Transmission line tower material
The main raw materials used in the tower manufacturing industry are steel sections, including angle steel, steel plate, flat steel, round steel, steel pipe, channel steel, etc. The materials of section steel are generally Q235 (ordinary carbon structural steel), Q345 (low alloy high-strength steel), 35, 45 steel, etc. However, with the implementation of UHV transmission line project, Q390, Q420, Q460 and other high-strength steel will gradually be widely used.
Type of transmission line tower
1、 Classification according to material properties
The tower is divided into reinforced concrete pole, steel pipe pole, angle steel tower and steel pipe tower according to its manufacturing materials.
(1) reinforced concrete pole
Reinforced concrete poles include ordinary reinforced concrete poles and prestressed concrete poles. The cross-section of the pole is square, octagonal, I-shaped, annular or some other special-shaped cross-sections. The most commonly used are annular and square sections. The length of the pole is generally 4.5-15m. There are two kinds of circular poles: conical pole and equal diameter pole. The tip diameter of conical pole is generally 100-230 mm, and the taper is 1:75; The diameter of the equal diameter rod is 300-550 mm; Both of which have a wall thickness of 30-60 mm.
(2) steel pipe pole
The main pole of the steel pipe pole is a pole of the transmission steel pipe structure composed of one or more steel pipe members. Steel pipe pole is widely used in urban high-voltage overhead lines due to its small footprint, beautiful appearance, simple structure, easy processing, convenient construction, safe and reliable operation and less maintenance work compared with conventional angle steel towers.
3 angle steel tower
Angle steel tower is a lattice iron tower structure composed of components made of angle steel profiles. The angle steel tower has the advantages of high strength and convenient manufacturing.
(4) steel pipe tower
The steel pipe tower is a lattice iron tower structure composed of steel pipe members for the main material and steel pipes or round steel and section steel members for the inclined material.
Composite head tower of transmission line crossing tower constructed of concrete
2、 Classified according to its mechanical properties
According to the force classification of the tower in the transmission and distribution line, it is generally divided into suspension type tower and tension type tower.
(1) suspension type tower
Suspension type tower is a tower that supports the gravity of conductor and overhead ground wire and the wind force acting on them, but does not bear the line tension during construction and normal operation. The conductor and overhead ground wire shall not be disconnected at the suspension type tower and shall be positioned in the straight line section between the conductor and overhead ground wire. The function of suspension type pole and tower is only the support structure of suspension conductor and overhead ground wire in the line. Suspension type tower is divided into suspension type straight line tower and suspension type angle tower.
(2) tension type tower
In addition to supporting the gravity and wind force of the conductor and overhead ground wire, the tension type tower also bears the tension of these lines. The conductor and overhead ground wire are disconnected at the tension type pole and tower, and are positioned in the straight line section of the conductor and overhead ground wire, which is used to reduce the length of the continuous gear along the longitudinal direction of the line, so as to facilitate the construction and maintenance of the line, and control the range of possible string collapse of the line along the longitudinal pole and tower. Tension type tower is divided into tension linear tower, tension angle tower and terminal tower.
3、 Classified by the number of circuits
The tower is divided into single circuit tower, double circuit tower and multi circuit tower according to its circuit.
1. Single circuit tower
The tower with only one circuit is called single circuit tower.
2. Double Circuit Tower
The tower with two circuits not necessarily of the same voltage and frequency installed on the same tower is called Double Circuit Tower.
3. Multi Circuit Tower
The tower with two or more y-circuits not necessarily of the same voltage and frequency installed on the same tower is called multi circuit tower.
4、 Classified by its purpose and function
According to its use and function in the transmission line, it can be divided into straight line, tension, angle, terminal, transposition, crossing tower, etc.
1. Linear pole tower
The straight line tower here is a suspension type straight line and angle tower according to the force classification, and its function is only the support structure of the suspended conductor and overhead ground wire in the line. This is also a suspension type straight line and a suspension type angle tower classified by force.
2. Tension tower
The tension tower here is the tension straight line tower classified according to the force, which not only supports the gravity and wind force of the conductor and overhead ground wire, but also bears the tension of these lines. The conductor and overhead ground wire are disconnected at the tension pole and tower, and are positioned in the straight line section of the conductor and overhead ground wire, which is used to reduce the length of the continuous gear along the longitudinal direction of the line, so as to facilitate the construction and maintenance of the line, and control the range of possible string collapse of the line along the longitudinal pole and tower. The tension pole tower here is the tension linear pole tower divided by stress.
3. Corner tower
The tension of supporting conductor and overhead ground wire will change the direction of the line to form a tower with a corner. When the conductor with angle and overhead ground wire are disconnected and directly tensioned on the tower, it is called tension angle tower; when the conductor and overhead ground wire are not disconnected, it is called suspension angle tower. The tension linear tower and the tension tower here are the tension angle tower according to the stress.
4. Terminal tower
The tower where the line starts or ends. The terminal tower is located in front of the portal frame of the power distribution device in the substation or substation. The conductor and overhead ground wire on one side of the line are directly tensioned on the terminal tower, while the other side is connected to the portal frame with a small tension. The tension tower here is the terminal tower according to the stress.
5. Transposed pole tower
A tower used to change the arrangement position of three-phase conductors in a line. When the conductor is not disconnected on the transposition tower, it is called the straight transposition tower; otherwise, it is called the tension or angle transposition tower.
6. Crossing poles and towers
Poles and towers used to support conductors and overhead ground wires crossing rivers, lakes and straits. When the conductor and overhead ground wire are not directly tensioned on the tower, it is called straight crossing the tower; when they are directly tensioned on the tower, it is called tension or angle crossing the tower. In order to meet the requirements of shipping clearance, the crossing towers are generally high. In order to reduce the bearing capacity of poles and towers, save materials and reduce the project cost, straight-line crossing poles and towers are generally used.
7. Slope pole tower
The lower conductor of the tower is arranged asymmetrically, and the conductor on the high side slope is moved to the low side slope, so as to solve the limitation on the ground distance when he is on the high side slope, thereby reducing the height of the tower, reducing the tower weight and reducing the cost.
8. T connecting pole tower
When the original line needs to supply power to another substation, the tower used for the branch point of the line is called T-connection tower. In fact, it is a combined tower of tension linear tower and terminal tower. T-connection tower may also be a combined tower of suspension linear tower and terminal tower. Generally, we classify it separately. This classification is for the convenience of everyone.
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