The grounding protection device of high and low voltage switchgear is to effectively ensure the safety of electricity. For high and low voltage switchgear equipment, safety measures must be taken to prevent electric shock. Only in this way can the safety of electricity use and the personal safety of maintenance personnel be truly guaranteed. . The following editor will share with you the working principle, characteristics and use of the high and low voltage switchgear grounding protection device. I hope that the suggestions in the article can provide a feasible reference for the safety of the high and low voltage switchgear grounding protection work.
(1) The characteristics of the grounding protection device for high and low voltage switchgear
1) Shared neutral system
In our country, the current wiring system for the grounding neutral line of the high and low voltage switch generally uses the "one-way two-wire system". The one-way system uses the same wire for connection, and the two-wire system is the line used for protective grounding and the working neutral line.
When wiring, the protective grounding wire can be contacted from the working neutral wire in front of the meter, and the other end needs to be connected to the grounding neutral wire of the three-hole socket. At the same time, the neutral wire behind the watt-hour meter should be used as the working neutral wire. : In the electrical knowledge class, it should be noted that you cannot directly use the working neutral wire as a protective grounding wire. At the same time, the protective neutral wire needs to be introduced directly from the main line, not through the fuse, because if it is not directly connected from the main line, it Will increase the contact coefficient in the later stage.
2) Dedicated grounding neutral wire
Compared with the shared neutral line system, the biggest difference of the dedicated grounded neutral line protection power supply system is the "single-phase three-wire system", which needs to be based on the original working neutral line layout. Public account: Electrical Knowledge Class, in addition When adding a dedicated grounding protection neutral line, the dedicated grounding protection neutral line does not need to be installed with a special fuse, and only needs to be directly connected to the outdoor repeated grounding position.
This system can ensure that the dedicated grounding protection neutral line does not break, and the equipment leakage will directly lead the equipment protection device and then start work. The system will actively cut off the power supply, which will effectively avoid electric shock accidents.
(2) Precautions for grounding protection of high and low voltage switchgear
The high-voltage switchgear must have the necessary mechanical knowledge for the opening and closing positions of the main switch and the grounding switch. At the same time, the mechanical instructions must be clear and reliable. The high-voltage switchgear must be equipped with a specific type of high-voltage live display device.
The "Electrical Industry Safety Work Regulations" pointed out that "the signal indicating that the equipment is disconnected or allowed to enter the interval, and the voltmeter that often needs to be connected cannot be used as the basis for the no-voltage of the equipment. It is necessary to prohibit work on the equipment." This means that the high-voltage live display device is only a reminder device, so it cannot be regarded as the basis for the judgment of the equipment when there is no voltage.
The high-voltage live display device must first have a button for testing. During the operation of the high-voltage switchgear, the high-voltage live display device should be in a non-display state, which can prolong the service life of the device. Press the button for the test, the official account: Electrical Knowledge Class. At this time, the charged display indicator will light up, and then operate the main switch to open. After the switch is opened, the charged indicator light will go out. Through this process, it can be judged whether the high-voltage live display device is good. Bad.
(3) Working principle of grounding protection device for low-voltage switchgear
The low-voltage panel grounding protection device is installed on the angle iron frame below the panel body. Public number: Electrical Knowledge Class. The distance between the welding of the fixed steel plate and the panel door hinge is about 120mm. When the low-voltage panel is in normal operation, the panel door is at In the closed state, the staff on duty at the substation will place the bolts in the specified position at this time.
Grounding is required during the maintenance process. The low-voltage panel can only open the panel door after the power is cut off. After the panel door is opened, the fixed coil of the fixed ground wire is tightened with bolts through the threads.
The previous operation was that the grounding wires were installed outside the panel, public account: Electrical Knowledge Classroom, and this operation was flawed, so the current practice is to remove all the fixed ground wires in other places. The prescribed grounding wires need to be removed. Connect at the place where it was removed.
After the line maintenance is completed, if the operator makes a mistake and the grounding wire is not completely removed, after the panel door is closed, the panel door cannot be closed normally when the panel door is closed and the bolt is blocked. Remove the ground wire and then remove the bolts, then the door cannot be closed, and the next operation cannot be carried out.