A test circuit for verifying the lightning protection capability of a signal surge protector

Abstract

A test circuit for verifying the lightning protection capability of a signal surge protector, comprising a lightning surge generator and a signal surge protector, characterized in that: it also comprises a chip 74LS00, a battery, a light emitting diode, and an inductor, wherein the A end and the B end of the chip 74LS00 are connected to the protected line terminals Y1 and Y2 of the signal surge protector, the VCC end thereof is connected to the positive electrode of the battery 4‑1, the Y end thereof and the GND end thereof are respectively connected to the positive electrode and the negative electrode of the light emitting diode, and the positive and negative electrodes of the battery 4‑2 are respectively connected to the line terminals X1 and X2 of the signal surge protector through the inductors 6‑1 and 6‑2. The circuit utilizes the low-priced chip 74LS00 to simulate the protected device of the signal surge protector, verifies the protection capability of the signal surge protector by the quality of the chip, has the characteristics of remarkable effect, economy and practicality, and is suitable for verifying the ability of the signal surge protector to protect the back-end equipment, especially the precision electronic equipment.

Description

Technical Field

[0001] The invention relates to a test circuit, in particular to a test circuit for verifying the lightning surge protection capability of a signal surge protector. Background Art

[0002] The signal surge protector is installed at the front end of the protected signal equipment. It protects the back-end equipment from being damaged by lightning by discharging the lightning current into the ground and limiting the voltage at both ends of the protected equipment to the tolerance range of the equipment. At present, the laboratory verification method for the lightning protection function of the signal surge protector is: according to the test circuit of 6.2.1.3 in GB / T18802.1-2016, the back end of the signal surge protector is connected to the voltage divider, and a lightning surge generator is used to apply a current or voltage of a specified waveform and amplitude at both ends of the signal surge protector to test its voltage protection level. The voltage protection level represents the characteristic parameter of the signal surge protector to limit the voltage at both ends. This parameter can indirectly reflect the protection capability of the back-end equipment. However, in actual applications, the signal surge protector is connected to the back-end protected equipment. When lightning occurs, the signal surge protector should play a lightning protection role for the entire circuit loop. Therefore, when doing laboratory tests to verify the lightning protection function of the signal surge protector, if it can be actually connected to the back-end equipment before testing, it will greatly increase the reliability of its performance. If real instruments and other equipment are used for simulation tests, the cost is very high and difficult to implement. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a test circuit for verifying the lightning protection capability of a signal surge protector. The circuit solves the problem that in laboratory tests, the signal surge protector can be connected to the rear-end protected equipment to form a complete protected circuit before implementing a lightning protection test, thereby increasing the reliability of its performance. The circuit is also very economical and has strong operability.

[0004] The technical solution adopted by the present invention to solve the technical problem is:

[0005] A test circuit for verifying the lightning protection capability of a signal surge protector comprises: a lightning surge generator (1) and a signal surge protector (2), and is characterized in that: it also comprises a chip 74LS00 (3), a battery (4-1), a battery (4-2), a light-emitting diode (5), an inductor (6-1), and an inductor (6-2); the positive electrode of the battery (4-2) is connected to the line terminal X1 of the signal surge protector (2) through the inductor (6-1), and the negative electrode of the battery (4-2) is connected to the line terminal X2 of the signal surge protector (2) through the inductor (6-2); The protected line terminals Y1 and Y2 of the signal surge protector (2) are respectively connected to the A terminal and the B terminal of the chip 74LS00 (3); the VCC terminal of the chip 74LS00 (3) is connected to the positive electrode of the battery (4-1); the positive electrode and the negative electrode of the light-emitting diode (5) are respectively connected to the Y terminal and the GND terminal of the chip 74LS00 (3); the negative electrode of the battery (4-2), the ground terminal of the signal surge protector (2), the negative electrode of the light-emitting diode (5), the GND terminal of the chip 74LS00 (3), and the negative electrode of the battery (4-1) are respectively connected to the grounding point PE.

[0006] Features and advantages of the present invention:

[0007] A test circuit for verifying the lightning protection capability of a signal surge protector, wherein the chip of the weakest part of an electronic device is selected to simulate the protected signal device, and after forming a simulation circuit connecting the signal surge protector and the subsequent protected device, a discharge current or voltage of a specified waveform and magnitude is applied to the signal surge protector, and the normal and fault states of the chip are judged by observing the working state of the light-emitting diode indicator light, so as to verify the lightning protection capability of the signal surge protector for the subsequent protected device. This test circuit can more accurately and reliably verify the lightning protection capability of the signal surge protector than simply applying voltage or current to the signal surge protector without connecting the subsequent protection device, and the chip is easy to obtain and the cost is very low. The chip is the weakest part of the electronic device, and using the chip as the back-end protection device of the signal surge protector to verify the lightning protection capability of the signal surge protector will undoubtedly make the verification results of the lightning protection capability of other signal surge protectors more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a test circuit connection schematic diagram of the present invention. DETAILED DESCRIPTION

[0009] As attached Figure 1 As shown, the signal surge protector (2) as the tested product may be a two-terminal signal surge protector for protecting two or more signal lines.

[0010] Before testing, select any two signal lines of the product to be tested for connection. Figure 1 As shown, the positive electrode of the battery (4-2) is connected to the line terminal X1 of the signal surge protector (2) through the inductor (6-1), and the negative electrode of the battery (4-2) is connected to the line terminal X2 of the signal surge protector (2) through the inductor (6-2); the protected line terminals Y1 and Y2 of the signal surge protector (2) are respectively connected to the A terminal and the B terminal of the chip 74LS00 (3); the VCC terminal of the chip 74LS00 (3) is connected to the positive electrode of the battery (4-1); the positive electrode and the negative electrode of the light-emitting diode (5) are respectively connected to the Y terminal and the GND terminal of the chip 74LS00 (3); the negative electrode of the battery (4-2), the ground terminal of the signal surge protector (2), the negative electrode of the light-emitting diode (5), the GND terminal of the chip 74LS00 (3), and the negative electrode of the battery (4-1) are respectively connected to the grounding point PE.

[0011] When a current or voltage of a specified waveform and magnitude is applied to X1-PE of the signal surge protector (2), the X1 terminal is connected to the lightning surge generator (1) through a wire or a test probe, and the lightning surge generator (1) is grounded. During the test, the normality or damage of the chip 74LS00 (3) is understood through the indication of the light-emitting diode (5). If the chip 74LS00 (3) is normal, it means that the signal surge protector (2) has the lightning surge protection capability. Otherwise, it means that the signal surge protector (2) does not have the lightning surge protection capability.

[0012] When a current or voltage of a specified waveform and magnitude is applied to X2-PE of the signal surge protector (2), the X2 terminal is connected to the lightning surge generator (1) through a wire or a test probe, and the lightning surge generator (1) is grounded. During the test, the normality or damage of the chip 74LS00 (3) is understood through the indication of the light-emitting diode (5). If the chip 74LS00 (3) is normal, it means that the signal surge protector (2) has the lightning surge protection capability. Otherwise, it means that the signal surge protector (2) does not have the lightning surge protection capability.

[0013] The implementation principle of the present invention is as follows: when the chip 74LS00 (3) works normally, the positive electrode and the negative electrode of the battery (4-2) respectively give a high level and a low level to the A terminal and the B terminal of the chip 74LS00 (3). The chip 74LS00 (3) is a NAND gate integrated circuit. If the A terminal is at a high level and the B terminal is at a low level, the Y terminal is at a high level. Therefore, when the chip 74LS00 (3) works normally, the light emitting diode (5) lights up. When the line terminal X1 or X2 of the signal surge protector (2) is connected and a prescribed surge current (or Voltage), if the light-emitting diode (5) still lights up normally, it verifies that the signal surge protector (2) has lightning surge protection capability and can protect the back-end equipment from being damaged by lightning; if the light-emitting diode (5) is not lit, it means that the A and B ends of the chip 74LS00 (3) have been damaged by breakdown, and the level states of the A and B ends are consistent. At this time, the Y end is at a low level, and the light-emitting diode (5) is not lit, which verifies that the signal surge protector (5) cannot achieve the surge protection effect, resulting in damage to the back-end protected device chip 74LS00 (3). The role of the inductor (6-1) and the inductor (6-2) in the test circuit is to prevent the impact current or impact voltage from rushing to the battery (4-2) during the test, thereby ensuring that the battery (4-2) can provide high and low levels for the chip 74LS00 (3) normally.

[0014] Determined through testing:

[0015] (1) The inductance of inductor (6-1) and inductor (6-2) is 50uH~1mH, and the rated current is ≥0.5A;

[0016] (2) The voltage of battery (4-1) and battery (4-2) is 3V~5V.

Claims

1. A test circuit for verifying the lightning protection capability of a signal surge protector, comprising: A lightning surge generator (1) and a signal surge protector (2), characterized in that they also include a chip 74LS00 (3), a first battery (4-1), a second battery (4-2), a light emitting diode (5), a first inductor (6-1), and a second inductor (6-2); the positive electrode of the second battery (4-2) is connected to a line terminal X1 of the signal surge protector (2) through the first inductor (6-1), and the negative electrode of the second battery (4-2) is connected to a line terminal X2 of the signal surge protector (2) through the second inductor (6-2); the signal surge protector (2 ) are connected to the A terminal and B terminal of the chip 74LS00 (3) respectively; the VCC terminal of the chip 74LS00 (3) is connected to the positive electrode of the first battery (4-1); the positive electrode and the negative electrode of the light-emitting diode (5) are connected to the Y terminal and the GND terminal of the chip 74LS00 (3) respectively; the negative electrode of the second battery (4-2), the ground terminal of the signal surge protector (2), the negative electrode of the light-emitting diode (5), the GND terminal of the chip 74LS00 (3), and the negative electrode of the first battery (4-1) are connected to the grounding point PE respectively.

2. A test circuit for verifying the lightning protection capability of a signal surge protector according to claim 1, characterized in that: Applicable to verify two-port signal surge protector that protects 2 or more signal lines.

3. A test circuit for verifying the lightning protection capability of a signal surge protector according to claim 1, characterized in that: The inductance of the first inductor (6-1) and the second inductor (6-2) ranges from 50uH to 1mH, and the rated current is ≥0.5A.

4. A test circuit for verifying the lightning protection capability of a signal surge protector according to claim 1, characterized in that: The voltage range of the first battery (4-1) and the second battery (4-2) is 3-5V.

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