Lightning protection device applicable to RS-485 transmission line

Abstract

The invention discloses a lightning protection device applicable to an RS-485 transmission line. A primary lightning protection circuit is realized by a GDT (gas discharging tube); a first inductor L1 and a first thermistor PPTC1 in a secondary lightning protection circuit are connected in series and are then connected onto an A connecting wire of an RS-485 bus; a second inductor L2 and a second thermistor PPTC2 are connected in series and are then connected onto a B connecting wire of the RS-485 bus; a first transient suppression diode TVS1 in a tertiary lightning protection circuit is in span connection between the A wiring end and the B wiring end of the RS-485 bus; a second transient suppression diode TVS2 and a third transient suppression diode TVS3 are connected in series and are then in span connection between the A wiring end and the B wiring end of the RS-485 bus. The lightning protection device has the advantages that in the lightning attack protection process, lightning protection devices per se are complete and are not damaged; high anti-electromagnetic interference capability is realized; in addition, the sufficient fast response speed is realized on the lightning attack.

Description

technical field [0001] The invention belongs to the technical field of lightning protection, and in particular relates to a lightning protection device suitable for RS-485 transmission lines. Background technique [0002] Systems such as smart meters have been widely used in the fields of industry and life. Automatic meter reading technology is used in the electricity meter to read the data through the communication port, and in most cases, the remote reading method is used, which is safe and saves time and money for the electricity meter application. The key to realizing this technology is to ensure that the communication lines are safe and reliable. Because the RS-485 circuit has the advantages of long-distance transmission, high signal noise suppression, convenient control, and low cost, it makes multi-point connection possible. Therefore, RS-485 has become a standard communication interface for smart meters. However, RS-485 transmission lines are usually exposed outdoo...

AI Technical Summary

Problems solved by technology

However, RS-485 transmission lines are usually exposed outdoors, so it is very easy to introduce overvoltage due to lightning strikes and other reasons

The working voltage of the RS-485 transceiver is relatively low, generally around 5V, and its withstand voltage is also very low, between -7V and +12V. Once overvoltage is introduced, it will break down and be damaged; when there is a strong surge When the energy appears, you can even see the transceiver burst and the circuit board burnt

[0003] The State Intellectual Property Office of the People's Republic of China has disclosed a lightning protection device for communication lines, the publication number is: CN203707770U, and the publication date is: 2014.07.09. The first-level lightning protection circuit is realized by TED485 lightning protection tube, and the second-level lightning protection circuit is realized by TVS lightning protection tube. Among them, FL is TED485 lightning protection tube, and TS is TVS lightning protection tube. The connection relationship is: TED485 lightning protection tube FL1, The positive poles of TED485 anti-detonator FL2, TVS anti-detonator TS1 and TVS anti-detonator TS3 are connected and grounded, and the negative poles of TED485 anti-detonator FL1, TVS anti-detonator TS1 and the positive pole of TVS anti-detonator TS2 are connected to the 485A terminal , TVS detonator TS2, TVS detonator TS3 and TED485 detonator FL2’s negative poles are connected to 485B terminal; this patent adopts parallel connection to RS-485 bus, only need to connect the lightning protection module to RS-485 It only needs to be connected to the terminal, which does not affect the communication and load-carrying capabilities of the centralized meter reading terminal, and ensures the safe and stable operation of the terminal in the thunderstorm season. However, the response speed of this patent needs to be improved

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