Multi-parameter electric signal measurement and self-diagnosis system and fault diagnosis method thereof

Abstract

The invention relates to a multi-parameter electric signal measurement and self-diagnosis system and a fault diagnosis method thereof in the technical field of product detection and inspection. The multi-parameter electric signal measurement and self-diagnosis system comprises an input unit, a loop, a switching circuit, an acquisition unit, an uploading control unit, an output unit and an upper computer. According to the invention, an automatic data acquisition mode is used to automatically acquire voltage and current data, in addition, an acquisition unit is used to acquire voltage and current of a loop according to different time periods, voltage and current electric signals output by four paths of a calibration power supply are displayed on an upper computer interface, and upper computer software determines the voltage and current of the calibration power supply according to the acquired and displayed data and a control logic relation. The fault position and the fault type are automatically judged, frequent opening of the shell of the spark ignition test device and frequent use of a universal meter for respectively measuring four paths of voltage and current are avoided, manpower and material resources are saved, and the working efficiency, the working quality and the measurement accuracy are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of product detection and testing, and particularly relates to a multi-parameter electrical signal measurement and self-diagnosis system and a fault diagnosis method thereof. Background Art

[0002] The calibration power supply of the existing intrinsically safe spark ignition test device has a single function. Each time a measurement is performed, the device casing needs to be opened and a multimeter needs to be used to measure and adjust the voltage and current of the four outputs of the calibration power supply. This is time-consuming and labor-intensive, inefficient, and results in large measurement errors. Summary of the Invention

[0003] The purpose of the present invention is to provide a multi-parameter electrical signal measurement and self-diagnosis system and a fault diagnosis method thereof, which uses an automatic data acquisition method to automatically collect voltage and current data. In addition, an acquisition unit is used to collect the voltage and current of the circuit according to different time periods, and the voltage and current electrical signals of the four outputs of the calibration power supply are displayed on the upper computer interface. The upper computer software automatically determines the fault location and fault type based on the collected and displayed data and the control logic relationship, avoiding frequent opening of the spark ignition test device shell and frequent use of a multimeter to measure the four-way voltage and current respectively, saving manpower and material resources, and improving work efficiency, work quality and measurement accuracy.

[0004] Based on the above technical problems, the present invention provides a multi-parameter electrical signal measurement and self-diagnosis system, including an input unit, a loop, a switching circuit, an acquisition unit, an upload control unit, an output unit and a host computer;

[0005] The input unit is used to send voltage and current signals in the power supply circuit;

[0006] The switching circuit is connected to the input unit via a loop, and is used to receive voltage and current signals sent by the input unit;

[0007] The acquisition unit is connected to the switching circuit and is used to acquire voltage signals and current signals and convert analog quantities into digital quantities;

[0008] The upload control unit is connected to the switching circuit, the acquisition unit, and the host computer respectively, and is used to control the closing or opening of the loop through the switching circuit, and upload the digital signal converted by the acquisition unit to the host computer;

[0009] The output unit is connected to the acquisition unit and is used to output the voltage signal and current signal acquired by the acquisition unit.

[0010] Furthermore, the loop and the switching circuit each have multiple paths, and each switching circuit is connected to one loop.

[0011] In a preferred embodiment of the present invention, the loop and the switching circuit each have four paths.

[0012] The present invention also provides a fault diagnosis method based on the above-mentioned multi-parameter electrical signal measurement and self-diagnosis system, comprising the following steps:

[0013] (1) The input unit sends the voltage and current signals in the power circuit to the circuit;

[0014] (2) The current flowing through loop one is x1, the current flowing through loop two is x2, the current flowing through loop three is x3, and the current flowing through loop four is x4. x1≠x2≠x3≠x4, that is, any two of x1, x2, x3, and x4 are not equal. x1+x2≠x1+x3≠x1+x4≠x2+x3≠x2+x4≠x3+x4, that is, the sum of any two of x1, x2, x3, and x4 is not equal. x1+x2+x3≠x1+x2+x4≠x2+x3+x4≠x1+x3+x4, that is, the sum of any three of x1, x2, x3, and x4 is not equal.

[0015] (3) The upload control unit uploads the digital signal converted by the acquisition unit to the host computer. When measuring the current signal parameters of loop 1:

[0016] If the measurement display value of the host computer is y1=x1, it is judged that the circuit 1 and the switching circuit 1 are normal;

[0017] If the measured value is y2 = x1 + x2, it is determined that the switching circuit 2 is short-circuited and recorded as parameter event E1;

[0018] If the measured value is y3 = x1 + x3, the switching circuit is judged to have a triple short-circuit fault and recorded as parameter event E2;

[0019] If the measured value is y4 = x1 + x4, the switching circuit is judged to have a short-circuit fault and recorded as parameter event E3;

[0020] If the measured value is y5 = x1 + x2 + x3, it is determined that the switching circuit 2 and the switching circuit 3 are short-circuited and recorded as parameter event E4;

[0021] If the measured value is y6 = x1 + x2 + x3 + x4, it is determined that the switching circuit 2, switching circuit 3, and switching circuit 4 are short-circuited and recorded as parameter event E5;

[0022] If the measured value is y7 = x1 + x2 + x4, it is determined that the switching circuit 2 and the switching circuit 4 are short-circuited and recorded as parameter event E6;

[0023] If the measured value is y8 = x1 + x3 + x4, it is determined that the switching circuit 3 and the switching circuit 4 are short-circuited and recorded as parameter event E7;

[0024] When measuring the current signal parameters of loop 2 (different fault types are recorded as different parameter event type numbers):

[0025] If the measured value displayed by the host computer is y9=x2, it is judged that loop 2 and switching circuit 2 are normal;

[0026] If the measured value is y 10 =x1+x2, then it is determined that the switching circuit has a fault;

[0027] If the measured value is y 11 =x2+x3, then it is determined that the switching circuit has three faults;

[0028] If the measured value is y 12 =x2+x4, then it is determined that the switching circuit has four faults;

[0029] If the measured value is y 13 =x1+x2+x3, then it is determined that switching circuit 1 and switching circuit 3 are faulty;

[0030] If the measured value is y 14 =x1+x2+x3+x4, then it is determined that switching circuit 1, switching circuit 3, and switching circuit 4 are faulty;

[0031] If the measured value is y 15 =x1+x2+x4, then it is determined that switching circuit 1 and switching circuit 4 are faulty;

[0032] If the measured value is y 16 =x2+x3+x4, then it is determined that switching circuit three and switching circuit four are faulty;

[0033] When measuring the current signal parameters of loop three (different fault types are recorded as different parameter event type numbers):

[0034] If the measurement display value of the host computer is y 17 =x3, then it is judged that loop three and switching circuit three are normal;

[0035] If the measured value is y 18 =x1+x3, then it is determined that the switching circuit has a fault;

[0036] If the measured value is y 19 =x2+x3, then it is determined that the switching circuit 2 is faulty;

[0037] If the measured value is y 20 =x3+x4, then it is determined that the switching circuit 4 is faulty;

[0038] If the measured value is y 21 =x1+x2+x3, then it is determined that switching circuit 1 and switching circuit 2 are faulty;

[0039] If the measured value is y 22 =x1+x2+x3+x4, then it is determined that switching circuit 1, switching circuit 2, and switching circuit 4 are faulty;

[0040] If the measured value is y 23 =x1+x3+x4, then it is determined that switching circuit 1 and switching circuit 4 are faulty;

[0041] If the measured value is y 24 =x2+x3+x4, then it is determined that switching circuit 2 and switching circuit 4 are faulty;

[0042] When measuring the current signal parameters of loop 4 (different fault types are recorded as different parameter event type numbers):

[0043] If the measurement display value of the host computer is y 25 =x4, then loop 4 and the switching circuit are judged to be normal;

[0044] If the measured value is y 26 =x1+x4, then it is determined that the switching circuit has a fault;

[0045] If the measured value is y 27 =x2+x4, then it is determined that the switching circuit 2 is faulty;

[0046] If the measured value is y 28 =x3+x4, then it is determined that the switching circuit has three faults;

[0047] If the measured value is y 29 =x1+x2+x4, then it is determined that switching circuit 1 and switching circuit 2 are faulty;

[0048] If the measured value is y 30 =x1+x2+x3+x4, then it is determined that switching circuit 1, switching circuit 2, and switching circuit 3 are faulty;

[0049] If the measured value is y 31 =x1+x3+x4, then it is determined that switching circuit 1 and switching circuit 3 are faulty;

[0050] If the measured value is y 32 =x2+x3+x4, then it is determined that switching circuit 2 and switching circuit 3 are faulty;

[0051] (4) The normal measured value of the voltage of loop 1 is m1, and the display value of the host computer is n1. The normal measured value of the current of loop 1 is x1, and the display value of the host computer is y1.

[0052] If y1 is greater than x 1， It is judged that circuit 1 has an overcurrent or short circuit fault and recorded as parameter event F1;

[0053] If n1 is less than m 1， It is determined that circuit 1 has an overcurrent or short circuit fault and recorded as parameter event F2;

[0054] The other three circuits can use the same fault judgment method to determine the type of fault and record it as different parameter events;

[0055] (5) The current signal x collected by the acquisition unit is added with a reference z as the final value uploaded to the upload control unit, and then uploaded to the host computer for display. The reference z is a value far away from x1, x2, x3, x4, and x5. 4、 x1+x2, x1+x3, x1+x4, x2+x3, x2+x4, x3+x 4、 x1+x2+x3, x1+x2+x4, x2+x3+x4, x1+x3+x 4、 The value of x1+x2+x3+x4.

[0056] (6) The fault tree analysis method is used to establish the logical relationship between the fault and each parameter event. The fault event is H, and the related parameter events are E1, E2...En, F1, F2...Fn, G1, G2...Gn. The fault source is located through the Boolean logic expression H=h(E1, E2...En, F1, F2...Fn, G1, G2...Gn).

[0057] The beneficial effects of the present invention are as follows: the present invention proposes a new design concept and method, which uses an automatic data acquisition method to automatically collect voltage and current data. In addition, a collection unit is used to collect the voltage and current of the circuit according to different time periods, and the voltage and current electrical signals of the four-way output of the calibration power supply are displayed on the upper computer interface, thereby avoiding frequent opening of the spark ignition test device shell and frequent use of a multimeter to measure the four-way voltage and current respectively, saving manpower and material resources, and improving work efficiency, work quality, and measurement accuracy; the present invention utilizes the data of the upper computer and, through the fault judgment logical relationship, can self-diagnose faults in the four-way power supply circuit, including normal operation, single-way fault, double-way fault, and three-way fault mode, thereby increasing the automation and intelligence of measurement, improving work efficiency, and reducing the cost of daily maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1Schematic diagram of the structure of the multi-parameter electrical signal measurement and self-diagnosis system of the present invention;

[0059] Figure 2 is a schematic structural diagram of a second embodiment of the present invention;

[0060] Figure 3 is a schematic structural diagram of a third embodiment of the present invention;

[0061] Figure 4 2 is a schematic structural diagram of a fourth embodiment of the present invention. DETAILED DESCRIPTION

[0062] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more precise definition of the protection scope of the present invention.

[0063] Example 1:

[0064] like Figure 1 A multi-parameter electrical signal measurement and self-diagnosis system is shown, comprising an input unit, a loop, a switching circuit, an acquisition unit, an upload control unit, an output unit, and a host computer; the input unit is used to send voltage and current signals in the power supply loop; the switching circuit is connected to the input unit via the loop, and is used to receive the voltage and current signals sent by the input unit; the acquisition unit is connected to the switching circuit, and is used to acquire voltage signals and current signals and convert analog quantities into digital quantities; the upload control unit is respectively connected to the switching circuit, the acquisition unit, and the host computer, and is used to control the closing or opening of the loop through the switching circuit, and upload the digital quantity signals converted by the acquisition unit to the host computer; the output unit is connected to the acquisition unit, and is used to output the voltage signal and current signal acquired by the acquisition unit.

[0065] The acquisition unit contains two independent AD analog-to-digital sampling circuits, one for collecting voltage and the other for collecting current. The voltage and current signals in the power supply circuit are collected and transmitted to the host computer for display. In the default state, the switching circuit is in a closed state. The acquisition unit collects the voltage and current of the circuit, converts the analog quantity into digital quantity, and uploads it to the host computer for display.

[0066] Example 2:

[0067] The difference from the first embodiment is that this embodiment adopts dual-loop signal measurement, such as Figure 2As shown, there are loop 1, loop 2, switching circuit 1, and switching circuit 2. The voltage of loop 1 and loop 2 is the same, and the current of loop 1 and loop 2 is different. The uploading control unit controls the switching circuit 1 and the switching circuit 2 to realize the collection of the voltage and current parameters of the two input loops. For example, when it is necessary to measure the electrical parameters of loop 2, the host computer sends a command to the uploading control unit, the uploading control unit sends a command to the switching circuit 1 to disconnect loop 1, and the uploading control unit simultaneously sends a command to the switching circuit 2 to close loop 2. The collection unit converts the collected analog electrical signal of loop 2 into a digital quantity and transmits it to the uploading control unit. The uploading control unit uploads the electrical signal to the host computer, and the host computer displays the electrical signal uploaded by the uploading control unit.

[0068] Example 3:

[0069] The difference from the first embodiment is that this embodiment adopts three-loop signal measurement, such as Figure 3 As shown, there are loop 1, loop 2, loop 3, switching circuit 1, switching circuit 2, and switching circuit 3. The uploading control unit controls switching circuit 1, switching circuit 2, and switching circuit 3 to realize the collection of voltage and current electrical signal parameters of the three input loops. For example, when it is necessary to measure the electrical signal parameters of loop 3, the host computer sends a command to the uploading control unit, which sends a command to switching circuit 1 to disconnect loop 1; the uploading control unit simultaneously sends a command to switching circuit 2 to disconnect loop 2; the uploading control unit simultaneously sends a command to switching circuit 3 to close loop 3. The collection unit converts the collected analog electrical signal of loop 3 into a digital quantity and transmits it to the uploading control unit. The uploading control unit uploads the electrical signal to the host computer, and the host computer displays the electrical signal uploaded by the uploading control unit.

[0070] Example 4:

[0071] The difference from the first embodiment is that this embodiment uses four-loop signal measurement, such as Figure 4 As shown, there are loop 1, loop 2, loop 3, loop 4, switching circuit 1, switching circuit 2, switching circuit 3, and switching circuit 4. The uploading control unit controls the switching circuits 1, 2, 3, and 4 to realize the collection of voltage and current electrical signal parameters of the four input loops. For example, when it is necessary to measure the electrical signal parameters of loop 4, the host computer sends a command to the uploading control unit, which sends a command to the switching circuit 1 to disconnect loop 1; the uploading control unit simultaneously sends a command to the switching circuit 2 to disconnect loop 2; the uploading control unit simultaneously sends a command to the switching circuit 3 to disconnect loop 3; the uploading control unit simultaneously sends a command to the switching circuit 4 to close loop 4. The collection unit converts the collected analog electrical signal of loop 4 into a digital quantity and transmits it to the uploading control unit. The uploading control unit uploads the electrical signal to the host computer, and the host computer displays the electrical signal uploaded by the uploading control unit.

[0072] Embodiment 5:

[0073] The present invention further provides a fault diagnosis method based on the above-mentioned multi-parameter electrical signal measurement and self-diagnosis system. Taking the fourth embodiment as an example, the method specifically includes the following steps:

[0074] The input unit sends the voltage and current signals in the power circuit to the circuit.

[0075] The current flowing through loop one is x1, the current flowing through loop two is x2, the current flowing through loop three is x3, and the current flowing through loop four is x4. x1≠x2≠x3≠x4, that is, any two of x1, x2, x3, and x4 are not equal. x1+x2≠x1+x3≠x1+x4≠x2+x3≠x2+x4≠x3+x4, that is, the sum of any two of x1, x2, x3, and x4 is not equal. x1+x2+x3≠x1+x2+x4≠x2+x3+x4≠x1+x3+x4, that is, the sum of any three of x1, x2, x3, and x4 is not equal.

[0076] The upload control unit uploads the digital signal converted by the acquisition unit to the host computer. When measuring the current signal parameters of loop 1:

[0077] If the measurement display value of the host computer is y1=x1, it is judged that the circuit 1 and the switching circuit 1 are normal;

[0078] If the measured value is y2 = x1 + x2, it is determined that the switching circuit 2 is short-circuited and recorded as parameter event E1;

[0079] If the measured value is y3 = x1 + x3, the switching circuit is judged to have a triple short-circuit fault and recorded as parameter event E2;

[0080] If the measured value is y4 = x1 + x4, the switching circuit is judged to have a short-circuit fault and recorded as parameter event E3;

[0081] If the measured value is y5 = x1 + x2 + x3, it is determined that the switching circuit 2 and the switching circuit 3 are short-circuited and recorded as parameter event E4;

[0082] If the measured value is y6 = x1 + x2 + x3 + x4, it is determined that the switching circuit 2, switching circuit 3, and switching circuit 4 are short-circuited and recorded as parameter event E5;

[0083] If the measured value is y7 = x1 + x2 + x4, it is determined that the switching circuit 2 and the switching circuit 4 are short-circuited and recorded as parameter event E6;

[0084] If the measured value is y8 = x1 + x3 + x4, it is determined that the switching circuit 3 and the switching circuit 4 are short-circuited and recorded as parameter event E7;

[0085] When measuring the current signal parameters of loop 2 (different fault types are recorded as different parameter event type numbers):

[0086] If the measured value displayed by the host computer is y9=x2, it is judged that loop 2 and switching circuit 2 are normal;

[0087] If the measured value is y 10 =x1+x2, then it is determined that the switching circuit has a fault;

[0088] If the measured value is y 11 =x2+x3, then it is determined that the switching circuit has three faults;

[0089] If the measured value is y 12 =x2+x4, then it is determined that the switching circuit has four faults;

[0090] If the measured value is y 13 =x1+x2+x3, then it is determined that switching circuit 1 and switching circuit 3 are faulty;

[0091] If the measured value is y 14 =x1+x2+x3+x4, then it is determined that switching circuit 1, switching circuit 3, and switching circuit 4 are faulty;

[0092] If the measured value is y 15 =x1+x2+x4, then it is determined that switching circuit 1 and switching circuit 4 are faulty;

[0093] If the measured value is y 16 =x2+x3+x4, then it is determined that switching circuit three and switching circuit four are faulty;

[0094] When measuring the current signal parameters of loop three (different fault types are recorded as different parameter event type numbers):

[0095] If the measurement display value of the host computer is y 17 =x3, then it is judged that loop three and switching circuit three are normal;

[0096] If the measured value is y 18 =x1+x3, then it is determined that the switching circuit has a fault;

[0097] If the measured value is y 19 =x2+x3, then it is determined that the switching circuit 2 is faulty;

[0098] If the measured value is y 20 =x3+x4, then it is determined that the switching circuit 4 is faulty;

[0099] If the measured value is y 21 =x1+x2+x3, then it is determined that switching circuit 1 and switching circuit 2 are faulty;

[0100] If the measured value is y 22 =x1+x2+x3+x4, then it is determined that switching circuit 1, switching circuit 2, and switching circuit 4 are faulty;

[0101] If the measured value is y 23 =x1+x3+x4, then it is determined that switching circuit 1 and switching circuit 4 are faulty;

[0102] If the measured value is y 24 =x2+x3+x4, then it is determined that switching circuit 2 and switching circuit 4 are faulty;

[0103] When measuring the current signal parameters of loop 4 (different fault types are recorded as different parameter event type numbers):

[0104] If the measurement display value of the host computer is y 25 =x4, then loop 4 and the switching circuit are judged to be normal;

[0105] If the measured value is y 26 =x1+x4, then it is determined that the switching circuit has a fault;

[0106] If the measured value is y 27 =x2+x4, then it is determined that the switching circuit 2 is faulty;

[0107] If the measured value is y 28 =x3+x4, then it is determined that the switching circuit has three faults;

[0108] If the measured value is y 29 =x1+x2+x4, then it is determined that switching circuit 1 and switching circuit 2 are faulty;

[0109] If the measured value is y 30 =x1+x2+x3+x4, then it is determined that switching circuit 1, switching circuit 2, and switching circuit 3 are faulty;

[0110] If the measured value is y 31 =x1+x3+x4, then it is determined that switching circuit 1 and switching circuit 3 are faulty;

[0111] If the measured value is y 32 =x2+x3+x4, then it is determined that switching circuit 2 and switching circuit 3 are faulty.

[0112] Furthermore, the normal measured value of the voltage of loop 1 is m1, and the display value of the host computer is n1. The normal measured value of the current of loop 1 is x1, and the display value of the host computer is y1.

[0113] If y1 is greater than x 1， It is judged that circuit 1 has an overcurrent or short circuit fault and recorded as parameter event F1;

[0114] If n1 is less than m 1， It is determined that circuit 1 has an overcurrent or short circuit fault and recorded as parameter event F2;

[0115] The other three circuits can use the same fault judgment method to determine the type of fault and record it as different parameter events.

[0116] Furthermore, the current signal x collected by the acquisition unit is added with a reference z as the final value uploaded to the upload control unit, and then uploaded to the host computer for display. The reference z is a value far away from x1, x2, x3, x4, and x5. 4、 x1+x2, x1+x3, x1+x4, x2+x3, x2+x4, x3+x 4、 x1+x2+x3, x1+x2+x4, x2+x3+x4, x1+x3+x 4、 The value of x1+x2+x3+x4. For example: when collecting the current signal of power circuit 1, if the value displayed by the host computer is z+x1, it can be judged that the current collection of power circuit 1 is normal; if the value displayed by the host computer is z, then the power circuit 1 is open circuit fault, the collection circuit is normal, and it is recorded as parameter event G1; if the value displayed by the host computer is 0, then the collection circuit is open circuit fault, and it is recorded as parameter event G2;

[0117] For other power supply circuits and acquisition circuits, this method can be used to determine whether the fault type is a power supply circuit open circuit fault or an acquisition circuit open circuit fault.

[0118] Finally, the present invention adopts the fault tree analysis method to establish the logical relationship between the fault and each parameter event. The fault event is H, and the related parameter events are E1, E2...En, F1, F2...Fn, G1, G2...Gn. The fault source is located through the Boolean logic expression H=h(E1, E2...En, F1, F2...Fn, G1, G2...Gn).

[0119] Finally, it should be noted that the above embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above embodiments within the technical scope disclosed by the present invention, or replace some of the technical features therein with equivalents. Such modifications, changes or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A multi-parameter electrical signal measurement and self-diagnosis system, characterized by: It includes input unit, loop, switching circuit, acquisition unit, upload control unit, output unit and host computer; The input unit is used to send voltage and current signals in the power supply circuit; The switching circuit is connected to the input unit via a loop, and is used to receive voltage and current signals sent by the input unit; The acquisition unit is connected to the switching circuit and is used to acquire voltage signals and current signals and convert analog quantities into digital quantities; The upload control unit is connected to the switching circuit, the acquisition unit, and the host computer respectively, and is used to control the closing or opening of the loop through the switching circuit, and upload the digital signal converted by the acquisition unit to the host computer; The output unit is connected to the acquisition unit and is used to output the voltage signal and current signal acquired by the acquisition unit.

2. The multi-parameter electrical signal measurement and self-diagnosis system according to claim 1, characterized in that: The loop and the switching circuit each have multiple paths, and each switching circuit is connected to one loop.

3. The multi-parameter electrical signal measurement and self-diagnosis system according to claim 2, characterized in that: The loop and the switching circuit each have four paths.

4. A fault diagnosis method for a multi-parameter electrical signal measurement and self-diagnosis system according to claim 3, characterized in that: The steps include: (1) The input unit sends the voltage and current signals in the power circuit to the circuit; (2) The current flowing through loop one is x1, the current flowing through loop two is x2, the current flowing through loop three is x3, and the current flowing through loop four is x4. x1≠x2≠x3≠x4, that is, any two of x1, x2, x3, and x4 are not equal. x1+x2≠x1+x3≠x1+x4≠x2+x3≠x2+x4≠x3+x4, that is, the sum of any two of x1, x2, x3, and x4 is not equal. x1+x2+x3≠x1+x2+x4≠x2+x3+x4≠x1+x3+x4, that is, the sum of any three of x1, x2, x3, and x4 is not equal. (3) The upload control unit uploads the digital signal converted by the acquisition unit to the host computer. When measuring the current signal parameters of loop 1: If the measurement display value of the host computer is y1=x1, it is judged that the circuit 1 and the switching circuit 1 are normal; If the measured value is y2 = x1 + x2, it is determined that the switching circuit 2 is short-circuited and recorded as parameter event E1; If the measured value is y3 = x1 + x3, the switching circuit is judged to have a triple short-circuit fault and recorded as parameter event E2; If the measured value is y4 = x1 + x4, the switching circuit is judged to have a short-circuit fault and recorded as parameter event E3; If the measured value is y5 = x1 + x2 + x3, it is determined that the switching circuit 2 and the switching circuit 3 are short-circuited and recorded as parameter event E4; If the measured value is y6 = x1 + x2 + x3 + x4, it is determined that the switching circuit 2, switching circuit 3, and switching circuit 4 are short-circuited and recorded as parameter event E5; If the measured value is y7 = x1 + x2 + x4, it is determined that the switching circuit 2 and the switching circuit 4 are short-circuited and recorded as parameter event E6; If the measured value is y8 = x1 + x3 + x4, it is determined that the switching circuit 3 and the switching circuit 4 are short-circuited and recorded as parameter event E7; When measuring the current signal parameters of loop 2: If the measured value displayed by the host computer is y9=x2, it is judged that loop 2 and switching circuit 2 are normal; If the measured value is y 10 =x1+x2, then it is determined that the switching circuit has a fault; If the measured value is y 11 =x2+x3, then it is determined that the switching circuit has three faults; If the measured value is y 12 =x2+x4, then it is determined that the switching circuit has four faults; If the measured value is y 13 =x1+x2+x3, then it is determined that switching circuit 1 and switching circuit 3 are faulty; If the measured value is y 14 =x1+x2+x3+x4, then it is determined that switching circuit 1, switching circuit 3, and switching circuit 4 are faulty; If the measured value is y 15 =x1+x2+x4, then it is determined that switching circuit 1 and switching circuit 4 are faulty; If the measured value is y 16 =x2+x3+x4, then it is determined that switching circuit three and switching circuit four are faulty; When measuring the current signal parameters of loop three: If the measurement display value of the host computer is y 17 =x3, then it is judged that loop three and switching circuit three are normal; If the measured value is y 18 =x1+x3, then it is determined that the switching circuit has a fault; If the measured value is y 19 =x2+x3, then it is determined that the switching circuit 2 is faulty; If the measured value is y 20 =x3+x4, then it is determined that the switching circuit 4 is faulty; If the measured value is y 21 =x1+x2+x3, then it is determined that switching circuit 1 and switching circuit 2 are faulty; If the measured value is y 22 =x1+x2+x3+x4, then it is determined that switching circuit 1, switching circuit 2, and switching circuit 4 are faulty; If the measured value is y 23 =x1+x3+x4, then it is determined that switching circuit 1 and switching circuit 4 are faulty; If the measured value is y 24 =x2+x3+x4, then it is determined that switching circuit 2 and switching circuit 4 are faulty; When measuring the current signal parameters of loop four: If the measurement display value of the host computer is y 25 =x4, then loop 4 and the switching circuit are judged to be normal; If the measured value is y 26 =x1+x4, then it is determined that the switching circuit has a fault; If the measured value is y 27 =x2+x4, then it is determined that the switching circuit 2 is faulty; If the measured value is y 28 =x3+x4, then it is determined that the switching circuit has three faults; If the measured value is y 29 =x1+x2+x4, then it is determined that switching circuit 1 and switching circuit 2 are faulty; If the measured value is y 30 =x1+x2+x3+x4, then it is determined that switching circuit 1, switching circuit 2, and switching circuit 3 are faulty; If the measured value is y 31 =x1+x3+x4, then it is determined that switching circuit 1 and switching circuit 3 are faulty; If the measured value is y 32 =x2+x3+x4, then it is determined that switching circuit 2 and switching circuit 3 are faulty; (4) The normal measured value of the voltage of loop 1 is m1, and the display value of the host computer is n1. The normal measured value of the current of loop 1 is x1, and the display value of the host computer is y1. If y1 is greater than x 1， It is judged that circuit 1 has an overcurrent or short circuit fault and recorded as parameter event F1; If n1 is less than m 1， It is determined that circuit 1 has an overcurrent or short circuit fault and recorded as parameter event F2; The other three circuits can use the same fault judgment method to determine the type of fault and record it as different parameter events; (5) The current signal x collected by the acquisition unit is added with a reference z as the final value uploaded to the upload control unit, and then uploaded to the host computer for display. The reference z is a value far away from x1, x2, x3, x4, and x5. 4、 x1+x2, x1+x3, x1+x4, x2+x3, x2+x4, x3+x 4、 x1+x2+x3, x1+x2+x4, x2+x3+x4, x1+x3+x 4、 The value of x1+x2+x3+x4; (6) The fault tree analysis method is used to establish the logical relationship between the fault and each parameter event. The fault event is H, and the related parameter events are E1, E2...En, F1, F2...Fn, G1, G2...Gn. The fault source is located through the Boolean logic expression H=h(E1, E2...En, F1, F2...Fn, G1, G2...Gn).

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