A leakage protection circuit

Abstract

The present invention provides a leakage protection circuit, comprising: a current mutual induction circuit, a controller, a coil control circuit, a tripping circuit and a self-test circuit, wherein the input end of the current mutual induction circuit is connected to the circuit to be detected, the output end of the current mutual induction circuit is connected to the first input end of the controller; the first output end of the controller is connected to the input end of the coil control circuit; the output end of the coil control circuit is connected to the tripping circuit; the input end of the self-test circuit is connected to the self-test output end of the controller, and the output end of the self-test circuit is connected to the self-test input end of the controller. The controller sends a self-test signal to the self-test circuit through the self-test output end, and determines whether the self-test is normal according to the signal received at the self-test input end, so as to check whether the components inside the leakage protection circuit are invalid, thereby realizing all-round self-test of the leakage protection circuit.

Description

Technical Field

[0001] The invention relates to the technical field of leakage protection, and in particular to a leakage protection circuit. Background Art

[0002] The increasing popularity of household appliances has brought a lot of convenience to our lives, but it also brings a lot of dangers to us. For example, when there are problems such as leakage, overload, short circuit, etc. in the line, it is not only easy to cause damage to the electrical appliances, but may even cause electrical fires that endanger personal safety. As a device to protect people’s lives and property in the power distribution system, the leakage protection device can quickly cut off the power supply when there is a danger of leakage, ensuring that people can use electricity safely and avoiding unnecessary losses. However, the existing leakage devices may have aging and damage of components during use, so that the leakage protection cannot be disconnected in time, posing a safety hazard. The regular inspection of the existing leakage protector requires manual operation, and there is a risk of missed detection, so that the safety of users and electrical equipment cannot be guaranteed. Summary of the invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the defects of the leakage protection device in the prior art, thereby providing a leakage protection circuit.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] An embodiment of the present invention provides a leakage protection circuit, comprising: a current mutual induction circuit, a controller, a coil control circuit, a tripping circuit and a self-test circuit, wherein the output end of the current mutual induction circuit is connected to the first input end of the controller, the current mutual induction circuit is used to detect a ground fault signal of a line to be detected, and send the ground fault signal to the controller; the first output end of the controller is connected to the input end of the coil control circuit, the controller is used to generate a tripping signal according to the ground fault signal, and send the tripping signal to the coil control circuit; the output end of the coil control circuit is connected to the tripping circuit, and the coil control circuit is used to control the tripping of a tripper in the tripping circuit according to the tripping signal; the input end of the self-test circuit is connected to the self-test output end of the controller, the output end of the self-test circuit is connected to the self-test input end of the controller, the self-test circuit is used to perform self-test according to the self-test signal sent by the controller, and the self-test result is sent to the controller.

[0006] Optionally, the coil control circuit includes: a first controllable switch, a second controllable switch, a third controllable switch and a first capacitor, wherein the first end of the first controllable switch is respectively connected to the control end of the trip circuit and the external power supply circuit, the second end of the first controllable switch is connected to the first end of the second controllable switch, the control end of the first controllable switch is respectively connected to the first end of the third controllable switch, one end of the first capacitor and the external power supply circuit, the second end of the second controllable switch is grounded, the control end of the second controllable switch is connected to the first output end of the controller, the second end of the third controllable switch is grounded, the control end of the third controllable switch is connected to the second output end of the controller, and the other end of the first capacitor is grounded.

[0007] Optionally, the self-test circuit includes: a first resistor and a second resistor, wherein one end of the first resistor is connected to the second output end of the controller, and the other end of the first resistor is connected to the control end of the third controllable switch; one end of the second resistor is connected to the third output end of the controller, and the other end of the second resistor is connected to the control end of the second controllable switch.

[0008] Optionally, the self-test circuit includes: a third resistor, a fourth resistor and a fourth controllable switch, wherein one end of the third resistor is connected to the second output end of the controller, and the other end of the third resistor is connected to the control end of the third controllable switch; one end of the fourth resistor is connected to the third output end of the controller, and the other end of the fourth resistor is connected to the control end of the fourth controllable switch, a first end of the fourth controllable switch is connected to the control end of the tripping circuit, and a second end of the fourth controllable switch is grounded.

[0009] Optionally, the self-test circuit also includes: a fifth resistor and a first LED lamp, wherein one end of the fifth resistor is connected to the third output end of the controller, the other end of the fifth resistor is connected to one end of the first LED lamp, and the other end of the first LED lamp is grounded.

[0010] Optionally, the tripping circuit includes: a tripping coil, a fifth controllable switch and a sixth controllable switch, wherein one end of the tripping coil is connected to an external power supply circuit, the other end of the tripping coil is connected to a first end of the fifth controllable switch, a second end of the fifth controllable switch is connected to a first end of the sixth controllable switch, a control end of the fifth controllable switch is connected to the external power supply circuit, a second end of the sixth controllable switch is grounded, and a control end of the sixth controllable switch is connected to the external power supply circuit.

[0011] Optionally, the leakage protection circuit also includes a first power supply circuit, an input end of the first power supply circuit is connected to the circuit to be detected, and an output end of the first power supply circuit is respectively connected to one end of the trip coil, the control end of the fifth controllable switch, and the control end of the sixth controllable switch.

[0012] Optionally, the leakage protection circuit further includes a second power supply circuit, an input end of the second power supply circuit is connected to an output end of the first power supply circuit, and an output end of the second power supply circuit is connected to a self-test power supply end of the controller.

[0013] Optionally, the leakage protection circuit further includes a third power supply circuit, an input end of the third power supply circuit is connected to an output end of the first power supply circuit, and an output end of the third power supply circuit is connected to a ground fault detection power supply end of the controller.

[0014] The technical solution of the present invention has the following advantages:

[0015] The leakage protection circuit provided by the present invention comprises: a current mutual induction circuit, a controller, a coil control circuit, a tripping circuit and a self-test circuit, wherein the output end of the current mutual induction circuit is connected to the first input end of the controller, the current mutual induction circuit is used to detect the ground fault signal of the circuit to be detected, and send the ground fault signal to the controller; the first output end of the controller is connected to the input end of the coil control circuit, the controller is used to generate a tripping signal according to the ground fault signal, and send the tripping signal to the coil control circuit; the output end of the coil control circuit is connected to the tripping circuit, and the coil control circuit is used to control the tripping of the tripping device in the tripping circuit according to the tripping signal; the input end of the self-test circuit is connected to the self-test output end of the controller, the output end of the self-test circuit is connected to the self-test input end of the controller, and the self-test circuit is used to perform self-test according to the self-test signal sent by the controller, and the self-test result is sent to the controller. By connecting the first controllable switch and the second controllable switch in series, using the third controllable switch to provide a discharge circuit for the first capacitor, when the second controllable switch receives the high level output by the controller, the potential in the tripping circuit is pulled down, the tripping coil is disconnected, and the main circuit switch is cut off, thereby disconnecting the power supply and the load. At the same time, the controller sends a self-test signal to the self-test circuit through the self-test output terminal, and determines whether the self-test is normal based on the signal received at the self-test input terminal, so as to check whether the components inside the leakage protection circuit fail, thereby realizing a full range of self-test of the leakage protection circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 is a principle block diagram of a specific example of a leakage protection circuit in an embodiment of the present invention;

[0018] Figure 2 A leakage protection circuit is a specific example of an embodiment of the present invention;

[0019] Figure 3 is a principle block diagram of another specific example of a leakage protection circuit in an embodiment of the present invention;

[0020] Figure 4 This is another specific example of a leakage protection circuit in the embodiment of the present invention. DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0023] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] The embodiment of the present invention provides a leakage protection circuit. Figure 1 As shown, the leakage protection circuit includes: a current mutual induction circuit 1, a controller 2, a coil control circuit 3, a tripping circuit 4 and a self-test circuit 5, wherein the input end of the current mutual induction circuit 1 is connected to the line to be detected, the output end of the current mutual induction circuit 1 is connected to the first input end of the controller 2, the current mutual induction circuit 1 is used to detect the ground fault signal of the line to be detected, and send the ground fault signal to the controller 2; the first output end of the controller 2 is connected to the input end of the coil control circuit 3, the controller 2 is used to generate a tripping signal according to the ground fault signal value, and send the tripping signal to the coil control circuit 3; the output end of the coil control circuit 3 is connected to the tripping circuit 4, and the coil control circuit 3 is used to control the tripping of the tripping device in the tripping circuit 4 according to the tripping signal. The input end of the self-test circuit 5 is connected to the self-test output end of the controller 2, the output end of the self-test circuit 5 is connected to the self-test input end of the controller 2, the self-test circuit 5 is used to perform self-test according to the self-test signal sent by the controller 2, and the self-test result is sent to the controller 2.

[0026] In a specific embodiment, if Figure 2 As shown, the current transformer circuit 1 includes: a zero-sequence current transformer ZCTA and a neutral ground fault transformer ZCTB. Among them, the zero-sequence current transformer ZCTA detects the leakage current signal, and sends the leakage current signal to the controller 2 for amplification, comparison and signal processing through a coupling and signal filtering circuit composed of a resistor R12, a resistor R13, a resistor R14 and a capacitor C7. When the leakage current value is greater than the set threshold, Pin13 TRIG of the controller 2 outputs a high-level pulse to the coil control circuit 3. The coil control circuit 3 controls the tripping device in the tripping circuit 4 to trip according to the tripping signal, and disconnects the connection between the power supply and the load. At the same time, the controller 2 performs periodic self-tests, sends a self-test signal to the self-test circuit 5 through the self-test output terminal, and determines whether the self-test is normal according to the signal received at the self-test input terminal, so as to check whether the components inside the leakage protection circuit are invalid, thereby realizing a full range of self-tests of the leakage protection circuit.

[0027] In one embodiment, if Figure 2As shown, the coil control circuit 3 includes: a first controllable switch Q3, a second controllable switch SCR, a third controllable switch Q4 and a first capacitor C5, wherein a first end of the first controllable switch Q3 is respectively connected to the control end of the trip circuit 4 and the external power supply circuit, a second end of the first controllable switch Q3 is connected to the first end of the second controllable switch SCR, a control end of the first controllable switch Q3 is respectively connected to the first end of the third controllable switch Q4, one end of the first capacitor C5 and the external power supply circuit, a second end of the second controllable switch SCR is grounded, a control end of the second controllable switch SCR is connected to the first output end of the controller 2, a second end of the third controllable switch Q4 is grounded, a control end of the third controllable switch Q4 is connected to the second output end of the controller 2, and the other end of the first capacitor C5 is grounded.

[0028] In a specific embodiment, when a neutral grounding fault occurs, the zero-sequence current transformer ZCTA, the neutral grounding fault transformer ZCTB, the capacitor C8, the capacitor C9, the resistor R15, and the internal amplifier of the controller 2 generate self-oscillation. When the amplitude of the self-oscillation is greater than the set threshold, Pin13 TRIG of the controller 2 outputs a high-level pulse to the coil control circuit 3. The coil control circuit 3 controls the tripping device in the tripping circuit 4 to trip according to the tripping signal, and disconnects the connection between the power supply and the load.

[0029] In the embodiment of the present invention, Figure 2 As shown, the trip circuit 4 includes: a trip coil Sol, a fifth controllable switch Q1 and a sixth controllable switch Q2, wherein one end of the trip coil Sol is connected to the external power supply circuit, the other end of the trip coil Sol is connected to the first end of the fifth controllable switch Q1, the second end of the fifth controllable switch Q1 is connected to the first end of the sixth controllable switch Q2, the control end of the fifth controllable switch Q1 is connected to the external power supply circuit, the second end of the sixth controllable switch Q2 is grounded, and the control end of the sixth controllable switch Q2 is connected to the external power supply circuit.

[0030] Furthermore, the tripping circuit 4 further includes: a resistor R5, a resistor R6, a resistor R8, a resistor R9, a resistor R10 and a diode D10, wherein the external power supply circuit is connected to the control end of the fifth controllable switch Q1 through the resistor R5, the resistor R6, the resistor R8 and the diode D10, and is used to provide a base bias current for the fifth controllable switch Q1. At the same time, the external power supply circuit is connected to the control end of the sixth controllable switch Q2 through the resistor R5, the resistor R6, the resistor R9 and the resistor R10, and is used to provide a base bias current for the sixth controllable switch Q2. The fifth controllable switch Q1 and the sixth controllable switch Q2 are directly connected in series with the tripping coil sol. When the base bias current of the fifth controllable switch Q1 and the sixth controllable switch Q2 is pulled down, the fifth controllable switch Q1 and the sixth controllable switch Q2 are turned off, the tripping coil Sol is disconnected, the main circuit switch SW is cut off, and the connection from the power supply to the load is disconnected.

[0031] Further, the coil control circuit 3 also includes: a resistor R7 and a capacitor C6. Specifically, the coil control circuit 3 is a base bias current control circuit of the fifth controllable switch Q1 and the sixth controllable switch Q2, wherein the resistor R7 provides a charging circuit for the first capacitor C5, and the third controllable switch Q4 provides a discharging circuit for the first capacitor C5; the S pole of the first controllable switch Q3 is connected in series with the A pole of the second controllable switch SCR, and the G pole of the second controllable switch SCR is connected to Pin13 of the controller 2 through R17. When Pin13 of the controller 2 outputs a high level and the voltage across the first capacitor C5 is higher than the minimum conduction voltage of the first controllable switch Q3, the first controllable switch Q3 and the second controllable switch SCR are turned on, the base bias current of the fifth controllable switch Q1 and the sixth controllable switch Q2 is pulled down, the fifth controllable switch Q1 and the sixth controllable switch Q2 are turned off, the trip coil Sol is disconnected, the main circuit switch SW is cut off, and the connection from the power supply to the load is disconnected.

[0032] The leakage protection circuit provided by the present invention comprises: a current mutual induction circuit, a controller, a coil control circuit, a tripping circuit and a self-test circuit, wherein the input end of the current mutual induction circuit is connected to a circuit to be detected, the output end of the current mutual induction circuit is connected to a first input end of the controller, the current mutual induction circuit is used to detect a ground fault signal of the circuit to be detected, and send the ground fault signal to the controller; the first output end of the controller is connected to the input end of the coil control circuit, the controller is used to generate a tripping signal according to the ground fault signal, and send the tripping signal to the coil control circuit; the output end of the coil control circuit is connected to the tripping circuit, and the coil control circuit is used to control the tripping of a tripper in the tripping circuit according to the tripping signal; the input end of the self-test circuit is connected to the self-test output end of the controller, the output end of the self-test circuit is connected to the self-test input end of the controller, the self-test circuit is used to perform self-test according to the self-test signal sent by the controller, and the self-test result is sent to the controller. By connecting the first controllable switch and the second controllable switch in series, using the third controllable switch to provide a discharge circuit for the first capacitor, when the second controllable switch receives the high level output by the controller, the potential in the tripping circuit is pulled down, the tripping coil is disconnected, and the main circuit switch is cut off, thereby disconnecting the power supply and the load. At the same time, the controller sends a self-test signal to the self-test circuit through the self-test output terminal, and determines whether the self-test is normal according to the signal received by the self-test input terminal, so as to check whether the components inside the leakage protection circuit are invalid, thereby realizing a full range of self-test of the leakage protection circuit.

[0033] In one embodiment, if Figure 2As shown, the self-test circuit 5 includes: a first resistor R21 and a second resistor R22, wherein one end of the first resistor R21 is connected to the second output end of the controller 2, and the other end of the first resistor R21 is connected to the control end of the third controllable switch Q4; one end of the second resistor R22 is connected to the third output end of the controller 2, and the other end of the second resistor R22 is connected to the control end of the second controllable switch SCR.

[0034] In an embodiment of the present invention, when Pin6 of controller 2 detects that the power supply is in the negative half cycle and in the set self-test cycle, controller 2 generates a self-test signal to simulate a neutral ground fault. During normal self-test, Pin10 FOUT of controller 2 outputs a high-level pulse, and the third controllable switch Q4 is turned on to provide a fast discharge circuit for the first capacitor C5. When the voltage across the first capacitor C5 is rapidly reduced to a voltage lower than the minimum on-voltage of the first controllable switch Q3, the first controllable switch Q3 is quickly turned off. That is, during the self-test period, the second controllable switch SCR is turned on, and the controller 2 provides current to the second controllable switch SCR through the diode D7. Pin6 STIN of controller 2 detects a low-level signal through the diode D7 path, and determines that the self-test function is normal. Although the second controllable switch SCR is turned on, because the first controllable switch Q3 is turned off during the self-test period, the tripping coil Sol remains working, and the power supply remains powered to the load, which does not affect the normal use of the leakage protection switch.

[0035] like Figure 2 As shown, Pin6 STIN of controller 2 detects a high-level signal through the diode D7 path, and determines that the self-test function fails. When a self-test fails, the self-test failure signal is connected to the G pole of the second controllable switch SCR, the second controllable switch SCR is turned on, the trip coil Sol is disconnected to cut off SW, and the connection between the power supply and the load is disconnected. At this time, the controller 2 also loses power. Of course, there is another way to choose, that is, R22 is not selected, that is, the self-test failure signal will not be connected to the G pole of the second controllable switch SCR, and the power supply continues to supply power to the load. At the same time, the first LED light (LED2) flashes to warn the user that the self-test has failed. It is suitable for places where the power cannot be cut off immediately.

[0036] Furthermore, the self-checking circuit 5 further includes: a fifth resistor R18 and a first LED lamp, wherein one end of the fifth resistor R18 is connected to the third output end of the controller 2, the other end of the fifth resistor R18 is connected to one end of the first LED lamp, and the other end of the first LED lamp is grounded. When a self-checking failure occurs, a self-checking failure signal is connected to the G pole of the second controllable switch SCR, the second controllable switch SCR is turned on, the tripping coil SOL is disconnected to cut off the main circuit switch SW, and the connection between the power supply and the load is disconnected.

[0037] In one embodiment, Figure 2The self-test circuit 5 shown can also be replaced by Figure 4 The self-test circuit shown. The self-test circuit includes: a third resistor R31, a fourth resistor R32 and a fourth controllable switch SCR2, wherein one end of the third resistor R31 is connected to the second output end of the controller 2, and the other end of the third resistor R31 is connected to the control end of the third controllable switch Q4; one end of the fourth resistor R32 is connected to the third output end of the controller 2, and the other end of the fourth resistor R32 is connected to the control end of the fourth controllable switch SCR2, a first end of the fourth controllable switch SCR2 is connected to the control end of the trip circuit 4, and a second end of the fourth controllable switch SCR2 is grounded.

[0038] In a specific embodiment, if Figure 4 As shown, the self-test failure signal is connected to the G pole of the fourth controllable switch SCR2. When the self-test failure occurs, the fourth controllable switch SCR2 is turned on, and the trip coil SOL is disconnected to cut off the main circuit switch SW, disconnecting the connection between the power supply and the load. At this time, the controller 2 is still energized. By connecting the self-test failure signal to the G pole of the fourth controllable switch SCR2, when the self-test fails, the fourth controllable switch SCR2 is turned on, so that the connection between the power supply and the load can be disconnected without turning on the second controllable switch SCR. At the same time, the first LED light (LED2) flashes to warn the user that the self-test fails, enriching the user's needs.

[0039] In one embodiment, if Figure 3 As shown, the leakage protection circuit further includes a first power supply circuit 6, the input end of the first power supply circuit 6 is connected to the circuit to be detected, and the output end is connected to the trip circuit 4, for supplying power to the trip circuit 4. Specifically, as Figure 2 As shown, the input end of the first power supply circuit 6 is connected to the circuit to be detected, and the output end of the first power supply circuit 6 is respectively connected to one end of the trip coil Sol, the control end of the fifth controllable switch Q1 and the control end of the sixth controllable switch Q2.

[0040] In a specific embodiment, if Figure 2As shown, the first power supply circuit 6 includes a capacitor C1, a resistor R1, a resistor R2, a diode D1, a diode D2, a diode D3, a diode D4 and a capacitor C2, wherein the AC power from the line to be detected is connected to one end of the tripping coil Sol through a resistor-capacitor voltage-dropping circuit composed of a capacitor C1, a resistor R1, and a resistor R2, a bridge rectifier circuit composed of a diode D1, a diode D2, a diode D3, and a diode D4, and a low-frequency filter and energy storage C2, to supply power to the tripping coil Sol. At the same time, it is connected to the control end of the fifth controllable switch Q1 through a resistor R5, a resistor R6, a resistor R8, and a diode D10, to provide a base bias current for the fifth controllable switch Q1. The first power supply circuit 6 is connected to the control end of the sixth controllable switch Q2 through a resistor R5, a resistor R6, a resistor R9, and a resistor R10, to provide a base bias current for the sixth controllable switch Q2.

[0041] In one embodiment, if Figure 3 As shown, the leakage protection circuit further includes a second power supply circuit 7 , the input end of the second power supply circuit 7 is connected to the output end of the first power supply circuit 6 , and the output end of the second power supply circuit 7 is connected to the self-test power supply end of the controller 2 .

[0042] In a specific embodiment, if Figure 2 As shown, the second power supply circuit 7 includes: a resistor R3 and a capacitor C3, wherein the DC power provided by the first power supply circuit 6 is stepped down and current limited by the resistor R3, and filtered and decoupled by the capacitor C3, and finally powers the self-test module of the controller 2.

[0043] In one embodiment, if Figure 3 As shown, the leakage protection circuit further includes a third power supply circuit 8 , the input end of the third power supply circuit 8 is connected to the output end of the first power supply circuit 6 , and the output end of the third power supply circuit 8 is connected to the ground fault detection power supply end of the controller 2 .

[0044] In a specific embodiment, if Figure 2 As shown, the third power supply circuit 8 includes: a resistor R4 and a capacitor C4, wherein the DC power provided by the first power supply circuit 6 is stepped down and current limited by the resistor R4, and filtered and decoupled by the capacitor C4, and finally supplies power to the ground fault detection module of the controller 2.

[0045] In one embodiment, if Figure 3 As shown, the leakage protection circuit also includes a zero-crossing detection circuit 9 , the input end of the zero-crossing detection circuit 9 is connected to the circuit to be detected, and the output end of the zero-crossing detection circuit 9 is connected to the zero-crossing detection end of the controller 2 .

[0046] In a specific embodiment, if Figure 2As shown, the zero-crossing detection circuit 9 includes a diode D8, a diode D7 and a resistor R11, wherein the diode D8 and the resistor R11 are used to provide a zero-crossing detection signal for Pin6 STIN of the controller 2. The diode D7 provides a path for the STIN signal detection and judgment, and provides current for the second controllable switch SCR during the negative half-cycle self-test of the power supply.

[0047] In one embodiment, if Figure 2 As shown, the leakage protection circuit also includes a leakage protection switch closed power indication circuit 10, wherein the leakage protection switch closed power indication circuit 10 is composed of a diode D9, a resistor R19, and an LED 1. When the leakage protection switch is closed, the LED 1 is on, and when the leakage protection switch is disconnected, the LED 1 is off.

[0048] In one embodiment, if Figure 2 As shown, the leakage protection circuit further includes a manual test circuit 11, wherein the manual test circuit 11 includes a TEST switch and a resistor R20. When the TEST switch is pressed, an unbalanced leakage current of about 8 mA is generated in the ZCT coil to simulate a leakage fault of the leakage protection switch.

[0049] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention.

Claims

1. A leakage protection circuit, characterized in that: include: Current mutual induction circuit, controller, coil control circuit, tripping circuit and self-test circuit, wherein: The output end of the current mutual induction circuit is connected to the first input end of the controller, and the current mutual induction circuit is used to detect a ground fault signal of the line to be detected and send the ground fault signal to the controller; The first output terminal of the controller is connected to the input terminal of the coil control circuit, and the controller is used to generate a trip signal according to the ground fault signal and send the trip signal to the coil control circuit; The output end of the coil control circuit is connected to the tripping circuit, and the coil control circuit is used to control the tripping of the tripping device in the tripping circuit according to the tripping signal; The input end of the self-test circuit is connected to the self-test output end of the controller, the output end of the self-test circuit is connected to the self-test input end of the controller, and the self-test circuit is used to perform self-test according to the self-test signal sent by the controller and send the self-test result to the controller; The coil control circuit includes: a first controllable switch, a second controllable switch, a third controllable switch and a first capacitor, wherein the first end of the first controllable switch is respectively connected to the control end of the trip circuit and the external power supply circuit, the second end of the first controllable switch is connected to the first end of the second controllable switch, the control end of the first controllable switch is respectively connected to the first end of the third controllable switch, one end of the first capacitor and the external power supply circuit, the second end of the second controllable switch is grounded, the control end of the second controllable switch is connected to the first output end of the controller, the second end of the third controllable switch is grounded, the control end of the third controllable switch is connected to the second output end of the controller, and the other end of the first capacitor is grounded.

2. The leakage protection circuit according to claim 1, characterized in that: The self-test circuit comprises: a first resistor and a second resistor, wherein: One end of the first resistor is connected to the second output end of the controller, and the other end of the first resistor is connected to the control end of the third controllable switch; One end of the second resistor is connected to the third output end of the controller, and the other end of the second resistor is connected to the control end of the second controllable switch.

3. The leakage protection circuit according to claim 1, characterized in that: The self-test circuit comprises: a third resistor, a fourth resistor and a fourth controllable switch, wherein: One end of the third resistor is connected to the second output end of the controller, and the other end of the third resistor is connected to the control end of the third controllable switch; One end of the fourth resistor is connected to the third output end of the controller, the other end of the fourth resistor is connected to the control end of the fourth controllable switch, the first end of the fourth controllable switch is connected to the control end of the tripping circuit, and the second end of the fourth controllable switch is grounded.

4. The leakage protection circuit according to claim 2 or 3, characterized in that: The self-test circuit also includes: a fifth resistor and a first LED lamp, wherein one end of the fifth resistor is connected to the third output end of the controller, the other end of the fifth resistor is connected to one end of the first LED lamp, and the other end of the first LED lamp is grounded.

5. The leakage protection circuit according to claim 1, characterized in that: The tripping circuit includes: a tripping coil, a fifth controllable switch and a sixth controllable switch, wherein one end of the tripping coil is connected to an external power supply circuit, the other end of the tripping coil is connected to a first end of the fifth controllable switch, a second end of the fifth controllable switch is connected to a first end of the sixth controllable switch, a control end of the fifth controllable switch is connected to the external power supply circuit, a second end of the sixth controllable switch is grounded, and a control end of the sixth controllable switch is connected to the external power supply circuit.

6. The leakage protection circuit according to claim 5, characterized in that: It also includes a first power supply circuit, the input end of the first power supply circuit is connected to the circuit to be detected, and the output end of the first power supply circuit is respectively connected to one end of the trip coil, the control end of the fifth controllable switch, and the control end of the sixth controllable switch.

7. The leakage protection circuit according to claim 6, characterized in that: It also includes a second power supply circuit, the input end of the second power supply circuit is connected to the output end of the first power supply circuit, and the output end of the second power supply circuit is connected to the self-test power supply end of the controller.

8. The leakage protection circuit according to claim 6, characterized in that: It also includes a third power supply circuit, the input end of the third power supply circuit is connected to the output end of the first power supply circuit, and the output end of the third power supply circuit is connected to the ground fault detection power supply end of the controller.

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