Grounding equipment in box-type substation
Jun 24, 2022
In order to improve the safety in operation, grounding lines will be installed in different internal devices to reduce internal leakage and electric shock devices. Several common grounding devices and their functions are described below.
1. Lightning protection grounding:
In order to quickly introduce lightning into the earth, it is the grounding for the purpose of preventing lightning damage.
If the lightning protection device is used with the working grounding of electrical equipment in a general grounding grid, the grounding resistance should meet the minimum requirements.
2. AC work grounding:
A certain point in the power system is connected to the earth directly or through special equipment.
Working grounding mainly refers to the grounding of the neutral point of the transformer or the neutral line (N line). The N wire must be insulated with copper core. There are auxiliary equipotential terminals in the power distribution, and the equipotential terminals are generally in the cabinet. It must be noted that this terminal cannot be exposed. It cannot be mixed with other grounding systems, such as DC grounding, shielding grounding, and anti-static grounding. It also cannot be connected with PE line.
3. Safety grounding:
Safety grounding is to make a good metal connection between the non-charged metal parts of electrical equipment and the grounding body. The electrical equipment in the building and some metal components near the equipment are connected with PE lines, but it is strictly forbidden to connect the PE line with the N line.
4. DC grounding:
In order to make each electronic device have good accuracy and high stability, in addition to a stable power supply, it must also have a stable reference potential. The insulated copper core wire with a larger cross-sectional area can be used as the lead wire, one end is directly connected to the reference potential, and the other end is used for DC grounding of the electronic equipment.
5. Shield grounding and anti-static grounding:
The grounding to prevent the interference of the static electricity generated by the dry environment of the computer room in the intelligent building to the electronic equipment is called anti-static grounding. In order to prevent the interference of external electromagnetic fields, the grounding of the outer casing of the electronic equipment and the shielded wires inside and outside the equipment or the metal pipes that pass through it is called shielding grounding.
6. Power grounding system:
In electronic equipment, AC and DC filters are installed to prevent interference voltages of various frequencies from intruding through AC and DC power lines and affecting the operation of low-level signals. The grounding of the filter is called power grounding.
