With the rapid development of science and technology and the economy in our country, as well as the continuous increase in social electricity consumption, we have put forward increasingly higher requirements for the quality, continuity and reliability of power supply. In order to ensure and improve the safe and reliable operation of the power grid, power supply enterprises must give top priority to the safety and reliability of power supply.
With the development of urban distribution networks, more and more urban distribution networks adopt the ring network power supply mode. Therefore, as the main equipment for ring network power supply, high and low voltage switchgear is increasingly widely used by power supply departments. Especially the 10kV outdoor universal box ring network, which adopts a fully sealed structure with gold insulation, can adapt to any harsh outdoor environment. It is small in size, light in structure, compact in design, easy to install, simple to operate, stable in operation and maintenance-free. It can not only meet the economic requirements of reducing the urban area, but also lower the overall cost, and is widely welcomed by the power supply department.
However, there are still some problems in the use of ring network high-voltage switchgear.
1. Due to the complex installation and manufacturing process of the elbow cable terminal head, the construction personnel are not familiar with the construction technology of the prefabricated cable accessories. The construction quality of the hanger-type connector does not meet the standards, and the installation and manufacturing are improper, which can easily lead to engineering quality problems and equipment failures.
2. If the connection rings between the main units and the cable terminals do not have good contact between the wires, the connection will be heated, which will cause damage to the elbow-shaped cable terminal head. At the same time, the main unit of the bushing ring will be damaged, which is very likely to leave hidden dangers until an accident occurs.
3. The grounding switch is installed on the inlet and outlet side of the ring-shaped main unit. Because the switch is off, it is impossible to check the power of the circuit. It is prone to cause misoperation accidents of the live closing grounding switch, resulting in equipment damage and power interruption.
4. Multiple cables are connected to a circular main unit (or at intervals), which is inconvenient for operation and maintenance. Meanwhile, the construction of the ring main unit and the cables is rather difficult. When dealing with faults in the main unit of the common box-type ring, the cables cross each other. To ensure personal safety, it is necessary to cut off the power supply of the entire common box-type ring main unit. Moreover, when handling cables, it is essential to use a method that may cause damage to the cable sheath or poor contact.
5. The seal between the annular main unit and the cable trench is not tight. The moist air in the cable trench is prone to enter the ring-shaped main unit. Further condensation water can cause the operating mechanism to rust and get stuck. Meanwhile, due to the entry of moist air into the ring-shaped main unit, the cabinet body is prone to corrosion and rust, thereby reducing the service life of the ring-shaped main unit.
6. Cable faults are very difficult to detect. With the continuous development of the economy, considerations of environmental factors, such as spider web elevated lines, are increasingly hindering the development of modern cities. Urban construction requires the use of high-voltage cables and underground laying. Electricity is transmitted through underground cables, and the distribution equipment is in harmony with the surrounding environment. At the same time, it also exposes the difficulties in locating short-circuit faults and grounding points.
The resolution of these problems will be able to enhance the reliability of power supply and provide a strong guarantee for accelerating the development of social and economic construction