summary, when a leakage current occurs in the power grid, the signal induced by the zero-sequence current transformer (TA) is impedance matched, modulated, and limited. Then, the voltage multiplier energy storage circuit 103 multiplies the TA signal and utilizes the energy storage process to achieve a short delay function. When the voltage detection circuit 105 detects that the voltage accumulated on the capacitor of the voltage multiplier energy storage circuit 103 reaches the set value, it outputs a signal to the MOSFET of the trip circuit 106. The MOSFET turns on, and the energy output by the zero-sequence current transformer (TA) and the energy accumulated in the voltage multiplier energy storage circuit 103 discharge together to the trip coil KM, ensuring that the trip coil KM operates and drives the protector to trip for protection.

[0053] A resistor R4 can be added to the secondary side of the zero-sequence current transformer TA, that is, R4 can be added at point b. One end of R4 is connected to the limiting circuit 101, and the other end is connected to the impedance matching circuit 102. This resistor R4 can balance the circuit. Figure 3 As shown.

[0054] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. 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. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0055] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A residual current circuit breaker, characterized in that: The circuit includes a zero-sequence current transformer (TA), a limiting circuit, an impedance matching circuit, a voltage multiplier integrated energy storage circuit, a voltage detection circuit, a tripping circuit, and a surge protection circuit. The zero-sequence TA is installed on the main line to induce leakage current. The limiting circuit and the impedance matching circuit are connected to the secondary side of the zero-sequence TA, limiting and modulating the signal induced by the TA before sending it to the voltage multiplier integrated energy storage circuit. The voltage multiplier integrated energy storage circuit is connected to the impedance matching circuit, the voltage detection circuit, and the tripping circuit. The voltage multiplier integrated energy storage circuit multiplies and superimposes the input voltage, providing a comparison signal for the voltage detection circuit and tripping energy for the tripping circuit. The voltage detection circuit is connected to the tripping circuit; when the comparison signal reaches the set value of the voltage detection circuit, the voltage detection circuit activates the tripping circuit to operate. The surge protection circuit is connected to the voltage multiplier integrated energy storage circuit; when an induced current is generated due to a surge current, the surge protection circuit activates to limit the voltage superposition of the voltage multiplier integrated energy storage circuit, thereby making the comparison signal lower than the set value of the voltage detection circuit.

2. A residual current circuit breaker according to claim 1, characterized in that: The impedance matching circuit includes capacitor C1 and resistor R1, which are connected in parallel on the secondary side of the zero-sequence current transformer TA. Alternatively, the impedance matching circuit includes capacitor C1, which is connected in parallel on the secondary side of the zero-sequence current transformer TA.

3. A residual current circuit breaker according to claim 1, characterized in that: The limiting circuit is a transient suppression diode D1, a discharge tube, or a varistor, which is connected in parallel to the secondary side of the zero-sequence current transformer TA.

4. A residual current circuit breaker according to claim 1, characterized in that: The voltage multiplier energy storage circuit includes resistors R2 and R3, diodes D2 and D3, and capacitors C2 and C3. The first terminal of resistor R2 is connected to the first terminal of capacitor C1, and the second terminal of resistor R2 is connected to the anode of diode D2. The cathode of diode D2 is connected to the first terminal of capacitor C2. The first terminal of resistor R3 is connected to the second terminal of capacitor C1, and the second terminal of resistor R3 is connected to the second terminal of capacitor C2 and the first terminal of capacitor C3. The second terminal of capacitor C3 is connected to the anode of diode D3, and the cathode of diode D3 is connected to the anode of diode D1. During the positive half-cycle of the leakage current, the signal induced by the current transformer (TA) charges capacitor C2, and during the negative half-cycle of the leakage current, the signal induced by the current transformer (TA) charges capacitor C3.

5. A residual current circuit breaker according to claim 1, characterized in that: The surge protection circuit includes two first electronic switches, both of which are connected to the voltage multiplier energy storage circuit. When the first electronic switches are turned on, they limit the charging of the voltage multiplier energy storage circuit. One of the first electronic switches turns on when the induced current of the surge current occurs during the positive half-cycle, and the other first electronic switch turns on when the induced current of the surge current occurs during the negative half-cycle.

6. A residual current circuit breaker according to claim 5, characterized in that: The two first electronic switches are a PNP transistor and an NPN transistor, respectively; or, the two first electronic switches are an N-channel MOSFET and a P-channel MOSFET, respectively.

7. A residual current circuit breaker according to claim 4, characterized in that: The surge protection circuit includes transistors Q1 and Q2. The base of transistor Q1 is connected to the second terminal of capacitor C2 and the second terminal of resistor R3, respectively. The collector of transistor Q1 is connected to the first terminal of capacitor C2 and the negative terminal of diode D2, respectively. The emitter of transistor Q1 is connected to the second terminal of capacitor C1 and the first terminal of resistor R3, respectively. The base of transistor Q2 is connected to the first terminal of capacitor C3 and the second terminal of resistor R3, respectively. The emitter of transistor Q2 is connected to the first terminal of resistor R3 and the second terminal of capacitor C1, respectively. The collector of transistor Q2 is connected to the second terminal of capacitor C3 and the positive terminal of diode D3, respectively. When an induced surge current occurs during the positive half-cycle, transistor Q1 conducts to limit the charging of C2. When an induced surge current occurs during the negative half-cycle, transistor Q2 conducts to limit the charging of C3.

8. A residual current circuit breaker according to claim 1, characterized in that: The voltage detection circuit includes diode D4, capacitor C4, and voltage detector U1. The positive terminal of diode D4 is connected to the voltage multiplier energy storage circuit, and the positive terminal of diode D4 is connected to the first terminal of capacitor C4 and the Vin pin of voltage detector U1. The second terminal of capacitor C4 is connected to the Vss pin of voltage detector U1 and the drive tripping circuit. The Vout pin of voltage detector U1 is connected to the drive tripping circuit. During the positive and negative half-cycles of the leakage current, the signals induced by the current transformer TA charge C4 after passing through the voltage multiplier energy storage circuit. The comparison signal is the voltage across capacitor C4. When voltage detector U1 detects that the comparison signal is greater than the detector set value, voltage detector U1 outputs a signal to drive the tripping circuit.

9. A residual current circuit breaker according to claim 1, characterized in that: The tripping circuit includes a second electronic switch and a trip coil KM. The control terminal of the second electronic switch is connected to the Vout pin of the voltage detector U1, and the second electronic switch is connected in series with the trip coil KM.

10. A residual current circuit breaker according to claim 9, characterized in that: The second electronic switch is a MOSFET or a silicon controlled rectifier (SCR).

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