LV, MV and HV cable lines

In recent years, technological progress has significantly reduced the costs associated with the construction of cable lines. Additionally, the dynamic increase in land prices and the associated higher cost of possible purchase of land for overhead power lines made cable installations even more attractive in terms of prices. As Alterga, we carry out projects related to the construction and modernization of cable lines, from the implementation of formal and legal aspects to the launch of an investment.

What is a cable line?

Cable lines are one of the basic components of power energy systems. They are installed wherever the installation of overhead lines is difficult or impossible, e.g. in densely populated urban areas. Cable lines are usually placed underground. Very often they are carried out along roads or plot boundaries.

An important argument in favour of installing cable lines is the need for greater reliability of energy supplies. Overhead lines, because of their construction, are exposed to atmospheric factors such as wind or rime. Weather phenomena cause overhead line failures to occur up to twice as often as cable line failures.

Cable networks also take up less space and have a lower environmental impact, are more easily accepted and better perceived by society.

Main types of cable lines

Alterga carries out all investments related to the construction of transmission networks, including cable lines:

1. LV cable line – lowest voltage, which supplies electricity to individual consumers.
2. MV cable line – medium voltage with values e.g. 10, 15 or 20 kV.
3. HV cable line – high voltage, which most often has a voltage of 110 kV. Such maximum voltages are usually reached by cable lines in Poland. Cable lines with voltages of 220 or 400 kV are not often built in our country for economic and environmental reasons.

Design and build, i.e. turnkey investments

Alterga offers both turnkey investments and modernization or servicing of existing cable lines.

Our projects are related to:

1. Construction of power installations and networks. We perform works related to, for example, the construction of low voltage (LV) cable lines and the necessary internal installations.
2. Construction of medium voltage lines (MV). These are various types of projects related to the construction of medium voltage cable lines. We modernize MV transformer stations and perform direct current installations, e.g. on traction substations powered by MV cable line.
3. Construction and modernization of high voltage cable lines (HV). This involves preparing projects, laying electricity networks underground and assembling the necessary equipment, such as heads or joints. HV cable lines with a voltage of 110 kV are the most frequently built new installations in Poland.
4. Construction of cable and fibre optic telecommunications lines. These are investments related to the construction of telecommunications lines, both cable and fibre optic. Our team of engineers is capable of carrying out large investments, including telecommunications and railway industries.

Design of cable power lines

It should be noted that the design of cable lines is the initial and one of the most important stages of the construction process. As Alterga, we prepare the necessary documentation in detail. Our specialists perform the following tasks:

• determine the optimal route for laying the cable line
• prepare a diagram of the cable line route
• select cables with the required parameters
• determine the best technical solution for the construction of a given cable line
• estimate construction and installation costs
• perform an expert opinion on the design and cost estimate documentation

Key stages of cable line construction

The construction of a cable line begins with a proper design, after preparing the necessary documentation and completing all formal aspects. Directly laying cables in the ground is the most cost-effective and technically simple method of laying transmission lines. Our company performs the following tasks:

• preparation and marking out the excavation route
• digging ditches
• preparation of excavations for laying cable lines
• installation of rollers for pulling in cables and additional equipment
• cable laying
• installing and fixing the cable line according to the design
• insulation resistance control
• installation of coupling sleeves and cable terminations
• testing and commissioning

It must be emphasized that all stages of construction – from designing the cable line to its commissioning – are carried out at the highest level, in accordance with the requirements of legal regulations and standards, within the time frame agreed with the investor. With highly qualified staff, specialized machines and devices, we are ready to perform all types of construction, installation, maintenance and commissioning works.

Renovation and maintenance of cable lines

Investments related to cable lines include not only the construction of new networks, but also all service works. Maintenance or renovation of cable lines is usually necessary in case of physical use or deterioration of the network, exposure of the cables to mechanical loads or when a higher current carrying capacity is required.

Alterga offers our clients a full package of services related to the maintenance and renovation of cable lines:

1. Measure the operating parameters of cable lines before and after the renovation works.
2. Locate damaged sections of cable lines.
3. Carry out repair work on damaged sections of cable lines.
4. Check and, if necessary, replace joints and cable terminations.
5. Replace damaged sections of cable lines.

We always carry out maintenance and renovation works on cable lines in accordance with previously prepared design documentation, which is developed on the basis of test data, measurement results and an assessment of the general condition of the cable line. They are performed by an experienced and trained team of employees, while maintaining the highest safety standards.