Leakage protection circuit

Abstract

The utility model belongs to the field of electric leakage protection, and particularly relates to an electric leakage protection circuit, which comprises a voltage following module serving as a voltage follower; the sampling module is used for being externally connected with an analog-to-digital converter to amplify the excitation current for sampling; the test output module is used for outputting a test result; the excitation terminal comprises an excitation terminal first pin and an excitation terminal second pin, the voltage following module is electrically connected with the excitation terminal first pin, and the sampling module is electrically connected with the excitation terminal second pin; the test output module is electrically connected with the test terminal; the MCU module is used for judging whether the sampling current of the sampling module is abnormal or not and outputting SOUT high level through the test output module when the sampling current is abnormal, and the voltage following module, the sampling module and the test output module are electrically connected with the MCU module. According to the utility model, timely feedback can be carried out during electric leakage, so that the safety of electric equipment and a user can be effectively guaranteed.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of leakage protection, especially relates to a leakage protection circuit. BACKGROUND

[0002] Residual current is the sum of all transmission line current vectors in the power transmission line and the part that is not zero, also called leakage current. In power supply and distribution and power utilization systems, short circuit accidents generally have two forms, phase-to-phase short circuit and phase-to-ground short circuit. Phase-to-phase short circuit can produce tens of kiloampere of current in an instant, and the transmission line temperature rises sharply, which can burn the insulation layer and cause danger, but the large current can make the circuit breaker cut off the line in an instant to avoid accidents. Phase-to-ground short circuit is generally caused by slow factors such as insulation aging, which causes the insulation resistance between the phase line and the equipment shell to decrease, forming a small residual current, and eventually causing a fire due to local heating. Generally speaking, the residual current value is not large, and the circuit breaker generally cannot detect it, but its safety threat to people's production and life is very large. According to statistics, about half of the fire accidents caused by household electricity in China are caused by phase-to-ground short circuit, and it can also cause the equipment shell to be electrified, and further cause electric shock accidents, therefore, a leakage protection circuit is needed to protect the safety of the electrical equipment and the user. SUMMARY

[0003] The utility model discloses a leakage protection circuit, which can effectively protect the safety of the electrical equipment and the user.

[0004] In order to achieve the above-mentioned purpose, the technical scheme of the utility model is as follows.

[0005] A leakage protection circuit, characterized in that it comprises:

[0006] A voltage following module as a voltage follower;

[0007] A sampling module for connecting an analog-to-digital converter externally to amplify the excitation current for sampling;

[0008] A test output module for outputting test results;

[0009] An excitation terminal, which comprises an excitation terminal first pin and an excitation terminal second pin, the voltage following module is electrically connected with the excitation terminal first pin, and the sampling module is electrically connected with the excitation terminal second pin;

[0010] A test terminal, the test output module is electrically connected with the test terminal;

[0011] The MCU module judges whether the sampling current of the sampling module is abnormal, and outputs high level SOUT through the test output module when the current is abnormal.

[0012] In the leakage protection circuit, the voltage follower module can be used as a voltage follower to ensure stable transmission of signals, impedance matching and isolation protection; the sampling module amplifies the excitation current through the second pin of the excitation terminal to sample, and the MCU module judges whether the sampling current of the sampling module is abnormal, and outputs high level SOUT through the test output module when there is abnormal current, so that feedback can be made in time when leakage occurs, and the safety of the electrical equipment and the user can be effectively ensured.

[0013] Further, the circuit further comprises a power supply module for connecting an external power supply to supply power, and the power supply module is electrically connected with the MCU module.

[0014] Further, the MCU module comprises a chip U1 with a model of MM32L0020.

[0015] Further, the voltage follower module comprises an operational amplifier U2A.

[0016] Further, the voltage follower module further comprises a resistor R2, a resistor R3, a resistor R9, a resistor R10, a resistor R12, a capacitor C1, a capacitor C2, a capacitor C3, and two Schottky diodes D4, one end of the resistor R9 is connected with the twentieth pin of the chip U1, the other end of the resistor R9, one end of the capacitor C1, the positive electrode of one Schottky diode D4, the negative electrode of another Schottky diode D4, and one end of the resistor R10 are all connected with the first pin of the excitation terminal, the output end of the operational amplifier U2A is connected with one end of the resistor R12 and the other end of the resistor R10, the other end of the resistor R12 is connected with the negative input end of the operational amplifier U2A, one end of the resistor R3, one end of the resistor R2, and one end of the capacitor C2 are all connected with the positive input end of the operational amplifier U2A, and the capacitor C3 is connected with the positive power supply end of the operational amplifier U2A.

[0017] Further, the sampling module comprises an operational amplifier U2B.

[0018] Further, the sampling module further includes resistance R11, resistance R13, two Schottky diodes D1, bidirectional TVS transient suppression diode D2, the positive input end of the operational amplifier U2B is connected with the sixteenth pin of the chip U1 through the resistance R11, the negative input end of the operational amplifier U2B is connected with one end of the resistance R13, the output end of the operational amplifier U2B, the other end of the resistance R13, the positive pole of one Schottky diode D1, the negative pole of another Schottky diode D1 and one end of the bidirectional TVS transient suppression diode D2 are all connected with the second pin of the excitation terminal, and the other end of the bidirectional TVS transient suppression diode D2 is connected with the voltage follower module.

[0019] Further, the power supply module is connected with interface J1 and interface J2, the test output module includes resistance R1, resistance R6, resistance R7, resistance R15, resistance R16, resistance R17, capacitor C9 and triode Q1, one end of the resistance R7 is connected with the power supply module and the eighth pin of the chip U1, the other end of the resistance R7 is connected with one end of the resistance R6 and one end of the capacitor C9, the other end of the resistance R6 and one end of the resistance R17 are all connected to the second pin of the interface J2, the other end of the resistance R17, one end of the resistance R16 and one end of the resistance R15 are all connected with the B pole of the triode Q1, the other end of the resistance R16 is connected with the twelfth pin of the chip U1, and the C pole of the triode Q1 is connected with the test terminal through the resistance R1.

[0020] The utility model discloses the beneficial effect lies in, in the leakage protection circuit, wherein voltage follower module can be used as voltage follower to ensure the stable transmission of signal, impedance matching and isolation protection, and sampling module amplifies excitation current to do sampling through the second pin of excitation terminal, at this moment, MCU module judges whether the sampling current of sampling module is abnormal, and then when there is abnormal current, through test output module output SOUT high level, can feedback in time when leaking, can effectively guarantee the safety of electrical equipment and user. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is the circuit schematic diagram of the utility model.

[0022] Figure 2 It is the circuit schematic diagram of MCU module.

[0023] Figure 3 It is the circuit schematic diagram of voltage follower module.

[0024] Figure 4 It is the circuit schematic diagram of sampling module.

[0025] Figure 5 It is the circuit schematic diagram of test output module.

[0026] Figure 6 is the circuit schematic diagram of the power supply module.

[0027] Figure 7 is the working principle diagram of the fluxgate.

[0028] Figure 8 is the schematic diagram of the excitation waveform and the sampling waveform of the utility model.

[0029] 1, MCU module;

[0030] 2, voltage follower module;

[0031] 3, sampling module;

[0032] 4, test output module;

[0033] 5, excitation terminal; 51, excitation terminal first pin; 52, excitation terminal second pin;

[0034] 6, test terminal;

[0035] 7, power supply module. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the utility model more clearly, the utility model is further described in detail below by combining with the drawings and examples. It should be understood that the specific examples described here are only used to explain the utility model, and are not used to limit the utility model.

[0037] Referring to Figures 1-6 , the embodiment provides a leakage protection circuit, comprising:

[0038] the voltage follower module 2 as the voltage follower;

[0039] the sampling module 3 for external analog-digital converter to amplify excitation current to sample;

[0040] the test output module 4 for outputting test result;

[0041] the excitation terminal 5, the excitation terminal 5 includes excitation terminal first pin 51 and excitation terminal second pin 52, and the voltage follower module 2 is electrically connected with the excitation terminal first pin 51, and the sampling module 3 is electrically connected with the excitation terminal second pin 52;

[0042] the test terminal 6, and the test output module 4 is electrically connected with the test terminal 6;

[0043] whether the sampling current of the sampling module 3 is abnormal is judged, and then the MCU module 1 of the SOUT high level is outputted through the test output module 4 when abnormal, and the voltage follower module 2, the sampling module 3 and the test output module 4 are all electrically connected with the MCU module 1.

[0044] In the leakage protection circuit, the voltage follower module 2 can generate a 1.5K 5V square wave as a voltage follower to ensure stable transmission of signals, impedance matching and isolation protection; the sampling module 3 amplifies the excitation current through the second pin 52 of the excitation terminal to sample, at which time the MCU module 1 judges whether the sampling current of the sampling module 3 is abnormal, and then outputs SOUT high level through the test output module 4 when there is abnormal current, which can feedback in time when leakage occurs, and can effectively protect the safety of the electrical equipment and the user;

[0045] Specifically, the abnormal current standard is as follows:

[0046] DC component detection: the current average value is greater than or equal to 6mA;

[0047] AC component detection: the current mean square value is greater than 60mA.

[0048] In the embodiment, the circuit further comprises a power supply module 7 for connecting an external power supply for power supply, and the power supply module is electrically connected with the MCU module 1.

[0049] In the embodiment, the MCU module 1 comprises a chip U1 with a model of MM32L0020.

[0050] In the embodiment, the voltage follower module 2 comprises an operational amplifier U2A.

[0051] In the embodiment, the voltage follower module 2 further comprises resistors R2, R3, R9, R10, R12, capacitors C1, C2, C3, and two Schottky diodes D4, one end of the resistor R9 is connected with the twentieth pin of the chip U1, the other end of the resistor R9, one end of the capacitor C1, the positive electrode of one Schottky diode D4, the negative electrode of the other Schottky diode D4, and one end of the resistor R10 are all connected with the first pin 51 of the excitation terminal, the output end of the operational amplifier U2A is connected with one end of the resistor R12 and the other end of the resistor R10, the other end of the resistor R12 is connected with the negative input end of the operational amplifier U2A, one end of the resistor R3, one end of the resistor R2, and one end of the capacitor C2 are all connected with the positive input end of the operational amplifier U2A, and the capacitor C3 is connected with the positive power supply end of the operational amplifier U2A.

[0052] In the embodiment, the sampling module 3 comprises an operational amplifier U2B.

[0053] In the embodiment, the sampling module 3 further comprises a resistor R11, a resistor R13, two Schottky diodes D1, a bidirectional TVS transient suppression diode D2, the positive input end of an operational amplifier U2B is connected with the sixteenth pin of the chip U1 through the resistor R11, the negative input end of the operational amplifier U2B is connected with one end of the resistor R13, the output end of the operational amplifier U2B, the other end of the resistor R13, the positive pole of one Schottky diode D1, the negative pole of another Schottky diode D1 and one end of the bidirectional TVS transient suppression diode D2 are all connected with the second pin 52 of the excitation terminal, and the other end of the bidirectional TVS transient suppression diode D2 is connected with the voltage follower module 2.

[0054] In the embodiment, the power supply module is connected with the interface J1 and the interface J2, the test output module 4 comprises a resistor R1, a resistor R6, a resistor R7, a resistor R15, a resistor R16, a resistor R17, a capacitor C9 and a triode Q1, one end of the resistor R7 is connected with the power supply module and the eighth pin of the chip U1, the other end of the resistor R7 is connected with one end of the resistor R6 and one end of the capacitor C9, the other end of the resistor R6 and one end of the resistor R17 are both connected with the second pin of the interface J2, the other end of the resistor R17, one end of the resistor R16 and one end of the resistor R15 are all connected with the B pole of the triode Q1, the other end of the resistor R16 is connected with the twelfth pin of the chip U1, and the C pole of the triode Q1 is connected with the test terminal 6 through the resistor R1. Figure 1 、 Figure 6 In the utility model, the circuit design of the power supply module is not described in detail.

[0055] The above are only the preferable embodiments of the utility model, and do not limit the utility model, and any modification, equivalent replacement and improvement made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. An electric leakage protection circuit, characterized by comprising: The circuit comprises: a voltage follower module as a voltage follower; a sampling module for sampling the excitation current amplified by the external analog-digital converter; a test output module for outputting test results; an excitation terminal comprising an excitation terminal first pin and an excitation terminal second pin, the voltage follower module being electrically connected to the excitation terminal first pin, and the sampling module being electrically connected to the excitation terminal second pin; a test terminal, the test output module being electrically connected to the test terminal; an MCU module for judging whether the sampling current of the sampling module is abnormal, and outputting SOUT high level from the test terminal through the test output module when the sampling current is abnormal, the voltage follower module, the sampling module, and the test output module all being electrically connected to the MCU module.

2. The electric leakage protection circuit according to claim 1, characterized in that, The circuit further comprises a power supply module for connecting to an external power supply for power supply, the power supply module being electrically connected to the MCU module.

3. The ground fault circuit of claim 1, wherein, The MCU module comprises a chip U1 with a model number of MM32L0020.

4. The ground fault circuit of claim 1, wherein, The voltage follower module comprises an operational amplifier U2A.

5. An electric leakage protection circuit according to claim 4, wherein The voltage follower module further comprises resistors R2, R3, R9, R10, R12, capacitors C1, C2, C3, and two Schottky diodes D4, one end of the resistor R9 being connected to the twentieth pin of the chip U1, the other end of the resistor R9, one end of the capacitor C1, the positive electrode of one Schottky diode D4, the negative electrode of the other Schottky diode D4, and one end of the resistor R10 all being connected to the excitation terminal first pin, the output end of the operational amplifier U2A being connected to one end of the resistor R12 and the other end of the resistor R10, the other end of the resistor R12 being connected to the negative input end of the operational amplifier U2A, one end of the resistor R3, one end of the resistor R2, and one end of the capacitor C2 all being connected to the positive input end of the operational amplifier U2A, and the capacitor C3 being connected to the positive power supply end of the operational amplifier U2A.

6. The ground fault circuit of claim 1, wherein, The sampling module comprises an operational amplifier U2B.

7. An electric leakage protection circuit according to claim 6, characterized in that, The sampling module further comprises a resistor R11, a resistor R13, two Schottky diodes D1, and a bidirectional TVS transient voltage suppressor D2, the positive input end of the operational amplifier U2B being connected to the sixteenth pin of the chip U1 through the resistor R11, the negative input end of the operational amplifier U2B being connected to one end of the resistor R13, the output end of the operational amplifier U2B, the other end of the resistor R13, the positive electrode of one Schottky diode D1, the negative electrode of the other Schottky diode D1, and one end of the bidirectional TVS transient voltage suppressor D2 all being connected to the excitation terminal second pin, and the other end of the bidirectional TVS transient voltage suppressor D2 being connected to the voltage follower module.

8. The ground fault circuit of claim 2, wherein, The power supply module is connected with interface J1 and interface J2, the test output module comprises resistance R1, resistance R6, resistance R7, resistance R15, resistance R16, resistance R17, capacitor C9, triode Q1, one end of resistance R7 is connected with the power supply module and the eighth pin of chip U1, the other end of resistance R7 is connected with one end of resistance R6 and one end of capacitor C9, the other end of resistance R6 and one end of resistance R17 are connected to the second pin of interface J2, the other end of resistance R17, one end of resistance R16 and one end of resistance R15 are all connected with the B electrode of triode Q1, the other end of resistance R16 is connected with the twelfth pin of chip U1, and the C electrode of triode Q1 is connected with the test terminal through resistance R1.

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