Contact current testing device

Abstract

The present disclosure provides a contact current testing device, comprising: a measuring circuit comprising a base circuit, a first weighting circuit, a second weighting circuit and a switching circuit, the switching circuit controlling one of the first weighting circuit and the second weighting circuit to be connected with the base circuit, the first weighting circuit and the basic circuit form a first measurement network, and the second weighting circuit and the basic circuit form a second measurement network; the sampling display circuit is connected with the measuring circuit and is used for displaying a measuring result; and the charging power supply circuit comprises a charging power supply, and the charging power supply circuit is connected with the switching circuit and the sampling display circuit and is used for providing power for the contact current testing device. According to the embodiment of the invention, the contact current testing device does not need to be detached from the tested equipment in the testing process, can achieve the testing of different contact currents, is convenient to operate and use, and is low in cost.

Description

Technical Field

[0001] The present disclosure relates to the field of equipment testing, and in particular to a contact current testing device. Background Art

[0002] Before electrical products are put on the market, they must pass safety assessment and testing. Among the safety tests, there is a test called contact current test, which aims to evaluate whether the current transmitted from the electrical equipment to the human body exceeds the safety threshold that the human body can withstand under normal use and fault conditions. The contact current test generally requires different current test networks to simulate the impedance of the human body, so as to obtain different contact current values. Generally, different current test networks are welded separately. When a certain contact current needs to be tested, the corresponding current test network is connected to the device under test. The test process is cumbersome and inconvenient to use. Utility Model Content

[0003] The present disclosure provides a contact current testing device to at least solve the above technical problems existing in the prior art.

[0004] According to a first aspect of the present disclosure, there is provided a contact current testing device, comprising:

[0005] A measurement circuit, comprising a basic circuit, a first weighted circuit, a second weighted circuit and a switching circuit, wherein the switching circuit controls one of the first weighted circuit and the second weighted circuit to be connected to the basic circuit, the first weighted circuit and the basic circuit constitute a first measurement network, and the second weighted circuit and the basic circuit constitute a second measurement network;

[0006] A sampling display circuit, connected to the measuring circuit, for displaying the measuring result;

[0007] The charging power supply circuit comprises a charging power supply, wherein the charging power supply circuit is connected to the switching circuit and the sampling display circuit and is used to provide power to the contact current testing device.

[0008] In one possible implementation, the basic circuit includes:

[0009] A skin impedance simulation circuit comprises a first end and a second end, wherein the first end is connected to a first sampling terminal, and the first sampling terminal is used to connect to a conductive part on a housing of a device under test;

[0010] A human body internal impedance simulation circuit, comprising a third end and a fourth end, wherein the third end is connected to the second end, the fourth end is connected to a second sampling terminal, the second sampling terminal is used to connect to a ground point of a device under test, and the second sampling terminal is connected to the sampling display circuit;

[0011] The first resistor includes a fifth end and a sixth end, wherein the fifth end is connected to the second end, and the sixth end is connected to the sampling display circuit.

[0012] In one possible implementation, the switching circuit includes:

[0013] a switching switch, comprising a first contact, a second contact and a third contact, wherein the first contact is connected to the sixth terminal, one end of the first weighted circuit is connected to the second contact and the other end is connected to the fourth terminal, one end of the second weighted circuit is connected to the third contact and the other end is connected to the fourth terminal, and the switching switch is used to conduct the first contact with the second contact or the third contact;

[0014] The control circuit includes an input end, an output end and a control end, wherein the input end is connected to the positive electrode of the charging power supply, the output end is grounded, and the sampling display circuit includes a control signal output end, wherein the control signal output end is connected to the control end through a network selection switch, and the switching switch is turned on or off by the network selection switch to control the first contact to be connected with the second contact or the third contact.

[0015] In one possible implementation manner, the skin impedance simulation circuit includes a second resistor and a first capacitor connected in parallel.

[0016] In one possible implementation, the human body internal impedance simulation circuit includes a third resistor.

[0017] In one possible implementation manner, the second weighting circuit includes:

[0018] a fourth resistor and a second capacitor connected in series, the fourth resistor being connected to the switching circuit, and the second capacitor being connected to the fourth end;

[0019] The third capacitor is connected in parallel with the fourth resistor and the second capacitor which are connected in series.

[0020] In one possible implementation manner, the first weighting circuit includes a fourth capacitor, and the fourth capacitor is respectively connected to the third connection point and the fourth end.

[0021] In one possible implementation manner, the charging power source is connected to the sampling display circuit via a power switch.

[0022] In one possible implementation manner, the contact current testing device further comprises a housing, a charging interface is provided on the housing, and the charging interface is connected to the charging power supply circuit.

[0023] In one possible implementation manner, a connector is provided on the housing, the connector is connected to the measurement circuit, and the connector is used to connect a sampling terminal.

[0024] In the contact current test device disclosed in the present invention, the measurement circuit includes a basic circuit, a first weighted circuit, a second weighted circuit and a switching circuit, the switching circuit controls one of the first weighted circuit and the second weighted circuit to be connected to the basic circuit, the first weighted circuit and the basic circuit constitute a first measurement network, and the second weighted circuit and the basic circuit constitute a second measurement network. The basic circuit is connected to the first weighted circuit or the second weighted circuit through the switching circuit, so that different measurement networks can be formed respectively. Different measurement networks have a common input and output end. During the test process, there is no need to disassemble the device under test, and different contact current tests can be achieved. It is easy to operate and use, and the cost is low. The sampling display circuit is connected to the measurement circuit for displaying the measurement results, and the test results can be displayed in real time without connecting other oscilloscope devices. It is easy to use. The charging power supply circuit includes a charging power supply, and the charging power supply circuit is connected to the switching circuit and the sampling display circuit to provide power to the contact current test device. The use of a charging power supply to provide the contact current test device with the power required for operation can reduce the overall volume and weight, and is easy to carry.

[0025] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and other objects, features and advantages of the exemplary embodiments of the present disclosure will become readily understood by reading the detailed description below with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present disclosure are shown in an exemplary and non-limiting manner, in which:

[0027] In the drawings, the same or corresponding reference numerals represent the same or corresponding parts.

[0028] Figure 1 A schematic structural diagram of a contact current testing device according to an embodiment of the present disclosure is shown;

[0029] Figure 2 A schematic diagram showing the circuit structure principle of the contact current testing device according to an embodiment of the present disclosure is shown;

[0030] Figure 3 A schematic diagram of the circuit structure of a first measurement network of a contact current testing device according to an embodiment of the present disclosure is shown;

[0031] Figure 4 A schematic diagram of the circuit structure of a second measurement network of the contact current testing device according to an embodiment of the present disclosure is shown.

[0032] Explanation of the numbers in the figure: 1-basic circuit, 11-skin impedance simulation circuit, 111-second resistor, 112-first capacitor, 12-human internal impedance simulation circuit, 13-first resistor, 2-second weighted circuit, 21-fourth resistor, 22-second capacitor, 23-third capacitor, 3-first weighted circuit, 4-switching circuit, 41-network selection switch, 42-switching switch, 43-control circuit, 431-transistor, 432-electromagnetic coil, 433-fifth resistor, 434-sixth resistor, 5-sampling display circuit, 6-charging power supply circuit, 61-charging power supply, 7-first sampling terminal, 8-second sampling terminal, 9-device under test, 10-power switch. DETAILED DESCRIPTION

[0033] In order to make the purpose, features, and advantages of the present disclosure more obvious and easy to understand, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present disclosure.

[0034] See also Figures 1 to 4 An embodiment of the present disclosure provides a contact current testing device, including a test circuit, wherein the measuring circuit includes a basic circuit 1, a first weighted circuit 3, a second weighted circuit 2 and a switching circuit 4, wherein the switching circuit 4 controls one of the first weighted circuit 3 and the second weighted circuit 2 to be connected to the basic circuit 1, the first weighted circuit 3 and the basic circuit 1 constitute a first measuring network, and the second weighted circuit 2 and the basic circuit 1 constitute a second measuring network.

[0035] The measuring circuit in the contact current test device disclosed in the present invention comprises a basic circuit 1, a first weighted circuit 3, a second weighted circuit 2 and a switching circuit 4. The switching circuit 4 controls one of the first weighted circuit 3 and the second weighted circuit 2 to be connected to the basic circuit 1. The first weighted circuit 3 and the basic circuit 1 constitute a first measuring network, and the second weighted circuit 2 and the basic circuit 1 constitute a second measuring network. The basic circuit 1 is connected to the first weighted circuit 3 or the second weighted circuit 2 through the switching circuit 4, so that different measuring networks can be formed respectively. Different measuring networks have a common input terminal and output terminal. During the test process, there is no need to disassemble the device 9 under test to realize the test of different contact currents, which is convenient for operation and simple to use. In addition, different test networks share part of the basic circuit 1, which reduces the cost of the test device.

[0036] One of the first test network and the second test network can be a sensing current test network, and the other can be a escaping current test network. The basic circuit 1 is connected to the first weighted circuit or the second weighted circuit 2 through the switching circuit 4, and the switching between the sensing current test network and the escaping current test network can be realized. After the test device of the embodiment of the present disclosure is connected to the device under test 9, the sensing current and the escaping current tests can be realized through the switching circuit 4, which is convenient to use.

[0037] See also Figure 1 and Figure 2 The contact current test device of the embodiment of the present disclosure further includes a sampling display circuit 5, which is connected to the measuring circuit and used to display the measurement result. The sampling display circuit 5 is connected to the measuring circuit and used to display the measurement result. The test result can be displayed in real time without connecting other oscilloscope devices such as an oscilloscope, which is convenient to use.

[0038] See also Figure 1 and Figure 2 The contact current test device of the embodiment of the present disclosure also includes a charging power supply circuit 6, and the charging power supply circuit 6 includes a charging power supply 61. The charging power supply circuit 6 is connected to the switching circuit 4 and the sampling display circuit 5, and is used to provide power to the contact current test device. The charging power supply 61 provides the contact current test device with the power required for operation, which can reduce the overall volume and weight and is easy to carry. An external power supply can charge the charging power supply 61 through the charging power supply circuit 6. The charging power supply 61 can specifically adopt a lithium-ion rechargeable battery, a lithium polymer rechargeable battery, a nickel-cadmium rechargeable battery, a nickel-metal hydride rechargeable battery or other rechargeable devices.

[0039] See also Figure 1 and Figure 2 The test circuit in the embodiment of the present disclosure includes a first sampling terminal 7 and a second sampling terminal 8, and the first sampling terminal 7 and the second sampling terminal 8 are used to connect to corresponding positions on the device under test 9 to collect the test signal.

[0040] The basic circuit 1 includes a human body impedance simulation circuit, which is used to simulate human body impedance. If the human body contacts the device in a possible way, the human body impedance simulation circuit will provide a measurement value indicating the level of current that may flow through the human body. The human body impedance simulation circuit may include a skin impedance simulation circuit 11 and a human body internal impedance simulation circuit 12. The first weighting circuit 3 and the second weighting circuit 2 are respectively used to weight the contact current measured by the basic circuit 1 to obtain different weighted currents. For example, the first weighting circuit 3 and the basic circuit 1 can form a sensed current test network, and the first weighting circuit 3 can weight the current measured by the basic circuit 1 to obtain the sensed current. The second weighting circuit 2 and the basic circuit 1 can form a get rid of current test network, and the second weighting circuit 2 can weight the current measured by the basic circuit 1 to obtain the get rid of current.

[0041] In one embodiment, the basic circuit 1 includes a skin impedance simulation circuit 11, a human body internal impedance simulation circuit 12 and a first resistor 13. The skin impedance simulation circuit 11 includes a first end and a second end. The first end is connected to the first sampling terminal 7. The first sampling terminal 7 is used to connect to the conductive part on the housing of the device under test 9. The skin impedance simulation circuit 11 is used to simulate the total skin impedance between the two sampling terminals.

[0042] The human body internal impedance simulation circuit 12 includes a third terminal and a fourth terminal, the third terminal is connected to the second terminal, the fourth terminal is connected to the second sampling terminal 8, the second sampling terminal 8 is used to connect the ground point of the device under test 9, and the second sampling terminal 8 is connected to the sampling display circuit 5. The human body internal impedance simulation circuit 12 is used to simulate the internal impedance of the human body. Figure 3 and Figure 4 The skin impedance simulation circuit 11 and the human body internal impedance simulation circuit 12 constitute an unweighted contact current measurement network. According to the voltage U1 across the human body internal impedance simulation circuit 12, the contact current related to electric burns can be obtained. Figure 3 According to the voltage U2 across the first weighting circuit 3, the touch current related to perception and reaction can be obtained. Figure 4 According to the voltage U3 across the second weighting circuit 2, the contact current about the escape current threshold can be obtained.

[0043] The first resistor 13 includes a fifth end and a sixth end, the fifth end is connected to the second end, and the sixth end is connected to the sampling display circuit 5. The first resistor 13 can be a metal film resistor.

[0044] In the embodiments of the present disclosure, see Figure 2, the switching circuit 4 may include a relay, and one of the two weighted circuits is connected to the basic circuit 1 by controlling the on and off of the electromagnetic coil 432 of the relay. For example, when the electromagnetic coil 432 of the relay is not energized, the first weighted circuit 3 is connected to the basic circuit 1, and the second weighted circuit 2 is disconnected; when the electromagnetic coil 432 of the relay is energized, the first weighted circuit 3 is disconnected from the basic circuit 1, and the second weighted circuit 2 is connected to the basic circuit 1. Of course, it is also possible that when the electromagnetic coil 432 of the relay is not energized, the first weighted circuit 3 is disconnected from the basic circuit 1, and the second weighted circuit 2 is connected to the basic circuit 1; when the electromagnetic coil 432 of the relay is energized, the first weighted circuit 3 is connected to the basic circuit 1, and the second weighted circuit 2 is disconnected from the basic circuit 1.

[0045] In one embodiment, see Figure 2 The switching circuit 4 includes a switching switch 42 and a control circuit 43. The switching switch 42 includes a first contact, a second contact and a third contact. The first contact is connected to the sixth end. One end of the first weighted circuit 3 is connected to the second contact, and the other end is connected to the fourth end. One end of the second weighted circuit 2 is connected to the third contact, and the other end is connected to the fourth end. The switching switch 42 is used to connect the first contact to the second contact or the third contact.

[0046] The control circuit 43 includes an input terminal, an output terminal and a control terminal. The input terminal is connected to the positive electrode of the charging power supply 61, and the output terminal is grounded. The sampling and display circuit 5 includes a control signal output terminal. The control signal output terminal is connected to the control terminal through the network selection switch 41. The network selection switch 41 is turned on or off to control the switching switch 42 to connect the first contact with the second contact or the third contact. The control circuit 43 controls the switching switch 42 to turn on the first weighted circuit 3 or the second weighted circuit 2 according to the signal of the control terminal. The signal of the control terminal is provided by the control signal output terminal of the sampling and display circuit 5. The signal of the control terminal can be a high level or a low level. When the network selection switch 41 is turned off, the control terminal is at a low level, and the control circuit 43 controls the first contact to be connected with the second contact, so that the first weighted circuit 3 is connected with the basic circuit 1 to form a first measurement network. When the network selection switch 41 is turned off, the sampling and display circuit 5 outputs a high level to the control terminal through the control signal output terminal, and the control circuit 43 controls the first contact to be connected with the third contact, so that the second weighted circuit 2 is connected with the basic circuit 1 to form a second measurement network.

[0047] The circuit structure of the test device of the embodiment of the present disclosure can be simplified by providing a control signal to the control circuit 43 through the sampling display circuit 5. In an exemplary embodiment, the sampling display circuit 5 may include a DC / DC conversion circuit, which converts the voltage of the charging power supply 61 to output a control signal to the control circuit 43.

[0048] For specific implementation, see Figure 2, the control circuit 43 includes a transistor 431, and the switching switch 42 is controlled by the transistor 431 to turn on the first weighted circuit 3 or the second weighted circuit 2. Specifically, an NPN transistor 431 can be used to drive the switching switch 42. The base of the transistor 431 is the control end. According to the current direction, one of the collector and the emitter is grounded, and the other is connected to one end of the electromagnetic coil 432. The other end of the electromagnetic coil 432 is connected to the positive pole of the charging power supply 61. For example, when the NPN transistor 431 is used, the collector is connected to the electromagnetic coil 432, and the emitter is grounded. When the base is at a low level, the transistor 431 is turned off, there is no current in the electromagnetic coil 432, and the switching switch 42 turns on the first weighted circuit 3. When the base is at a high level, the transistor 431 is saturated, and current flows in the electromagnetic coil 432, thereby attracting the switching switch 42 to turn on the second weighted circuit 2.

[0049] The base is connected to a fifth resistor 433, and the base is connected to the control signal output terminal of the sampling and display circuit 5 through the fifth resistor 433. A sixth resistor 434 is connected between the collector and the emitter. The values ​​of the fifth resistor 433 and the sixth resistor 434 enable the transistor 431 to be reliably saturated when the base input is a high level.

[0050] In one embodiment, see Figures 2 to 4 The skin impedance simulation circuit 11 includes a second resistor 111 and a first capacitor 112 connected in parallel. The value of the first capacitor 112 is determined by the area of ​​skin contact, for example, 0.22 μF. For a larger contact area, a larger value can be used, for example, 0.33 μF. The first capacitor 112 can be a film capacitor with an extended metal foil structure, and the second resistor 111 can be a metal film resistor.

[0051] In one embodiment, see Figures 2 to 4 The human body internal impedance simulation circuit 12 includes a third resistor. The third resistor can be a metal film resistor.

[0052] In one embodiment, see Figure 2 and Figure 4 The second weighted circuit 2 includes a fourth resistor 21 and a second capacitor 22 connected in series, the fourth resistor 21 is connected to the switching circuit 4, and the second capacitor 22 is connected to the fourth end; the third capacitor 23 is connected in parallel with the fourth resistor 21 and the second capacitor 22 connected in series. The fourth resistor 21 can be a metal film resistor. The second capacitor 22 and the third capacitor 23 can be film capacitors with an extended metal foil structure.

[0053] In one embodiment, see Figure 2 and Figure 3The first weighted circuit 3 includes a fourth capacitor, which is connected to the third connection point and the fourth terminal respectively. The fourth capacitor can be a film capacitor with an extended metal foil structure.

[0054] In one embodiment, see Figure 2 , the charging power supply 61 is connected to the sampling display circuit 5 through the power switch 10. When the power switch 10 is closed, the charging power supply 61 supplies power to the sampling display circuit 5, and the sampling display circuit 5 converts the voltage of the charging power supply 61 and outputs a high level to the control end of the control circuit 43, and the control switching circuit 4 switches from turning on the first weighted circuit 3 to turning on the second weighted circuit 2.

[0055] In one embodiment, the contact current test device further includes a housing, on which a charging interface is provided, and the charging interface is connected to the charging power circuit 6. The charging interface may be, for example, a Type-C interface. A power adapter is connected via the Type-C interface to charge the charging power supply 61, and the test device may be powered via the charging power circuit 6.

[0056] In one embodiment, a connector is provided on the housing, the connector is connected to the measuring circuit, and the connector is used to connect the sampling terminal. Two connectors are provided on the housing, one is connected to the first sampling terminal 7, and the other is connected to the second sampling terminal 8. The connector is used to connect the test probe, and the test probe contacts the corresponding part on the device under test 9 to perform the contact current test. In a specific implementation, the connector can be a circular connector.

[0057] When starting to use the test device of the embodiment of the present disclosure, you can first close the power switch 10 to allow the charging power supply 61 to provide power to the test device. At this time, the test device will check the battery power. In order to prevent insufficient power during the test, the charging power supply 61 can only be used when the power exceeds the minimum threshold. When the power is lower than the threshold, the green power indicator light on the outer casing lights up, prompting the user to charge first.

[0058] The test probe connected to the second sampling terminal 8 is connected to the main grounding point of the electrical equipment. The test probe connected to the first sampling terminal 7 is connected to the conductive part of the housing of the electrical equipment. When the housing is made of all plastic, a layer of copper foil can be attached to the housing to connect the test probe to the copper foil.

[0059] According to the test scenario, when the electrical equipment is in a normal state and it is necessary to test whether the contact current of the electrical equipment exceeds the limit of the authentication sensing current, the network selection switch 41 remains in an off state. At this time, the first weighted circuit 3 is connected to the basic circuit 1 to form a sensing current test network. For details, see Figure 3 , used to test the sensing current. By sampling at U2 and then calculating, the test results can be read intuitively on the display.

[0060] When the electrical equipment is in a single fault state and needs to test whether the contact current of the electrical equipment exceeds the escape current limit, the network selection switch 41 needs to be closed. At this time, the second weighted circuit 2 is connected to the basic circuit 1 to form an escape current test network. For details, see Figure 4 , used to test the escape current. By sampling and calculating U3, the measurement results can also be read intuitively on the display.

[0061] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this disclosure can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved, and this document does not limit this.

[0062] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present disclosure, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0063] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A contact current testing device, characterized in that: include: A measurement circuit, comprising a basic circuit, a first weighted circuit, a second weighted circuit and a switching circuit, wherein the switching circuit controls one of the first weighted circuit and the second weighted circuit to be connected to the basic circuit, the first weighted circuit and the basic circuit constitute a first measurement network, and the second weighted circuit and the basic circuit constitute a second measurement network; A sampling display circuit, connected to the measuring circuit, for displaying the measuring result; The charging power supply circuit comprises a charging power supply, wherein the charging power supply circuit is connected to the switching circuit and the sampling display circuit and is used to provide power to the contact current testing device.

2. The contact current testing device according to claim 1, characterized in that: The basic circuit comprises: A skin impedance simulation circuit comprises a first end and a second end, wherein the first end is connected to a first sampling terminal, and the first sampling terminal is used to connect to a conductive part on a housing of a device under test; A human body internal impedance simulation circuit, comprising a third end and a fourth end, wherein the third end is connected to the second end, the fourth end is connected to a second sampling terminal, the second sampling terminal is used to connect to a ground point of a device under test, and the second sampling terminal is connected to the sampling display circuit; The first resistor includes a fifth end and a sixth end, wherein the fifth end is connected to the second end, and the sixth end is connected to the sampling display circuit.

3. The contact current testing device according to claim 2, characterized in that: The switching circuit comprises: a switching switch, comprising a first contact, a second contact and a third contact, wherein the first contact is connected to the sixth terminal, one end of the first weighted circuit is connected to the second contact and the other end is connected to the fourth terminal, one end of the second weighted circuit is connected to the third contact and the other end is connected to the fourth terminal, and the switching switch is used to conduct the first contact with the second contact or the third contact; The control circuit includes an input end, an output end and a control end, wherein the input end is connected to the positive electrode of the charging power supply, the output end is grounded, and the sampling display circuit includes a control signal output end, wherein the control signal output end is connected to the control end through a network selection switch, and the switching switch is turned on or off by the network selection switch to control the first contact to be connected with the second contact or the third contact.

4. The contact current testing device according to claim 2, characterized in that: The skin impedance simulation circuit includes a second resistor and a first capacitor connected in parallel.

5. The contact current testing device according to claim 2, characterized in that: The human body internal impedance simulation circuit includes a third resistor.

6. The contact current testing device according to claim 2, characterized in that: The second weighting circuit comprises: a fourth resistor and a second capacitor connected in series, the fourth resistor being connected to the switching circuit, and the second capacitor being connected to the fourth end; The third capacitor is connected in parallel with the fourth resistor and the second capacitor which are connected in series.

7. The contact current testing device according to claim 3, characterized in that: The first weighting circuit includes a fourth capacitor, and the fourth capacitor is respectively connected to the third connection point and the fourth end.

8. The contact current testing device according to claim 1, characterized in that: The charging power source is connected to the sampling display circuit through a power switch.

9. The contact current testing device according to claim 1, characterized in that: It also includes a shell, on which a charging interface is provided, and the charging interface is connected to the charging power supply circuit.

10. The contact current testing device according to claim 9, characterized in that: The housing is provided with a connector, the connector is connected to the measuring circuit, and the connector is used to connect a sampling terminal.

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