First of all, we first "electromagnetic compatibility" is about the meaning of the terms were clear.
EMC This term can be applied to all aspects of the electronic system. In the circuit level, device level, system level can be applied. Most hardware engineers concerned about electromagnetic compatibility of this term, or from their research and development of electronic devices must be compatible with the start of the test by electromagnetic. In China, the electromagnetic compatibility requirements as a mandatory certification program has, therefore, to master the EMC knowledge has become a hardware engineer unavoidable requirements. Therefore, this course is to set an example to explain this level of equipment.
An electronic device having good electromagnetic compatibility, comprising the two meanings.
First, the system of the electronic device, the electronic device or configuration capable of reliable operation at a predetermined electromagnetic environment.
Second: between the electronic device or system, no adverse effect.
First, we look at a system and the environment did not meet electromagnetic compatibility example of state.
Right it occurred in 2011 in the high-speed rail rear-end accidents. As the lights error, leading to two high-speed train rear-end collision occurred, causing serious casualties. One explanation about the cause of the accident is that the lightning interferes with the signal control system, causing the system sends the wrong signal.
If this is the cause due to lightning, which is a typical electromagnetic compatibility malfunction. Because lightning is a common natural phenomenon, any electronic system must consider the environment in which to work reliably.
Lightning is essentially instantaneous air breakdown discharge. As the air breakdown is conductive, it sent a bright glow, which is what we see lightning phenomenon. Since the current discharge process of this large, it can be up to 200,000 amps, huge currents generated tremendous heat, heated air expands after that we heard thunder.
This phenomenon can only occur between two clouds fast, it can also occur between clouds and the earth. When two clouds with different charge polarity, when the electric field strength between them sufficient insulation breakdown of air therebetween, lightning occurs between clouds, people sometimes called "Trick" . When this phenomenon occurs between the clouds and the ground, as shown on the left, people called "touch mines."
Traditionally, we pay special attention to touch mines. Because of this direct lightning cause harm to buildings and personnel. It was found that the earth conductor projections are more susceptible to lightning strikes, so the invention is of the "lightning rod." As a lightning rod, actually "triggered lightning needle", in order to prevent the occurrence of lightning strikes on important buildings, people install a higher metal objects next to important buildings, attract lightning.
In fact, the thunder and lightning process is accompanied by strong electromagnetic radiation, the electromagnetic wave will affect the normal operation of electronic circuits. Traditional electronic system lightning protection design, are to protect the system during lightning storms do not occur for the purpose of hardware damage. Modern mine design, not just hardware damage, also requires data signals without error. Electromagnetic compatibility test is an important project called "surge test", it is to simulate electromagnetic disturbance generated by lightning. The CS116 GJB151 simulated lightning effects mainly generated on the cable.