The ground wire is also called the ground wire or lightning arrester. It is divided into working ground and safety ground. The popular explanation is that it is a wire that introduces current into the earth. It can reduce the voltage to zero volts. It is a form of electrical protection that can ensure the safety of personnel and equipment. Article 3 of my country's current standard GB2681 stipulates that phase A is yellow, phase B is green, phase C is red, and the neutral line is light blue. The ground wire is yellow and green, and its symbol is E (Earth).
In the power system, the grounding wire is an important tool to ensure the safety of workers when power outage equipment and lines are accidentally overvoltage; according to regulations, the grounding wire is made of bare copper soft wire with a size of more than 25mm2.
Electrical equipment: The grounding wire is the lead-out line for unsafe charges or leakage currents connected to the outer shell of electrical equipment and other parts.
When testing the power cable fault during the flashover test, failure to connect the ground wire or connecting the wrong ground wire may cause equipment damage or even personal injury accidents.
This is also the case in people's daily lives. For example, if the metal shell of a household rice cooker is grounded, when a single-phase grounding fault occurs, both the RCD (residual current device) and the main switch can trip for protection; if there is no grounding, when a single-phase grounding fault occurs, neither the RCD (residual current device) nor the main switch will trip for protection, and personal injury accidents may occur.
Whether it is the grounding of household appliances or electrical test projects including cable fault detection tests, special attention should be paid to the grounding wire problem. Once vigilance is relaxed, accidents may occur.
Different grounding types and circuits with different functions have different grounding methods. Common grounding methods in power equipment include safety grounding, lightning protection grounding, working grounding, signal, analog grounding, digital grounding, and power grounding.
Cable fault detection generally uses safe grounding, that is, the high-voltage equipment casing is connected to the ground. It has two functions. One is to prevent the accumulation of charge in the casing, generate electrostatic discharge, and endanger the safety of equipment and personnel; the other is that when the insulation of the equipment is damaged, the casing is energized and the power must be cut off immediately for protection.
Therefore, before involving electrical test projects, the grounding wire should be checked (whether the soft copper wire is broken, whether the screw joint is loose, and whether the hook elasticity is normal, etc.). Secondly, the grounding wire should be tested before hanging, and the grounding wire should not be in contact with the body when hanging; in addition, it is necessary to pay attention to the selection of grounding wires of corresponding specifications for different voltage levels. Under normal circumstances, the grounding wire should be taken care of (do not twist it during use, coil the soft copper wire when not in use, and place it neatly after disassembly), and pay attention to the cleaning of the grounding wire.
(RCD is the English abbreviation for residual current device)
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