Ground wire resistance test circuit

Abstract

The utility model relates to a socket testing device and a grounding wire resistance testing circuit. The socket testing device comprises a first voltage detection circuit, a second voltage detection circuit, a third voltage detection circuit and a first current flowing circuit. The first voltage detection circuit comprises a diode D1, the anode of the diode D1 is connected with the contact L, and the cathode of the diode D1 is grounded after passing through a resistor R7 and a resistor R8 which are sequentially connected in series; the second voltage detection circuit comprises a diode D2, the anode of the diode D2 is connected with the contact PE, and the cathode of the diode D2 is grounded after passing through a resistor R9 and a resistor R10 which are sequentially connected in series; the third voltage detection circuit comprises a diode D3, the anode of the diode D3 is connected with the contact N, and the cathode of the diode D3 is grounded after passing through a resistor R11 and a resistor R12 which are sequentially connected in series; the first current flowing circuit comprises a diode D10, a resistor R13 and a silicon controlled rectifier D13, and the first current flowing circuit generates pulse large current for ground wire resistance measurement. The device can detect the wiring condition of three plugs of the socket and test the resistance of the grounding wire.

Description

Technical Field

[0001] The utility model relates to a grounding wire resistance test circuit, belonging to the technical field of socket testing. Background Technique

[0002] In modern family and commercial environments, sockets, as important interfaces for power supply, shoulder the heavy responsibility of daily electricity consumption needs. However, with the increase in the types of electrical appliances and the improvement in usage frequency, the safety and reliability issues of sockets have gradually emerged. Socket failures may not only cause damage to electrical appliances but also pose safety hazards such as fires. Therefore, the detection and maintenance of sockets are particularly important.

[0003] A socket testing device is a portable testing instrument used to measure the wiring condition of a socket and the quality of the grounding wire, facilitating the installation and repair work of household circuits.

[0004] In related technologies, three LED indicators are usually used in combination to indicate the socket wiring status, and users still have to look up a comparison table to determine the socket wiring status, which is rather troublesome. Existing socket testers cannot test the grounding wire condition of the current socket. Content of the Utility Model

[0005] In order to solve the problems existing in the above-mentioned prior art, the utility model proposes a grounding wire resistance test circuit.

[0006] The technical solution of the utility model is as follows:

[0007] The utility model provides a socket testing device, including a first voltage detection circuit, a second voltage detection circuit, a third voltage detection circuit, and a first current flow circuit;

[0008] The first voltage detection circuit includes a diode D1, the anode of the diode D1 is connected to the contact L, and the cathode is grounded through the resistors R7 and R8 connected in series in sequence;

[0009] The second voltage detection circuit includes a diode D2, the anode of the diode D2 is connected to the contact PE, and the cathode is grounded through the resistors R9 and R10 connected in series in sequence;

[0010] The third voltage detection circuit includes a diode D3, the anode of the diode D3 is connected to the contact N, and the cathode is grounded through the resistors R11 and R12 connected in series in sequence;

[0011] The first current flow circuit includes a diode D10, a resistor R13, and a thyristor D13. The anode of the diode D10 is connected to the contact L. The cathode of the diode D10 is connected to the anode of the thyristor D13 through the resistor R13. The cathode of the thyristor D13 is connected to the contact PE. The cathode of the diode D10 is connected to the collector of the optocoupler U2 through the resistor R15. The emitter of the optocoupler U2 is connected to the control terminal of the thyristor D13 and one end of the resistor R17. The other end of the resistor R17 is connected to the contact PE. The anode of the optocoupler U2 is connected to one end of the resistor R16, and the cathode of the optocoupler U2 is grounded.

[0012] As a preferred embodiment of the present invention, it further includes a three-pin plug, and the three pins of the three-pin plug are respectively connected to the contact L, the contact PE, and the contact N.

[0013] As a preferred embodiment of the present invention, it further includes a power supply module and a single-chip microcomputer of model N76E003AT20.

[0014] As a preferred embodiment of the present invention, the diode D1 is connected to the 1st pin of the single-chip microcomputer through the resistor R7;

[0015] The diode D2 is connected to the 2nd pin of the single-chip microcomputer through the resistor R9;

[0016] The diode D3 is connected to the 3rd pin of the single-chip microcomputer through the resistor R11;

[0017] The 7th pin of the single-chip microcomputer is grounded;

[0018] The 9th pin of the single-chip microcomputer is connected to the positive pole of the power supply module;

[0019] The anode of the optocoupler U2 is connected to the 14th pin of the single-chip microcomputer through the resistor R16;

[0020] The 15th pin of the single-chip microcomputer is connected to the cathode of the diode LED1, and the anode of the diode LED1 is connected to the positive pole of the power supply module through the resistor R5;

[0021] The 16th pin of the single-chip microcomputer is connected to the cathode of the diode LED4, and the anode of the diode LED4 is connected to the positive pole of the power supply module through the resistor R5;

[0022] The 17th pin of the single-chip microcomputer is connected to the cathode of the diode LED5, and the anode of the diode LED5 is connected to the positive pole of the power supply module through the resistor R5;

[0023] The 19th pin of the single-chip microcomputer is connected to the cathode of the diode LED2, and the anode of the diode LED2 is connected to the positive pole of the power supply module through the resistor R5;

[0024] The 20th pin of the single-chip microcomputer is connected to the cathode of the diode LED3, and the anode of the diode LED3 is connected to the positive pole of the power supply module through the resistor R5.

[0025] The utility model also provides a grounding wire resistance testing circuit, which is characterized by comprising a first voltage detection circuit, a second voltage detection circuit, a third voltage detection circuit and a first current flow circuit;

[0026] The first voltage detection circuit includes a diode D1, the anode of the diode D1 is connected to the contact L, and the cathode is grounded through the resistors R7 and R8 connected in series in sequence;

[0027] The second voltage detection circuit includes a diode D2, the anode of the diode D2 is connected to the contact PE, and the cathode is grounded through the resistors R9 and R10 connected in series in sequence;

[0028] The third voltage detection circuit includes a diode D3, the anode of the diode D3 is connected to the contact N, and the cathode is grounded through the resistors R11 and R12 connected in series in sequence;

[0029] The first current flow circuit includes a diode D10, a resistor R13 and a thyristor D13. The anode of the diode D10 is connected to the contact L. The cathode of the diode D10 is connected to the anode of the thyristor D13 through the resistor R13. The cathode of the thyristor D13 is connected to the contact PE. The cathode of the diode D10 is connected to the collector of the optocoupler U2 through the resistor R15. The emitter of the optocoupler U2 is connected to the control end of the thyristor D13 and one end of the resistor R17. The other end of the resistor R17 is connected to the contact PE. The anode of the optocoupler U2 is connected to one end of the resistor R16, and the cathode of the optocoupler U2 is grounded.

[0030] As a preferred embodiment of the utility model, it further includes a three-pin plug, and the three pins of the three-pin plug are respectively connected to the contact L, the contact PE and the contact N.

[0031] As a preferred embodiment of the utility model, it further includes a power supply module and a single-chip microcomputer of model N76E003AT20.

[0032] As a preferred embodiment of the utility model, the diode D1 is connected to the 1st pin of the single-chip microcomputer through the resistor R7;

[0033] The diode D2 is connected to the 2nd pin of the single-chip microcomputer through the resistor R9;

[0034] The diode D3 is connected to the 3rd pin of the single-chip microcomputer through the resistor R11;

[0035] The 7th pin of the single-chip microcomputer is grounded;

[0036] The 9th pin of the single-chip microcomputer is connected to the positive pole of the power supply module;

[0037] The anode of the optocoupler U2 is connected to the 14th pin of the single-chip microcomputer through the resistor R16;

[0038] The 15th pin of the single-chip microcomputer is connected to the cathode of the diode LED1, and the anode of the diode LED1 is connected to the positive pole of the power supply module through the resistor R5;

[0039] The 16th pin of the single-chip microcomputer is connected to the cathode of the diode LED4, and the anode of the diode LED4 is connected to the positive pole of the power supply module through the resistor R5;

[0040] The 17th pin of the single-chip microcomputer is connected to the cathode of the diode LED5, and the anode of the diode LED5 is connected to the positive pole of the power supply module through the resistor R5;

[0041] The 19th pin of the single-chip microcomputer is connected to the cathode of the diode LED2, and the anode of the diode LED2 is connected to the positive pole of the power supply module through the resistor R5;

[0042] The 20th pin of the single-chip microcomputer is connected to the cathode of the diode LED3, and the anode of the diode LED3 is connected to the positive pole of the power supply module through the resistor R5.

[0043] The utility model has the following beneficial effects:

[0044] 1. Through the first, second, and third voltage detection circuits, the device of the utility model can respectively detect the voltage conditions of the three contacts of L (live wire), PE (ground wire), and N (neutral wire) of the socket. This multi-voltage detection function enables the device to comprehensively evaluate the voltage status of the socket, ensuring that each contact is correctly connected and the voltage is normal.

[0045] 2. The first current flow circuit of the utility model provides a pulsed large current for detecting the resistance value of the grounding wire, realizing the intelligent detection of the grounding wire resistance. This helps to quickly identify whether the wiring of the socket is abnormal and avoid potential safety hazards caused by abnormal grounding wires.

[0046] 3. Through multiple LED indicators (LED1, LED2, LED3, LED4, LED5) connected to the single-chip microcomputer, the device of the utility model can intuitively display the test results of the socket. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is the circuit diagram of the socket test module of the utility model.

[0048] Figure 2This is the circuit diagram of the display module of the present utility model.

[0049] Figure 3 This is the circuit diagram of the power supply module of the present utility model. Specific embodiments

[0050] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0051] It should be understood that the step numbers used in the text are only for convenient description and do not limit the execution order of the steps.

[0052] It should be understood that the terms used in the specification of the present utility model are only for the purpose of describing specific embodiments and are not intended to limit the present utility model. As used in the specification of the present utility model and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0053] The terms "comprising" and "including" indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their combinations.

[0054] The term " / and / " refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0055] Embodiment 1:

[0056] Refer to Figure 1 , the present utility model provides a socket testing device, including a first voltage detection circuit, a second voltage detection circuit, a third voltage detection circuit and a first current flow circuit;

[0057] The first voltage detection circuit includes a diode D1. The anode of the diode D1 is connected to the contact L, and the cathode is grounded through a series of resistors R7 and R8 in sequence. The voltage signal detected by the first voltage detection circuit will be transmitted to the single-chip microcomputer through the AIN_L port;

[0058] The second voltage detection circuit includes a diode D2. The anode of the diode D2 is connected to the contact PE, and the cathode is grounded through a series connection of a resistor R9 and a resistor R10 in sequence. The voltage signal detected by the second voltage detection circuit is transmitted to the single-chip microcomputer through the AIN_E port;

[0059] The third voltage detection circuit includes a diode D3. The anode of the diode D3 is connected to the contact N, and the cathode is grounded through a series connection of a resistor R11 and a resistor R12 in sequence. The voltage signal detected by the third voltage detection circuit is transmitted to the single-chip microcomputer through the AIN_N port;

[0060] The first current flow circuit includes a diode D10, a resistor R13, and a thyristor D13. The anode of the diode D10 is connected to the contact L. The cathode of the diode D10 is connected to the anode of the thyristor D13 through the resistor R13. The cathode of the thyristor D13 is connected to the contact PE. The cathode of the diode D10 is connected to the collector of the optocoupler U2 through the resistor R15. The emitter of the optocoupler U2 is connected to the control terminal of the thyristor D13 and one end of the resistor R17. The other end of the resistor R17 is connected to the contact PE. The anode of the optocoupler U2 is connected to one end of the resistor R16, and the cathode of the optocoupler U2 is grounded.

[0061] The first current flow circuit generates a pulsed large current for testing the ground wire resistance.

[0062] When the socket tester is powered on, the PC3 port of the single-chip microcomputer does not work, and the optocoupler U2 does not work. Due to the action of the resistor R17, the voltage at the control terminal of the thyristor D13 makes the unidirectional thyristor D13 cut off.

[0063] When the single-chip microcomputer detects that the wiring is correct, it uses the AIN_L port to detect the highest value of the live wire voltage and records this highest value as VL. When the live wire voltage reaches the highest value, at this time, the PC3 port of the single-chip microcomputer outputs a low level to make the unidirectional thyristor D13 conduct. The conduction time is 1 millisecond, generating a pulsed large current. Due to the existence of the ground wire resistance RE, a pulsed voltage will be generated. At the same time, the single-chip microcomputer's AIN_E port detects the ground wire pulsed voltage VE when the unidirectional thyristor D13 conducts.

[0064] The ground wire resistance of the socket can be obtained through calculation, and the calculation formula is:

[0065]

[0066] When the measured ground wire resistance is greater than 10 Ω, the indicating circuit indicates a ground wire defect at this time.

[0067] As a preferred embodiment of the present utility model, it further includes a three-pin plug, and the three pins of the three-pin plug are respectively connected to the contact L, the contact PE, and the contact N for accessing the socket circuit to be tested.

[0068] See Figures 2-3 , as a preferred embodiment of the present utility model, it further includes a power supply module and a single-chip microcomputer of model N76E003AT20.

[0069] The single-chip microcomputer is used to control the output of the measurement result of the socket circuit.

[0070] The power supply module provides a stable 3.3V DC power supply for the single-chip microcomputer.

[0071] As a preferred embodiment of the present utility model, the diode D1 is connected to the 1st pin of the single-chip microcomputer through the resistor R7;

[0072] The diode D2 is connected to the 2nd pin of the single-chip microcomputer through the resistor R9;

[0073] The diode D3 is connected to the 3rd pin of the single-chip microcomputer through the resistor R11;

[0074] The 7th pin of the single-chip microcomputer is grounded;

[0075] The 9th pin of the single-chip microcomputer is connected to the positive pole of the power supply module;

[0076] The anode of the optocoupler U2 is connected to the 14th pin of the single-chip microcomputer through the resistor R16;

[0077] The 15th pin of the single-chip microcomputer is connected to the cathode of the diode LED1, and the anode of the diode LED1 is connected to the positive pole of the power supply module through the resistor R5;

[0078] The 16th pin of the single-chip microcomputer is connected to the cathode of the diode LED4, and the anode of the diode LED4 is connected to the positive pole of the power supply module through the resistor R5;

[0079] The 17th pin of the single-chip microcomputer is connected to the cathode of the diode LED5, and the anode of the diode LED5 is connected to the positive pole of the power supply module through the resistor R5;

[0080] The 19th pin of the single-chip microcomputer is connected to the cathode of the diode LED2, and the anode of the diode LED2 is connected to the positive pole of the power supply module through the resistor R5;

[0081] The 20th pin of the single-chip microcomputer is connected to the cathode of the diode LED3, and the anode of the diode LED3 is connected to the positive pole of the power supply module through the resistor R5.

[0082] The diodes LED1, LED2, LED3, LED4, and LED5 are used to display the measurement results.

[0083] See Figure 1 , the present utility model also provides a ground wire resistance test circuit, which is characterized in that it includes a first voltage detection circuit, a second voltage detection circuit, a third voltage detection circuit, and a first current flow circuit;

[0084] The first voltage detection circuit includes a diode D1. The anode of the diode D1 is connected to the contact L, and the cathode is grounded through the resistors R7 and R8 connected in series in sequence. The voltage signal detected by the first voltage detection circuit will be transmitted to the single-chip microcomputer through the AIN_L port;

[0085] The second voltage detection circuit includes a diode D2. The anode of the diode D2 is connected to the contact PE, and the cathode is grounded through the resistors R9 and R10 connected in series in sequence. The voltage signal detected by the second voltage detection circuit will be transmitted to the single-chip microcomputer through the AIN_E port;

[0086] The third voltage detection circuit includes a diode D3. The anode of the diode D3 is connected to the contact N, and the cathode is grounded through the resistors R11 and R12 connected in series in sequence. The voltage signal detected by the third voltage detection circuit will be transmitted to the single-chip microcomputer through the AIN_N port;

[0087] The first current flow circuit includes a diode D10, a resistor R13, and a thyristor D13. The anode of the diode D10 is connected to the contact L. The cathode of the diode D10 is connected to the anode of the thyristor D13 through the resistor R13. The cathode of the thyristor D13 is connected to the contact PE. The cathode of the diode D10 is connected to the collector of the optocoupler U2 through the resistor R15. The emitter of the optocoupler U2 is connected to the control terminal of the thyristor D13 and one end of the resistor R17. The other end of the resistor R17 is connected to the contact PE. The anode of the optocoupler U2 is connected to one end of the resistor R16, and the cathode of the optocoupler U2 is grounded.

[0088] The first current flow circuit generates a pulsed large current for ground wire resistance testing.

[0089] When the socket tester is powered on, the PC3 port of the single-chip microcomputer does not work, the optocoupler U2 does not work, and the voltage at the control terminal of the thyristor D13 makes the unidirectional thyristor D13 cut off due to the action of the resistor R17.

[0090] When the microcontroller detects that the wiring is correct, it uses the AIN_L port to detect the highest value of the live wire voltage and records this highest value as VL. When the live wire voltage reaches the highest value, the microcontroller outputs a low level at the PC3 port to turn on the unidirectional thyristor D13 for 1 millisecond, generating a pulsed large current. Since there is a resistance RE in the ground wire, a pulsed voltage will be generated. At the same time, the microcontroller uses the AIN_E port to detect the ground wire pulsed voltage VE when the unidirectional thyristor D13 is turned on. The resistance of the socket ground wire can be calculated as the value of RE, and the calculation formula is:

[0091]

[0092] When the measured ground wire resistance is greater than 10Ω, the indicating circuit indicates a ground wire defect at this time.

[0093] As a preferred embodiment of the present invention, it further includes a three - prong plug. The three prongs of the three - prong plug are respectively connected to the contact L, contact PE, and contact N for connecting to the socket circuit to be tested.

[0094] See Figures 2-3 , as a preferred embodiment of the present invention, it further includes a power supply module and a microcontroller of model N76E003AT20.

[0095] The microcontroller is used to control the output of the measurement result of the socket circuit.

[0096] The power supply module provides a stable 3.3V DC power supply for the microcontroller.

[0097] As a preferred embodiment of the present invention, the diode D1 is connected to the 1 - pin of the microcontroller through the resistor R7;

[0098] The diode D2 is connected to the 2 - pin of the microcontroller through the resistor R9;

[0099] The diode D3 is connected to the 3 - pin of the microcontroller through the resistor R11;

[0100] The 7 - pin of the microcontroller is grounded;

[0101] The 9 - pin of the microcontroller is connected to the positive pole of the power supply module;

[0102] The anode of the optocoupler U2 is connected to the 14 - pin of the microcontroller through the resistor R16;

[0103] The 15 - pin of the microcontroller is connected to the cathode of the diode LED1. The anode of the diode LED1 is connected to the positive pole of the power supply module through the resistor R5;

[0104] The 16th pin of the single-chip microcomputer is connected to the cathode of the diode LED4, and the anode of the diode LED4 is connected to the positive pole of the power supply module through the resistor R5;

[0105] The 17th pin of the single-chip microcomputer is connected to the cathode of the diode LED5, and the anode of the diode LED5 is connected to the positive pole of the power supply module through the resistor R5;

[0106] The 19th pin of the single-chip microcomputer is connected to the cathode of the diode LED2, and the anode of the diode LED2 is connected to the positive pole of the power supply module through the resistor R5;

[0107] The 20th pin of the single-chip microcomputer is connected to the cathode of the diode LED3, and the anode of the diode LED3 is connected to the positive pole of the power supply module through the resistor R5.

[0108] The diodes LED1, LED2, LED3, LED4 and LED5 are used to display the measurement results.

[0109] Embodiment 2:

[0110] The AIN_L, AIN_N and AIN_E ports of the single-chip microcomputer are used to detect the socket wiring. A diode D1, a resistor R7 and a resistor R8 are connected between the plug L pin and the neutral point. One end of the resistor R8 is connected to the AIN_L port of the single-chip microcomputer, and the other end is connected to the neutral point.

[0111] A diode D2, a resistor R9 and a resistor R10 are connected between the plug PE pin and the neutral point. One end of the resistor R10 is connected to the AIN_E port of the single-chip microcomputer, and the other end is connected to the neutral point.

[0112] A diode D3, a resistor R11 and a resistor R12 are connected between the plug N pin and the neutral point. One end of the resistor R12 is connected to the AIN_E port of the single-chip microcomputer, and the other end is connected to the neutral point.

[0113] After the socket tester is connected to the socket, in the positive half cycle of the voltage, it enters from the live wire, passes through the above-mentioned various devices, then passes through the neutral point, and then flows out to the neutral wire through the diode D9, forming a complete loop. There is a divided voltage across the resistor R8. Due to the unidirectional conduction of the diodes D2 and D3, the voltage across the resistors R10 and R12 is 0V.

[0114] In the positive and negative cycles of the voltage, it enters from the ground wire, passes through the above-mentioned various devices, then passes through the neutral point, and then flows out to the live wire through the diode D7, forming a complete loop. There is a divided voltage across the resistor R10. Due to the unidirectional conduction of the diode D1, the voltage across the resistor R8 is 0V.

[0115] The positive and negative cycles of the voltage enter from the neutral line, pass through the above-mentioned various devices, pass through the neutral point, and then flow out through the diode D7 to the live wire, forming a complete circuit. There is a voltage after voltage division across both ends of the resistor R12. Due to the unidirectional conduction of the diode D1, the voltage across both ends of the resistor R8 is 0V.

[0116] The present utility model also provides a socket testing device for automatically detecting the wiring of the above socket, including the following steps:

[0117] S1: In a normal power supply system, since the voltage between the neutral line and the ground wire is very small, and the voltage of the live wire relative to the neutral line / ground wire is 220V.

[0118] S2: If the plug L pin is connected to the live wire, the plug N pin is connected to the neutral line, and the plug PE pin is connected to the ground wire, then the states of the AIN_L, AIN_N, and AIN_E ports of the single-chip microcomputer are: during the positive half-cycle of the voltage: high voltage, 0V, 0V; during the negative half-cycle of the voltage: 0V, high voltage, high voltage. At this time, the indication circuit indicates that the wiring is correct and lights up the LED1 lamp.

[0119] S3: If the plug L pin is connected to the neutral line, the plug N pin is connected to the live wire, and the plug PE pin is connected to the ground wire, then the states of the AIN_L, AIN_N, and AIN_E ports of the single-chip microcomputer are: during the positive half-cycle of the voltage: 0V, high voltage, 0V; during the negative half-cycle of the voltage: high voltage, 0V, high voltage. At this time, the indication circuit indicates that the live wire and the neutral line are connected reversely and lights up the LED2 lamp.

[0120] S4: If the plug L pin is connected to the ground wire, the plug N pin is connected to the neutral line, and the plug PE pin is connected to the live wire, then the states of the AIN_L, AIN_N, and AIN_E ports of the single-chip microcomputer are: during the positive half-cycle of the voltage: 0V, 0V, high voltage; during the negative half-cycle of the voltage: high voltage, high voltage, 0V. At this time, the indication circuit indicates that the live wire and the ground wire are connected and lights up the LED3 lamp.

[0121] S5: If the plug L pin is connected to the live wire, the plug N pin is connected to the neutral line, and the plug PE pin is suspended, then the states of the AIN_L, AIN_N, and AIN_E ports of the single-chip microcomputer are: during the positive half-cycle of the voltage: high voltage, 0V, 0V; during the negative half-cycle of the voltage: 0V, high voltage, 0V. At this time, the indication circuit indicates a ground wire defect and lights up the LED4 lamp.

[0122] S6: If the plug L pin is connected to the live wire, the plug N pin is suspended, and the plug PE pin is connected to the ground wire, then the states of the AIN_L, AIN_N, and AIN_E ports of the single-chip microcomputer are: during the positive half-cycle of the voltage: high voltage, 0V, 0V; during the negative half-cycle of the voltage: 0V, 0V, high voltage. At this time, the indication circuit indicates a lack of neutral line and lights up the LED5 lamp.

[0123] S8: The single-chip microcomputer measures the wiring sequence of the socket by detecting the state voltages of the AIN_L, AIN_N, and AIN_E ports.

[0124] Socket Grounding Wire Resistance Test

[0125] The plug L pin and the plug PE pin are connected with a diode D10, a resistor R13, and a thyristor D13.

[0126] Resistor R15, resistor R16, resistor R17, and optocoupler U2. One end of the resistor R15 is connected to the other end of the diode D10 and the other end is connected to the control end of the thyristor. One end of the resistor R17 is connected to the control end of the thyristor and the other end is connected to the PE pin. The collector and emitter of the optocoupler U2 are connected in parallel across the two ends of the resistor R17. One end of the resistor R16 is connected to the PC3 port of the single-chip microcomputer and the other end is connected to the anode of the optocoupler U2. The cathode of the optocoupler U2 is connected to the neutral point.

[0127] The present utility model also provides a socket tester for testing the resistance value of the socket grounding wire as described above, including the following steps:

[0128] S1: When the socket tester is powered on, the PC3 port of the single-chip microcomputer does not work, the optocoupler U2 does not work, and the voltage at the control end of the thyristor D13 is due to the action of the resistor R17, making the unidirectional thyristor D13 cut off.

[0129] S2: When the single-chip microcomputer detects that the wiring is correct, it uses the AIN_L port to detect the highest value of the live wire voltage and records this highest value as VL. When the live wire voltage reaches the highest value, at this time, the PC3 port of the single-chip microcomputer outputs a low level to make the unidirectional thyristor D13 conduct, and the conduction time is 1 millisecond, generating a pulsed large current. Due to the existence of the resistance RE of the ground wire, a pulsed voltage will be generated, and at the same time, the single-chip microcomputer's AIN_E port detects the ground wire pulsed voltage VE when the unidirectional thyristor D13 conducts. S3: The resistance of the socket grounding wire can be obtained by calculation as the value of RE, and the calculation formula is:

[0130]

[0131] When the measured ground wire resistance is greater than 10 Ω, at this time, the indication circuit indicates a ground wire defect.

[0132] In the embodiments of the present application, "at least one" means one or more, and "a plurality" means two or more. "And / or" describes the association relationship of associated objects and indicates that three relationships may exist. For example, A and / or B may represent the cases where A exists alone, A and B exist simultaneously, and B exists alone. Here, A and B may be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship. "At least one of the following" and its similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, and c may represent: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, and c may be single or multiple.

[0133] The above are only the embodiments of the present utility model, and thus do not limit the patent scope of the present utility model. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present utility model, or directly or indirectly applied in other related technical fields, shall be similarly included in the patent protection scope of the present utility model.

Claims

1. A grounding wire resistance test circuit, characterized in that It includes a first voltage detection circuit, a second voltage detection circuit, a third voltage detection circuit, and a first current flow circuit; The first voltage detection circuit includes a diode D1. The anode of the diode D1 is connected to the contact L, and the cathode is grounded after being sequentially connected in series with a resistor R7 and a resistor R8; The second voltage detection circuit includes a diode D2. The anode of the diode D2 is connected to the contact PE, and the cathode is grounded after being sequentially connected in series with a resistor R9 and a resistor R10; The third voltage detection circuit includes a diode D3. The anode of the diode D3 is connected to the contact N, and the cathode is grounded after being sequentially connected in series with a resistor R11 and a resistor R12; The first current flow circuit includes a diode D10, a resistor R13, and a thyristor D13. The anode of the diode D10 is connected to the contact L. The cathode of the diode D10 is connected to the anode of the thyristor D13 through the resistor R13. The cathode of the thyristor D13 is connected to the contact PE. The cathode of the diode D10 is connected to the collector of the optocoupler U2 through the resistor R15. The emitter of the optocoupler U2 is connected to the control terminal of the thyristor D13 and one end of the resistor R17. The other end of the resistor R17 is connected to the contact PE. The anode of the optocoupler U2 is connected to one end of the resistor R16, and the cathode of the optocoupler U2 is grounded.

2. The grounding wire resistance test circuit according to claim 1, characterized in that, It further includes a three-pin plug, and the three pins of the three-pin plug are respectively connected to the contact L, the contact PE, and the contact N.

3. The grounding wire resistance test circuit according to claim 1, wherein It further includes a power supply module and a single-chip microcomputer of model N76E003AT20.

4. The grounding wire resistance test circuit according to claim 3, characterized in that, The diode D1 is connected to the 1st pin of the single-chip microcomputer through the resistor R7; The diode D2 is connected to the 2nd pin of the single-chip microcomputer through the resistor R9; The diode D3 is connected to the 3rd pin of the single-chip microcomputer through the resistor R11; The 7th pin of the single-chip microcomputer is grounded; The 9th pin of the single-chip microcomputer is connected to the positive pole of the power supply module; The anode of the optocoupler U2 is connected to the 14th pin of the single-chip microcomputer through the resistor R16; The 15th pin of the single-chip microcomputer is connected to the cathode of the diode LED1, and the anode of the diode LED1 is connected to the positive pole of the power supply module through the resistor R5; The 16th pin of the single-chip microcomputer is connected to the cathode of the diode LED4, and the anode of the diode LED4 is connected to the positive pole of the power supply module through the resistor R5; The 17th pin of the single-chip microcomputer is connected to the cathode of the diode LED5, and the anode of the diode LED5 is connected to the positive pole of the power supply module through the resistor R5; The 19th pin of the single-chip microcomputer is connected to the cathode of the diode LED2, and the anode of the diode LED2 is connected to the positive pole of the power supply module through the resistor R5; The 20th pin of the single-chip microcomputer is connected to the cathode of the diode LED3, and the anode of the diode LED3 is connected to the positive pole of the power supply module through the resistor R5.

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