Leakage protection circuit and circuit breaker

Abstract

The leakage protection circuit comprises a mutual inductor and a control unit, the mutual inductor is coupled to a power line, the mutual inductor is connected with the control unit through a sampling circuit and a leakage detection circuit in sequence, a leakage test circuit is connected between the mutual inductor and the control unit, and the leakage test circuit generates simulation leakage current under the control of the control unit. The sampling circuit is used for collecting leakage current or simulating leakage current, the precision self-checking circuit is connected between the sampling circuit and the control unit, and when the sampling circuit collects the simulating leakage current, the precision self-checking circuit is connected with the sampling circuit. The control unit obtains an analog leakage current value through the precision self-checking circuit and compares the analog leakage current value with a preset value of the analog leakage current of the control unit to judge the precision of the mutual inductor. According to the utility model, the precision self-checking circuit is arranged, so that the control unit obtains the analog leakage current value from the precision self-checking circuit and compares the analog leakage current value with a preset value, thereby realizing the detection of the precision of the mutual inductor, and ensuring the use safety of the circuit breaker.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of low voltage electrical apparatus, concretely relates to a leakage protection circuit and circuit breaker. BACKGROUND

[0002] The leakage circuit breaker is a switch with overload, short circuit and leakage protection function, which can prevent fire caused by circuit short circuit or overload, and can quickly cut off power supply to protect personal safety when leakage occurs. At present, the leakage circuit breaker usually has remote monitoring function, which makes it more intelligent and efficient, thereby improving the management convenience of electrical system.

[0003] The leakage protection device of the adjustable leakage circuit breaker is usually selected from a zero sequence transformer with high precision. Since the leakage protection device directly relates to the safety of electricity, it is necessary to periodically perform self-checking on the leakage protection device. However, in the existing equipment, the self-checking of the leakage protection device mainly focuses on whether it can normally act, and lacks the step of self-checking the precision of the zero sequence transformer. In the use process, if the precision of the zero sequence transformer changes, it may lead to incorrect judgment, and the leakage circuit breaker may be prematurely tripped or not tripped, which affects the safety in use. SUMMARY

[0004] The utility model discloses a leakage protection circuit and circuit breaker which overcome at least one defect of the prior art.

[0005] To achieve the above-mentioned purpose, the utility model adopts the following technical scheme:

[0006] The utility model provides a leakage protection circuit, including mutual inductor and control unit, the mutual inductor is coupled on the power supply circuit, the mutual inductor passes through sampling circuit, leakage detection circuit and control unit connection in proper order, still be connected with leakage test circuit between the mutual inductor and control unit, leakage test circuit generates analog leakage current under the control of control unit, the sampling circuit is used to gather leakage current or analog leakage current on the power supply circuit, still include precision self -checking circuit, precision self -checking circuit is connected between sampling circuit and control unit, when sampling circuit gathers analog leakage current, control unit obtains analog leakage current value for comparing with the preset value of control unit analog leakage current through precision self -checking circuit and judges the precision of mutual inductor.

[0007] Preferably, the mutual inductor includes a sampling coil and a detection coil coupled to each other, the sampling circuit obtains the leakage current or the analog leakage current on the power supply circuit through the sampling coil, and the leakage test circuit is connected with the detection coil, so that the self-checking signal output by the control unit generates an analog current through the detection coil.

[0008] Preferably, the self-checking signal is divided into an accuracy self-checking signal and a leakage self-checking signal, the accuracy self-checking signal generates an analog current for detecting the accuracy of the transformer through the detection coil, and the leakage self-checking signal generates an analog current for detecting the leakage detection circuit through the detection coil.

[0009] Preferably, the accuracy self-checking signal is a PWM signal with a frequency of 500 Hz or above, and the leakage self-checking signal is a PWM signal with a frequency of 50-60 Hz.

[0010] Preferably, the accuracy self-checking circuit includes an amplification circuit connected between the sampling circuit and the control unit, and the amplification circuit amplifies the analog leakage current obtained by the sampling circuit and feeds back to the control unit.

[0011] Preferably, the amplification circuit includes resistors R2, R3, R4, R5, capacitors C3, C4, and an operational amplifier U1, the positive input terminal and the negative input terminal of the operational amplifier U1 are connected to the sampling circuit through resistors R2 and R3, respectively, the capacitors C3 are connected in parallel to the positive input terminal and the negative input terminal of the operational amplifier U1, the positive input terminal of the operational amplifier U1 is connected with the resistor R4, the other end of the resistor R4 is connected with a reference power supply, the negative input terminal and the output terminal of the operational amplifier U1 are connected through the resistor R5, one power supply terminal of the operational amplifier U1 is connected with the working power supply and connected with the GND through the capacitor C4, and the other power supply terminal of the operational amplifier U1 is connected with the GND.

[0012] Preferably, the accuracy self-checking circuit includes a high-pass filter circuit connected with the amplification circuit and the control unit, respectively, and the control unit obtains the analog leakage component for calculating the analog leakage current value through the high-pass filter circuit.

[0013] Preferably, the high-pass filter circuit includes resistors R10, R11, R12, R13, capacitors C6, C7, C8, and an operational amplifier U2, the negative input terminal and the output terminal of the operational amplifier U2 are connected through the resistor R13, the output terminal of the amplification circuit is connected to the positive input terminal of the operational amplifier U2 through the series-connected capacitors C6 and C7, the positive input terminal and the output terminal of the operational amplifier U2 are connected through the resistor R11, the positive input terminal and the negative input terminal of the operational amplifier U2 are connected with the GND through the resistors R10 and R12, respectively, one power supply terminal of the operational amplifier U2 is connected with the working power supply and connected with the GND through the capacitor C8, the other power supply terminal of the operational amplifier U2 is connected with the GND, and the output terminal of the operational amplifier U2 is connected with the control unit.

[0014] Preferably, the sampling circuit comprises a resistor R1, a TVS transient voltage suppression diode D1, a capacitor C1 and a capacitor C2, two ends of the resistor R1 connected with the TVS transient voltage suppression diode D1 in parallel are connected with two connection terminals of a sampling coil respectively, two ends of the resistor R1 are connected with GND through the capacitor C1 and the capacitor C2 respectively.

[0015] Preferably, the leakage test circuit comprises a resistor R6, a resistor R7, a resistor R8, a resistor R9, a TVS transient voltage suppression diode D2, a triode Q1 and a capacitor C5, the control unit is connected with a base of the triode Q1 through the resistor R6, one connection terminal of a detection coil is connected with a collector of the triode Q1, the other connection terminal of the detection coil is connected with the collector of the triode Q1 through the TVS transient voltage suppression diode D2, working power supply of the triode Q1 is connected with the collector of the triode Q1 through the resistor R8, the resistor R9 and the TVS transient voltage suppression diode D2 in series, two ends of the resistor R7 connected with the capacitor C5 in parallel are connected with the base and an emitter of the triode Q1 respectively, the emitter of the triode Q1 is connected with GND.

[0016] Preferably, the control unit is further connected with a tripping device, and the control unit drives the tripping device to act according to the received leakage current or analog leakage current.

[0017] The utility model provides a circuit breaker, including at least one circuit breaker pole, the circuit breaker pole is connected on power supply circuit, still include the leakage protection circuit as above.

[0018] Further, after the circuit breaker is powered off, the analog leakage test circuit and the precision self-checking circuit in the leakage protection circuit cooperate to perform precision detection.

[0019] The leakage protection circuit and the circuit breaker of the utility model, through setting precision self-checking circuit, make control unit compare and judge from analog leakage current value and preset value in precision self-checking circuit, thereby realize the detection of mutual inductor precision, guarantee the use safety of circuit breaker.

[0020] In addition, by configuring a high-pass filter circuit, low-frequency signals are filtered out, and precision is improved.

[0021] In addition, the high-pass filter circuit is omitted, which is suitable for circuit breakers with low self-checking precision, has wide application range, and is helpful for reducing cost.

[0022] In addition, the circuit breaker can select to perform precision detection when powered off, so as to avoid analog leakage current interference on the detection result and optimize cost. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is the schematic diagram of the leakage protection circuit in the utility model.

[0024] Figure 2 is a schematic diagram of the leakage protection circuit of the first embodiment of the utility model;

[0025] Figure 3 is a schematic diagram of the leakage protection circuit of the second embodiment of the utility model;

[0026] Figure 4 is a schematic diagram of the leakage protection circuit of the third embodiment of the utility model;

[0027] Figure 5 is a circuit diagram of the sampling circuit and the amplification circuit of the utility model;

[0028] Figure 6 is a circuit diagram of the high-pass filter circuit of the utility model;

[0029] Figure 7 is a circuit diagram of the leakage test circuit of the utility model. DETAILED DESCRIPTION

[0030] The embodiments given below in conjunction with the drawings further illustrate the specific embodiments of the leakage protection circuit and the circuit breaker of the utility model. The leakage protection circuit and the circuit breaker of the utility model are not limited to the description of the following embodiments.

[0031] The circuit breaker comprises a shell, at least one circuit breaker pole is arranged in the shell, the circuit breaker pole is connected to the power supply line for controlling the on and off of the power supply line, a leakage protection circuit is further arranged in the shell, the leakage protection circuit comprises a mutual inductor and a control unit, wherein the mutual inductor is coupled to the power supply line, the mutual inductor is connected in sequence through a sampling circuit, a leakage detection circuit and the control unit, at present, the leakage detection circuit usually uses an RC low-pass filter circuit, mainly for calculating the waveform appeared when the leakage occurs in the power grid (frequency 50Hz / 60Hz); a leakage test circuit is further connected between the mutual inductor and the control unit, the on and off of the leakage test circuit is controlled by the control unit, the control unit usually comprises a controller, when the leakage current is generated on the power supply line, the leakage current collected by the sampling circuit is fed back to the control unit after being processed by the leakage detection circuit, a control signal is output by the control unit, an alarm element controlled by the control unit issues a warning and / or drives the connected release to act, so as to realize the leakage protection; when it is needed to detect whether the action of the leakage protection circuit is normal, the control unit outputs a self-checking signal to the leakage test circuit, the analog leakage current collected by the sampling circuit in the leakage test circuit is fed back to the control unit through the leakage detection circuit, a control signal is output by the control unit to issue a warning and / or drive the connected release to act, which is the prior art in the field.

[0032] As Figure 1As shown, the improvement of the present application lies in that the leakage protection circuit further comprises a precision self-checking circuit, the precision self-checking circuit is connected between the sampling circuit and the control unit, when the sampling circuit collects the analog leakage current, the control unit obtains the analog leakage current value from the precision self-checking circuit for comparison with the preset value of the analog leakage current in the control unit to judge the precision of the mutual inductor.

[0033] In this way, by setting the precision self-checking circuit, the control unit compares the analog leakage current value obtained from the precision self-checking circuit with the preset value to judge, thereby realizing the detection of the precision of the mutual inductor and ensuring the use safety of the circuit breaker.

[0034] Specifically, the mutual inductor comprises a sampling coil and a detection coil, wherein the sampling circuit obtains the leakage current on the power line through the sampling coil, the detection coil is connected to the leakage test circuit, when the control unit outputs a self-checking signal to the leakage test circuit, the self-checking signal is usually a PWM signal with a special frequency, the detection coil generates an analog current, the mutual coupling of the sampling coil and the detection coil enables the sampling circuit to obtain the analog leakage current through the sampling coil and feed back to the control unit.

[0035] Preferably, the self-checking signal is divided into a precision self-checking signal and a leakage self-checking signal, the precision self-checking signal generates an analog current through the detection coil for detecting the precision of the mutual inductor, the mutual coupling of the sampling coil and the detection coil enables the sampling circuit to obtain the analog leakage current that can detect the precision of the mutual inductor and feed back to the control unit, the analog leakage current that can detect the precision of the mutual inductor is processed by the precision self-checking circuit and then fed back to the control unit, so that the control unit compares and calculates to obtain the precision of the mutual inductor, the precision self-checking signal is a PWM signal with a frequency of 500Hz or above, and the precision self-checking signal is adjusted according to the number of turns of the coil in the mutual inductor to avoid high-frequency distortion and low-frequency interference.

[0036] The leakage self-checking signal generates an analog current through the detection coil for detecting the leakage detection circuit, usually, the leakage self-checking signal adopts a PWM signal with a frequency of 50-60Hz, the mutual coupling of the sampling coil and the detection coil enables the sampling circuit to obtain the analog leakage current that can detect the leakage detection circuit and feed back to the control unit, the analog leakage current that can detect the leakage detection circuit is processed by the leakage detection circuit and then fed back to the control unit, at this time, the control unit can drive the action device connected to the control unit, for example, drive the action of the release, the self-checking signal of the control unit for detecting the leakage detection circuit can adopt a frequency close to the conventional leakage, that is, the leakage self-checking signal is a PWM signal with a frequency of 50-60Hz.

[0037] In addition, the precision self-checking signal and the leakage self-checking signal can be generated separately, simultaneously or at intervals, so as to realize separate or simultaneous detection of the precision of the mutual inductor and the leakage detection circuit. As a poor embodiment, the precision self-checking signal and the leakage self-checking signal also adopt PWM signals of the same frequency.

[0038] The precision self-checking circuit comprises an amplification circuit connected between the sampling circuit and the control unit. After the control unit outputs the self-checking signal to the leakage test circuit, the analog leakage current collected by the sampling circuit is fed back to the control unit after being amplified by the amplification circuit. On one hand, the control unit obtains the analog leakage current value through the analog leakage current, compares the analog leakage current value with the preset value of the analog leakage current, and if the difference between the two exceeds a threshold value, it indicates that the mutual inductor is damaged or the precision deviates. On the other hand, the control unit can drive the alarm element connected thereto to issue a warning and / or drive the trip connected thereto to act, that is, the analog leakage current is fed back to the control unit after being processed by the leakage detection circuit, and the alarm element or the trip connected to the control unit is driven to act, wherein the alarm element and the trip are generally prior art, that is, the alarm element can be an indicator light, a bell, etc., and the trip can be an electromagnetic trip.

[0039] Preferably, the precision self-checking circuit further comprises a high-pass filter circuit connected with the amplification circuit and the control unit. The control unit obtains the analog leakage component in the analog leakage current through the high-pass filter circuit, compares the analog leakage component with the preset value in the control unit, and judges through the filtering of low-frequency signals to improve the self-checking precision. Of course, for circuit breakers with low requirements for self-checking precision, the high-pass filter circuit can be omitted to reduce the cost. By introducing the high-pass filter circuit and the amplification circuit in the precision self-checking circuit, the circuit breaker can filter out the leakage interference (i.e. the leakage generated by the grounding wire of part of the equipment) in the power grid without tripping, so as to extract the corresponding analog leakage signal. Further, the circuit breaker can perform precision self-checking in the power-on state or in the power-off state, so as to avoid the analog leakage current interference with the detection result and optimize the cost.

[0040] In combination with Figure 1 , 2 and 5-7, the first embodiment of the leakage protection circuit in the circuit breaker is provided.

[0041] The leakage protection circuit comprises a mutual inductor and a control unit, the mutual inductor is coupled to a three-phase four-wire power supply line, a leakage test circuit is connected between the mutual inductor and the control unit, the control unit outputs a self-checking signal to the leakage test circuit, the mutual inductor is connected with a sampling circuit, the sampling circuit is connected with the control unit through a precision self-checking circuit, in addition, the sampling circuit is also connected with the control unit through the leakage detection circuit, and a tripping device is further connected to the control unit, and the leakage detection circuit in the embodiment can adopt the prior art, and thus will not be described herein.

[0042] Specifically in the embodiment, the mutual inductor comprises a sampling coil and a detection coil coupled to each other, the sampling coil and the detection coil are coupled to a three-phase four-wire power supply line, a leakage test circuit is connected between the detection coil and the control unit, the precision self-checking circuit comprises an amplification circuit and a high-pass filter circuit, the sampling coil is connected with the control unit through the amplification circuit, and the amplification circuit is further connected with the control unit through the high-pass filter circuit; when the sampling circuit collects the leakage current on the power supply line, the leakage detection circuit feeds back to the control unit, and the control unit drives the tripping device to act; when the control unit outputs a self-checking signal, that is, outputs a PWM signal with a special frequency to the leakage test circuit, the leakage test circuit generates an analog leakage current with a special frequency and is coupled to the sampling coil, and is transmitted to the control unit through the sampling circuit and the leakage detection circuit to drive the tripping device, at the same time, the analog leakage current sequentially passes through the amplification circuit and the high-pass filter circuit, the low-frequency signal is filtered out by the high-pass filter circuit, the analog leakage component signal in the analog leakage current is stripped and fed back to the control unit, and the analog leakage component and the preset value of the analog leakage current in the control unit are compared and judged, if the difference between the two exceeds the preset deviation threshold, the mutual inductor is damaged or the precision deviates.

[0043] In combination Figures 5-7 A circuit diagram of the precision self-checking circuit applied in the embodiment is provided.

[0044] As Figure 5 shown, the sampling circuit comprises a resistor R1, a TVS transient suppression diode D1, a capacitor C1 and a capacitor C2, the two ends of the resistor R1 and the TVS transient suppression diode D1 are connected with two wiring ends of the sampling coil in parallel, respectively, for collecting the total leakage current in the power supply line, the two ends of the resistor R1 are connected with GND through the capacitor C1 and the capacitor C2, respectively, the output current of the mutual inductor is converted into a differential voltage after flowing through the resistor R1, and then passes through the amplification circuit;

[0045] In the embodiment, the amplification circuit comprises resistors R2, R3, R4, R5, capacitors C3, C4 and an operational amplifier U1, the positive input terminal and the negative input terminal of the operational amplifier U1 are connected to the sampling circuit through resistors R2 and R3 respectively, capacitor C3 is connected in parallel to the positive input terminal and the negative input terminal of the operational amplifier U1, the positive input terminal of the operational amplifier U1 is connected with resistor R4, the other end of resistor R4 is connected with a reference power supply, the negative input terminal of the operational amplifier U1 is connected with the output terminal through resistor R5, one power supply terminal of the operational amplifier U1 is connected with the working power supply (+3.3V_A) and connected with GND through capacitor C4, the other power supply terminal of the operational amplifier U1 is connected with GND, the differential voltage converted by R1 in the sampling circuit is converted by the amplification circuit, and is lifted to the reference voltage (Verf) at the voltage zero point, the amplification multiple is the ratio of resistor R5 to resistor R3, and the leakage sampling signal output by the amplification circuit is Leakage_1.

[0046] As shown in Figure 6 , the high-pass filter circuit comprises resistors R10, R11, R12, R13, capacitors C6, C7, C8 and an operational amplifier U2, the negative input terminal and the output terminal of the operational amplifier U2 are connected through resistor R13, the output terminal of the amplification circuit is connected to the positive input terminal of the operational amplifier U2 through capacitors C6 and C7 in series, that is, Leakage_1 is input to the positive input terminal of the operational amplifier U2 through capacitors C6 and C7 in sequence, the positive input terminal and the output terminal of the operational amplifier U2 are connected through resistor R11, the positive input terminal and the negative input terminal of the operational amplifier U2 are connected with GND through resistors R10 and R12 respectively, one power supply terminal of the operational amplifier U2 is connected with the working power supply (+3.3V_A) and connected with GND through capacitor C8, the other power supply terminal of the operational amplifier U2 is connected with GND, the output terminal of the operational amplifier U2 is connected with the control unit, the high-frequency analog leakage component signal is stripped to obtain signal Leakage_2 after the processing of the high-pass filter circuit, the signal Leakage_2 is compared with the preset value of the analog leakage current in the control unit after the calculation and processing by the software of the control unit, and whether the transformer is damaged or the precision is deviated is judged according to the comparison result.

[0047] As shown in Figure 7As shown, the leakage test circuit includes resistor R6, resistor R7, resistor R8, resistor R9, TVS transient voltage suppressor D2, triode Q1 and capacitor C5, the control unit is connected with the base of triode Q1 through resistor R6, one terminal of the detection coil is connected with the collector of triode Q1, the other terminal of the detection coil is connected with the collector of triode Q1 through TVS transient voltage suppressor D2, the working power supply of triode Q1 is connected with the collector of triode Q1 through resistor R8, resistor R9 and TVS transient voltage suppressor D2 in series, the two ends of resistor R7 and capacitor C5 in parallel are respectively connected with the base and the emitter of triode Q1, the emitter of triode Q1 is connected with GND, the on-off of triode Q1 is controlled by the control unit, and the PWM signal of specific frequency is outputted to generate the analog current of specific frequency on the detection coil, the analog current is coupled to the sampling coil, so that the signal is superimposed in the signal Leakag_1 of the sampling circuit and inputted into the precision self-checking circuit into the control unit, thereby completing the analog leakage detection and precision self-checking.

[0048] In combination Figure 1 , 3 , 5 and 7, a second embodiment of the leakage protection circuit in the circuit breaker is provided, and the leakage protection circuit of the embodiment is suitable for the circuit breaker with low self-checking precision.

[0049] As Figure 1 , 3 shown, the leakage protection circuit includes the mutual inductor and the control unit, the mutual inductor is coupled to the three-phase four-wire power supply circuit, the leakage test circuit is connected between the control unit and the mutual inductor, the self-checking signal is outputted from the control unit to the leakage test circuit, the mutual inductor is connected with the sampling circuit, the sampling circuit is connected with the control unit through the precision self-checking circuit, and meanwhile, in the embodiment, the sampling circuit is also connected with the control unit through the leakage detection circuit.

[0050] Different from the first embodiment, the precision self-checking circuit of the embodiment omits the high-pass filter circuit, that is, the precision self-checking circuit only includes the amplification circuit, the control unit inputs the PWM signal of specific frequency to the leakage test circuit first, the PWM signal is processed by the amplification circuit after passing through the mutual inductor and the sampling circuit and then is fed back to the control unit, the control unit calculates the analog leakage component through the software, that is, acquires the analog signal, the analog signal is in the superimposed state of the high-frequency square wave and the low-frequency sine wave, a plurality of high-frequency periodic waveforms are extracted therefrom, the peak-to-peak value is compared with the preset value of the analog leakage current, and whether the mutual inductor is damaged or the precision is deviated is judged according to the comparison.

[0051] The leakage test circuit in the embodiment is same as the first embodiment, and the mutual inductor, the control unit and the sampling circuit can adopt the circuit connection mode in the first embodiment.

[0052] In combination with Figure 1 、 4 , 5 and 7, a third embodiment of the leakage protection circuit in the circuit breaker is provided, when the accuracy self-checking of the mutual inductor using the leakage protection circuit in the embodiment is performed, the power supply line is first controlled to be disconnected by the circuit breaker, so that the low-frequency leakage current superposition in the leakage protection circuit can be avoided, and the self-checking accuracy can be improved.

[0053] In the embodiment, the connection mode of the leakage protection circuit is same as the second embodiment, and the control unit is connected with the tripping device, the control unit can drive the tripping device to disconnect the power supply line, and then the same detection steps as the second embodiment are performed by the control unit, compared with the second embodiment, the low-frequency leakage superposition component does not interfere in the detection process.

[0054] It should be noted that in the description of the utility model, the terms "upper", "lower", "left", "right", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in use, and are only for the convenience of description, and do not indicate that the device or element referred to must have a particular orientation, therefore, it cannot be understood as a limitation on the utility model. In addition, the terms "first", "second", "third" and the like are only used for distinguishing description, and cannot be understood as indicating relative importance.

[0055] The above content is a further detailed description of the utility model in combination with the specific preferred embodiment, and the specific implementation of the utility model cannot be limited to these descriptions. For ordinary skilled persons in the technical field to which the utility model belongs, some simple deductions or substitutions can be made without departing from the concept of the utility model, and all of them should be regarded as belonging to the protection range of the utility model.

Claims

1. An electric leakage protection circuit, comprising a mutual inductor and a control unit, the mutual inductor being coupled to a power line, the mutual inductor being connected to the control unit in sequence through a sampling circuit and an electric leakage detection circuit, an electric leakage test circuit being further connected between the mutual inductor and the control unit, the electric leakage test circuit generating an analog electric leakage current under the control of the control unit, the sampling circuit being used for collecting the electric leakage current on the power line or the analog electric leakage current, characterized in that: The precision self-checking circuit is connected between the sampling circuit and the control unit, and when the sampling circuit collects the analog leakage current, the control unit obtains the analog leakage current value through the precision self-checking circuit for comparison with the preset value of the analog leakage current of the control unit to determine the precision of the transformer. ​ 2. The ground-fault circuit of claim 1, wherein: The transformer comprises a sampling coil and a detection coil coupled with each other, the sampling circuit obtains the leakage current or the analog leakage current on the power line through the sampling coil, and the leakage test circuit is connected with the detection coil to make the self-checking signal output by the control unit generate the analog current through the detection coil.

3. The ground-fault circuit of claim 2, wherein: The self-checking signal is divided into a precision self-checking signal and a leakage self-checking signal, the precision self-checking signal generates the analog current for detecting the precision of the transformer through the detection coil, and the leakage self-checking signal generates the analog current for detecting the leakage test circuit through the detection coil.

4. The ground-fault circuit of claim 3, wherein: The precision self-checking signal is a PWM signal with a frequency of 500 Hz or above, and the leakage self-checking signal is a PWM signal with a frequency of 50-60 Hz.

5. The ground-fault circuit of claim 2, wherein: The precision self-checking circuit comprises an amplification circuit connected between the sampling circuit and the control unit, and the analog leakage current obtained by the sampling circuit is amplified by the amplification circuit and then fed back to the control unit.

6. The ground-fault circuit of claim 5, wherein: The amplification circuit comprises a resistor R2, a resistor R3, a resistor R4, a resistor R5, a capacitor C3, a capacitor C4 and an operational amplifier U1, the positive input end and the reverse input end of the operational amplifier U1 are connected to the sampling circuit through the resistor R2 and the resistor R3 respectively, the capacitor C3 is connected in parallel to the positive input end and the reverse input end of the operational amplifier U1, the resistor R4 is connected to the positive input end of the operational amplifier U1, the other end of the resistor R4 is connected to a reference power supply, the reverse input end and the output end of the operational amplifier U1 are connected through the resistor R5, one power supply end of the operational amplifier U1 is connected to a working power supply and connected to GND through the capacitor C4, and the other power supply end of the operational amplifier U1 is connected to GND.

7. The ground-fault circuit interrupter of claim 5, wherein: The precision self-checking circuit comprises a high-pass filter circuit connected with the amplification circuit and the control unit respectively, and the control unit obtains the analog leakage component for calculating the analog leakage current value through the high-pass filter circuit.

8. The ground-fault circuit interrupter of claim 7, wherein: The high-pass filter circuit comprises resistors R10, R11, R12, R13, capacitors C6, C7, C8 and an operational amplifier U2, the reverse input end of the operational amplifier U2 is connected with the output end through the resistor R13, the output end of the amplification circuit is connected with the positive input end of the operational amplifier U2 through the capacitors C6, C7 in series, the positive input end and the output end of the operational amplifier U2 are connected through the resistor R11, the positive input end and the reverse input end of the operational amplifier U2 are connected with the GND through the resistors R10, R12 respectively, one power supply end of the operational amplifier U2 is connected with the working power supply and connected with the GND through the capacitor C8, the other power supply end of the operational amplifier U2 is connected with the GND, and the output end of the operational amplifier U2 is connected with the control unit.

9. The ground fault protection circuit of claim 2, wherein: The sampling circuit comprises resistors R1, a TVS transient suppression diode D1, capacitors C1 and C2, the two ends of the resistor R1 connected with the TVS transient suppression diode D1 in parallel are respectively connected with two wire ends of the sampling coil, and the two ends of the resistor R1 are respectively connected with the GND through the capacitors C1 and C2.

10. The ground fault protection circuit of claim 2, wherein: The leakage test circuit comprises resistors R6, R7, R8, R9, a TVS transient suppression diode D2, a triode Q1 and a capacitor C5, the control unit is connected with the base of the triode Q1 through the resistor R6, one wire end of the detection coil is connected with the collector of the triode Q1, the other wire end of the detection coil is connected with the collector of the triode Q1 through the TVS transient suppression diode D2, the working power supply of the triode Q1 is connected with the collector of the triode Q1 through the resistors R8, R9 and the TVS transient suppression diode D2 in series, the two ends of the resistor R7 connected with the capacitor C5 in parallel are respectively connected with the base and the emitter of the triode Q1, and the emitter of the triode Q1 is connected with the GND.

11. The ground fault protection circuit of claim 1, wherein: The control unit is further connected with a tripping device, and the control unit drives the tripping device to act according to the received leakage current or analog leakage current.

12. A circuit breaker comprising at least one circuit breaker pole connected to a power line, characterized in that: The leakage protection circuit also comprises the leakage protection circuit according to any one of claims 1-11.

13. The circuit breaker of claim 12, wherein: After the circuit breaker is powered off, the analog leakage test circuit and the precision self-checking circuit in the leakage protection circuit cooperate to perform precision detection. After the circuit breaker is powered off, the analog leakage test circuit and the precision self-checking circuit in the leakage protection circuit cooperate to perform precision detection.

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