A multi-core cable testing circuit and testing method

Abstract

The present invention belongs to the technical field of multi-core cable testing, and particularly relates to a multi-core cable testing circuit and a testing method. The upper contacts of the left-end coils of N input relays are all connected to a high-voltage power supply U through a first switch and a second resistor HV in communication; the lower contacts of the left-end coils are all connected to a constant current source through a second single-pole double-throw switch or grounded through a third resistor; the upper contacts of the right-end coils of the N input relays are all floating, and the lower contacts of the right-end coils are respectively connected to an ADC voltage acquisition circuit; the upper contacts of the left-end coils of the N output relays are all floating, and the lower contacts of the left-end coils are respectively connected to an ADC voltage acquisition circuit; the upper contacts of the right-end coils of the N output relays are all connected to the high-voltage power supply U through a first switch and a second resistor HV in communication; the lower contacts of the right-end coils are all directly grounded through a third single-pole double-throw switch or grounded through a fourth resistor; the common contacts of the left-end coils and the common contacts of the right-end coils of the input relays and the output relays are respectively connected to the same test point.

Description

Technical Field

[0001] The present invention belongs to the technical field of cable testing, and particularly relates to a multi-core cable testing circuit and a testing method. Background Technique

[0002] With the rapid development of the fields of aircraft and missile technologies. During the production process, various types of cables are often used. To ensure the accuracy of manufacturing and installation, we usually use testing equipment to detect the short circuits and open circuits of the cables.

[0003] Since the current testers on the market are mainly targeted at the commercial market and are not well applicable to the military industry. First, the cable tester has only a limited number of core wire interfaces, which are not only small in number but also lack scalability and cannot meet the growing needs of cable testing; second, due to the single form and type of the interfaces, if it is necessary to test various different types of cables, additional adapter cables need to be made, resulting in an increase in the complexity of the operation and the inability to measure the short circuit situation of the core wires inside the same connector; third, since most of the testers are oriented to the relatively simple wire harness relationships in the commercial field and generally adopt a polling test method, when facing the complex wire harness connection relationships in the military industry, especially in the fields of aircraft and missiles, the test time is long and it is difficult to meet the usage requirements. Summary of the Invention

[0004] Object of the present invention:

[0005] To provide a multi-core cable testing circuit and a testing method to solve the problems existing in the background technique.

[0006] The technical solution adopted by the present invention to solve its technical problems is:

[0007] A multi-core cable testing circuit includes: 2N double-coil magnetic latching relays, 4N first resistors, a second resistor, a third resistor, a fourth resistor, a constant current source, a high-voltage power supply U HV , N input test points, N output test points, and 2N ADC voltage acquisition circuits;

[0008] The 2N double-coil magnetic latching relays are divided into N input relays and N output relays;

[0009] The upper contacts 3 of the left coils of the N input relays are all connected to the high-voltage power supply U through a first switch and the second resistor HV and are connected; the lower contacts 5 of the left coils are all connected to the common terminal of the second single-pole double-throw switch. One fixed terminal of the second single-pole double-throw switch is connected to the constant current source, and the other fixed terminal is grounded through the third resistor; the upper contacts 10 of the right coils of the N input relays are all floating, and the lower contacts 8 of the right coils are respectively connected to one ADC voltage acquisition circuit;

[0010] The upper contacts 3 of the left - hand coils of N output relays are all floating, and the lower contacts 5 of the left - hand coils are respectively connected to an ADC voltage acquisition circuit; the upper contacts 10 of the right - hand coils of N output relays are all connected to the high - voltage power supply U through a first switch and a second resistor HV in communication; the lower contacts 8 of the right - hand coils are all connected to the common terminal of a third single - pole double - throw switch. One fixed terminal of the third single - pole double - throw switch is directly grounded, and the other fixed terminal is grounded through a fourth resistor;

[0011] The common contact 4 of the left - hand coil and the common contact 9 of the right - hand coil of the same input relay are respectively connected to the same input test point through a first resistor;

[0012] The common contact 4 of the left - hand coil and the common contact 9 of the right - hand coil of the same output relay are respectively connected to the same output test point through a first resistor.

[0013] Furthermore, the N input test points are integrated through an N - way input connector, and the N output test points are integrated through an N - way output connector.

[0014] A multi - core cable testing method, which is implemented through the above - mentioned circuit. The method includes:

[0015] Step 1: Connect the two ends of the multi - core cable to the N input test points and the N output test points respectively;

[0016] Step 2: Control the first switch to be disconnected, switch the second single - pole double - throw switch to connect to the constant - current source, and switch the third single - pole double - throw switch to be directly grounded;

[0017] Step 3: Select a certain core as the test core, and the input relay connected to the test core as the test relay. Drive the common contact (4) and the lower contact (5) of the left - hand coil of the test relay to be connected, and the common contact (9) and the lower contact (8) of the right - hand coil to be connected. Drive the common contact (4) and the upper contact (3) of the left - hand coil of other input relays to be connected, and the common contact (9) and the upper contact (10) of the right - hand coil to be connected;

[0018] Step 4: Drive the common contact (4) and the lower contact (5) of the left - hand coil of all output relays to be connected, and the common contact (9) and the lower contact (8) of the right - hand coil to be connected;

[0019] Step 5: Collect the voltage data of the ADC voltage acquisition circuit connected to the test relay selected in Step 3 and the N ADC voltage acquisition circuits connected to the N output relays;

[0020] Step 6: If there are multiple non-zero voltage data among the voltage data collected by the N-channel ADC voltage acquisition circuits connected to the N-channel output relays, it is considered that the wire cores connected to the test points corresponding to the non-zero data are all connected to the wire cores connected to the test relays.

[0021] Further, the method further includes: Step 7: Calculate the conduction resistance of the wire core corresponding to the test relay according to the voltage data collected in Step 5.

[0022] Further, in the said Step 7, the conduction resistance calculation formula is as follows:

[0023]

[0024] Wherein, U T1 is the acquisition voltage value of the ADC voltage acquisition circuit corresponding to the test relay, U TX is any voltage value among the non-zero voltage data in the output relay, and I is the constant current source current value.

[0025] Further, the method further includes: Step 8: Switch the second single-pole double-throw switch to ground through the third resistor, and switch the third single-pole double-throw switch to ground through the fourth resistor;

[0026] Step 9: Drive the common contact (4) of the left coil of the test relay selected in Step 3 to connect with the upper contact (3), and the common contact (9) of the right coil to connect with the upper contact (10). Drive the common contact (4) of the left coil of other input relays to connect with the lower contact (5), and the common contact (9) of the right coil to connect with the lower contact (8);

[0027] Switch the common contact (4) of the left coil of the output relays corresponding to all the wire cores determined to be connected to the test wire core in Step 6 to connect with the upper contact (3), and the common contact (9) of the right coil to connect with the upper contact (10). Drive the common contact (4) of the left coil of other output relays to connect with the lower contact (5), and the common contact (9) of the right coil to connect with the lower contact (8);

[0028] Step 10: Control the first switch to turn on; collect the voltage values of the ADC voltage acquisition circuits of the output relays corresponding to all the wire cores that have no connection with the test wire core, and calculate the insulation resistance between the test wire core and the wire cores that have no connection with the test wire core.

[0029] Further, in the said Step 10, the calculation method of the insulation resistance value between any wire core that has no connection with the test wire core and the test wire core is as follows:

[0030]

[0031] Wherein, U HVis the high-voltage power supply U HV is the voltage value, R4 is the resistance value of the fourth resistor, U ADC is the voltage value of the output relay ADC voltage acquisition circuit corresponding to any wire core that has no connection relationship with the test wire core.

[0032] Further, step eleven: Repeat steps two to ten, and sequentially select different fixed wire cores as the test wire cores to complete the testing of all wire cores of the multi-core cable.

[0033] Beneficial effects:

[0034] Through the form of adding switches, this test circuit realizes the effective separation between the high-voltage and low-voltage circuits. At the same time, through reasonable parameter settings, it effectively protects the low-voltage components in the high-voltage state, enabling this circuit to have multiple functions such as testing the cable connection relationship, conduction resistance, and insulation resistance. Description of the drawings

[0035] Figure 1 is a schematic diagram of the multi-core cable test circuit;

[0036] Figure 2 is a schematic diagram of the conduction resistance test principle of the cable test circuit;

[0037] Figure 3 is a schematic diagram of the insulation resistance test principle of the cable test circuit. Specific implementation manners

[0038] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0039] This circuit is mainly aimed at the relatively complex cables on airplanes and missiles, and can test the connection relationship, conduction resistance, and relative insulation resistance between the wire cores of the cables.

[0040] As Figure 1 shown, this test circuit has K1 to K n , n relays as the input relays for testing, C1 to C n , n relays as the output relays for testing, and also has a constant current source, a high-voltage power supply, two single-pole double-throw switches, a single-pole single-throw switch, and is configured with 4n first resistors, 1 second resistor, 1 third resistor, and 1 fourth resistor. Two connectors with n wire core connection points. Each of the 2 connectors has n wire core connection points. When testing, the two ends of the cable to be tested need to be connected to the two connectors respectively and tightened.

[0041] K1 to Kn , C1 to C n is a double-coil, magnetic latching relay. The 1st, 6th; 7th, 12th pins of the relay are drive pins. The pins 3, 4, 5, 8, 9, 10 are coil contacts. If the 1st, 6th pins are driven, the coil contacts between 3 and 4, and between 9 and 10 are conducting; if the 7th, 12th pins are driven, the contacts between pins 4 and 5, and between coil contacts 8 and 9 are conducting;

[0042] There are two connection methods for the relay on the test circuit. One is that the 5th pin of the relay is selected by the circuit switch to be connected to a 50 mA constant current source or grounded through a 500 Ω resistor, such as Figure 1 K1 to K n ; the other is that the 8th pin of the relay is selected by the circuit switch to be directly grounded or grounded through a 500 Ω resistor, such as Figure 1 C1 to C n .

[0043] When conducting a test, the two ends of the cable need to be fixed to the corresponding connector 1 and connector 2 through a connector. The two ends of the core 1 in the cable are respectively connected to the TEST1 and TEST2 test points through wires, and the two ends of the core 2 in the cable are respectively connected to the TEST n , TEST 2n test points. Taking the core 1 and core 2 in the cable as examples, the test methods for their connection relationship, conduction resistance, and insulation resistance are described below.

[0044] ① The circuit operation steps for the connection relationship and conduction resistance test are as follows:

[0045] When testing the connection relationship and conduction resistance, switch 1 is disconnected from the high-voltage power supply U HV , switch 2 is selected to be connected to a 50 mA constant current source, and switch 3 is selected to be directly connected to ground;

[0046] Drive the 7th and 12th pins of any one of the test relays (such as K1) to make the contacts between pins 4 and 5, and between pins 8 and 9 conducting, and drive the 7th and 12th pins of all the output relays (C1 to C n ) in the drive circuit to make the contacts between pins 4 and 5, and between pins 8 and 9 conducting.

[0047] At this time, the ADC channel of the test relay collects the voltage and records it as U T1 , the voltage data of the N-channel ADC voltage acquisition circuits connected to the N output relays are recorded as U Tn , and the non-zero value among them is recorded as U TX . If there are multiple non-zero U Tn , it indicates that there is a short circuit at multiple points, and record the test points where multiple short circuits occur. Due to the short circuit between multiple points, the measured voltage UTn The values are consistent.

[0048] If TEST is detected n There is a certain connection relationship with the core wire under test. At this time, the test circuit is simplified as Figure 2 shown. A current of 50 mA flows into one end of the core wire under test of the cable, and the voltage collected by the ADC corresponding to pin 8 of relay K1 is denoted as U T1 ; the voltage collected by the ADC corresponding to pin 5 of relay C1 is denoted as U T3 . Since the current I is a constant value of 50 mA, the conduction resistance R of the core wire under test can be obtained 测 ,

[0049] where U T1 is the voltage acquisition value of the ADC voltage acquisition circuit corresponding to the test relay, Y TX is any voltage value among the non-zero voltage data in the output relay, and I is the constant current source current value.

[0050] ② Insulation resistance test

[0051] Before conducting the insulation resistance test, it is necessary to first conduct a connection relationship test.

[0052] The insulation resistance between cables is generally 5 MΩ to 1 GΩ, and the high-voltage power supplies used are two gears of 500 V and 1000 V.

[0053] As Figure 1 shown, when conducting the insulation resistance test, both switch 2 and switch 3 are selected to be grounded through a 500 Ω resistor.

[0054] Taking the insulation resistance test between core wire 1 and core wire n as an example, drive relay K1 to make it conductive between 3 and 4 (9 and 10); drive relay K corresponding to any core wire n that has no connection relationship with the core wire 1 under test n and C n select to be conductive between pins 4 and 5, and between pins 8 and 9. At this time, switch 1 is closed, and the simplified circuit diagram is as Figure 3 shown. Denote the values collected by ADC n and ADC 2n of the ADC acquisition channel as U ADC . (Since ADC n and ADC 2n are connected through core wire n, the collected voltage values are consistent). Therefore, the insulation resistance value of test core wire 1 relative to core wire n is

[0055] It should be noted that the insulation resistance value is a relative value. If the position of the core wire in the cable changes, the insulation resistance value will also change.

[0056] If the insulation outside the core wire is punctured and a short - circuit occurs during the test, then at this time, it is equivalent to a short - circuit existing between the two core wires. Under the condition of a 1000V voltage, the voltage at the test point is estimated to be about

[0057] Under this voltage condition, selecting appropriate circuit parameters such as an ADC chip or taking appropriate circuit protection can avoid damage to the components.

[0058] After the above - mentioned test is carried out, the tester can send the corresponding test data to the host computer. After receiving the test data, the host computer will display the data on the software, and the user can choose to save the test results as needed.

[0059] The first resistor is 68Ω, the second resistor is 100kΩ, the third resistor is 500Ω, and the fourth resistor is 500Ω.

Claims

1. A multi-core cable test circuit, characterized in that: The circuit includes: 2N double-coil magnetic latching relays, 4N first resistors, a second resistor, a third resistor, a fourth resistor, a constant current source, and a high-voltage power supply U HV , N input test points, N output test points, and 2N ADC voltage acquisition circuits; The 2N double - coil magnetic latching relays are divided into N input relays and N output relays; The upper contacts (3) of the left coils of N input relays are all connected to the high-voltage power supply U through the first switch and the second resistor. HV They are connected; the lower contacts (5) of the left coils are all connected to the common terminal of the second single-pole double-throw switch. One fixed terminal of the second single-pole double-throw switch is connected to the constant current source, and the other fixed terminal is grounded through the third resistor; the upper contacts (10) of the right coils of N input relays are all floating, and the lower contacts (8) of the right coils are respectively connected to an ADC voltage acquisition circuit. The upper contacts (3) of the left - hand coils of N output relays are all floating, and the lower contacts (5) of the left - hand coils are respectively connected to an ADC voltage acquisition circuit; the upper contacts (10) of the right - hand coils of N output relays are all connected to the high - voltage power supply U through a first switch and a second resistor HV to be connected; the lower contacts (8) of the right - hand coils are all connected to the common terminal of a third single - pole double - throw switch. One fixed terminal of the third single - pole double - throw switch is directly grounded, and the other fixed terminal is grounded through a fourth resistor; The common contacts (4) of the left - hand coils and the common contacts (9) of the right - hand coils of the same input relay are respectively connected to the same input test point through a first resistor; The common contacts (4) of the left - hand coils and the common contacts (9) of the right - hand coils of the same output relay are respectively connected to the same output test point through a first resistor.

2. The multi-core cable testing circuit according to claim 1, characterized in that: The N input test points are integrated through an N - way input connector, and the N output test points are integrated through an N - way output connector.

3. A multi-core cable testing method, which is implemented by the circuit described in any one of claims 1-2, and is characterized in that: The method includes: Step 1: Connect both ends of the multi - core cable to the N input test points and the N output test points respectively; Step 2: Control the first switch to be off, switch the second single - pole double - throw switch to connect to the constant current source, and switch the third single - pole double - throw switch to directly ground; Step 3: Select a certain core as the test core, and the input relay connected to the test core as the test relay. Drive the common contact (4) of the left - hand coil of the test relay to connect to the lower contact (5), and the common contact (9) of the right - hand coil to connect to the lower contact (8). Drive the common contacts (4) of the left - hand coils of other input relays to connect to the upper contact (3), and the common contacts (9) of the right - hand coils to connect to the upper contact (10); Step 4: Drive the common contacts (4) of the left - hand coils of all output relays to connect to the lower contact (5), and the common contacts (9) of the right - hand coils to connect to the lower contact (8); Step 5: Collect the voltage data of an ADC voltage acquisition circuit connected to the test relay selected in Step 3 and the N ADC voltage acquisition circuits connected to the N output relays; Step 6: If there are multiple non - zero data among the voltage data collected by the N ADC voltage acquisition circuits connected to the N output relays, it is considered that the cores corresponding to the non - zero data - connected test points are all connected to the core connected to the test relay; Step 7: Calculate the on - resistance of the core corresponding to the test relay according to the voltage data collected in Step 5; Step 8: Switch the second single - pole double - throw switch to ground through the third resistor, and switch the third single - pole double - throw switch to ground through the fourth resistor; Step 9: Drive the common contact (4) of the left - hand coil of the test relay selected in Step 3 to connect to the upper contact (3), and the common contact (9) of the right - hand coil to connect to the upper contact (10). Drive the common contacts (4) of the left - hand coils of other input relays to connect to the lower contact (5), and the common contacts (9) of the right - hand coils to connect to the lower contact (8); Switch the left - hand coils of all output relays corresponding to the cores determined to be connected to the test core in Step 6 to have the common contact (4) connect to the upper contact (3), and the common contact (9) of the right - hand coils to connect to the upper contact (10). Drive the common contacts (4) of the left - hand coils of other output relays to connect to the lower contact (5), and the common contacts (9) of the right - hand coils to connect to the lower contact (8); Step Ten: Control the first switch to turn on; collect the voltage values of the output relay ADC voltage acquisition circuits corresponding to all the cores that have no connection relationship with the test core, and calculate the insulation resistance between the test core and the cores that have no connection relationship with the test core.

4. The multi-core cable testing method according to claim 3, wherein: In the seventh step described above, the conduction resistance calculation formula is as follows: Among them, U T1 is the collected voltage value of the ADC voltage acquisition circuit corresponding to the test relay, and U TX is any voltage value among the non-zero voltage data in the output relay, and I is the constant current source current value.

5. The multi-core cable testing method according to claim 4, wherein: In the tenth step described above, the calculation method of the insulation resistance value between any core that has no connection relationship with the test core and the test core is as follows: Among them, U HV is the high-voltage power supply U HV voltage value, R4 is the resistance value of the fourth resistor, and U ADC is the voltage value of the output relay ADC voltage acquisition circuit corresponding to any wire core that has no connection relationship with the test wire core.

6. The multi-core cable testing method according to claim 5, characterized in that: Step Eleven: Repeat steps two to ten, and sequentially select different fixed cores as the test cores to complete the testing of all cores of the multi-core cable.

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