The difference between lightning protection grounding and electrical grounding

The difference between lightning protection grounding and electrical grounding
1. Protective grounding refers to connecting the metal part of the electrical device that is not charged under normal conditions with the grounding device to prevent the part from being charged suddenly under fault conditions and causing harm to the human body.

2. Working grounding is to ground the neutral point of the transformer. Its main function is the stability of the system potential.

3. Lightning protection grounding and electrical grounding can be connected together. However, the lightning protection down-conductor and the protection down-conductor cannot be connected together on the ground and then connected to the grounding electrode, because when lightning strikes, the lightning current enters the ground through the lightning protection down-conductor, and it will also be shunted to the equipment by the PE line. In addition, people will be struck by lightning if they touch it.

4. The down-conductor of the protective grounding of the PE line should be connected to the grounding electrode separately. The farther the distance between the down-conductor of the PE line and the lightning-proof down-conductor, the better. It requires more than 10m. After the lightning current enters the ground along the lightning-proof down-conductor , Let the lightning current flow into the ground, it will not spread from the down conductor of the PE line to the equipment shell.

What is the difference between lightning protection grounding and general electrical equipment grounding
For lightning protection and grounding of general equipment, the grounding resistance is required to be less than 4 ohms. For lightning protection grounding of power plants and substations, the resistance of the grounding grid is required to be less than 0.5 ohms.

It is generally required to use 40×4 mm flat iron for lightning protection grounding, and it is required to check the grounding resistance and grounding condition before the thunderstorm season every year.

Other groundings are not so strictly regulated.

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