Welding Joint Inspection,Waterproof Camera Detection,Video Pipeline InspectionThe Pipe Inspection Camera is usually for pipes diameter from 23mm-200mm according to different camera .
Main application : automobile making,Petroleum, chemical field and other industrial pipe field.
Portable Inspection Camera Portable Video Camera,Portable Inspection Camera,Casting Inspection Camera,Small Pipe Inspection ZHENGZHOU JIUTAI TECHNOLOGY CO.,LTD , https://www.jiutaiendoscope.com
The grounding line in the power system is an important tool to ensure the staff when unexpected voltages occur on the power-off equipment and lines. According to ministerial regulations, the grounding wire must be made of bare copper wire of 25mm2 or more.
Introduction:
In the electric field, the grounding line is a line that leads to unsafe electric charges or leakage currents that are generated due to various reasons in a timely manner in the parts of the electric equipment housing.
The role of high-voltage grounding line: high-voltage grounding line is used for the line and substation construction, in order to prevent the adjacent charged body from generating electrostatic induction or electric shock or when closing the gate to ensure safety.
High-voltage grounding wire structure: The portable high-voltage grounding wire consists of insulated operating rod, wire clamp, short-circuit wire, grounding wire, grounding terminal, bus clamp, and grounding clamp.
High-voltage grounding wire production process: excellent production process, wire clamp, grounding clamp is made of high-quality aluminum alloy die-casting; operating rod using epoxy color tube, good insulation properties, high strength, light weight, bright colors, smooth appearance; grounding soft The copper wire is made of stranded high-quality soft copper wire and covered with a soft, high-temperature transparent insulation covering, which can prevent the wear of the grounding copper wire in use. The copper wire meets the fatigue test requirements to ensure that the operators are Operational safety.
Ground wire specifications: According to the regulations, the ground wire must be made of bare copper wire of 25mm2 or more.
The basic composition of the grounding method:
The components of the grounding method can be divided into two parts: electrical equipment and distribution system.
1. Grounding part of electrical equipment (1) Grounding body: One or a group of conductors that are in close contact with the earth and form an electrical connection with the earth.
(2) Exposed conductive parts: Conductive parts that are accessible to electrical equipment. Normally it is not energized, and it may be energized in case of fault. It is usually the metal casing of the electrical equipment.
(3) Main Ground Terminal Block: A combination of various grounding (such as work grounding, protective earthing) terminals and equipotential bonding wire terminals in a building or part of a building. If arranged in rows, it is called the main grounding terminal strip.
(4)Protection line (PE): Conductor that electrically connects any part of the exposed conductive part, the main grounding terminal board, the grounding body, and the power supply grounding point (or artificial grounding point). Double conductors that connect multiple exposed conductive parts are called protection trunks.
(5) Grounding wire: Connect the main grounding terminal board or the exposed conductive part directly to the protective wire of the grounding body. The grounding wire connecting multiple grounding terminal boards is called grounding mains.
(6) Equipotential bonding: An electrical connection in which the potentials of the exposed conductive parts and the conductive parts of the device are substantially equal.
2. The grounding part of the power distribution system (1) Phase (L): Conductor for the transmission of electrical energy, which is not grounded under normal circumstances.
(2) Neutral (N): A conductor connected to the neutral point of the system and capable of acting as a power source.
(3) Protected neutral (PEN): A conductor that acts both as a protective conductor and as a neutral conductor.
(4) Power grounding point: Ground the power supply to a point (usually a neutral point).
Grounding classification:
China's distribution system grounding method has been used IEC regulations, the classification is still based on the distribution system and electrical equipment grounding combination points, generally divided into TN, TT, IT systems. The meaning of the above letters indicates that the first letter represents the relationship between the power supply ground point and the ground. Where T stands for direct grounding; I stands for ungrounded or grounded through impedance. The second letter indicates the exposed electrically conductive portion of the electrical device in relation to ground. Where T represents a separate direct ground connection with no connection to the power supply ground point; N denotes a direct connection to the ground point of the power supply system or conductors leading to it.
According to whether the neutral line and the protection line are combined, the TN system is further divided into TN-C, TN-S, and TN-C-S systems. TN-C system: The protection line and the neutral line are combined into the PEN line. TN-S system: The protection line is separated from the neutral line. TN-C-S system: In the near side of the power supply side, the protection line and the neutral line are combined into the PEN line. After a certain point, it is divided into the protection line and the neutral line.
Resistance requirements:
The high-voltage short-circuit grounding resistance to ground requires the quality of the grounding wire. Generally, according to the DL-T879-2004 technical regulations of the power industry, the grounding resistance of each cross-sectional area does not exceed the following values:
Measure the DC resistance between the wiring nose. For various sections of 16mm2, 25mm2, 35mm2, 50mm2, 70mm2, 95mm2, 120mm2, the average resistance per meter should be less than 1.24mΩ, 0.79mΩ, 0.56mΩ, 0.40mΩ, 0.28mΩ, respectively. 0.21mΩ, 0.16mΩ.
Classification of High-Voltage Grounding Lines (1) High-voltage grounding lines can be divided into: indoor bus-type grounding lines (JDX-NL) and outdoor line-type grounding lines (JDX-WS) according to the use environment. (2) The high-voltage grounding line can be divided into 10KV grounding line, 35KV high-voltage grounding line, 110KV grounding line, 220KV high-voltage grounding line, and 500KV high-voltage grounding line according to the voltage level. Technical parameters:
(1) 10KV high voltage grounding wire insulation rod part length: 700mm Handshake part length: 300mm Metal fitting part length: 50mm Number of sections: 1 Rod diameter: 30mm Total length (excluding clamps): 1050mm
(2) 35KV ground wire Nominal section: 25mm2 Total number of roots: 810 Average diameter (mm): 0.2mm Calculated section: (mm2): 25.43 Length of metal joint part: 50mm Number of sections: 1 Rod diameter: 30mm
(3) 110KV high-voltage grounding conductor Nominal cross-section: 35mm2 Total number of roots: 1136 Average diameter (mm): 0.2mm Calculated cross-section: (mm2): 35.67 Insulation rod section length: 1360mm Handshake section length: 700mm Metal joint section length: 140mm Number of Sections: 2 Rod Size: 30mm Total Length (Excluding Clips): 2200mm
Instructions for use:
(1) When connecting the grounding wire: Connect the grounding clamp first and then connect the clamp; when removing the grounding wire, you must disconnect the clamp first according to the procedure and then remove the grounding clamp.
(2) Installation: Attach the grounding wire to the eyelet of the eye with copper eyes fixed on the grounding rod (with fixed and movable clamps). It is fixed on the ground clamp or ground pin to form a complete set of grounding wire.
(3) Verify that the voltage level of the grounding rod is the same as the voltage level of the operating equipment.
(4) The grounding soft copper wire has the split-phase and combined type, and the grounding rod has the flat mouth type and the double reed hook clamp.
Use maintenance:
Before using the portable short-circuit grounding wire, check the power before confirming that the power has been cut off and confirming that there is no voltage on the equipment. Connect the grounding clamp to the grounding net or flat iron first, and then use the grounding operating rod to tighten the wire end to the device wire. When removing a shorted ground wire, the sequence is exactly the opposite of the above.
The short-circuit grounding wire installed, and the distance between it and the charged equipment, taking into account the influence of the ground pendulum, the safety distance should not be less than the value specified in the new "Regulations on power safety work".
It is forbidden to use a winding method to make a short circuit to ground without using a clamp.
If the suspension point has a grounding point, use a grounding clamp or a dedicated copper rod for grounding connection; if no fixed grounding point is available, use a temporary grounding point. The depth of the grounding electrode buried in the ground should not be less than 0.6 m.
The portable short-circuit ground wire should be properly kept. Before every use, you should check whether it is in good condition. The soft copper wire is not exposed and the nuts are not loose. Otherwise, they must not be used.
The inspection period of the portable short-circuit grounding line is once every five years, and the inspection item is the same as the factory inspection. After passing the test, the qualified short-circuiting grounding wire should be judged according to the magnitude of the short-circuit current and the visual inspection after being subjected to the short circuit, and should generally be scrapped.
Precautions:
1. The ground wire must be checked before working. Whether the soft copper wire is broken or not, whether the screw connection is loose or not, and whether the elastic force of the wire hook is normal, and if it does not meet the requirements, it should be replaced or repaired before use.
2.Before hanging the grounding wire, it is necessary to inspect the electricity first. The untested grounding wire is the more common habitual violation in the grassroots. When the grounding wire is suspended, it cannot contact with the body.
3. Suspend the grounding wire at both ends of the work site to prevent users from being able to reverse power transmission or inductive power. There are many examples of injuries.
4. When you hit the grounding pile, you must dial the physical ability to quickly clear the accident large current and ensure the grounding quality.
5. Take care of the grounding wire. The grounding wire must not be twisted during use. When not in use, the soft copper wire should be properly grounded. After the grounding wire is dismantled, it must not be dropped from the air or thrown anywhere. It must be transmitted by ropes and attention should be paid to the cleanliness of the grounding wire.
6. The new staff must be trained and learned about the use of the grounding wire. After passing the assessment, they can only perform the grounding line operation or use.
7. According to different voltage levels select the corresponding specifications of the ground wire.
8. It is forbidden to use other metal wires instead of ground wires.
9. Do not hang the ground wire or change the location of the ground wire without authorization.
10. The grounding wire is double-sided. It has a safe function. If it is used improperly, it will also have a damaging effect. Therefore, the grounding wire must be removed in time after the work is completed. Switching with a grounding wire can damage the electrical equipment and damage the stability of the power grid, which can lead to serious and vicious electrical accidents.
A grounding wire is a wire directly connected to the earth. It can also be called a safety circuit wire. When it is dangerous, it passes the high voltage directly to the earth and is considered a lifeline.