What is the use of hardware protection for 4G industrial routers?

13-04-2021

1. Anti-surge protection

The encyclopedic explanation of    surge is that this thing is also called surge, surge, which refers to the peak value that exceeds the stable value instantaneously, including surge voltage and surge current.


Source of surge: Surge is usually caused by natural lightning and power system (inductive load) switching. The generation of surge will bring huge energy transient overvoltage or overcurrent, such as inductive lightning on RS485 serial transmission line The transient interference caused by the above energy can instantly burn all the devices on the connected transmission line.


   There are two withstand voltage indicators for surge protection: common mode and differential mode.


  ● Common mode: surges generated by natural lightning or high current switching;


  ● Differential mode: The current generated by the poor insulation between the data cable and the high-voltage line when the high-voltage line near the data cable passes.


   Although the voltage and current of the differential mode are much smaller than that of the common mode, the duration of the differential mode surge is longer, usually in the data communication network for a longer time.


   There are two reasons for the surge in the power supply system:


  ● External cause: lightning strike (caused voltage is microsecond level);


  ● Internal reasons: electrical equipment start or stop or malfunction (causing voltage is milliseconds);


   Surge is characterized by a very short time. Although the voltage time of a lightning strike is very short, the instantaneous voltage and current are extremely large, which causes a high probability of harm to electrical equipment. Therefore, the surge protection of 4G industrial routers is used to limit over-voltage and discharge surge current, and industrial routers can avoid short-circuit problems under high voltage, lightning strikes and other environments.


  2, anti-static protection (ESD: Electrostatic Discharge)

The generation of static electricity is usually man-made. For example, during equipment production, assembly, testing, storage, and the process, static electricity may accumulate in the equipment or instrument. In the process of handling and friction, the discharge path is formed by the contact of charged objects. . Because the instantaneous voltage of static electricity can reach several thousand volts, this damage is called the main culprit of excessive electrical stress damage caused by electronic components or integrated circuit systems, and it is also the number one problem in IC design. This is why you must wear static protective clothing, protective bracelets and other equipment in the power workshop, computer room, and factory assembly line near the electrical equipment.


  The cause of static electricity:


  ● Contact separation and electrification: static electricity generated by the separation of two objects of different materials after contact;


  ● Frictional electrification: A process of unbalanced positive and negative charges caused by contact and separation;


  ● Inductive electrification: For conductive materials, because electrons can flow on the surface, such as placing them in an electric field, they are caused by the transfer of positive and negative ions due to the repulsion of the same sex and the attraction of the opposite sex.


  ● Conductive electrification: Generated by a conductor. Electrons can move on the surface, and charge transfer occurs after contact with charged objects.


   Two mechanisms of ESD interference to the circuit:


  ● The electrostatic discharge current passes through the circuit directly, causing damage to the circuit;


  ● The electromagnetic field generated by the electrostatic discharge current causes interference to the circuit through capacitive coupling, inductive coupling or spatial radiation coupling.


The anti-static protection in the 4G industrial router is a built-in diode with forward conduction and reverse blocking. It also has the reputation of "circuit lightning rod". The above description has been very clear, that is, when static electricity accumulates to discharge, the circuit lightning rod realizes electrostatic protection. effect.


  3, watchdog protection

   Watchdog technology is a microprocessor embedded on a chip.


   When the single-chip microcomputer or microcomputer system is subject to strong interference, it can cause the program to run out of control, cause the CPU to enter an endless loop, or cause the program to run away. The use of "watchdog" technology can continuously monitor the running time of the program. Once the limited time is exceeded, the system is confirmed to be "dead" and the watchdog immediately resets the CPU to return to the normal program flow. The watchdog protection function can be realized by hardware and software.


   If you want to know more about watchdog knowledge, click to view: How does watchdog protection work?


Watchdog protection of 4G industrial routers


  4, anti-reverse power supply

   Anti-reverse power connection, this is basic physics knowledge. Connect the positive and negative poles of the power supply in reverse to cause damage to the circuit. In order to prevent operation errors, it is generally protected against reverse connection of the power supply.


  Power supply anti-reverse connection protection method


  ● Anti-reverse diode connection: The diode is used for protection, the circuit is simple, the cost is low, and the space is small. However, when the PN junction of the diode is turned on, there is a voltage drop of <= 0.7V, which causes unnecessary loss to the circuit. For example, for battery-powered systems, circuits with larger currents will have a more obvious impact. (In the circuit, power consumption and heat generation are not negligible problems).


  ● Fuse protection: Fuse protection is also common in daily life, such as the fuse of electric lights. When the power supply is reversed and there is a short circuit in the circuit, the fuse is blown out due to the large current, which plays a role in protecting the circuit, but this method is more troublesome to repair and replace.


● MOS tube protection: due to factors such as process improvement and its own nature, the conduction resistance of MOS tubes is mostly milliohms or even smaller. This will cause extremely small losses to the voltage drop and power consumption of the circuit, even It can be ignored, so choosing a MOS tube to protect the circuit is a more recommended way.


  ● NMOS protection: When it is positively connected, the circuit provides VGS voltage, and MOS is saturated and turned on. When reverse connection, MOS cannot be turned on, so it plays a role in preventing reverse connection.


  5, sheet metal shell

  The sheet metal material has the characteristics of light weight, high strength, conductivity and electromagnetic shielding. Therefore, it is often used in industries such as electronic devices and industrial power.


  What are the protective features of the sheet metal shell:


  ● Excellent resistance to both high and low temperatures


  ● It is almost impermeable to many common industrial chemicals, such as alcohol and solvents


  ● When used with high-performance rubber gaskets, it provides excellent protection against splashes and direct water ingress into the hose


  ● High resistance to impact from tools and machinery


  ● Durable


  6, rail installation

   To be precise, guide rail installation is not considered protection, the main advantage is convenience.


  ● Easy to install and easy to replace. The slide rail has high straightness, and the installation screw hole error is small;


  ● Significantly reduce drive power consumption and reduce friction;


  ● High working accuracy, reduce shock and vibration, and realize smooth movement;


  ●Because the two ends of the slider are equipped with sealing covers, the bottom is selected with a sealing film, which has strong dust-proof and sealing ability;


  ● The sliding block of the linear guide is equipped with an oil injection hole, which can be directly injected and lubricated, and the lubrication structure is simple.


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