ČEPS has implemented an internal technical standard known as the “Preventative Maintenance Code for Electrical Installations within the Transmission System” which is a basic regulation concerning the inspection and maintenance of installations and equipment within the ČEPS transmission system.
The following maintenance cycles are specified in the Code: a walking inspection once a year, a tower leaning inspection once a year or, in undermined areas, twice a year, a protection zone inspection focusing on the height of vegetation once a year, an aerial inspection every three years, a 5-yearly preventative visual above-ground inspection or a 6-monthly such inspection in undermined areas, a 10-yearly detailed visual above-ground inspection or a 3-yearly such inspection in undermined areas, an extraordinary visual above-ground inspection following extensive repair work, routine maintenance based on inspection results, 10-yearly earthing measurement, 4-yearly repeated earthing measurement, and an aerial thermo-visual inspection conducted one year after construction and followed by 6-yearly inspections. A UV diagnostics system for the detection of corona sources is currently in the preparation stage.
Additional maintenance work is also carried out, primarily protection zone maintenance which comprises the pruning of vegetation in order to maintain a vegetation height of below 3 metres as required by law, the application of protective paint to protect towers against corrosion, and a number of other smaller repairs and the replacement of line elements.
Construction of new power lines
The construction of new lines is governed by legal regulations concerned with the preparation and execution of line construction projects. All the relevant rules covering construction by the Company, including environmental impact assessments (EIA), are meticulously followed. This also applies to new lines built alongside existing lines. A balance between conserving the natural environment and landscape and the most feasible or most technically and economically advantageous solution for the Company and its customers is always sought when preparing a new power line project.
Construction execution
Towers or their individual segments are assembled on-site and then erected using either the gradual extension method, i.e. stage-by-stage assembly, or the tilting method, when a completely pre-assembled tower is erected by crane. In inaccessible areas, helicopters are used to erect towers. Insulators are installed on towers using simple but ingenious and highly reliable hoists.
Conductors (phase and ground wires) are transported to the site on reels (drums) each with an average weight of 3 tonnes and strung on the towers using special stringing machines (pullers and tensioners).
The time of construction of a line section, from excavation of tower foundation holes to site reclamation after construction completion, is typically no more than 3 months depending on the route section within which the power line is built and the particular region. Except for the tower construction itself, no heavy building machinery or other equipment for which special access roads have to be constructed is required. No plant depots or temporary stores for materials need be built on or near the line construction site; the construction schedule is designed to fully take into account the natural growing cycle and local farmland use.
Brochure: Construction of power lines for download.
Video of formation the substation Kletné for download.