Power Transmission Towers
Transmission towers, also known as an electricity pylons are designed, produced and implemented for transmission from one point to another. They are designed based on the required voltage, its application, available space, weather and atmospheric conditions of the region, etc. The Transmission Towers are tall structures often made of iron and used in high voltage lines to transmit electrical energy and in alternating current and direct current systems. It has many variations in shape (grid-telescopic) and many sizes, and its length varies from 15 to 55 meters.
Height of power transmission towers
The height of the masts are different from each other, and many factors must be considered to determine the height of the masts, such as: span distance (horizontal distances between two consecutive towers are called span power transmission lines), wind speed and angle, ice thickness in that area, the diameter of the conductors, their location and…
But it should be kept in mind that the distance between the masts is a phase that determines the size of the branches, arms and insulators, and there is no need to say that the more the phase is, the height and weight will increase, and as a result, the price of the transmission line will increase.
Connections of power transmission towers
- Bolts are used in 99% of connections.
- Anchor bolts are used for telescopic masts and equipment bases and gantry.
- Calculating the length of bolts and nuts suitable for connections is calculated as follows:
- The total thickness of the number of parts that are connected to each other + 25 mm
The masts are divided into the following groups based on the voltage level:
33KV / 66KV / 132KV / 230KV / 400KV
The employer chooses one of the types of masts based on his needs and assigns tasks to the consultant to follow up the construction, and then the consultant cooperates with the contractor until the completion of the work for production.
The cross arm (cantilever) is used to keep wires and insulators on the mast. The construction of appropriate types of cantilever and crossarm depends on factors such as weather conditions, the type and type of conductor used, and economic issues in construction and operation. Keeping the electrical privacy of the conductors from each other is the purpose of installing the arm or cross arm in addition to keeping the conductors and insulators on the beam. Points such as simplicity of implementation, cost of construction and maintenance, use of the least screws and connections, ease of work by operators, observing the distance between conductors, maintaining symmetry on the beam, etc. should be considered in the design and construction of the cantilever and crossarm.
Cross Arms are designed in two types of needle and book. The book type withstands and distributes more pressure, for this reason book-needle or single book crossarms are used in tension masts, but basically needle-shaped crossarms are used in hanging masts. The figure below shows both book/needle-shaped crossarms.
Lattice towers are the most common type of transmission towers, consisting of steel frames that form a triangular or square shape. They are strong, flexible, and easy to assemble and transport. Lattice towers can support multiple circuits and span long distances, making them suitable for most terrains and weather conditions. However, they also have some drawbacks, such as high maintenance costs, visual impact, and susceptibility to corrosion and bird collisions.
Tubular towers are made of hollow steel tubes that are welded or bolted together. They are more compact, aesthetic, and resistant to corrosion than lattice towers, but they are also more expensive, heavier, and harder to transport and install. Tubular towers can support single or double circuits and are often used in urban areas, where space is limited and visual appeal is important. They can also be designed to have different shapes, such as monopoles, H-frames, or delta configurations.
Types of transmission towers
Single, Double, Multiple, Circuits, Covering Voltages From 33KV to 765KV