Among the electrical insulators used in overhead lines, porcelain insulators still occupy 1/3 share. It often appears in the operation of the defective fault including zero value, broken string, rust, etc. Once the above problems occur will seriously affect the line safety, today to talk about the causes of the above problems and countermeasures.
Post insulator products consist of the iron cap, tempered glass parts, and steel feet, and are glued together with cement. The product all adopts the most advanced international cylindrical head structure, which is characterized by small head size. Lightweight, high strength, and large creep age distance. It can save metal materials and reduce the cost of the line. In order to meet the needs of live operation, the traditional domestic structure shape is adopted on the brim of the cap.
The typical products of suspension clamp now retain the U-bolt style (usually called ship clamp). It is composed of a hanger U-bolt, clamp hull, and pressing plate made of malleable cast iron. The other is a pre-twisted suspension clamp. The suspension clamp is used to fix the conductor on the insulator string of the linear pole and tower or hang the lightning conductor on the linear pole and tower. It can also be used to support the transposition conductor on the transposition pole and tower and fix the jumper of the tension angle pole and tower.
The Differences Between Switchgear and Distribution Cabinets are as Follows
1. The function is different: switchgear is a complete set of electrical switchgear and control equipment, it is used as a power center and the main distribution device, mainly to play the role of a switch on and off. And distribution cabinet is to plays the function of distribution of electrical energy, line overload, short circuit, leakage protection role.
What are overhead line fittings?
Overhead line fitting is an accessory that connects and combines various devices in the power system to transfer mechanical and electrical loads or to play a protective role.
Overhead line fitting is an important part applied to the “power grid”, there are very many cross nodes in the power system of power transmission and distribution. Line crossings form a network, and each line crossing point needs to be fixed. There are many substations in the grid that form the intermediate nodes of the grid, and there are many power towers that support the main lines of the grid. The transmission of electrical energy requires conductor contact to be carried out and sufficient current-carrying area to be maintained at high power levels. That is, the grid equipment and conductors such as conductors ensure good and solid contact between.
For the straight-line connection of cable lugs single-strand copper-core wires. First, cut the two wire ends to form a certain length of wire core, remove the surface oxide layer of the wire core, cross the two wire cores in an X shape, and twist each other 2 to 3 turns, Pull the straight head again.
When the general wire is connected to the terminal lugs, if it is a single-strand wire of 10mm2 and below, it needs to bend a circle at the end of the wire and connect it to the terminal. If it is a multi-strand copper wire of 4m㎡ or more, a terminal lug must be installed and then connected to the terminal.
Insulator is a special insulation control, which plays an important role in overhead transmission lines. Mainly used for the connection of wires and cables. For example, a lot of disk-shaped insulators are hung on one end of the high-voltage wire connection tower, which is to increase the creepage distance, usually made of glass or ceramic, which is the insulator.
The development of new energy in China is now on the fast track, and wind power generation accounts for a significant share of it. Many wind farms are built on the grasslands of Inner Mongolia, and the 35kV collector lines of wind farms are laid using direct burial cables to protect the grassland vegetation and the overall appearance of the grassland. From the operation situation, the cable intermediate head has the phenomenon of discharge.
Cold-shrinkable cable accessories are a kind of prefabricated cable accessories that can be constructed at room temperature without heating. The cold-shrinkable power cable accessories are made of imported liquid silicone rubber. After installation, they always maintain a proper radial pressure on the cable body. The interface characteristics are relatively good, and there will be no creepage breakdown due to cable operation. The stress control part is integrated with the main insulation, which effectively solves the problem of electric stress concentration at the outer shielding section of the cable and ensures reliable insulation. It is a very important cable accessory.
1、High Voltage Cable Termination Structure and Insulation Mdium
1.1 Overall Structure
High-voltage cable terminations can be divided into porcelain sleeve type, composite sleeve type, integral prefabricated type, GIS termination, etc. Their core structure is similar. The description here is based on the ceramic sleeve type cable termination structure as an example.
Figure 1 Typical structure of porcelain sleeve type cable termination
1—Outlet fittings, 2—Wiring post, 3—Shield cover, 4—Insulation filler, 5—Porcelain sleeve, 6—Stress cone protective cover, 7—Stress cone, 8—cone support, 9—support insulator, 10— Tailpipe