Static characteristic resistance detection device of circuit board power supply load

Abstract

The invention provides a static characteristic resistance detection device for a circuit board power supply load, which comprises a positive power supply and a negative power supply which are input into a circuit board to be detected, a function selection unit, a channel selection unit, a signal conditioning unit, a signal acquisition unit and a processing and control unit, the processing and control unit determines that the function selection unit selects an operation mode or a detection mode according to an instruction and controls the channel selection unit and a relay array of the function selection unit according to measured characteristic resistance, and the channel selection unit comprises a third relay array and a fourth relay array; the function selection unit comprises a relay array I and a relay array II, each relay array comprises 2n switches, and the channel selection unit selects one signal conditioning unit to be switched on every time and detects the characteristic resistance connected with the signal conditioning unit. The defects of low detection efficiency and high cost in the prior art can be overcome.

Description

Technical Field

[0001] The present invention belongs to the technical field of circuit board detection, and particularly relates to a static characteristic resistance detection device for a power supply load of a circuit board. Background Art

[0002] After a circuit board is designed and produced, it has its own inherent electrical characteristics, which are stable. However, due to the influence of factors such as adverse environment, improper operation, and time, the electrical characteristics of the circuit board will change, directly affecting the function and performance of the circuit. In particular, changes in the power supply load may cause serious failures of the circuit board.

[0003] Circuit boards are usually not used alone, but are installed in systems and devices and have an electrical connection relationship with other circuits. When a circuit board fails, it affects the normal operation of the entire system. Moreover, since it is installed in the system and device, it is difficult to troubleshoot the faults of the entire system, which is not conducive to fault location. The power supply load characteristic of the circuit board is a key indicator and the first step in troubleshooting problems. Therefore, it is necessary and meaningful to automatically detect the characteristic resistance of the power supply load of the circuit board.

[0004] In traditional resistance detection methods, some use a digital multimeter for measurement. The input terminal of the circuit board power supply is connected to the red and black test leads of the multimeter, and accurate measurement is achieved by switching the range. When measuring the loads of multiple power supplies, manual wiring replacement is required, resulting in low efficiency, and the operator needs to have certain circuit knowledge. When using different digital multimeters for measurement, the results deviate greatly, causing difficulties in selecting the measurement instrument. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a static characteristic resistance detection device for a power supply load of a circuit board. The solution of the present invention can solve the problems existing in the above prior art.

[0006] The technical solution of the present invention:

[0007] A static characteristic resistance detection device for a circuit board power supply load, comprising a positive power supply and a negative power supply for inputting a circuit board to be measured, a function selection unit, a channel selection unit, a signal conditioning unit, a signal acquisition unit, and a processing and control unit. The processing and control unit determines, according to an instruction, that the function selection unit selects an operation mode or a detection mode, and controls a relay array of the channel selection unit and the function selection unit according to the measured characteristic resistance. The channel selection unit includes a relay array three and a relay array four, and the function selection unit includes a relay array one and a relay array two. Each relay array contains 2n switches. The relay array one of the function selection unit is connected to the positive power supply and the power ground, and the relay array two is connected to the negative power supply and the negative power ground. One of the relay array one and the relay array two is connected at the same time. One end of the channel selection unit is connected to the function selection unit, the relay array three is connected to the relay array one, the relay array four is connected to the relay array two, and the other ends of one switch in the relay array three and the relay array four are connected to the plurality of signal conditioning units. The channel selection unit selects one signal conditioning unit to be connected each time to detect the characteristic resistance connected to this signal conditioning unit.

[0008] Further, the signal conditioning unit includes a reference power supply, a first operational amplifier, a first resistor, a second resistor, a third resistor, a measuring point resistor, and a first capacitor. The reference power supply is connected in series with the first resistor and then input to the negative electrode of the first operational amplifier. The second resistor is connected to the positive electrode of the first operational amplifier. The base of the first operational amplifier is connected to one end of the third resistor, and the other end of the third resistor is connected to the first capacitor. One end of the measuring point resistor is connected to the negative electrode of the first operational amplifier and the relay array three, and the other end is connected to the base of the first operational amplifier and the relay array four.

[0009] Further, if the signal conditioning unit is connected to the negative power supply, the positive electrode of the reference power supply is connected to the first resistor; if the signal conditioning unit is connected to the positive power supply, the negative electrode of the reference power supply is connected to the first resistor.

[0010] Further, the processing and control unit includes a driver, a DSP processor, an ADC converter, and a communication interface. The output end of the signal conditioning is connected to the ADC converter. The ADC converter converts the analog voltage signal into a digital signal and provides it to the DSP processor. The DSP processor communicates with the ADC converter through SPI. The DSP processor receives a control command from the communication interface, parses the control command, and transmits it to the driver. The driver controls the corresponding relay array.

[0011] Further, the relay array 1, relay array 2, relay array 3, and relay array 4 are all composed of double-pole double-throw relays.

[0012] Further, all the relays in the relay array 1 are simultaneously energized or simultaneously turned off, and all the relays in the relay array 2 are simultaneously energized or simultaneously turned off.

[0013] Further, the first resistor and the measured point resistor are high-value resistors, and the resistance value ranges from 500K to 2M ohms.

[0014] Advantages of the present invention compared with the prior art:

[0015] In the present invention, a signal conditioning circuit is formed by a relay that is energized and an operational amplifier across both ends of a load powered by a circuit board. The output voltage signal of the signal conditioning is collected by an ADC, converted into a digital signal, and then sent to a DSP processor. After the DSP completes data processing, it is transmitted to the outside through a communication port. The detection method of the present invention has a simple structure and reasonable design, can complete the detection of the characteristic resistance of multiple channels of loads, and realizes the function switching between the detection of the characteristic resistance and normal power supply by controlling the relay. Compared with the prior art, the technical solution of the present invention can solve the disadvantages of low detection efficiency and high cost in the prior art. Description of the Drawings

[0016] The accompanying drawings included are used to provide a further understanding of the embodiments of the present invention, which form a part of the specification, are used to illustrate the embodiments of the present invention, and together with the textual description are used to explain the principles of the present invention. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings without creative efforts based on these drawings.

[0017] Figure 1 Shows a schematic diagram of a static characteristic resistance detection device for a load powered by a circuit board according to an embodiment of the present invention;

[0018] Figure 2 Shows a schematic circuit diagram of a static characteristic resistance automatic detection device for a load powered by a circuit board according to an embodiment of the present invention. Detailed Embodiments

[0019] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The description of at least one exemplary embodiment below is actually only illustrative and in no way limits the present invention and its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts belong to the scope of protection of the present invention.

[0020] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0021] Unless otherwise specifically stated, the relative arrangements of the components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and devices should be regarded as part of the authorized specification. In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0022] As Figure 1As shown, according to an embodiment of the first aspect of the present invention, a static characteristic resistance detection device for a circuit board power supply load is provided, including a positive power supply and a negative power supply for inputting a circuit board to be measured, a function selection unit, a channel selection unit, a signal conditioning unit, a signal acquisition unit, and a processing and control unit. The processing and control unit determines, according to an instruction, that the function selection unit selects an operation mode or a detection mode, and controls the relay arrays of the channel selection unit and the function selection unit according to the measured characteristic resistance. The channel selection unit includes relay array three and relay array four, and the function selection unit includes relay array one and relay array two. Each relay array contains 2n switches; the relay array one of the function selection unit is connected to the positive power supply and the power ground, the relay array two is connected to the negative power supply and the negative power ground, and one of the relay array one and the relay array two is connected at the same time; one end of the channel selection unit is connected to the function selection unit, and the relay array three is connected to the relay array one, the relay array four is connected to the relay array two, and the other ends of one switch in the relay array three and the relay array four are connected to the several signal conditioning units respectively. The channel selection unit selects one signal conditioning unit to be connected each time to detect the characteristic resistance connected to this signal conditioning unit.

[0023] Further, in an embodiment, the signal conditioning unit includes a reference power supply, a first operational amplifier, a first resistor, a second resistor, a third resistor, a measuring point resistor, and a first capacitor. The reference power supply is connected in series with the first resistor and then input to the negative pole of the first operational amplifier. The second resistor is connected to the positive pole of the first operational amplifier. The base of the first operational amplifier is connected to one end of the third resistor, and the other end of the third resistor is connected to the first capacitor. One end of the measuring point resistor is connected to the negative pole of the first operational amplifier and the relay array three, and the other end is connected to the base of the first operational amplifier and the relay array four.

[0024] Further, in an embodiment, if the signal conditioning unit is connected to the negative power supply, the positive pole of the reference power supply is connected to the first resistor; if the signal conditioning unit is connected to the positive power supply, the negative pole of the reference power supply is connected to the first resistor.

[0025] Further, in an embodiment, the processing and control unit includes a driver, a DSP processor, an ADC converter, and a communication interface. The output end of the signal conditioning is connected to the ADC converter. The ADC converter converts the analog voltage signal into a digital signal and provides it to the DSP processor. The DSP processor communicates with the ADC converter through SPI. The DSP processor receives the control command from the communication interface, parses the control command, and then transmits it to the driver, and the driver controls the corresponding relay array.

[0026] Further, in one embodiment, Relay Array 1, Relay Array 2, Relay Array 3, and Relay Array 4 are all composed of double-pole double-throw relays.

[0027] Further, in one embodiment, all the relays in Relay Array 1 are simultaneously pulled in or simultaneously turned off, and all the relays in Relay Array 2 are simultaneously pulled in or simultaneously turned off.

[0028] Further, in one embodiment, the first resistor and the measured point resistor are high-value resistors, and the value range of the resistors is: 500K to 2M ohms.

[0029] In order to further elaborate on a static characteristic resistance detection device for a circuit board power supply load according to the present invention, the present invention will be described in detail below with reference to the accompanying drawings.

[0030] As Figure 1 and Figure 2 shown, according to a specific embodiment of the present invention, there is provided a static characteristic resistance automatic detection device for a circuit board power supply load. The device includes a relay array unit, a signal conditioning unit, a reference voltage unit, a processor and a control unit, an ADC conversion unit, and a communication unit. The relay array unit is divided into 4 groups of relay arrays: Array 1, Array 2, Array 3, and Array 4. Relay Arrays 1 and 2 complete function selection, selecting either the normal power supply function or the characteristic resistance detection function. Relay Array 1 is composed of n double-pole double-throw relays. The COM terminal of each relay is connected to the positive and negative ends of the positive power supply input of the circuit board, the NC terminal is connected to the positive power supply terminal, and the NO terminal is connected to Relay Array 3. Relay Array 2 is composed of n double-pole double-throw relays. The COM terminal of each relay is connected to the positive and negative ends of the negative power supply input of the circuit board, the NC terminal is connected to the negative power supply terminal, and the NO terminal is connected to Relay Array 4. The COM terminal of Relay Array 3 is connected to the NO terminal of Relay Array 1, the NC terminal of Relay Array 3 is left floating, and its NO terminal is connected to the signal conditioning unit. The COM terminal of Relay Array 4 is connected to the NO terminal of Relay Array 2, the NC terminal of Relay Array 4 is left floating, and its NO terminal is connected to the signal conditioning unit. The signal conditioning unit is composed of Signal Conditioning 1 and Signal Conditioning 2. The signal processing unit and the relay array unit form a detection circuit, and the conditioned voltage signal is used to calculate and obtain the characteristic resistance value. The voltage signal output by the signal processing unit is connected to the ADC conversion unit, and the ADC conversion unit converts the voltage signal output by the signal processing unit into a digital signal. The processor and the control unit are connected to the ADC conversion unit and the relay array unit, and the processor and the control unit control the pulling in and turning off of the relays in the relay array unit. The reference voltage unit is connected to the signal conditioning unit to provide a high-precision reference voltage for the signal conditioning unit.

[0031] In this configuration, a static characteristic resistance automatic detection device for a circuit board power supply load is provided. The relay array 1 and the relay array 2 of the detection device are connected to the multi-channel power supply input of the circuit board. The relay array 1 is composed of n double-pole double-throw relays K1 to Kn. The two ends of the positive power supply input of the n channels of the circuit board are respectively connected to the COM terminals of the n relays in the relay array 1 one by one. The double knives of the relays K1 to Kn are divided into a first knife and a second knife. The low end of the positive power supply input terminal is connected to the second knife, and the high end of the positive power supply input terminal of the same channel is connected to the first knife. There cannot be a situation where the first knife of the relay is connected to both the high end and the low end of the power supply. Similarly, there cannot be a situation where the second knife of the relay is connected to both the high end and the low end of the power supply. The relay array 2 is composed of n double-pole double-throw relays Kn+1 to K2n. The two ends of the negative power supply input of the n channels of the circuit board are respectively connected to the COM terminals of the n relays in the relay array 2 one by one. The low end of the negative power supply input terminal is connected to the second knife, and the high end of the negative power supply input terminal of the same channel is connected to the first knife. Similar to the relay array 1, there cannot be a situation where the same knife is connected to both the high end and the low end of the power supply.

[0032] As Figure 1 and Figure 2 shown, the NO terminals of the relay array 1 are respectively connected to the relay COM terminals of the relay array 3. The relay array 3 is composed of n relays K2n+1 to K3n. Considering reducing the types of relay selections, double-pole double-throw relays are used in the present invention, and the relay array 3 can be implemented by double-pole single-throw relays. The NO terminals of the relay array 2 are respectively connected to the relay COM terminals of the relay array 4. The relay array 4 is composed of n relays K3n+1 to K4n. Similarly, the relay array 4 can be implemented by double-pole single-throw relays.

[0033] Furthermore, each relay of the relay array 3 has its double knife divided into a first knife and a second knife. The NO terminals of the first knives of these n relays are connected together, and the NO terminals of the second knives are connected together. Similarly, each relay of the relay array 4 has its double knife divided into a first knife and a second knife. The NO terminals of the first knives of these n relays are connected together, and the NO terminals of the second knives are connected together.

[0034] As Figure 1 and Figure 2 shown, in the present invention, the signal conditioning unit includes signal conditioning 1 and signal conditioning 2. The NO terminal of the first knife of the relay in the relay array 3 is connected to the "test point 1" of the signal conditioning 1, and the NO terminal of the second knife of the relay is connected to the "test point 2" of the signal conditioning 1. Figure 2 Rx in the dotted line represents the characteristic resistance of the positive power supply load. The NO terminal of the first knife of the relay in the relay array 4 is connected to the "test point 3" of the signal conditioning 2, and the NO terminal of the second knife of the relay is connected to the "test point 4" of the signal conditioning 2.Figure 2 The dashed line Ry in

[0035] As shown in Figure 1 and Figure 2 In the present invention, signal conditioning 1 includes operational amplifier A1, resistors R1, R2, R3, Rf1, and capacitor C1. The operational amplifier is designed in a negative feedback manner. The non-inverting terminal of operational amplifier A1 is connected to one end of resistor R2, and the other end of resistor R2 is connected to the ground of the power supply of the operational amplifier. The inverting terminal of operational amplifier A1 is connected to the NO terminal of relay array 3. Resistor R1 is connected to the reference voltage output terminal of the reference voltage unit. Resistor Rf1 is the feedback resistor in the negative feedback design. One end of Rf1 is connected to the inverting terminal of the operational amplifier, and the other end is connected to the output terminal of the operational amplifier. One end of resistor R3 is connected to the output terminal of operational amplifier A1, and the other end is connected to the ADC conversion unit. One end of capacitor C1 is connected to the ADC conversion unit, and the other end is connected to the ground of the power supply for operational amplifier A1. Signal conditioning 2 includes operational amplifier A2, resistors R4, R5, R6, Rf2, and capacitor C2. The operational amplifier is designed in a negative feedback manner. The non-inverting terminal of operational amplifier A2 is connected to one end of resistor R5, and the other end of resistor R5 is connected to the ground of the power supply of the operational amplifier. The inverting terminal of operational amplifier A2 is connected to the NO terminal of relay array 4. Resistor R4 is connected to the reference voltage output terminal of the reference voltage unit and the other end is connected to the inverting terminal of operational amplifier A2. Resistor Rf2 is the feedback resistor in the negative feedback design. One end of Rf2 is connected to the inverting terminal of the operational amplifier, and the other end is connected to the output terminal of the operational amplifier. One end of resistor R6 is connected to the output terminal of operational amplifier A2, and the other end is connected to the ADC conversion unit. One end of capacitor C2 is connected to the ADC conversion unit, and the other end is connected to the ground of the power supply for operational amplifier A2.

[0036] Furthermore, resistor R3 and capacitor C1 form a low-pass filter, and resistor R6 and capacitor C2 form a low-pass filter for filtering the voltage signal output by the operational amplifier. R1, R4, and Rf1, Rf2 are high-value resistors. To improve the test accuracy, resistors R1, R4, Rf1, Rf2 are not limited to single resistors and can be series-parallel combinations of multiple resistors.

[0037] Furthermore, the voltage value at "test point 2" is a positive voltage and cannot be a negative voltage value, and the voltage value at "test point 4" is a negative voltage and cannot be a positive voltage value.

[0038] As shown in Figure 1 and Figure 2As shown, in the present invention, the reference voltage unit is connected to the signal conditioning unit, and the reference voltage unit provides a 5V reference voltage for the signal conditioning unit. The reference voltage unit includes a +5V reference voltage and a -5V reference voltage. The -5V reference voltage is composed of resistor R7 and diode V1, and the +5V reference voltage is composed of resistor R8 and diode V2. V1 and V2 are precision reference shunt regulators, serving as positive and negative reference voltages.

[0039] As Figure 1 and Figure 2 shown, the processor and control unit are composed of a DSP processor and a driver. The DSP processor is connected to the ADC conversion unit, and the DSP processor controls the ADC acquisition timing and data exchange through SPI. The GPIO of the DSP processor is connected to the driver, and the driver is connected to the relay array unit. After the DSP processor receives an external control command, it controls the relay by changing the high and low level states of the GPIO.

[0040] Furthermore, after the processor and control unit receive the characteristic resistance detection command, the "function selection instruction" becomes valid, and all the relays in relay arrays 1 and 2 are closed, and the detection device is in the characteristic resistance detection state. When the "function selection instruction" is invalid, all the relays in relay arrays 1 and 2 are turned off, and the detection device is in the circuit board power supply working state. In the valid state of the "function selection instruction", the DSP processor controls relay arrays 3 and 4. Relay arrays 3 and 4 have a total of 2n relays. At the same time, only one of these 2n relays can be closed. When the "function selection instruction" is valid and a certain relay in arrays 3 and 4 is closed, the input end of the detection device and the signal processing unit form a detection circuit.

[0041] Furthermore, the ultimate goal of the present invention is to obtain the characteristic resistances Rx and Ry. After the input end of the detection device and the signal processing unit form a detection circuit, the output voltage formula of signal conditioning 1 is:

[0042]

[0043] where, V ADIN1 is the output voltage of conditioning 1, R xf is the resistance value of the feedback resistor R f1 in parallel with the characteristic resistance R x , that is, R xf =R f1 ||R x , V ref1 is the reference -5V voltage. Given R f1 , R1, V ref1 , V ADIN1 is the acquisition value, and according to formula (1), the characteristic resistance R x。

[0044] Signal conditioning 2 output voltage formula:

[0045]

[0046] Among them, V ADIN2 is the conditioning 2 output voltage, R yf is the resistance value of the feedback resistor R f2 in parallel with the characteristic resistor R y , that is, R yf = R f2 ||R y , V ref2 is the reference +5V voltage. Given R f2 , R4, V ref2 , V ADIN2 is the acquisition value, and according to formula (2), the characteristic resistor R y can be calculated.

[0047] In summary, the beneficial effects of a static characteristic resistor detection device for a circuit board power supply load provided by the present invention compared with the prior art:

[0048] In the present invention, a signal conditioning circuit is formed by a relay that is attracted at both ends of the circuit board power supply load and an operational amplifier. The output voltage signal of the signal conditioning is collected by an ADC and converted into a digital signal, and then sent to a DSP processor. After the DSP completes data processing, it is transmitted to the outside through a communication port. The detection method of the present invention has a simple structure and reasonable design, can complete the detection of the characteristic resistors of multiple channels, and can complete the function switching between the detection of the characteristic resistor and normal power supply by controlling the relay. Compared with the prior art, the technical solution of the present invention can solve the problems of low detection efficiency and high cost in the prior art.

[0049] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A static characteristic resistance detection device for a circuit board power supply load, characterized in that It includes a positive power supply and a negative power supply for the circuit board to be measured, a function selection unit, a channel selection unit, a signal conditioning unit, a signal acquisition unit, and a processing and control unit. The processing and control unit determines, according to an instruction, whether the function selection unit selects an operation mode or a detection mode, and controls the relay arrays of the channel selection unit and the function selection unit according to the measured characteristic resistance. The channel selection unit includes relay array three and relay array four, and the function selection unit includes relay array one and relay array two. Each relay array contains 2n switches; the relay array one of the function selection unit is connected to the positive power supply and the power ground, and relay array two is connected to the negative power supply and the negative power ground. One of the relay array one and the relay array two is connected at the same time; one end of the channel selection unit is connected to the function selection unit, relay array three is connected to relay array one, relay array four is connected to relay array two, and the other ends of one switch in relay array three and relay array four are connected to the several signal conditioning units respectively. The channel selection unit selects one signal conditioning unit to be connected each time to detect the characteristic resistance connected to this signal conditioning unit.

2. The static characteristic resistance detection device for a circuit board power supply load according to claim 1, characterized in that, The signal conditioning unit includes a reference power supply, a first operational amplifier, a first resistor, a second resistor, a third resistor, a measurement point resistor, and a first capacitor. The reference power supply is connected in series with the first resistor and then input to the negative pole of the first operational amplifier. The second resistor is connected to the positive pole of the first operational amplifier. The base of the first operational amplifier is connected to one end of the third resistor, and the other end of the third resistor is connected to the first capacitor. One end of the measurement point resistor is connected to the negative pole of the first operational amplifier and relay array three, and the other end is connected to the base of the first operational amplifier and relay array four.

3. The static characteristic resistance detection device for a circuit board power supply load according to claim 2, wherein If the signal conditioning unit is connected to the negative power supply, the positive pole of the reference power supply is connected to the first resistor; if the signal conditioning unit is connected to the positive power supply, the negative pole of the reference power supply is connected to the first resistor.

4. The static characteristic resistance detection device for a circuit board power supply load according to claim 3, wherein The processing and control unit includes a driver, a DSP processor, an ADC converter, and a communication interface. The output end of the signal conditioning is connected to the ADC converter. The ADC converter converts the analog voltage signal into a digital signal and provides it to the DSP processor. The DSP processor communicates with the ADC converter through SPI. The DSP processor receives the control command from the communication interface, and after parsing the control command, transmits it to the driver, and the driver controls the corresponding relay array.

5. The static characteristic resistance detection device for a circuit board power supply load according to claim 4, wherein, Relay array one, relay array two, relay array three, and relay array four are all composed of double - pole double - throw relays.

6. The static characteristic resistance detection device for a circuit board power supply load according to claim 5, wherein All the relays in relay array one are simultaneously attracted or simultaneously turned off, and all the relays in relay array two are simultaneously attracted or simultaneously turned off.

7. The static characteristic resistance detection device for a circuit board power supply load according to claim 6, characterized in that, The first resistor and the measurement point resistor are high - value resistors, and the resistance value ranges from 500K to 2M ohms.

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