A, equipment grounding resistance requirements standard 4-10 ohms, the highest can not be greater than 10 ohms, 4 ohms better;
1, specifically for the prevention of electrostatic hazards of the grounding system, the grounding resistance value is not greater than 100MΩ. But if the grounding system with the other grounding *** with the grounding system, then *** with the grounding system grounding resistance should be Meet the requirements of the minimum value of each grounding.
2, computer and other rooms generally use grounded conductive floor. When it is below 1MΩ with the earth, it can prevent electrostatic hazards.
3, in the room where electrostatic hazards may occur, the staff should wear conductive shoes, and should make the conductive shoes and the conductive floor between the resistance of the conductive floor to stay below 0.01 ~ 1MΩ.
4, in order to prevent static hazards, in some special places, the staff should not wear silk or certain synthetic fibers, and should wear a grounding ring on the wrist to ensure grounding.
Second, the shell grounding requirements:
1, the shell of the fully enclosed combination of appliances should be grounded in accordance with the provisions of the manufacturer; flange pieces should be connected by jumper cables, and to ensure good electrical access.
2, high-pressure power distribution room partition static compensation device fence door hinges, should be connected by soft copper wire to maintain good grounding.
3, high-frequency induction heating device shielding network, filters, power supply device metal shielding shell, high-frequency circuit of exposed conductors and electrical equipment, and all the shielding part of the electrical equipment and its connection to the metal piping should be grounded, and it is appropriate to connect with the grounding trunk.
4, the grounding device consists of more than one part of the grounding device, should be set according to the design requirements to facilitate the separation of the disconnection card. Natural grounding and artificial ground connection should be easy to separate the disconnect card. Disconnect card should be protected.
Expanded information:
When the cable passes through the zero-sequence current transformer, the ground wire of the cable head should be passed through the zero sequence current transformer and then grounded; from the cable head to the section of the cable through the zero sequence current transformer metal sheath and grounding wire should be insulated to ground.
Directly grounded or grounded through the arcing coil transformer, rotating motor neutral point and grounding body or grounding trunk connection, should be used to separate grounding wire. The lightning arrester of the substation and distribution house shall be connected to the main earthing network by the shortest earthing wire.
The metal casing or base of mobile machinery supplied with power from fixed power sources or mobile power generating equipment shall have a metallic connection to the earthing device of these power sources; in power grids where the neutral point is not earthed, an earthing device may be fitted in the vicinity of the small mobile machinery in lieu of the laying of an earthing wire, and a natural earthing body in the vicinity shall be utilized first.
All tanks with a volume greater than 50m3 and a diameter greater than 2.5m, the grounding point should be no less than two. And should be evenly distributed along the periphery of the equipment, its spacing should not be 30m. when the resistance of the lubricant is greater than 1MΩ, the rotating part of the incidental must be grounded, otherwise contact brushes or conductive lubricants should be used.
Mobile conductive capacitor or apparatus may produce electrostatic hazards should be grounded. When the use of the conductive floor, conductive workbench and other grounding objects connected to the method can not ensure that it is reliably grounded, must be used flexible copper wire will be directly grounded. The use of tools to operate or overhaul such equipment, tools should also be reliably grounded.
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