An impedance detector

Abstract

The utility model discloses an impedance detector, including the casing, be equipped with the circuit board in the casing, be equipped with detection loop, shunt loop, detect electricity loop, leakage protection measuring circuit and phase zero mistake tripping circuit on the circuit board, detection loop, shunt loop, detect electricity loop, leakage protection measuring circuit all are linked with the fuse, the fuse is linked with the leakage protector, the leakage protector is linked with 220V power supply, be connected with the shunt voltage reducing circuit and signal loop on the detection loop, detection loop and shunt loop are linked with the comparison resistance respectively, the comparison resistance is linked with the leakage protector through the switch. Have efficient, convenient realization electricity, pure water, alcohol detection's advantage.

Description

Technical Field

[0001] This utility model relates to the field of detection technology, and more specifically, to an impedance detector. Background Technology

[0002] Currently, testing the safety performance of household power supplies and appliances, such as power supply voltage, grounding resistance, insulation resistance, and continuity resistance, generally requires specialized instruments, such as insulation resistance testers, grounding resistance testers, insulation megohmmeters, continuity testers, and multimeters. These instruments operate on different principles and display methods, making them suitable only for professionals and not for general public use, let alone widespread adoption. Even multimeters, despite their numerous functions and widespread availability, are primarily used for testing electronic equipment and components. Testing insulation resistance and grounding resistance requires a separate power supply and additional components, which is not only cumbersome but also unsafe.

[0003] Currently, TDS (Total Dissolved Solids) water quality testers are generally used to test the purity of purified water. However, these testers have low resolution and a narrow detection range, and cannot detect high-purity purified water. Purified water analyzers, on the other hand, test for multiple parameters and have high precision; they are professional instruments and not widely available. Alcohol content testing is typically done with alcohol meters, which are also professional instruments. These analyzers perform segmented testing and require adjustment tables, making them complex to use and unsuitable for ordinary households. Utility Model Content

[0004] The main objective of this invention is to provide an impedance detector to solve at least one technical problem in the prior art.

[0005] To achieve the above objectives, according to one aspect of this utility model, an impedance detector is provided, comprising a housing, within which a circuit board is provided. The circuit board is provided with a detection circuit, a shunt circuit, a current detection circuit, a leakage current protection measurement circuit, and a phase-zero error tripping circuit. The detection circuit, shunt circuit, current detection circuit, and leakage current protection measurement circuit are all connected to a fuse, which is connected to a leakage current protector, which is connected to a 220V power supply. A shunt voltage reduction circuit and a signal circuit are connected to the detection circuit. The detection circuit and the shunt circuit are respectively connected to a comparison resistor, which is connected to the leakage current protector via a switch.

[0006] Preferably, the detection circuit includes a first 4007 diode, one end of which is connected to a fuse and the other end to a first current-limiting resistor. The first current-limiting resistor is connected to a second 4007 diode, which is connected to a second single-pole double-throw switch. The second single-pole double-throw switch is connected in series with the R2-1 voltmeter signal sampling resistor and the signal sampling resistor, or individually connected to the signal sampling resistor. The signal sampling resistor is connected to a comparison resistor, which is connected to a corresponding resistor single-pole double-throw switch. The resistor single-pole double-throw switches connected to the comparison resistor are all connected to a first single-pole double-throw switch. The first single-pole double-throw switch is connected to a residual current device (RCD) and the RCD.

[0007] Preferably, the shunt circuit includes a fourth 4007 diode, one end of which is connected to a fuse, and the other end is connected to a first shunt resistor and a second shunt resistor respectively. The first shunt resistor and the second shunt resistor are connected in parallel. The first shunt resistor and the second shunt resistor are respectively connected to a fourth single-pole double-throw switch. The fourth single-pole double-throw switch is connected to a comparison resistor. The comparison resistor is connected to a corresponding resistor single-pole double-throw switch. The resistor single-pole double-throw switches connected to the comparison resistor are all connected to a first single-pole double-throw switch. The first single-pole double-throw switch is connected to a residual current device (RCD) and a residual current device (RCD).

[0008] Preferably, the shunt-voltage step-down circuit includes a step-down shunt circuit node. One end of the step-down shunt circuit node is disposed between the first current-limiting resistor and the second 4007 diode, and the other end is connected to the third 4007 diode. The third 4007 diode is connected to the third shunt resistor and the fourth shunt resistor respectively. The third shunt resistor and the fourth shunt resistor are connected in parallel. The third shunt resistor and the fourth shunt resistor are connected to the third single-pole double-throw switch respectively. The third single-pole double-throw switch is connected to the N terminal of the 220V power supply.

[0009] Preferably, the phase zero trip circuit includes a second current-limiting resistor, one end of which is connected to one end of the first normally open button, and the other end is connected to a residual current device (RCD). The RCD is connected to the N terminal of a 220V power supply, and the other end of the first normally open button is connected to the RCD, which is connected to the E terminal of a 220V power supply.

[0010] Preferably, the leakage current protection measurement circuit includes a third current-limiting resistor, one end of which is connected to a fuse and the other end of which is connected to one end of a second normally open button, the other end of which is connected to a leakage current protector; the current detection circuit includes a fourth current-limiting resistor, one end of which is connected to a fuse and the other end of which is connected to one end of a neon bulb, the other end of which is connected to a contact.

[0011] Preferably, the signal circuit includes a positive signal output node, one end of which is connected to the positive terminal of a 200mV DC voltmeter, and the other end is connected to a second single-pole double-throw switch and a second 4007 diode; one end of the negative signal output node is connected to the negative terminal of a 200mV DC voltmeter, and the other end is connected to the center tap of a signal sampling resistor, wherein the 200mV DC voltmeter is connected to a 5V DC power supply module.

[0012] Preferably, the equivalent circuit for measuring solid resistance and liquid resistance includes: a first 4007 diode, one end of which is connected to the phase line of a 220V power supply, and the other end of which is connected to a first current-limiting resistor and a second shunt resistor, wherein the first current-limiting resistor and the second shunt resistor are connected in parallel; the first current-limiting resistor is connected to one end of a signal sampling resistor; the other end of the signal sampling resistor is connected to the positive terminal of a probe socket node; the positive terminal of the probe socket node is connected to the impedance to be measured; the impedance to be measured is connected to the negative terminal of the probe socket node; the probe socket node is connected to a first single-pole double-throw switch; and the first single-pole double-throw switch is connected to a 220V power supply.

[0013] Preferably, a step-down shunt circuit node and a positive signal output node are provided between the first current-limiting resistor and the signal sampling resistor. A negative signal output node is provided on the signal sampling resistor. The positive signal output node is connected to the positive terminal of the sampling voltage, and the negative signal output node is connected to the negative terminal of the sampling voltage. The step-down shunt circuit node is connected to a third single-pole double-throw switch. The third single-pole double-throw switch is connected to a fourth shunt resistor. The fourth shunt resistor is connected to the neutral line of the 220V power supply. The second current-limiting resistor is connected to the fourth single-pole double-throw switch, and the fourth single-pole double-throw switch is connected to the positive node of the test probe socket.

[0014] Preferably, the current detection circuit includes a fourth current-limiting resistor, one end of which is connected to a fuse and the other end of which is connected to a neon bulb, which is connected to a contact.

[0015] The application of the technical solution of this utility model has the following technical effects:

[0016] Using 220V AC mains power as its power source, this multi-functional device can test the voltage, phase, grounding resistance, and RCD leakage protection function of household power supplies. It can also test the insulation performance of household appliances, the conductivity of electrical appliances, circuits, and electronic components, as well as the purity of purified water and the alcohol content of beverages.

[0017] This device measures grounding resistance using high voltage and low current (less than 30 mA, DC 99V), ensuring the RCD doesn't trip and doesn't affect household electricity during testing. Furthermore, by improving resolution, it enables the use of such a low current to detect the insulation resistance of household appliances, circuit continuity, and the purity and alcohol content of purified water and beverages. This achieves multi-functionality, ease of adoption, and suitability for general use.

[0018] This instrument features a simple circuit, a wide range of testing capabilities, extremely high resolution, and is easy to operate, safe, reliable, and readily adopted, making it particularly suitable for use in homes, communities, and offices. Through testing, it can promptly detect equipment or beverages with substandard grounding, insulation, or conductivity. This will play a significant role in preventing personal injury and fire accidents.

[0019] Although the instrument has a simple circuit, it involves a lot of basic electrical knowledge and can also be used as a training instrument for electricians and a teaching instrument for middle school students.

[0020] Using mains power as the instrument's power source, a 99V pulsating DC voltage is obtained through half-wave rectification as the detection voltage, providing a wide testing range and a simple circuit.

[0021] When testing grounding resistance at home, the current needs to flow through the RCD, but the RCD setting current for household electricity is generally 30 mA. Obviously, the current of the instrument testing grounding resistance must be much less than 30 mA.

[0022] Using a 99V DC voltage and a current of less than 30mA (the RCD setting current for household electricity), the impedance of low-voltage grounding resistance, insulation resistance of household appliances, and conduction resistance of appliances can be tested.

[0023] Using a 99V DC voltage and a current of less than 10mA (the instrument's RCD setting current), the purity of purified water and the alcohol content of alcohol and spirits were tested.

[0024] Within the same low-voltage power supply network (10 kV / 0.4 kV, yn0 connection), the grounding resistance and neutral connection continuity of the mains power supply were tested at home using the mains power supply grounding electrode. The grounding resistance at any grounding point was also tested.

[0025] By designing circuit current shunting and voltage reduction current shunting, the instrument resolution is greatly improved, thus enabling the measurement of impedance from 0 to infinity.

[0026] The grounding resistance was tested, and linear measurement was achieved for ground resistance less than 30 ohms, ensuring the accuracy of the measurement.

[0027] By varying the instrument's resolution, all measurements can be displayed using only a digital DC voltmeter with a 200 mA range.

[0028] In terms of metrology, a comparison resistance value has been set. Although the measurement result is not an exact value, it can accurately determine the range of the test result, and for civilian use, it can fully meet the requirements of safe measurement. Attached Figure Description

[0029] The accompanying drawings, which form part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an undue limitation of the present invention. In the drawings:

[0030] Figure 1 The schematic diagram of the impedance detector according to this utility model is shown.

[0031] Figure 2 It shows Figure 1 The equivalent diagram of insulation resistance measurement of the impedance detector in the figure.

[0032] The above figures include the following reference numerals:

[0033] L is the phase wire of the 220V power supply; E is the ground wire of the 220V power supply; N is the neutral wire of the 220V power supply; XP is the single-phase three-pole plug on the power supply side of the RCD residual current device (RCD); RCD is the residual current device; A, B, and C are the three single-phase plugs on the output side of the instrument's power supply RCD; a, b, and c are the three single-phase sockets on the instrument's power supply box for connecting to the power supply; FUSE is the fuse.

[0034] D1 is the first 4007 diode; R1 is the first current-limiting resistor; D2 is the second 4007 diode; S2 is the second single-pole double-throw switch; R2 is the signal sampling resistor; R2-1 is the voltmeter signal sampling resistor; R5, R5-1, R6, R6-1, R7, R7-1, R8, R8-1, R12, R12-1, R13, and R13-1 are all comparison resistors; S1 is the first single-pole double-throw switch; S3 is the third single-pole double-throw switch; S4 is the fourth single-pole double-throw switch; S5, S6, S7, S8, S9, and S10 are resistive single-pole double-throw switches;

[0035] D4 is the fourth 4007 diode; R4-1 is the first shunt resistor; R4 is the second shunt resistor;

[0036] A1 is the step-down shunt circuit node; D3 is the third 4007 diode; R3-1 is the third shunt resistor; R3 is the fourth shunt resistor;

[0037] R11 is the second current-limiting resistor; K1 is the first normally open push button;

[0038] R10 is the third current-limiting resistor; K2 is the second normally open button;

[0039] R9 is the fourth current-limiting resistor; nip is the neon bulb; di is the contact;

[0040] A2 is the positive terminal for signal output; 200mV is the positive terminal of the DC voltmeter; A3 is the negative terminal for signal output.

[0041] A4 is the positive terminal of the meter probe socket; A5 is the negative terminal of the meter probe socket.

[0042] Rz is the load impedance;

[0043] I1 is the detection loop current before node A1; I12 is the detection loop current after node A1; I2 is the shunt loop current; I3 is the shunt step-down loop current; Ia is the total monitoring loop current when both the third and fourth single-pole double-throw switches are open; Ib is the total detection circuit current when the third single-pole double-throw switch is open and the fourth single-pole double-throw switch is closed; Ic is the total detection circuit current when both the third and fourth single-pole double-throw switches are closed; Rd is the grounding resistance; R0 is the neutral wire conduction resistance; E and e are grounding connection lines; E and E0 are neutral connection lines. Detailed Implementation

[0044] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0045] like Figures 1 to 2 As shown in the figure, this utility model embodiment provides an impedance detector, including a housing, within which a circuit board is provided. The circuit board has a detection circuit, a shunt circuit, a current detection circuit, a leakage current protection measurement circuit, and a phase-zero error tripping circuit. The detection circuit, shunt circuit, current detection circuit, and leakage current protection measurement circuit are all connected to a fuse (FUSE). The fuse (FUSE) is connected to a leakage current device (RCD), which is connected to a 220V power supply. The detection circuit... The circuit is connected to a shunt step-down circuit and a signal circuit. The detection circuit and the shunt circuit are respectively connected to comparison resistors R5, R5-1, R6, R6-1, R7, R7-1, R8, R8-1, R12, R12-1, R13, and R13-1. The comparison resistors R5, R5-1, R6, R6-1, R7, R7-1, R8, R8-1, R12, R12-1, R13, and R13-1 are connected to the residual current device (RCD) through a switch.

[0046] In this embodiment, the detection circuit includes a first 4007 diode D1. One end of the first 4007 diode D1 is connected to a fuse FUSE, and the other end is connected to a first current-limiting resistor R1. The first current-limiting resistor R1 is connected to a second 4007 diode D2. The second 4007 diode is connected to a second single-pole double-throw switch S2. The second single-pole double-throw switch S2 is connected in series with a voltmeter signal sampling resistor R2-1 and a signal sampling resistor R2, or individually connected to the signal sampling resistor R2. The signal sampling resistor R2 is connected to comparison resistors R5, R5-1, R6, R6-1, R7, R7-1, R8, R8-1, R12, R12-1, R13, and R13-1. The comparison resistors R5, R5-1, R6, R6-1, R7, R7-1, R8, R8-1, R12, R12-1, R13, and R13-1 are connected to the corresponding single-pole double-throw (SPD) switches S5, S6, S7, S8, S9, and S10. The SPD switches S5, S6, S7, S8, S9, and S10 connected to the comparison resistors R5, R5-1, R6, R6-1, R7, R7-1, R8, R8-1, R12, R12-1, R13, and R13-1 are all connected to the first SPD switch S1. The first SPD switch S1 is connected to the residual current device (RCD) and the residual current device (RCD), which is connected to a 220V power supply.

[0047] In this embodiment, the shunt circuit includes a fourth 4007 diode D4. One end of the fourth 4007 diode D4 is connected to a fuse FUSE, and the other end is connected to a first shunt resistor R4-1 and a second shunt resistor R4. The first shunt resistor R4-1 and the second shunt resistor R4 are connected in parallel. The first shunt resistor R4-1 and the second shunt resistor R4 are respectively connected to a fourth single-pole double-throw switch S4. The fourth single-pole double-throw switch S4 is connected to comparison resistors R5, R5-1, R6, R6-1, R7, R7-1, R8, R8-1, R12, R12-1, R13, and R13-1. The comparison resistors R5, R5-1, R6, R7, R8, R8-1, R12, R12-1, R13, and R13-1 are connected in parallel. 6. R6-1, R7, R7-1, R8, R8-1, R12, R12-1, R13, and R13-1 are connected to the corresponding resistor single-pole double-throw switches S5, S6, S7, S8, S9, and S10. Among them, the resistor single-pole double-throw switches S5, S6, S7, S8, S9, and S10 connected to the comparison resistors R5, R5-1, R6, R6-1, R7, R7-1, R8, R8-1, R12, R12-1, R13, and R13-1 are all connected to the first single-pole double-throw switch S1. The first single-pole double-throw switch S1 is connected to the residual current device (RCD) and the residual current device (RCD), which is connected to a 220V power supply.

[0048] In this embodiment, the shunt-voltage reduction circuit includes a shunt-voltage reduction circuit node A1. One end of the shunt-voltage reduction circuit node A1 is located between the first current-limiting resistor and the second 4007 diode D2, and the other end is connected to the third 4007 diode D3. The third 4007 diode D3 is connected to the third shunt resistor R3-1 and the fourth shunt resistor R3 respectively. The third shunt resistor R3-1 and the fourth shunt resistor R3 are connected in parallel. The third shunt resistor R3-1 and the fourth shunt resistor R3 are connected to the third single-pole double-throw switch S3 respectively. The third single-pole double-throw switch S3 is connected to the residual current device RCD, and the residual current device RCD is connected to the N terminal of the 220V power supply.

[0049] In this embodiment, the phase-zero trip circuit includes a second current-limiting resistor R11. One end of the second current-limiting resistor R11 is connected to the residual current device (RCD), which is connected to the neutral (N) terminal of the 220V power supply. The other end of the second current-limiting resistor R11 is connected to the first normally open button K1, which is also connected to the RCD. The RCD is connected to the emitter (E) terminal of the 220V power supply. The RCD trip test circuit includes a third current-limiting resistor R10. One end of the third current-limiting resistor R10 is connected to the fuse FUSE, and the other end is connected to one end of the second normally open button K2. The other end of the second normally open button K2 is connected to the RCD, which is connected to the emitter (E) terminal. The current detection circuit includes a fourth current-limiting resistor R9. One end of the fourth current-limiting resistor R9 is connected to the fuse FUSE, and the other end is connected to one end of a neon bulb. The other end of the neon bulb is connected to a hand contact.

[0050] In this embodiment, the signal circuit includes a positive signal output node. One end of the positive signal output node is connected to the positive terminal of a 200mV DC voltmeter, and the other end is connected to the second single-pole double-throw switch S2 and the second 4007 diode D2. One end of the negative signal output node A3 is connected to the negative terminal of a 200mV DC voltmeter, and the other end is connected to the center tap of the signal sampling resistor R2. The 200mV DC voltmeter is connected to a 5V DC power supply module.

[0051] In this embodiment, the equivalent circuit for measuring solid resistance and liquid resistance includes: a first 4007 diode D1, one end of which is connected to the phase line L of the 220V power supply, and the other end is connected to a first current-limiting resistor R1 and a second shunt resistor R4, wherein the first current-limiting resistor R1 and the second shunt resistor R4 are connected in parallel; the first current-limiting resistor R1 is connected to one end of a signal sampling resistor R2; the other end of the signal sampling resistor R2 is connected to the positive terminal A4 of the test probe socket; the positive terminal A4 of the test probe socket is connected to the impedance to be measured; the impedance to be measured is connected to the negative terminal A5 of the test probe socket; and the negative terminal A5 of the test probe socket is connected to the neutral line N of the 220V power supply. The circuit is connected as follows: a step-down shunt circuit node A1 and a positive signal output node are provided between the first current-limiting resistor R1 and the signal sampling resistor R2; a negative signal output node A3 is provided on the signal sampling resistor R2; the positive signal output node is connected to the positive terminal of the sampling voltage; the negative signal output node A3 is connected to the negative terminal of the sampling voltage; the step-down shunt circuit node A1 is connected to the third single-pole double-throw switch S3; the third single-pole double-throw switch S3 is connected to the fourth shunt resistor R3; the fourth shunt resistor R3 is connected to the neutral line N of the 220V power supply; the second current-limiting resistor R11 is connected to the fourth single-pole double-throw switch S4; and the fourth single-pole double-throw switch S4 is connected to the positive terminal A4 of the test probe socket node.

[0052] In this embodiment, as shown in the appendix Figure 1 The wiring diagram is shown below, and the connection relationships of each circuit are as follows:

[0053] Detection circuit connection: LA-FUSE-D1-R1-D2-S2-[R2, (R2-1+R2)]-(R5, R5-1, R6, R6-1, R7, R7-1, R8, R8-1, R12, R12-1, R13, R13-1)-(S5, S6, S7, S8, S9, S10)-S1-(BN, CE).

[0054] Shunt circuit connection: LA-FUSE-D4-(R4, R4-1)-S4-(R5, R5-1, R6, R6-1, R7, R7-1, R8, R8-1, R12, R12-1, R13, R13-1)-(S5, S6, S7, S8, S9, S10)-S1-(BN, CE).

[0055] Shunt step-down circuit connection: A1-D3-(R3, R3-1)-S3-BN.

[0056] Phase zero error trip circuit connection: NB-R11-K1-CE.

[0057] RCD trip test circuit connection: LA-FUSE-R10-K2-CE.

[0058] Connection of the detection circuit: LA-FUSE-R9-nip-di.

[0059] Signal circuit: D2-S2-A2 positive - positive terminal of 200MV DC digital voltmeter. R2 center tap - A3 negative - negative terminal of 200MV DC digital voltmeter.

[0060] In this embodiment, for the attached Figure 1 The symbols are explained as follows:

[0061] L-220V power supply phase line L: live wire.

[0062] Ground wire of E-220V power supply: Ground wire.

[0063] N-220V power supply neutral line N: neutral wire.

[0064] XP is the single-phase three-pole plug XP on the power supply side of the residual current device (RCDRCD).

[0065] RCD (Residual Current Device); RCD for power supply of detectors: I△n=10mA, less than the 30mA setting current of household power supply RCD, protecting instruments and personal safety.

[0066] A, B, C: Three single-phase plugs on the RCD output side of the instrument's power supply. ABC: Insert into the three single-phase power input sockets on the instrument to connect the power supply. Used for phase adjustment when detecting phase or training operators.

[0067] a, b, and c: These are three single-phase sockets (abc) on the instrument's power supply box for connecting to the power source; the power is turned on after the plug is inserted.

[0068] FUSE is a fuse. FUSE: fuse=0.1A: If the leakage current of the instrument is greater than 0.1A, the fuse will blow to ensure the safety of the instrument and the user.

[0069] D1 is a 4007 diode: used for rectification in the detection circuit. It converts the instrument's 220V AC mains power supply to 99V pulsating DC power for testing the impedance of electrical appliances or components.

[0070] R1 current-limiting resistor: Used for current limiting in the detection circuit, limiting the current to 4 microamps. This is the instrument's base current.

[0071] K1 is a normally open button: used to detect phase zero error.

[0072] R11 current-limiting resistor: limits current to 10 mA. When phase zero error occurs, the line current causes the instrument's RCD to trip, preventing operators from accidentally touching live contacts.

[0073] K2 is a normally open button: used during RCD testing.

[0074] R10 is a current-limiting resistor: limiting current to 30 mA. During RCD testing, ensure that the RCD trips in the corresponding circuit of the instrument power supply and the household distribution box.

[0075] R9 is a current-limiting resistor: used in the current detection circuit, also known as the test pen circuit, it limits the current to 0.2 microamps. This ensures personal safety.

[0076] NIP neon bulb: Indicator for continuity of the current detection circuit. A lit neon bulb indicates power; an unlit bulb indicates no power.

[0077] 'di' stands for contact: the hand contact in the current detection circuit. When the instrument is connected to a power source, touching the contact will light up the neon bulb (indicating power) or deactivate it (indicating no power).

[0078] A1 is the step-down and shunt circuit node: connected to the step-down and shunt circuit.

[0079] D3 is a 4007 type diode: to prevent neutral current from flowing into the ground wire.

[0080] R3-1 is a shunt resistor: a small resistor that shunts and reduces voltage, serving to provide a large current shunt and a large voltage drop, and is used to measure extremely small on-resistance.

[0081] R3 is a shunt resistor: a large resistor that shunts and reduces voltage, serving the purpose of small current shunting and small voltage drop, and is used to measure the grounding resistance Rd.

[0082] D4 is a 4007 diode: used for rectification in the shunt circuit, converting the instrument's 200V AC mains power to 99V pulsating DC, which is then connected to the detection circuit at node A4 via R4 or R4-1, forming a parallel circuit. This reduces impedance, increases the current flowing into Rz, and improves measurement resolution.

[0083] R4-1 is a shunt resistor: it is the current-limiting resistor for the shunt circuit. When the shunt circuit and the detection circuit are connected in parallel, the impedance is reduced, the current is increased, and the instrument's resolution is greatly improved. Low resistance, high current, high resolution.

[0084] R4 is a shunt resistor: it is the current-limiting resistor in the shunt circuit. Due to its relatively high resistance, it draws a small current, resulting in lower resolution.

[0085] R2 signal sampling resistor: This is an adjustable resistor. The voltage signal is extracted across its terminals and input to the signal terminals of the digital voltmeter for display. The resistance value can be adjusted according to the instrument's testing requirements.

[0086] R2-1 is the voltmeter signal sampling resistor: it is a fixed resistor. After the signal is taken from R2-1, it is input to the meter to display the AC voltage value of the instrument's power supply. It can also be used to test AC power supply voltages of 250V and below.

[0087] A3 is the negative node for signal output.

[0088] A2 is the positive node for signal output.

[0089] 200mV DC voltmeter: Displays measurement results.

[0090] 5V DC power supply module: 5V DC power supply for a 200mV DC voltmeter.

[0091] Rz is the load impedance, i.e., the impedance being measured. Examples include insulation resistance, conduction resistance, grounding resistance, water resistance, and alcohol resistance.

[0092] A4 is the positive terminal of the probe socket.

[0093] A5 is the negative terminal of the probe socket.

[0094] R5, R5-1, R6, R6-1, R7, R7-1, R8, R8-1, R12, R12-1, R13, and R13-1 are all comparison resistors: used to compare the results with the measured impedance Rz.

[0095] S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10 are single-pole double-throw switches.

[0096] Used for gear shifting and connecting different circuits.

[0097] I1 is the current in the detection loop before node A1; I12 is the current in the detection loop after node A1; I2 is the current in the shunt loop; I3 is the current in the shunt step-down loop; Ia is the total current in the detection loop when both the third and fourth single-pole double-throw switches S4 are open; Ib is the total current in the detection circuit when the third single-pole double-throw switch S3 is open and the fourth single-pole double-throw switch S4 is closed; Ic is the total current in the detection circuit when both the third and fourth single-pole double-throw switches S4 are closed; Rd is the grounding resistance; R0 is the neutral wire conduction resistance; E and e are the grounding connection lines; E and E0 are the neutral connection lines.

[0098] In this embodiment, the appendix Figure 2 The diagram shows the equivalent circuits for solid and liquid resistance measurements. The meanings of the letters L, N, E, D1, R1, A1, A2, R2, A3, A4, R2, A5, R4, S4, and S1, along with their wiring connections and attachments, are also provided. Figure 1The circuit is identical to the circuit in the diagram below, except for the addition of current flow diagrams for each loop: I1 - current in the detection loop; I12 - current in the detection loop; I2 - current in the shunt loop; I3 - current in the shunt-voltage-reducing loop; Ia, Ib, and Ic represent the total current in the detection circuit. Ia is the total current when S3 and S4 are disconnected, Ib is the total current when S3 is disconnected and S4 is closed, and Ic is the total current when both S3 and S4 are closed. The current starts from the 220V AC phase line L, flows through D1 and is rectified to form a 99V DC voltage. It then passes through the current-limiting resistor R1, nodes A1 and A2, sampling resistor R2, A4 probe node, the impedance to be measured Rz, and A5 probe node to enter the neutral line N, forming a test loop. A current shunt occurs at the positive node of D1, and the shunt current I2 flows through the current-limiting resistor R4 and switch S4, converging into the detection loop at the positive node of the A4 probe. A shunt and step-down circuit is connected at node A1. I3 flows through switch S3 and current-limiting resistor R3 to the neutral line N. S3 and S4 are switched on and off according to the required resolution. The system's neutral and ground connections are marked on the N and E terminals of the 220V AC power supply. Ee is the grounding wire, Rd is the grounding resistance, E and E0 are the neutral wires, and R0 is the neutral connection resistance.

[0099] In this embodiment Figure 2 In the test, S3 and S4 are both disconnected, and S1 is connected to the N terminal. The megohm-level impedance is tested: the current starts from the AC 220V phase line L, flows through D1 and is rectified to form a 99V DC voltage. It then passes through the current-limiting resistor R1, nodes A1 and A2, sampling resistor R2 or R2-1, the positive node of the A4 probe, the impedance to be measured Rz, the negative node of the A5 probe, and enters the neutral line N through S1, forming a test loop.

[0100] Specifically, this is a basic circuit used to test insulation resistance. The object being tested is the insulation of household appliances, and the value is typically in the megaohm range. The I1 value in this circuit is used as a reference to analyze the resolution amplification in other cases.

[0101] (1) Calculation of the output voltage of the half-wave rectifier circuit:

[0102] Vdc = 0.45 * Vin

[0103] Where Vdc is the output DC voltage; Vin is the input AC voltage, Vin = 220V.

[0104] Vdc = 0.45 * 220 = 99V

[0105] (2) Calculation of I1:

[0106] In the appendix Figure 2 middle:

[0107] I1 = 99 / (R1 + R2 + Rz) (1)

[0108] Where R1 is the first current-limiting resistor; R2 is the signal sampling resistor; and Rz is the load impedance.

[0109] Approximate calculation: I1 = 99 / 25000000 = 0.00000396 ≈ 4 μA

[0110] (3) Calculation of sampling resistor R2-1:

[0111] Let the sampling resistor be X:

[0112] (25000+X ) / X =99 / 0.022 X =56000Ω=5.6KΩ

[0113] For ease of selecting a resistor, the instrument uses a value of 5.5 kΩ.

[0114] Based on a resistance of 5500Ω, the sampling voltage would be:

[0115] V=R2*I1; V=5500*0.000004; V=0.022V

[0116] At this time, the meter displays 220, which is 22.0 millivolts, indicating that the instrument's AC power supply voltage is 220V. Since I is a variable, the sampling voltage V changes with I, thus displaying the real-time voltage value.

[0117] exist Figure 2 In the middle section, only S4 is closed, and S1 is connected to the N terminal: test the impedance in the kilohm range.

[0118] Let the resolution magnification factor be α, then:

[0119] α = Ib / I1 where Ib = I1 + I2 (2)

[0120] Where Ib is the total current of the detection circuit; I1 is the current of the detection loop; and I2 is the current of the shunt loop.

[0121] Approximate calculation: Take R⁴⁻¹ = 4.5 kΩ, I² = 99 / 4500 = 0.022 A

[0122] 0.022 / 0.000004=5500(times)

[0123] The calculation results from equation (2) show that, Figure 2 When only S4 is closed, the resolution is magnified by more than 5,000 times, which can be used to test impedances in the kiloohm range.

[0124] exist Figure 2 In the middle, closing S4 and S3: testing ohmic impedance.

[0125] Let the resolution magnification factor be β, then:

[0126] β = Ic / I12; where Ib is the total current of the detection circuit; and I12 is the current of the detection loop.

[0127] When R3 is in the ohm range, I12 is extremely small, while Ib hardly changes, so the resolution amplification factor β is very large, reaching millions or even hundreds of millions. Under these conditions, extremely small on-resistances can be tested.

[0128] This embodiment, appendix Figure 2 The principle of testing the grounding resistance Rd in a grounding system is revealed in the paper:

[0129] During testing, S1 is connected to the emitter (E) of a 220V power supply. If the system is grounded, Rd is the grounding resistance, and the current flows directly to the ground through the grounding wire Ee. If the system is connected to neutral, R0 is the neutral-connection resistance, and the current flows to the neutral terminal (N) through the neutral wire EE0. Under these conditions, grounding resistance in the hundreds of ohms, ohms, and even milliohms can be tested.

[0130] Instrument safety: The instrument's power supply uses a 10mA leakage protection plug, a 0.1A fuse, and a phase-zero error tripping circuit to ensure the safety of personnel and the instrument.

[0131] Specific applications:

[0132] A: The detector's initial state: no power supply, all switches are in their original positions (the same applies below).

[0133] B: Power-on status of the detector: S1 set to 1 (connected to zero), S2 set to 1 (voltage display sampling resistor connected), S5 set to 1 (circuit connected), power supply connected, meter displays real-time voltage value. (The same applies below)

[0134] C: The instrument has two power supplies: 220V AC mains power and 220V power frequency inverter power, which can be selected according to the testing needs.

[0135] The main functions are as follows:

[0136] (1) Detection and phase identification:

[0137] The meter displays nothing after the detector is turned on. Touching the contact point does not light up the neon bulb, indicating a lack of power.

[0138] The meter displays nothing after being turned on. Touching the contact point illuminates the neon bulb, indicating a meter malfunction.

[0139] The detector trips instantly upon power-on: short circuit fault, ground-neutral error, or phase-neutral error.

[0140] After the detector is powered on, the meter displays the real-time voltage value, S1 rotates to 2 digits to display 000, the neon bulb lights up when the contact is touched, indicating a missing ground wire.

[0141] After the detector is turned on, the meter displays 000, S1 rotates to 2 digits to display the real-time voltage value, the neon bulb lights up when the contact is touched, indicating a missing neutral wire.

[0142] After the detector is powered on, the meter displays the real-time voltage value. S1 rotates to 2 digits, and the meter still displays the real-time voltage value. Touching the contact point causes the neon bulb to light up, indicating that the phase is correct.

[0143] (2) Power supply voltage display

[0144] When the device is powered on, the meter displays the AC power supply voltage in real time.

[0145] (3) Voltage measurement:

[0146] To measure other AC voltages, simply disconnect the mains power supply, connect the AC power source to be measured, and ensure the device is powered on. Measurement range: 0-250V.

[0147] (4) RCD trip flexibility test:

[0148] To test the RCD of the detector, simply press the trip button while the device is powered on. To test the RCD of the detector's power supply (indoor power supply), press K2. If both the instrument's and the indoor power supply's RCDs trip, the RCD protection is working correctly and tripping flexibly. If the indoor power supply's RCD fails to trip, it indicates a fault in the power supply's RCD, requiring inspection and repair by a qualified electrician.

[0149] (5) Grounding resistance Rd test: resolution less than 1Ω

[0150] In a 10kV power supply system, the secondary winding of the mains transformer is star-connected. When testing the grounding resistance Rd, S1 needs to be set to position 2 to form a grounding loop that includes the ground resistance Rd.

[0151] Test the grounding resistance Rd of the mains power supply:

[0152] Test Method: With the device powered on, first set S1 to position 2 and check if the displayed value is close to the value when it is set to position 1. If they are the same or very close, the grounding resistance Rd test can be performed. Next, set S3 to position 1, S2 to position 2, and adjust R2 until the display shows 230. Then set S4 to position 1; the displayed value is now the measured value. Compare the displayed value with the comparison value 230; the difference is the grounding resistance Rd in ohms. If there is no difference, the grounding resistance Rd is less than 1 ohm. For a TN-C grounding system, the measured value is the on-resistance of the power supply to neutral; for a TT grounding system, the measured value is the grounding resistance Rd.

[0153] Test the grounding resistance Rd of online (powered on) and offline (powered on but not powered on) electrical equipment:

[0154] Test method: With the device powered on, first set S1 to position 2 and check if the displayed value is close to that when it is set to position 1. If they are the same or very close, the grounding resistance Rd test can be performed. Then set S3 to position 1 and adjust R2 until the displayed value is 230 (comparison value). Next, disconnect S5, insert the red probe into hole A4, touch the conductive metal casing of the appliance with the probe, and set S4 to position 1. Record the displayed value, and compare the difference between the displayed value and the comparison value. The difference is the grounding resistance Rd value of the online electrical equipment, in ohms.

[0155] Test the grounding resistance Rd at any point indoors or outdoors:

[0156] Test method: The method is the same as that for testing the grounding resistance Rd of online electrical equipment. Simply touch the red probe to the point to be tested, such as a conductive point on a metal water pipe or metal radiator.

[0157] Example: If the measured value is 226, then 230-226=4, so the ground resistance is 4Ω; if the measured value is 220, then 230-220=10, so the ground resistance is 10Ω. The grounding resistance Rd is approximately linear within 30 ohms. As the grounding resistance Rd increases, the test error also increases. Therefore, for accuracy, when testing ground resistance with a detector, 30 ohms is used as the upper limit for testing; ground resistance tests greater than 30 ohms are for reference only.

[0158] (6) Insulation resistance test function: Range: 0-0.5 MΩ-∞Ω

[0159] Test method: After powering on, first set S2 to position 2 and rotate R2 to adjust the meter display to 230. Then disconnect S5 and touch the two probes to the two ends of the insulator being tested. The measured value will be displayed. Then compare it with the comparison value to determine the range of insulation resistance of the tested electrical appliance.

[0160] Comparison Value Display Operation: The instrument is equipped with resistors of 0Ω, 500KΩ, 5MΩ, and 50MΩ comparison values, corresponding to half positions of S5 and S6, respectively. During insulation testing, simply connect position 2 of S5 and positions 1, 2, and 3 of S6 as needed to display the corresponding comparison values ​​of 500KΩ, 5MΩ, and 50MΩ. If the displayed value is greater than 500KΩ, the insulation is considered unqualified; if it is less than this comparison value, the insulation is considered qualified. When the displayed value is close to 0, the insulation resistance is close to infinity.

[0161] (7) Continuity resistance test function: Range: 30Ω-10Ω-1Ω-0.1Ω-0

[0162] Test method: First, set S2 to position 2 and S3 to position 1. Then, adjust the meter display to 230 and disconnect S5. Next, touch the two probes to the two ends of the object being tested. Then, set S4 to position 1. The measured value will then be displayed. Compare the measured value with the comparison value to determine the range of the conduction resistance of the tested electrical appliance.

[0163] Comparison value display operation: The instrument is equipped with resistors of 30Ω, 10Ω, 1Ω, and 0.1Ω (corresponding to positions 1 and 2 of S7 and S8, respectively). When testing continuity resistance, positions 1 and 2 of S7 and S8 are turned on as needed to display the corresponding comparison value. The measured display value is then compared with the comparison value to determine the range of continuity resistance of the conductor under test. If the measured display value is less than the comparison value, the continuity resistance of the conductor under test is greater than the comparison value; if the measured value is greater than the comparison value, the continuity resistance of the conductor under test is less than the comparison value. The larger the measured display value, the smaller the continuity resistance. When the measured display value is close to 230, the continuity resistance is close to infinitesimal. When S3 and S4 are both set to position 2, the resolution for continuity resistance testing can reach 0.05 ohms and below.

[0164] (8) Pure water testing function

[0165] Water purity refers to the amount of conductive impurity ions such as potassium, sodium, calcium, and magnesium in the water. High water purity indicates fewer impurity ions, and vice versa.

[0166] The principle of pure water purity measurement: Pure water is non-conductive while impurity ions (such as potassium, sodium, calcium, and magnesium ions) in the water are conductive. The purity of pure water is detected by directly measuring the water resistance.

[0167] The instrument contains resistors with comparison values ​​of 1.1KΩ and 200KΩ, corresponding to the purity of tap water, Yibao purified water, and Wahaha purified water, respectively, and corresponding to bits 1 and 2 of S12. During testing, the measured value can be compared with the comparison value to determine the range of purity of the purified water being tested.

[0168] Test Method: With the machine powered on, first disconnect S5, insert the test leads into the socket, align the two leads, pinch them tightly, and insert them into the water (the water level should just cover the metal tips of the test leads). Then set S4 to position 1. The value displayed on the meter at this point represents the purity of the water. Compare this value with the values ​​displayed on positions 1 and 2 of S12 to determine the purity level. The lower the displayed value, the higher the purity. For accurate measurement, the sample should be kept clean to prevent contamination. The test should be conducted immediately after the sample cap is opened or the sample is poured into the measuring cup. The test should also be performed under identical conditions, such as when the sample temperatures are approximately the same, and the distance and height of the two test leads in the water should be consistent. The temperature during testing is approximately 25 degrees Celsius.

[0169] (9) Detection of alcohol content and alcohol strength:

[0170] The alcohol content of alcoholic beverages refers to the amount of ethanol they contain. The higher the alcohol content, the more ethanol and the less water, resulting in less conductive medium and a lower measured value, and vice versa.

[0171] The principle of measuring alcohol content is based on the fact that ethanol and pure water in alcohol or liquor are non-conductive, while impurity ions (such as potassium, sodium, calcium, and magnesium ions) are conductive. This is achieved by directly measuring the alcohol or liquor.

[0172] The testing method is the same as that for purified water. The comparison values ​​of 32KΩ and 500KΩ correspond to 42-degree baijiu (Chinese liquor) and 95-degree alcohol, respectively, corresponding to bits 1 and 2 of S13. The smaller the displayed value, the higher the purity. The testing method is the same as that for purified water.

[0173] Whether it's purified water or alcoholic beverages, comparing multiple samples is very convenient; simply compare the test values ​​to determine which is superior.

[0174] (10) Parameter settings for the detector:

[0175] R1=25MΩ R2=10KΩ R2-1=5.5KΩ R3=160K R3-1=20Ω R4=30KΩ R4-1=4.5KΩ R5=0 R5-1=0.5MΩ R6=5MΩ R6-1=50MΩ R7=0.1Ω R7-1=1Ω R8=10Ω R8-1= 30Ω R9= 2MΩ R10=7.2 R11=22KΩ fuse=0.1AF=22μF (50V) R12=1.1 kΩ R12-1=200 kΩ R13=32 kΩ R13-1=500 kΩ

[0176] illustrate:

[0177] R1=25MΩ: Current-limiting resistor, which generates a small current in the circuit. It can test insulation resistance in the megaohm range and lays the foundation for expanding the test range and improving resolution.

[0178] R2=10KΩ: Sampling resistor; the voltage across its terminals is taken and sent to the signal terminal of a 200MV DC digital voltmeter. It is also an adjustable resistor, adjustable from 0 to 10 kΩ. Different resistor values ​​are selected based on the different safety parameters being tested.

[0179] R2-1 = 5.5KΩ: When the instrument's power supply voltmeter is connected to this resistor, the instrument displays the power supply voltage in real time. (When R2-1 is connected, R2 is initially at position 0.)

[0180] R5=0: Used after the instrument is powered on.

[0181] R5-1=0.5MΩ R6=5MΩ R6-1=50MΩ: Comparison value for measuring insulation resistance.

[0182] R7=0.1Ω R7-1=1Ω R8=10Ω R8-1=30Ω: Comparison value for measuring on-resistance.

[0183] R12 = 1.1 kΩ ------ Comparison value of tap water

[0184] R12-1=200 kΩ --- Comparison value of Yibao purified water

[0185] R13 = 32 kΩ ------ Comparison value of 42-degree baijiu (Chinese liquor)

[0186] R13-1=500 kΩ ------ Comparison value of 95% alcohol

[0187] R10=7.2kΩ: For leakage protection measurement. Press K2, leakage current is 30mA, indoor power trips.

[0188] R11=22KΩ: Current-limiting resistor for phase-zero error tripping circuit. When the phase line and neutral line are incorrectly connected, the instrument power supply trips with a tripping current of 10mA.

[0189] fuse=0.1A: Fuse. If the leakage current of the instrument is greater than 0.1A, the fuse will blow to ensure the safety of the instrument and the user.

[0190] A capacitor with a capacitance of F=22μF (50V) is used for sampling voltage filtering to stabilize the digital display on the meter.

[0191] General parameters:

[0192] Detector RCD: ∽220V I△n=10mA t≤0.1s: Detector RCD leakage current protection device

[0193] DC power supply module: Input AC 220V, output DC 5V, power supply for DC voltage digital meter.

[0194] DC digital voltmeter: 200mV range, 5V DC power supply, LED display, instrument display.

[0195] Working principle:

[0196] In the detection circuit of the instrument, the 220V power supply is half-wave rectified by the diode D1. The rectified 99V DC voltage forms a pulsating current through the current-limiting resistor R1, diode D2, single-pole double-throw switch S2, sampling resistor R2 or R2-1, the measured impedance Rz, and single-pole double-throw switch S1 to enter the neutral line N or the ground wire E of the 220V power supply, completing the impedance test. The resistance of R1 is large, which can reduce the circuit current to the microamp level, making the measurement of insulation resistance almost infinite and laying a foundation for expanding the measurement range. By shunting and reducing the voltage of the measurement circuit, the resolution of impedance measurement is greatly improved. Therefore, in addition to measuring insulation resistance and liquid resistance, it can also measure the grounding resistance Rd, conduction resistance, etc. And it can make the measurement of the grounding resistance Rd and conduction resistance as small as below 1 ohm, even infinitely small. D2 is set to prevent the neutral line current from flowing into the ground wire. S2 is set to connect R2 and R2-1 respectively. R2 is the detection sampling resistor, and R2-1 is the voltmeter sampling resistor. When S2 connects R2-1, the instantaneous value of the 220V AC voltage of the instrument power supply is displayed on the meter head, and other AC voltages equal to or less than 250V can also be tested. When the meter head shows 220, the real meaning of the number is 22.0 millivolts, which is the DC voltage across the sampling resistor. For other various tests, the millivolt voltage display value shown on the meter head is used. The instrument can measure the impedance voltage Rz because in the measurement circuit, except for Rz, other values are fixed values, and only Rz is a variable. Therefore, only the difference in Rz will cause the change of the current in the detection circuit, thus changing the voltage of the sampling resistor and the corresponding change of the digital value on the meter head. So the size of the measured impedance can be judged from the size of the digital value shown on the meter head. Furthermore, the range or size of the measured impedance can be determined through the pre-implanted comparison resistor, and it can be confirmed whether it is qualified according to the standards of the test items and the size of the measured impedance. The difference from the display and measurement results of various electrical and electronic instruments is that various instruments can accurately display the measurement numbers or images, while the detector uses the interval where the detection result is located to judge whether various detection items are qualified. The measurement of insulation resistance and conduction resistance uses this method. For example, the start and end points of one interval of the insulation resistance are 0.5 megohm and 5 megohm, corresponding to two display numbers on the voltmeter. When measuring the resistance, if the displayed number is between the two numbers, it means the insulation is qualified. I call this method comparison measurement. Because the test result is non-linear, the comparison resistor is pre-implanted. The comparison resistor and the measured resistor are tested under the same conditions, so they can be compared. The size of the digital value shown on the meter head changes with the size of the measured impedance. The larger the impedance, the smaller the displayed number; the smaller the impedance, the larger the displayed number. The pre-implanted comparison resistor is an industrial standard resistor selected according to needs. The number of comparison resistors is set according to the required measurement accuracy. This instrument is for simple measurement and public use, as long as the result can be accurately judged through the measurement.Therefore, the instrument only uses the most basic comparison values. Even so, it can accurately determine the measurement results and thus ascertain the safety and reliability of the mains power supply and low-voltage electrical appliances. On the other hand, the instrument's impedance testing range from infinity to infinitesimal is achieved through a gradual increase in resolution. This increase in resolution is achieved through shunt circuits and shunt-voltage-drop circuits. Different resistors in the shunt circuit or shunt-voltage-drop circuit result in different levels of resolution.

[0197] In addition, digitizing analog and digital signals enables intelligent measurement; using the instrument as a terminal allows for safe remote control and detection of remote devices.

[0198] As can be seen from the above description, the embodiments of this utility model achieve the following technical effects:

[0199] Using 220V AC mains power as its power source, this multi-functional device can test the voltage, phase, grounding resistance Rd, and RCD leakage protection function of household power supplies. It can also test the insulation performance of household appliances, the conductivity of electrical appliances, circuits, and electronic components, as well as the purity of purified water and the alcohol content of beverages.

[0200] This device measures grounding resistance Rd using high voltage and low current (less than 30 mA, DC 99V), ensuring the RCD doesn't trip and doesn't affect household electricity during testing. Furthermore, by improving resolution, it enables the detection of insulation resistance of household appliances, circuit continuity resistance, and the purity and alcohol content of purified water and beverages using such low current. This achieves multi-functionality, ease of adoption, and suitability for general use.

[0201] This instrument features a simple circuit, a wide range of testing capabilities, extremely high resolution, and is easy to operate, safe, reliable, and readily adopted, making it particularly suitable for use in homes, communities, and offices. Through testing, it can promptly detect equipment or beverages with substandard grounding, insulation, or conductivity. This will play a significant role in preventing personal injury and fire accidents.

[0202] Although the instrument has a simple circuit, it involves a lot of basic electrical knowledge and can also be used as a training instrument for electricians and a teaching instrument for middle school students.

[0203] Using mains power as the instrument's power source, a 99V pulsating DC voltage is obtained through half-wave rectification as the detection voltage, providing a wide testing range and a simple circuit.

[0204] When testing the grounding resistance Rd at home, the current needs to flow through the RCD. However, the RCD setting current for household electricity is generally 30 mA. Obviously, the current of the instrument testing the grounding resistance Rd must be much less than 30 mA.

[0205] Using a 99V DC voltage and a current of less than 30mA (the RCD setting current for household electricity), the impedance of low-voltage grounding resistance Rd, insulation resistance of household appliances, and conduction resistance of appliances can be tested.

[0206] Using a 99V DC voltage and a current of less than 10mA (the instrument's RCD setting current), the purity of purified water and the alcohol content of alcohol and spirits were tested.

[0207] Within the same low-voltage power supply network (10 kV / 0.4 kV, yn0 connection), the grounding resistance Rd and neutral connection continuity resistance of the mains power supply were tested at home using the mains power supply grounding electrode. The grounding resistance Rd at any grounding point was also tested.

[0208] By designing circuit current shunting and voltage reduction current shunting, the instrument resolution is greatly improved, thus enabling the measurement of impedance from 0 to infinity.

[0209] The grounding resistance Rd was tested, and linear measurement was achieved for ground resistance less than 30 ohms, ensuring the accuracy of the measurement.

[0210] By varying the instrument's resolution, all measurements can be displayed using only a digital DC voltmeter with a 200 mA range.

[0211] In terms of metrology, a comparison resistance value has been set. Although the measurement result is not an exact value, it can accurately determine the range of the test result, and for civilian use, it can fully meet the requirements of safe measurement.

[0212] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. An impedance detector, characterized in that, The device includes a housing, within which a circuit board is provided. The circuit board has a detection circuit, a shunt circuit, a current detection circuit, a leakage current protection measurement circuit, and a phase-zero error tripping circuit. The detection circuit, shunt circuit, current detection circuit, and leakage current protection measurement circuit are all connected to a fuse. The fuse is connected to a leakage current protector, which is connected to a 220V power supply. The detection circuit is connected to a shunt voltage reduction circuit and a signal circuit. The detection circuit and the shunt circuit are respectively connected to a comparison resistor. The comparison resistor is connected to the leakage current protector through a switch.

2. The impedance detector as described in claim 1, characterized in that, The detection circuit includes a first 4007 diode, one end of which is connected to a fuse and the other end to a first current-limiting resistor. The first current-limiting resistor is connected to a second 4007 diode. The second 4007 diode is connected to a second single-pole double-throw switch. The second single-pole double-throw switch is connected in series with the R2-1 voltmeter signal sampling resistor and the signal sampling resistor, or individually connected to the signal sampling resistor. The signal sampling resistor is connected to a comparison resistor. The comparison resistor is connected to a corresponding resistor single-pole double-throw switch. The resistor single-pole double-throw switches connected to the comparison resistor are all connected to the first single-pole double-throw switch. The first single-pole double-throw switch is connected to a residual current device (RCD) and the residual current device (RCD).

3. The impedance detector as described in claim 1, characterized in that, The shunt circuit includes a fourth 4007 diode. One end of the fourth 4007 diode is connected to a fuse, and the other end is connected to a first shunt resistor and a second shunt resistor. The first shunt resistor and the second shunt resistor are connected in parallel. The first shunt resistor and the second shunt resistor are respectively connected to a fourth single-pole double-throw switch. The fourth single-pole double-throw switch is connected to a comparison resistor. The comparison resistor is connected to a corresponding resistor single-pole double-throw switch. The resistor single-pole double-throw switches connected to the comparison resistor are all connected to the first single-pole double-throw switch. The first single-pole double-throw switch is connected to a residual current device (RCD) and a residual current device (RCD).

4. The impedance detector as described in claim 1, characterized in that, The shunt-and-step-down circuit includes a step-down shunt circuit node. One end of the step-down shunt circuit node is located between the first current-limiting resistor and the second 4007 diode, and the other end is connected to the third 4007 diode. The third 4007 diode is connected to the third shunt resistor and the fourth shunt resistor respectively. The third shunt resistor and the fourth shunt resistor are connected in parallel. The third shunt resistor and the fourth shunt resistor are connected to the third single-pole double-throw switch respectively. The third single-pole double-throw switch is connected to the N terminal of the 220V power supply.

5. The impedance detector as described in claim 1, characterized in that, The phase zero error tripping circuit includes a second current-limiting resistor. One end of the second current-limiting resistor is connected to one end of the first normally open button, and the other end is connected to the residual current device (RCD). The RCD is connected to the N terminal of the 220V power supply. The other end of the first normally open button is connected to the RCD, and the RCD is connected to the E terminal of the 220V power supply.

6. The impedance detector as described in claim 1, characterized in that, The leakage current protection measurement circuit includes a third current-limiting resistor, one end of which is connected to a fuse and the other end of which is connected to one end of a second normally open button. The other end of the second normally open button is connected to the leakage current protector. The current detection circuit includes a fourth current-limiting resistor, one end of which is connected to a fuse and the other end of which is connected to one end of a neon bulb. The other end of the neon bulb is connected to a contact.

7. The impedance detector as described in claim 1, characterized in that, The signal circuit includes a positive signal output node, one end of which is connected to the positive terminal of a 200mV DC voltmeter, and the other end is connected to a second single-pole double-throw switch and a second 4007 diode; one end of the negative signal output node is connected to the negative terminal of a 200mV DC voltmeter, and the other end is connected to the center tap of a signal sampling resistor, wherein the 200mV DC voltmeter is connected to a 5V DC power supply module.

8. The impedance detector as described in claim 1, characterized in that, The equivalent circuit for measuring solid and liquid resistance includes: a first 4007 diode, one end of which is connected to the phase line of a 220V power supply, and the other end of which is connected to a first current-limiting resistor and a second shunt resistor, wherein the first current-limiting resistor and the second shunt resistor are connected in parallel; the first current-limiting resistor is connected to one end of a signal sampling resistor; the other end of the signal sampling resistor is connected to the positive terminal of a probe socket node; the positive terminal of the probe socket node is connected to the impedance to be measured; the impedance to be measured is connected to the negative terminal of the probe socket node; the probe socket node is connected to a first single-pole double-throw switch; and the first single-pole double-throw switch is connected to a 220V power supply.

9. The impedance detector as described in claim 8, characterized in that, A step-down shunt circuit node and a positive signal output node are provided between the first current-limiting resistor and the signal sampling resistor. A negative signal output node is provided on the signal sampling resistor. The positive signal output node is connected to the positive terminal of the sampling voltage, and the negative signal output node is connected to the negative terminal of the sampling voltage. The step-down shunt circuit node is connected to the third single-pole double-throw switch. The third single-pole double-throw switch is connected to the fourth shunt resistor. The fourth shunt resistor is connected to the neutral line of the 220V power supply. The second current-limiting resistor is connected to the fourth single-pole double-throw switch, and the fourth single-pole double-throw switch is connected to the positive node of the test probe socket.

10. The impedance detector as described in claim 1, characterized in that, The current detection circuit includes a fourth current-limiting resistor, one end of which is connected to a fuse and the other end is connected to a neon bulb, which is connected to a contact.

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