TOWER TYPES AND STRENGTH CAPACITY
Tower types
Basic purpose:
The order of towers corresponds to the tower weight order and their implementation from lighter conditions towards the heavier load on the transmission line route.
Tension towers for transmission lines, besides their main purpose to decrease the load, angle-tension, end-tower and towers with tap-offs, can also be used as suspension ones (in case larger medium spans and/or higher towers are required).
Nominal height: 9 m, 11 m, 13 m, 15 m – all towers (tower NAH2 up to 13 m for standard use) 17 m, 19 m and 21 m – additional height for tension towers
Nominal heights are specific for all tower types, and they should be used when placing orders. The actual height from bottom to top, according to the manufacturing documentation is equal to nominal height with tolerance between - 0.5 m and + 0.25 m, depending on the tower type and height. It is indicated on the sketch of each tower, above the nominal height indicated in brackets. Tower height from the connection point on the tower top to the ground is equal to the real height of the structure, according to the sketch of the tower + height of the foundation. Overall standard increase of height from the foundations amounts to 30 cm and can be increased for certain tower locations if necessary.
To reduce the costs of solving property issues when constructing transmission lines, additional tower heights were designed. They make possible to use towers with longer spans and to reduce the number of towers in the transmission line route.
Tower strength capacity - nominal tower load
The strength capacity of each single tower is conditioned by the basic implementation i.e. load conditions for which the tower is designed for, and are defined by the nominal load and allowed torque with the resulting sum of horizontal forces. Nominal load corresponds to the maximum force on the top of the tower, that tower main legs can support for certain load according to the mentioned Regulation for Overhead Power-lines. Values stated for loads caused by wind relate to payload.
The strength capacity of each tower is controlled by testing the structure prototype used for its basic purpose, and this is certified by the adequate attest.