Isolation application method for surge testing of shielded communication lines

Abstract

An isolation application method for surge testing of shielded communication lines, in which signals are transmitted between a device under test and a monitoring device through an isolation communication module using optical fiber as a communication medium. The isolation application method for surge testing of shielded communication lines has the advantages of isolating high voltage, preventing electromagnetic interference, and resisting lightning strikes, thereby improving the reliability and safety of communication. The present invention uses optical fiber as a communication medium, thereby effectively isolating high voltage, electromagnetic interference, and resisting lightning strikes, protecting the monitoring device, thereby providing the possibility for the monitoring device to monitor the device under test throughout the process. In addition, the present invention uses optical fiber, thereby having the advantage of long-distance signal transmission.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic compatibility testing of electronic and electrical products, and in particular to an isolation application method for surge testing of shielded communication lines. Background Art

[0002] Relay protection, distribution network automation terminals, instruments, communication management machines, online monitoring, smart terminals and other devices containing Ethernet or serial communication products need to be connected to auxiliary devices for real-time monitoring during surge testing.

[0003] For Ethernet port devices, the existing method generally uses an Ethernet cable to directly connect or connect to a monitoring device (such as the manufacturer's own computer background monitoring software or auxiliary monitoring device) through a switch for communication; for serial port devices, the existing technical method generally uses a shielded twisted pair cable to connect a bidirectional data converter (USB to RS-485 / 422) and a monitoring device (a background monitoring computer for communication or a shielded twisted pair cable to connect an auxiliary downstream device or an auxiliary monitoring device).

[0004] When testing the shielded cable of the communication port, the product under test is insulated from the ground, and the surge is directly applied to its metal casing. If the device under test does not have a metal casing, the surge is directly applied to the shielded cable on the device under test side, and the terminal of the communication port, that is, the auxiliary equipment end, is reliably grounded. Except for the communication port, all ports connected to the device under test are isolated from the ground by a safety isolation transformer or a suitable coupling and decoupling network. Although the auxiliary equipment connected to the communication port is reliably grounded, the auxiliary equipment is easily damaged due to the huge energy of high-level surge interference. Existing technology In the national standard "GB / T17626.5-2019 Electromagnetic Compatibility Test and Measurement Technology Surge (Impact) Immunity Test", for double-ended grounded shielded cables specified by the manufacturer to be greater than 10m, the length L is preferably 20m, and a surge signal generator with a source impedance of 2Ω and an 18μF capacitor is used, such as Figure 1 The test configuration is used for interference testing. This method does not further isolate the monitoring equipment and is therefore more destructive to the monitoring equipment.

[0005] Although the existing technology can meet the requirements of lower-level surge immunity tests and achieve normal connection between the device under test and auxiliary equipment, for higher levels, in order to ensure that the device under test and auxiliary equipment are not damaged by surge pulse shock, the test results can only be verified by retesting after the test, which cannot guarantee the authenticity, rigor and effectiveness of the test results.

[0006] The specific reasons for the above shortcomings are: 1. Products and auxiliary devices from different manufacturers are directly connected or connected through switches via Ethernet networks. The outer shells and casings of the various Ethernet ports of the switch are connected, which cannot effectively isolate surge interference. Moreover, most auxiliary devices are portable computers or bare communication boards without surge protectors, which are at great risk of damage during surge interference. 2. During the research and development and testing stages, most manufacturers' products operate in an environment without electromagnetic compatibility interference, especially without considering the demand for surge interference during testing. Therefore, the auxiliary devices selected during surge interference have very weak anti-interference capabilities. 3. For a long time, there have been bottlenecks in the physical interface and transmission medium technology of shielded communication lines under surge immunity conditions, and no effective breakthroughs have been achieved. 4. The reliability and security of communications under surge immunity conditions have not been effectively solved.

[0007] Therefore, in view of the shortcomings of the prior art, it is necessary to provide an isolation application method for surge testing of shielded communication lines to solve the shortcomings of the prior art. Summary of the invention

[0008] The purpose of the present invention is to avoid the shortcomings of the prior art and provide an isolation application method for shielded communication line surge testing. The isolation application method for shielded communication line surge testing has the advantages of isolating high voltage, preventing electromagnetic interference, and resisting lightning strikes, thereby improving the reliability and safety of communication.

[0009] The above-mentioned purpose of the present invention is achieved by the following technical measures:

[0010] Provided is an isolation application method for surge testing of a shielded communication line, in which signal transmission is performed between a device under test and a monitoring device through an isolation communication module using optical fiber as a communication medium.

[0011] Preferably, the above-mentioned isolation communication module converts the electrical signal of the device under test into an optical signal, transmits the optical signal through an optical fiber, and then converts the optical signal into an electrical signal and sends it to the monitoring device.

[0012] Preferably, the above-mentioned isolation communication module is provided with a pair of connection ports and a pair of photoelectric conversion communication modules, and the pair of connection ports are correspondingly defined as a first connection port and a second connection port, and the pair of photoelectric conversion communication modules are correspondingly defined as a first photoelectric conversion communication module and a second photoelectric conversion communication module.

[0013] Preferably, the above-mentioned first connection port is signal-connected to the device under test, the first connection port is connected to the first photoelectric conversion communication module, the first photoelectric conversion communication module is signal-connected to the second photoelectric conversion communication module via optical fiber, the second photoelectric conversion communication module is signal-connected to the second connection port, and the second connection port is signal-connected to the monitoring equipment.

[0014] Preferably, the above-mentioned isolation communication module supports at least one of the IEC61850-MMS communication protocol, the IEC60870-5-101 communication protocol, the IEC60870-104 communication protocol or the Modbus communication protocol.

[0015] Preferably, the connection port is at least one of an RJ45 Ethernet port or an RS485 serial port.

[0016] Each of the photoelectric conversion communication modules is provided with a TX interface and an RX interface. The TX interface of the first photoelectric conversion communication module and the RX interface of the second photoelectric conversion communication module communicate and transmit via optical fiber. The RX interface of the first photoelectric conversion communication module and the TX interface of the second photoelectric conversion communication module communicate and transmit via optical fiber.

[0017] Preferably, the first connection port transmits signals to the device under test via a double-ended shielded Ethernet cable or an RS485 communication cable.

[0018] Preferably, the second connection port is connected to the monitoring device signal via a network cable.

[0019] The device under test is connected to a surge tester or a surge signal generator.

[0020] Preferably, the above-mentioned monitoring device is a computer or a switch.

[0021] Preferably, the above-mentioned connection port is protected against lightning.

[0022] Preferably, the model of the above-mentioned photoelectric conversion communication module is NS577RS232 / 485 / 422 serial port fiber optic converter or 10 / 100Base-TX to 100Base-FX Fast Ethernet Converter HTB-1100Full / halfDuplex.

[0023] The present invention discloses an isolation application method for surge testing of a shielded communication line, in which a signal is transmitted between a device under test and a monitoring device through an isolation communication module using an optical fiber as a communication medium. The isolation application method for surge testing of a shielded communication line has the advantages of isolating high voltage, preventing electromagnetic interference, and resisting lightning strikes, thereby improving the reliability and safety of communication. The present invention uses optical fiber as a communication medium, thereby effectively isolating high voltage, electromagnetic interference, and resisting lightning strikes, protecting the monitoring device, thereby providing the monitoring device with the possibility of full monitoring of the device under test. Moreover, the present invention uses optical fiber, thereby having the advantage of long-distance signal transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention is further described with reference to the accompanying drawings, but the contents in the accompanying drawings do not constitute any limitation to the present invention.

[0025] Figure 1 This is a test configuration diagram for shielded cables in the surge immunity standard of the prior art.

[0026] Figure 2 It is a connection schematic diagram of the isolation application method of the present invention.

[0027] Figure 3 The following is a diagram of the test configuration for shielded cables in the surge immunity standard for comparison.

[0028] Figure 4 This is a connection diagram of the isolation application method of Example 2.

[0029] exist Figures 1 to 4 Including:

[0030] Device under test 100,

[0031] Isolation communication module 200, connection port 210, photoelectric conversion communication module 220,

[0032] Monitoring equipment 300,

[0033] Network Analyzer 400,

[0034] Surge Tester / Surge Signal Generator 500. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described in conjunction with the following embodiments.

[0036] Example 1.

[0037] An isolation application method for surge testing of shielded communication lines, such as Figure 2 As shown, signal transmission is performed between the device under test 100 and the monitoring equipment 300 via an isolated communication module 200 using optical fiber as a communication medium.

[0038] The isolated communication module 200 converts the electrical signal of the device under test 100 into an optical signal, transmits the optical signal through an optical fiber, and then converts the optical signal into an electrical signal and sends it to the monitoring device 300 .

[0039] It should be noted that the isolated communication module 200 of the present invention realizes the back-to-back conversion of electrical signals to optical signals and optical signals to electrical signals. The communication medium in the intermediate link is replaced by optical fiber instead of cable, thereby isolating surge interference and being free from surge interference. At the same time, the fidelity transmission of communication signals can be realized. Because the optical fiber medium has the advantage of unlimited extension, the transmission distance of optical signals is long.

[0040] The isolation communication module 200 is provided with a pair of connection ports 210 and a pair of photoelectric conversion communication modules 220, the pair of connection ports 210 are correspondingly defined as a first connection port 210 and a second connection port 210, and the pair of photoelectric conversion communication modules 220 are correspondingly defined as a first photoelectric conversion communication module 220 and a second photoelectric conversion communication module 220. The first connection port 210 is connected to the device under test 100 by signal, the first connection port 210 is connected to the first photoelectric conversion communication module 220, the first photoelectric conversion communication module 220 is connected to the second photoelectric conversion communication module 220 by signal through an optical fiber, the second photoelectric conversion communication module 220 is connected to the second connection port 210 by signal, and the second connection port 210 is connected to the monitoring device 300 by signal.

[0041] It should be noted that the connection port 210 of the present invention and the optoelectronic conversion communication module 220 perform conversion between optical signals and electrical signals through an optoelectronic conversion circuit, and this optoelectronic conversion circuit is a conventional technology. Those skilled in the art can select a specific optoelectronic conversion circuit according to actual conditions, which will not be described one by one here.

[0042] The isolated communication module 200 supports at least one of the IEC61850-MMS communication protocol, the IEC60870-5-101 communication protocol, the IEC60870-104 communication protocol or the Modbus communication protocol. The connection port 210 is at least one of the RJ45 Ethernet port or the RS485 serial port.

[0043] It should be noted that for products with communication functions such as relay protection, distribution network automation terminals, measurement and control equipment, and measuring instruments, four communication protocols are generally supported in the station control layer communication, namely, IEC61850-MMS communication protocol, IEC60870-5-101 communication protocol, IEC60870-104 communication protocol, and Modbus communication protocol. When the communication protocol of the present invention is IEC61850-MMS, the connection port 210 adopts an RJ45 interface; when it is IEC60870-101 / 104, the connection port 210 adopts an RS485 serial port or an RJ45 interface; when it is Modbus, the connection port 210 adopts an RS485 serial port interface.

[0044] The isolated communication module 200 of the present invention communicates with the device under test through the RJ45 Ethernet interface or the RS485 serial port through the above four communication protocols, and performs communication connection according to the requirements for monitoring the device under test during the electromagnetic compatibility test, thereby evaluating whether the function of the device under test 100 during the communication port test caused by surge interference is normal.

[0045] When the connector 210 is an RJ45 interface, it can support automatic identification of parallel lines and cross lines, thereby improving the versatility of the isolated communication module 200. The connector 210 of the present invention has high conversion efficiency, stable performance, realizes automatic identification of multiple physical interfaces, and reduces the workload of wiring debugging.

[0046] When the connection port 210 includes an RJ45 Ethernet interface and an RS485 serial port, the isolation application method of the present invention adopts a variety of communication protocols, and the communication protocols can be adaptively converted, thereby realizing transparent transmission of communication data. Moreover, the matching connection port 210 of the present invention is plug-and-play and supports hot plugging, thereby realizing full-duplex / half-duplex automatic conversion communication. When changing the test layout or test site, there is no need to perform secondary settings on the isolation communication module 200, thereby improving test efficiency.

[0047] Each photoelectric conversion communication module 220 is provided with a TX interface and an RX interface. The TX interface of the first photoelectric conversion communication module 220 and the RX interface of the second photoelectric conversion communication module 220 communicate and transmit via optical fiber, and the RX interface of the first photoelectric conversion communication module 220 and the TX interface of the second photoelectric conversion communication module 220 communicate and transmit via optical fiber. The model of the photoelectric conversion communication module 220 of the present invention is NS577RS232 / 485 / 422 serial port optical fiber converter or 10 / 100Base-TX to 100Base-FX Fast Ethernet Converter HTB-1100Full / half Duplex. The photoelectric conversion communication module 220 of this embodiment is specifically NS577 RS232 / 485 / 422 serial port optical fiber converter.

[0048] The first connection port 210 transmits signals to the device under test 100 via a double-ended shielded Ethernet cable or an RS485 communication cable; the second connection port 210 is signal-connected to the monitoring device 300 via a network cable.

[0049] The device under test 100 is connected to a surge tester 500 or a surge signal generator 500. The monitoring device 300 is a computer or a switch.

[0050] It should be noted that the monitoring device of the present invention is used to monitor the operation of the device under test 100 and read the data in the device under test. In addition, the surge tester 500 or the surge signal generator 500 is used to apply an interference signal to the device under test 100.

[0051] The connection port 210 of the present invention is protected against lightning. The specific lightning protection may be grounding or other lightning protection measures. The present invention provides lightning protection for the connection port 210, thereby better isolating surge interference.

[0052] The isolation application method for surge testing of shielded communication lines has the advantages of isolating high voltage, preventing electromagnetic interference, and resisting lightning strikes, thereby improving the reliability and safety of communication. The present invention uses optical fiber as a communication medium, thereby effectively isolating high voltage, electromagnetic interference and resisting lightning strikes, protecting the monitoring device 300, thereby providing the possibility for the monitoring device 300 to monitor the device under test 100 throughout the process. Moreover, the present invention uses optical fiber, thereby having the advantage of long-distance signal transmission. The isolation communication module 200 of the present invention is only provided with a pair of connection ports 210 and a pair of photoelectric conversion communication modules 220, so that it is small in size and convenient and flexible to use. The isolation application method of the present invention also breaks through the traditional dielectric communication and realizes the electrical isolation of communication transmission.

[0053] Comparative example 1.

[0054] When performing a surge test on an Ethernet switch, the communication interface is an RJ45 Ethernet interface, and the communication protocol is IEC61850. According to the national standard "GB / T 14598.26-2015 Measuring relays and protection devices Part 26: Electromagnetic compatibility requirements", the device under test and the monitoring device 300 (also called an auxiliary device, specifically another switch) are connected according to the existing technology, such as Figure 3 .

[0055] exist Figure 3 In the test, the network analyzer 400 sends a data packet to the device under test via the optical fiber channel. The device under test transmits the received data packet to the monitoring device via the Ethernet line. The monitoring device 300 transmits the data packet back to the network analyzer 400 via the optical fiber channel for comparison, and finds the packet loss during the monitoring data transmission process. When the Ethernet port of the device under test 100 is subjected to a surge test, the communication is interrupted. After inspection, the Ethernet port of the monitoring device 300 is damaged.

[0056] In this comparative example, the conduction path of the surge interference is the generator output terminal (not shown in the figure) → the metal shell of the device under test → the shielding layer of the Ethernet cable → the metal shell of the monitoring device 300 → the ground. When the surge pulse current flows through the shielding layer of the Ethernet cable, due to the mutual inductance coupling between the shielding layer and the core wire, a higher transient pulse voltage is induced on the core wire of the Ethernet cable, resulting in damage to the Ethernet port of the monitoring device 300. Example 2.

[0057] Based on an isolation application method for surge testing of shielded communication lines as in Example 1, when a surge test is performed on an Ethernet switch, the communication interface is an RJ45 Ethernet interface, the communication protocol is IEC 61850, and the national standard "GB / T 14598.26-2015 Measuring relays and protection devices Part 26: Electromagnetic compatibility requirements" is followed.

[0058] The connection port 210 of this embodiment is an RJ45 Ethernet interface, and the communication protocol is IEC61850. At the same time, the data packet of the monitoring device 300 is transmitted back to the network analyzer 400 via the optical fiber channel for comparison. Figure 4 shown.

[0059] After optical medium isolation, this embodiment reliably protects the monitoring device 300 and successfully completes the surge interference test.

[0060] Example 4.

[0061] Based on the application of an isolation application method for surge testing of a shielded communication line in Example 1 in a three-remote feeder terminal device, the three-remote feeder terminal device has data measurement functions such as three-phase current, three-phase voltage, frequency, and power.

[0062] The connection port 210 of this embodiment is an RS485 serial port interface, and the communication protocol is the MODBUS protocol. According to the national standard "DL / T 721-2013 Distribution Automation Remote Terminal", when conducting a serial port communication test during surge interference, it is required to monitor the three-phase current, three-phase voltage, frequency, power and other data through the monitoring device 300, specifically the computer background software during the test.

[0063] This embodiment realizes the whole process monitoring of the device under test 100 during the test, and no re-inspection after the test is required.

[0064] Example 5.

[0065] Based on the application of an isolation application method for surge testing of a shielded communication line in Example 1 in an integrated measurement and control communication unit, the integrated measurement and control communication unit has data measurement functions such as three-phase current, three-phase voltage, frequency, power, and has remote control, remote signaling and other functions.

[0066] The connection port 210 of this embodiment is an RS485 serial port interface and an RJ45 Ethernet port, and the communication protocols are IEC60870-101 and IEC60870-104. According to the national standard "GB / T13729-2019 Telecontrol Terminal Equipment", when conducting serial port communication and Ethernet port communication tests during surge interference, it is required to use the monitoring device 300, specifically the computer background software, to monitor the three-phase current, three-phase voltage, frequency, power and other data during the test, and monitor the telesignal displacement information.

[0067] This embodiment realizes the whole process monitoring of the device under test 100 during the test, and no re-inspection after the test is required.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. An isolation application method for surge testing of shielded communication lines, characterized in that: Signal transmission is performed between the device under test and the monitoring equipment through an isolated communication module using optical fiber as a communication medium; The isolated communication module converts the electrical signal of the device under test into an optical signal, transmits the optical signal through an optical fiber, and then converts the optical signal into an electrical signal and sends it to the monitoring device; The isolation communication module is provided with a pair of connection ports and a pair of photoelectric conversion communication modules, the pair of connection ports are correspondingly defined as a first connection port and a second connection port, and the pair of photoelectric conversion communication modules are correspondingly defined as a first photoelectric conversion communication module and a second photoelectric conversion communication module. The first connection port is connected to the device under test by signal, the first connection port is connected to the first photoelectric conversion communication module, the first photoelectric conversion communication module is connected to the second photoelectric conversion communication module by signal through an optical fiber, the second photoelectric conversion communication module is connected to the second connection port by signal, and the second connection port is connected to the monitoring device by signal; The device under test is connected to a surge tester or a surge signal generator; The monitoring device is a computer or a switch; The isolated communication module supports at least one of the IEC61850-MMS communication protocol, the IEC60870-5-101 communication protocol, the IEC60870-104 communication protocol or the Modbus communication protocol; The connection port is at least one of an RJ45 Ethernet port or an RS485 serial port; Each of the photoelectric conversion communication modules is provided with a TX interface and an RX interface, the TX interface of the first photoelectric conversion communication module and the RX interface of the second photoelectric conversion communication module are communicated and transmitted via optical fiber, and the RX interface of the first photoelectric conversion communication module and the TX interface of the second photoelectric conversion communication module are communicated and transmitted via optical fiber; The first connection port transmits signals to the device under test via a double-ended shielded Ethernet cable or an RS485 communication cable; The second connection port is connected to the monitoring device signal via a network cable; The model of the photoelectric conversion communication module is NS577 RS232 / 485 / 422 serial port optical fiber converter or 10 / 100Base-TXto 100Base-FX Fast Ethernet Converter HTB-1100Full / half Duplex.

2. The isolation application method for surge testing of shielded communication lines according to claim 1, characterized in that: The connection port is protected against lightning.

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