An improved segmented loop resistance tester

Abstract

The present invention discloses an improved segmented loop resistance tester, comprising: a constant current source, an adjustment unit, a voltage sampling unit, a current sampling unit, an AD conversion circuit, and a single-chip controller unit. The positive electrode of the constant current source is connected to the first node of the measured resistor, the negative electrode of the constant current source is connected to the fourth node of the measured resistor, the constant current source and the measured resistor form a current loop, the output end of the current sampling unit is connected to the second input end of the AD conversion circuit, the output end of the voltage sampling unit is connected to the first input end of the AD conversion circuit, and the output end of the AD conversion circuit is connected to the input end of the single-chip controller unit. The present invention increases the test nodes during the loop resistance test through the design of the adjustment unit, and realizes the detection of whether the connection clamp is in good contact by making the fourth contact in the adjustment unit vacant. The present invention improves the detection efficiency and has strong practicality.

Description

Technical Field

[0001] The invention relates to the field of testing technology, and more particularly to an improved segmented loop resistance tester. Background Art

[0002] The loop resistance of power equipment is an important parameter to characterize whether the connection of the conductive circuit is good. Its value directly affects the current carrying capacity and short-circuit current cutting capacity during normal operation. Therefore, the loop resistance tester has become a commonly used test instrument in the power system. In the use of loop resistance testers today, due to the single test contact and poor contact of the tester, users often need to change the connection points of the test line clamps many times, which seriously affects the work efficiency of the staff. This problem is most obvious in the maintenance and repair of 110kV and above disconnector equipment in substations. When the staff is carrying out maintenance and repair of 110kV and above disconnectors, due to the poor contact of the connection clamps of the test voltage line, discharge occurs, and the connection points of the connection clamps are changed to determine the hot spots of the disconnectors. They need to climb onto the disconnector frame many times to operate, resulting in repeated work, wasting a lot of working time, and increasing the safety hazards of high-altitude operations. Summary of the invention

[0003] The present invention provides an improved segmented loop resistance tester to overcome the defects of the loop resistance tester in the prior art, namely, a single test contact, inability to detect whether the wiring clamp is in good contact, and low detection efficiency.

[0004] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0005] An improved segmented loop resistance tester includes: a constant current source, a regulating unit, a voltage sampling unit, a current sampling unit, an AD conversion circuit, and a single-chip microcomputer controller unit.

[0006] The positive electrode of the constant current source is connected to the first node of the measured resistor, the negative electrode of the constant current source is connected to the fourth node of the measured resistor, the constant current source and the measured resistor form a current loop, the first contact of the adjustment unit is connected to the positive electrode of the constant current source, the second contact of the adjustment unit is connected to the second node of the measured resistor, the third contact of the adjustment unit is connected to the third node of the measured resistor, the fixed end of the variable contact of the adjustment unit is electrically connected to the input end of the current sampling unit, the output end of the current sampling unit is connected to the second input end of the AD conversion circuit, the fixed end of the variable contact of the adjustment unit is connected to the positive electrode of the input end of the voltage sampling unit, the negative electrode of the input end of the voltage sampling unit is connected to the fourth node of the measured resistor, the output end of the voltage sampling unit is connected to the first input end of the AD conversion circuit, and the output end of the AD conversion circuit is connected to the input end of the single-chip controller unit.

[0007] The present invention applies a constant current source to both ends of the resistor to be measured, adjusts the contact selection through an adjustment unit, uses a voltage sampling unit to collect the voltage across the resistor connected to the loop, and uses a current sampling unit to collect the loop current. The voltage and current are connected to the input end of a single-chip control chip through an A / D conversion circuit. In the present invention, the fourth contact in the adjustment unit is suspended as a reference contact. When the adjustment end of the variable contact is adjusted to the fourth contact, the adjustment unit and the resistor to be measured are in an open circuit state, and the voltage collection value is zero, that is, the loop voltage value is zero. When the adjustment end of the variable contact is connected to the first contact or the second contact or any third contact, if the voltage collection value is zero, it indicates that the loop resistance test node corresponding to the contact is in poor contact, that is, the wiring clamp is in poor contact.

[0008] In this solution, the current sampling unit includes: current sensor JLB-11, amplifier U4B, amplifier U4B, amplifier U5, resistor R15, resistor R16, resistor R12, resistor R11, capacitor C1;

[0009] The current sampling unit is specifically connected as follows: the fixed end of the variable contact of the regulating unit is connected to the primary input end of the current sensor JLB-11, the output end of the current sensor JLB-11 is connected to the in-phase input end of the amplifier U4B, the inverting input end of the amplifier U4B is connected to the output end of the amplifier U4B, the positive power input end of the amplifier U4B is connected to the positive 12V power supply, the negative power input end of the amplifier U4B is connected to the negative 12V power supply, the output end of the amplifier U4B is connected to one end of the resistor R15, and the other end of the resistor R15 is connected to the resistor R16 respectively. and one end of the capacitor C1, the other end of the capacitor C1 is grounded, the other end of the resistor R16 is connected to the positive input terminal of the amplifier U5, the direction input terminals of the amplifier U5 are respectively connected to one end of the resistor R12 and one end of the resistor R11, the other end of the resistor R12 is grounded, the other end of the resistor R11 is connected to the output terminal of the amplifier U5, the positive power input terminal of the amplifier U5 is connected to the positive 12V power supply, the negative power input terminal of the amplifier U5 is connected to the negative 12V power supply, and the output terminal of the amplifier U5 is connected to the second input terminal AIN2 of the AD conversion circuit.

[0010] In this solution, the voltage sampling unit includes: amplifier U1A, amplifier U2B, amplifier U2, resistor R1, resistor R2, resistor R3, resistor R4, resistor R5, resistor R6, resistor R7;

[0011] The specific connection of the voltage sampling unit is:

[0012] The fixed end of the variable contact of the regulating unit is connected to the positive input end of the amplifier U1A, the reverse input end of the amplifier U1A is respectively connected to one end of the resistor R1 and one end of the resistor R2, the other end of the resistor R2 is connected to the output end of the amplifier U1A, the other end of the resistor R1 is respectively connected to the reverse input end of the amplifier U2B and one end of the resistor R3, the other end of the resistor R3 is connected to the output end of the amplifier U2B, the output end of the amplifier U1A is connected to one end of the resistor R4, the other end of the resistor R4 is respectively connected to one end of the resistor R5 and the reverse input end of the amplifier U2, the other end of the resistor R5 is connected to the output end of the amplifier U2, The positive input terminal of the amplifier U2B is connected to the negative electrode of the constant current source, the output terminal of the amplifier U2B is connected to one end of the resistor R6, the other end of the resistor R6 is respectively connected to one end of the resistor R7 and the positive input terminal of the amplifier U2, the other end of the resistor R7 is grounded, the output terminal of the amplifier U2 is connected to the first input terminal AIN1 of the AD conversion circuit, the positive power input terminals of the amplifiers U1A and U2B are both connected to the positive 15V power supply, the negative power input terminals of the amplifiers U1A and U2B are both connected to the negative 15V power supply, the positive power input terminal of the amplifier U2 is connected to the positive 12V power supply, and the negative power input terminal of the amplifier U2 is connected to the negative 12V power supply.

[0013] In this solution, the AD conversion circuit uses the conversion chip AD7714.

[0014] In this solution, the AD conversion circuit and the single-chip controller unit include: a single-chip control chip, an AD conversion chip AD7714, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a resistor R8, a resistor R9, a resistor R10, a diode D3, a crystal oscillator Z2, and an optical coupler 6N137;

[0015] The connection circuit between the AD conversion circuit and the single-chip microcomputer control unit is as follows:

[0016] Pin 8 of the AD conversion chip AD7714, i.e., the second input terminal AIN2 of the AD conversion circuit is connected to the output terminal of the amplifier U5, pin 7 of the AD conversion chip AD7714, i.e., the first input terminal AIN1 of the AD conversion circuit is connected to the output terminal of the amplifier U2, pins 12, 11, and 5 of the AD conversion chip AD7714 are all connected to a positive 5V power supply, pin 5 of the AD conversion chip AD7714 is simultaneously connected to one end of a capacitor C3 and one end of a capacitor C2, the other end of C3 and the other end of capacitor C2 are both grounded, pins 1, 22, 20, and 6 of the AD conversion chip AD7714 are respectively connected to pins 16, 17, 20, and 14 of the single-chip microcomputer control chip, and pins 17, 18, 14, 13, 24, and 19 of the AD conversion chip AD7714 are respectively connected to pins 16, 17, 20, and 14 of the single-chip microcomputer control chip. Pin 15 of the AD conversion chip AD7714 is connected to one end of the resistor R8 and the cathode of the diode D3, the anode of the diode D3 is grounded, the other end of the resistor R8 is connected to a positive 5V power supply, pin 2 of the AD conversion chip AD7714 is connected to one end of the crystal oscillator Z2 and one end of the capacitor C5, the other end of the capacitor C5 is grounded and connected to one end of the capacitor C4, the other end of the capacitor C4 is connected to the other end of the crystal oscillator Z2, pin 21 of the AD conversion chip AD7714 is connected to the cathode of the optocoupler 6N137, the anode of the optocoupler 6N137 is connected to one end of the resistor R8, the other end of the resistor R9 is connected to a positive 3.3V power supply, the enable pins of the optocoupler 6N137 are connected to one end of the resistor R10 and pin 50 of the microcontroller control chip, and the other end of the resistor R10 is connected to a positive 3.3V power supply.

[0017] In this solution, the single-chip microcomputer control chip is a STM32F103RBT6 chip.

[0018] In this solution, the single-chip microcomputer controller unit further includes a crystal oscillator circuit and an auxiliary circuit, and the crystal oscillator circuit and the auxiliary circuit include:

[0019] Resistor R11, crystal oscillator Y1, diode D2, battery BT1, capacitor C10, capacitor C9, capacitor C8, capacitor C7, capacitor C6,

[0020] The specific connection is as follows: the 5th pin of the single-chip control chip is respectively connected to one end of the resistor R11, one end of the crystal oscillator Y1 and one end of the capacitor C6, the other end of the resistor R11, the other end of the crystal oscillator Y1 and the 6th pin of the single-chip control chip are connected to one end of the capacitor C7, and the other end of the capacitor C6 and the other end of the capacitor C7 are both grounded;

[0021] Pin 3 of the single-chip control chip is respectively connected to one end of the crystal oscillator Y2 and one end of the capacitor C8, and the other end of the capacitor C8 is grounded; pin 4 of the single-chip control chip is respectively connected to the other end of the crystal oscillator Y2 and one end of the capacitor C9, and the other end of the capacitor C9 is grounded;

[0022] Pin 1 of the single-chip control chip is connected to the cathode of the diode D2, the anode of the diode D2 is connected to the anode of the battery BT1, and the cathode of the battery BT1 is grounded;

[0023] Pins 32, 48, 64, 19 and 13 of the single-chip microcomputer control chip are all connected to one end of capacitor C10, one end of capacitor C10 is connected to a positive 3.3V power supply, and the other end of capacitor C10 is respectively connected to pins 31, 47, 63, 18 and 12 of the single-chip microcomputer control chip, and the other end of capacitor C10 is grounded at the same time.

[0024] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0025] The present invention increases the test nodes during loop resistance testing by designing the adjustment unit, and uses the fourth contact in the adjustment unit to be suspended to detect whether the connection clamp is in good contact. The present invention improves the detection efficiency and has strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The schematic diagram of an improved segmented loop resistance tester is shown in FIG.

[0027] Figure 2 This is the schematic diagram of the current sampling circuit.

[0028] Figure 3 This is the schematic diagram of the voltage sampling circuit.

[0029] Figure 4 This is the circuit connection schematic diagram of the AD conversion circuit and the single-chip microcomputer control chip.

[0030] Figure 5 This is a working connection diagram of an improved segmented loop resistance tester. DETAILED DESCRIPTION

[0031] The drawings are for illustrative purposes only and should not be construed as limiting the present patent;

[0032] In order to better illustrate the present embodiment, some parts in the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product;

[0033] It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0034] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0035] Example 1

[0036] like Figure 1 As shown, an improved segmented loop resistance tester includes: a constant current source, a regulating unit, a voltage sampling unit, a current sampling unit, an AD conversion circuit, and a single-chip microcomputer controller unit.

[0037] The positive electrode of the constant current source is connected to the first node of the measured resistor, the negative electrode of the constant current source is connected to the fourth node of the measured resistor, the constant current source and the measured resistor form a current loop, the first contact of the adjustment unit is connected to the positive electrode of the constant current source, the second contact of the adjustment unit is connected to the second node of the measured resistor, the third contact of the adjustment unit is connected to the third node of the measured resistor, the fixed end of the variable contact of the adjustment unit is electrically connected to the input end of the current sampling unit, the output end of the current sampling unit is connected to the second input end of the AD conversion circuit, the fixed end of the variable contact of the adjustment unit is connected to the positive electrode of the input end of the voltage sampling unit, the negative electrode of the input end of the voltage sampling unit is connected to the fourth node of the measured resistor, the output end of the voltage sampling unit is connected to the first input end of the AD conversion circuit, and the output end of the AD conversion circuit is connected to the input end of the single-chip controller unit.

[0038] It should be noted that the present invention can connect an indication unit, such as a display indication circuit, to the single-chip controller unit to display the processing result of the single-chip controller unit. At the same time, the single-chip controller unit can also be provided with an audio-visual indication circuit (such as a buzzer and an LED indicator) to warn of poor contact of the wiring clip. At the same time, the present invention can also connect a communication interface unit to the single-chip controller unit to externally test historical data through the communication interface.

[0039] The present invention applies a constant current source to both ends of the resistor to be measured, adjusts the contact selection through an adjustment unit, uses a voltage sampling unit to collect the voltage across the resistor connected to the loop, and uses a current sampling unit to collect the loop current. The voltage and current are connected to the input end of the single-chip control chip through an A / D conversion circuit. In the present invention, the fourth contact in the adjustment unit is suspended as a reference contact. When the adjustment end of the variable contact is adjusted to the fourth contact, the adjustment unit and the resistor to be measured are in an open circuit state, and the voltage collection value is zero, that is, the loop voltage value is zero. When the adjustment end of the variable contact is connected to the first contact or the second contact or any third contact, if the voltage collection value is zero, it indicates that the loop resistance test node corresponding to the contact is in poor contact, that is, the wiring clamp is in poor contact, and the tester issues an alarm prompt.

[0040] like Figure 2As shown, in this solution, the current sampling unit includes: current sensor JLB-11, amplifier U4B, amplifier U4B, amplifier U5, resistor R15, resistor R16, resistor R12, resistor R11, capacitor C1;

[0041] The current sampling unit is specifically connected as follows: the fixed end of the variable contact of the regulating unit is connected to the primary input end of the current sensor JLB-11, the output end of the current sensor JLB-11 is connected to the in-phase input end of the amplifier U4B, the inverting input end of the amplifier U4B is connected to the output end of the amplifier U4B, the positive power input end of the amplifier U4B is connected to the positive 12V power supply, the negative power input end of the amplifier U4B is connected to the negative 12V power supply, the output end of the amplifier U4B is connected to one end of the resistor R15, and the other end of the resistor R15 is connected to the resistor R15 respectively. 6 and one end of the capacitor C1, the other end of the capacitor C1 is grounded, the other end of the resistor R16 is connected to the positive input terminal of the amplifier U5, the direction input terminal of the amplifier U5 is respectively connected to one end of the resistor R12 and one end of the resistor R11, the other end of the resistor R12 is grounded, the other end of the resistor R11 is connected to the output terminal of the amplifier U5, the positive power input terminal of the amplifier U5 is connected to the positive 12V power supply, the negative power input terminal of the amplifier U5 is connected to the negative 12V power supply, and the output terminal of the amplifier U5 is connected to the second input terminal AIN2 of the AD conversion circuit.

[0042] like Figure 3 As shown, in this solution, the voltage sampling unit includes: amplifier U1A, amplifier U2B, amplifier U2, resistor R1, resistor R2, resistor R3, resistor R4, resistor R5, resistor R6, resistor R7;

[0043] The voltage sampling unit is specifically connected as follows:

[0044] The fixed end of the variable contact of the regulating unit is connected to the positive input end of the amplifier U1A, the reverse input end of the amplifier U1A is respectively connected to one end of the resistor R1 and one end of the resistor R2, the other end of the resistor R2 is connected to the output end of the amplifier U1A, the other end of the resistor R1 is respectively connected to the reverse input end of the amplifier U2B and one end of the resistor R3, the other end of the resistor R3 is connected to the output end of the amplifier U2B, the output end of the amplifier U1A is connected to one end of the resistor R4, the other end of the resistor R4 is respectively connected to one end of the resistor R5 and the reverse input end of the amplifier U2, the other end of the resistor R5 is connected to the output end of the amplifier U2, The positive input terminal of the amplifier U2B is connected to the negative electrode of the constant current source, the output terminal of the amplifier U2B is connected to one end of the resistor R6, the other end of the resistor R6 is respectively connected to one end of the resistor R7 and the positive input terminal of the amplifier U2, the other end of the resistor R7 is grounded, the output terminal of the amplifier U2 is connected to the first input terminal AIN1 of the AD conversion circuit, the positive power input terminals of the amplifiers U1A and U2B are both connected to the positive 15V power supply, the negative power input terminals of the amplifiers U1A and U2B are both connected to the negative 15V power supply, the positive power input terminal of the amplifier U2 is connected to the positive 12V power supply, and the negative power input terminal of the amplifier U2 is connected to the negative 12V power supply.

[0045] In this solution, the AD conversion circuit uses the conversion chip AD7714.

[0046] like Figure 4 As shown, in this scheme, the AD conversion circuit and the single-chip controller unit include: a single-chip control chip, an AD conversion chip AD7714, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a resistor R8, a resistor R9, a resistor R10, a diode D3, a crystal oscillator Z2, and an optical coupler 6N137;

[0047] The connection circuit between the AD conversion circuit and the single-chip microcomputer control unit is as follows:

[0048] Pin 8 of the AD conversion chip AD7714, i.e., the second input terminal AIN2 of the AD conversion circuit is connected to the output terminal of the amplifier U5, pin 7 of the AD conversion chip AD7714, i.e., the first input terminal AIN1 of the AD conversion circuit is connected to the output terminal of the amplifier U2, pins 12, 11, and 5 of the AD conversion chip AD7714 are all connected to a positive 5V power supply, pin 5 of the AD conversion chip AD7714 is simultaneously connected to one end of a capacitor C3 and one end of a capacitor C2, the other end of C3 and the other end of capacitor C2 are both grounded, pins 1, 22, 20, and 6 of the AD conversion chip AD7714 are respectively connected to pins 16, 17, 20, and 14 of the single-chip microcomputer control chip, and pins 17, 18, 14, 13, 24, and 19 of the AD conversion chip AD7714 are respectively connected to pins 16, 17, 20, and 14 of the single-chip microcomputer control chip. Pin 15 of the AD conversion chip AD7714 is connected to one end of the resistor R8 and the cathode of the diode D3, the anode of the diode D3 is grounded, the other end of the resistor R8 is connected to a positive 5V power supply, pin 2 of the AD conversion chip AD7714 is connected to one end of the crystal oscillator Z2 and one end of the capacitor C5, the other end of the capacitor C5 is grounded and connected to one end of the capacitor C4, the other end of the capacitor C4 is connected to the other end of the crystal oscillator Z2, pin 21 of the AD conversion chip AD7714 is connected to the cathode of the optocoupler 6N137, the anode of the optocoupler 6N137 is connected to one end of the resistor R8, the other end of the resistor R9 is connected to a positive 3.3V power supply, the enable pins of the optocoupler 6N137 are connected to one end of the resistor R10 and pin 50 of the microcontroller control chip, and the other end of the resistor R10 is connected to a positive 3.3V power supply.

[0049] In this solution, the single-chip microcomputer control chip is a STM32F103RBT6 chip.

[0050] In this solution, the single-chip microcomputer controller unit further includes a crystal oscillator circuit and an auxiliary circuit, and the crystal oscillator circuit and the auxiliary circuit include:

[0051] Resistor R11, crystal oscillator Y1, diode D2, battery BT1, capacitor C10, capacitor C9, capacitor C8, capacitor C7, capacitor C6,

[0052] The specific connection is as follows: the 5th pin of the single-chip control chip is respectively connected to one end of the resistor R11, one end of the crystal oscillator Y1 and one end of the capacitor C6, the other end of the resistor R11, the other end of the crystal oscillator Y1 and the 6th pin of the single-chip control chip are connected to one end of the capacitor C7, and the other end of the capacitor C6 and the other end of the capacitor C7 are both grounded;

[0053] Pin 3 of the single-chip control chip is respectively connected to one end of the crystal oscillator Y2 and one end of the capacitor C8, and the other end of the capacitor C8 is grounded; pin 4 of the single-chip control chip is respectively connected to the other end of the crystal oscillator Y2 and one end of the capacitor C9, and the other end of the capacitor C9 is grounded;

[0054] Pin 1 of the single-chip control chip is connected to the cathode of the diode D2, the anode of the diode D2 is connected to the anode of the battery BT1, and the cathode of the battery BT1 is grounded;

[0055] Pins 32, 48, 64, 19 and 13 of the single-chip microcomputer control chip are all connected to one end of capacitor C10, one end of capacitor C10 is connected to a positive 3.3V power supply, and the other end of capacitor C10 is respectively connected to pins 31, 47, 63, 18 and 12 of the single-chip microcomputer control chip, and the other end of capacitor C10 is grounded at the same time.

[0056] The use process of Example 1 is as follows:

[0057] like Figure 5 As shown, when the present invention is used to perform maintenance and repair work on disconnectors of 110 kV and above, the conductive circuit of the disconnector is first connected with the test line, and the connection points of the wiring clamps of the test current line are the two ends of the disconnector (i.e., point B and point M), and the connection points of the wiring clamps of the test voltage line include three easily heated points of the disconnector (the connection board, the connection point between the general cap and the conductive arm, and the connection point of the disconnector contact finger), wherein, Figure 5 Point B is the first node, point C is the second node, point D is the third node, and point M is the fourth node. Connect the first contact of the regulating unit and the positive electrode of the constant current source at the same time. Connect the second contact of the regulating unit, Connect the third contact of the regulating unit, Connected to the negative pole of the constant current source. Before the test, adjust the adjustment end of the variable contact of the adjustment unit to the first contact, the second contact, and the third contact to determine whether the corresponding B, C, and D node clamps are in contact normally. After the detection is completed, turn on the power supply to start the test. First, select the whole group resistance measurement function, turn on the first contact, measure the whole group resistance of the isolating switch, and determine whether the isolating switch has a defect of excessive resistance causing the knife switch to heat up; if there is a heating defect, select the segmented resistance measurement function, automatically adjust the contact selection of the switch selector, and measure the segmented loop resistance of the three hot spots on the isolating switch, so as to determine the exact position of the hot spot of the isolating switch through the size of the three-segment resistance.

[0058] The same or similar reference numerals correspond to the same or similar components;

[0059] The terms used in the drawings to describe positional relationships are only used for illustrative purposes and should not be construed as limiting this patent;

[0060] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. An improved segmented loop resistance tester, characterized in that: include: Constant current source, adjustment unit, voltage sampling unit, current sampling unit, AD conversion circuit, single chip controller unit, The positive electrode of the constant current source is connected to the first node of the measured resistor, the negative electrode of the constant current source is connected to the fourth node of the measured resistor, the constant current source and the measured resistor form a current loop, the first contact of the adjustment unit is connected to the positive electrode of the constant current source, the second contact of the adjustment unit is connected to the second node of the measured resistor, the third contact of the adjustment unit is connected to the third node of the measured resistor, the fixed end of the variable contact of the adjustment unit is electrically connected to the input end of the current sampling unit, the output end of the current sampling unit is connected to the second input end of the AD conversion circuit, the fixed end of the variable contact of the adjustment unit is connected to the positive electrode of the input end of the voltage sampling unit, and the voltage sampling The negative electrode of the input terminal of the unit is connected to the fourth node of the measured resistor, the output terminal of the voltage sampling unit is connected to the first input terminal of the AD conversion circuit, and the output terminal of the AD conversion circuit is connected to the input terminal of the single-chip controller unit; the fourth contact in the adjustment unit is suspended as a reference contact, when the adjustment terminal of the variable contact is adjusted to the fourth contact, the adjustment unit and the measured resistor are in an open circuit state, and the voltage collection value is zero, that is, the loop voltage value is zero, when the adjustment terminal of the variable contact is connected to the first contact or the second contact or the third contact, if the voltage collection value is zero, it indicates that the loop resistance test node corresponding to the contact is in poor contact, that is, the wiring clamp is in poor contact; The current sampling unit includes: a current sensor JLB-11, an amplifier U4B, an amplifier U4B, an amplifier U5, a resistor R15, a resistor R16, a resistor R12, a resistor R11, and a capacitor C1; The current sampling unit is specifically connected as follows: the fixed end of the variable contact of the regulating unit is connected to the primary input end of the current sensor JLB-11, the output end of the current sensor JLB-11 is connected to the in-phase input end of the amplifier U4B, the inverting input end of the amplifier U4B is connected to the output end of the amplifier U4B, the positive power input end of the amplifier U4B is connected to the positive 12V power supply, the negative power input end of the amplifier U4B is connected to the negative 12V power supply, the output end of the amplifier U4B is connected to one end of the resistor R15, and the other end of the resistor R15 is connected to the resistor R16 respectively. and one end of the capacitor C1, the other end of the capacitor C1 is grounded, the other end of the resistor R16 is connected to the positive input end of the amplifier U5, the reverse input end of the amplifier U5 is respectively connected to one end of the resistor R12 and one end of the resistor R11, the other end of the resistor R12 is grounded, the other end of the resistor R11 is connected to the output end of the amplifier U5, the positive input end of the power supply of the amplifier U5 is connected to the positive 12V power supply, the negative input end of the power supply of the amplifier U5 is connected to the negative 12V power supply, and the output end of the amplifier U5 is connected to the second input end AIN2 of the AD conversion circuit; The voltage sampling unit includes: an amplifier U1A, an amplifier U2B, an amplifier U2, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, and a resistor R7; The voltage sampling unit is specifically connected as follows: The fixed end of the variable contact of the regulating unit is connected to the positive input end of the amplifier U1A, the reverse input end of the amplifier U1A is respectively connected to one end of the resistor R1 and one end of the resistor R2, the other end of the resistor R2 is connected to the output end of the amplifier U1A, the other end of the resistor R1 is respectively connected to the reverse input end of the amplifier U2B and one end of the resistor R3, the other end of the resistor R3 is connected to the output end of the amplifier U2B, the output end of the amplifier U1A is connected to one end of the resistor R4, the other end of the resistor R4 is respectively connected to one end of the resistor R5 and the reverse input end of the amplifier U2, the other end of the resistor R5 is connected to the output end of the amplifier U2, The positive input terminal of the amplifier U2B is connected to the negative electrode of the constant current source, the output terminal of the amplifier U2B is connected to one end of the resistor R6, the other end of the resistor R6 is respectively connected to one end of the resistor R7 and the positive input terminal of the amplifier U2, the other end of the resistor R7 is grounded, the output terminal of the amplifier U2 is connected to the first input terminal AIN1 of the AD conversion circuit, the positive power input terminals of the amplifiers U1A and U2B are both connected to the positive 15V power supply, the negative power input terminals of the amplifiers U1A and U2B are both connected to the negative 15V power supply, the positive power input terminal of the amplifier U2 is connected to the positive 12V power supply, and the negative power input terminal of the amplifier U2 is connected to the negative 12V power supply; The AD conversion circuit adopts the conversion chip AD7714; The AD conversion circuit and the single-chip controller unit include: a single-chip control chip, an AD conversion chip AD7714, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a resistor R8, a resistor R9, a resistor R10, a diode D3, a crystal oscillator Z2, and an optical coupler 6N137; The connection circuit between the AD conversion circuit and the single-chip microcomputer control unit is specifically as follows: Pin 8 of the AD conversion chip AD7714, i.e., the second input terminal AIN2 of the AD conversion circuit, is connected to the output terminal of the amplifier U5; pin 7 of the AD conversion chip AD7714, i.e., the first input terminal AIN1 of the AD conversion circuit, is connected to the output terminal of the amplifier U2; pins 12, 11, and 5 of the AD conversion chip AD7714 are all connected to a positive 5V power supply; pin 5 of the AD conversion chip AD7714 is simultaneously connected to one end of a capacitor C3 and one end of a capacitor C2; the other end of C3 and the other end of capacitor C2 are both grounded; pins 1, 22, 20, and 6 of the AD conversion chip AD7714 are respectively connected to pins 16, 17, 20, and 14 of the single-chip control chip; pins 17, 18, 14, 13, 24, and 19 of the AD conversion chip AD7714 are respectively connected to pins 16, 17, 20, and 14 of the single-chip control chip; , 4 pins are grounded, the 15th pin of the AD conversion chip AD7714 is respectively connected to one end of the resistor R8 and the cathode of the diode D3, the anode of the diode D3 is grounded, the other end of the resistor R8 is connected to a positive 5V power supply, the 2nd pin of the AD conversion chip AD7714 is respectively connected to one end of the crystal oscillator Z2 and one end of the capacitor C5, the other end of the capacitor C5 is grounded and connected to one end of the capacitor C4, the other end of the capacitor C4 is connected to the other end of the crystal oscillator Z2, the 21st pin of the AD conversion chip AD7714 is connected to the cathode of the optical coupler 6N137, the anode of the optical coupler 6N137 is connected to one end of the resistor R9, the other end of the resistor R9 is connected to a positive 3.3V power supply, the enable pin of the optical coupler 6N137 is respectively connected to one end of the resistor R10 and the 50th pin of the single-chip control chip, the other end of the resistor R10 is connected to a positive 3.3V power supply; The single-chip microcomputer controller unit further includes a crystal oscillator circuit and an auxiliary circuit, wherein the crystal oscillator circuit and the auxiliary circuit include: Resistor R11, crystal oscillator Y1, diode D2, battery BT1, capacitor C10, capacitor C9, capacitor C8, capacitor C7, capacitor C6, The specific connection is as follows: the 5th pin of the single-chip control chip is respectively connected to one end of the resistor R11, one end of the crystal oscillator Y1 and one end of the capacitor C6, the other end of the resistor R11, the other end of the crystal oscillator Y1 and the 6th pin of the single-chip control chip are connected to one end of the capacitor C7, and the other end of the capacitor C6 and the other end of the capacitor C7 are both grounded; Pin 3 of the single-chip control chip is respectively connected to one end of the crystal oscillator Y2 and one end of the capacitor C8, and the other end of the capacitor C8 is grounded; pin 4 of the single-chip control chip is respectively connected to the other end of the crystal oscillator Y2 and one end of the capacitor C9, and the other end of the capacitor C9 is grounded; Pin 1 of the single-chip control chip is connected to the cathode of the diode D2, the anode of the diode D2 is connected to the anode of the battery BT1, and the cathode of the battery BT1 is grounded; Pins 32, 48, 64, 19 and 13 of the single-chip microcomputer control chip are all connected to one end of capacitor C10, one end of capacitor C10 is connected to a positive 3.3V power supply, and the other end of capacitor C10 is respectively connected to pins 31, 47, 63, 18 and 12 of the single-chip microcomputer control chip, and the other end of capacitor C10 is grounded at the same time.

2. An improved segmented loop resistance tester according to claim 1, characterized in that: The single-chip microcomputer control chip is a STM32F103RBT6 chip.

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