Ground is in the electrical system or electronic equipment, connected to the earth, connected to the shell or connected to the reference potential of zero wire. General electrical appliances, ground wire connected to the shell, in order to prevent electrical appliances due to the destruction of internal insulation shell charged and caused by electric shock accidents.
Preventing people from using home appliances and office and other electronic equipment in the event of an electric shock and take the protective grounding, is a security grounding guard. Safety grounding generally includes lightning protection and electromagnetic radiation protection
Expanded Information:
Working Ground
Working ground is a metallic conductor, copper, buried in the soil. Buried in the soil, and then a bit of it with a wire out of the ground, with which to complete the circuit so that the equipment to achieve the performance requirements of the grounding line. Ground wire requires grounding resistance ≤ 4 Ω. Such as the 1960s and 1970s, rural households use a radio ground wire, and in the ground to be frequently wet with water.
Safety grounding
Electricity regulations stipulate that the protective grounding resistance should be ≤ 4 Ω, and the human body's resistance is generally greater than 2000 Ω, according to Ohm's law, insulation damage through the human body's current is only 1/500 of the total current, which in turn plays a protective role. Household appliances and office equipment are equipped with a metal shell grounding wire, such as its insulation damage shell charged, then the current along the installation of the grounding wire into the earth, to achieve the purpose of safety, otherwise it will cause harm to personal safety.
Lightning strike grounding to prevent in the thunderstorm season, tall buildings, various types of communication systems, as well as a variety of antennae erected on the building and some other facilities were struck by lightning, need to install lightning rods, and then lead to the installation of the lightning strike with a wire to the grounding system.
In addition, there are electromagnetic radiation grounding. In some important departments in order to prevent electromagnetic interference, the electronic equipment installed shielding network, the installation of the shielding network should be connected to the corresponding grounding system, and requires grounding resistance ≤ 4Ω.
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