Hybrid mast
Left: Kornwestheim-Neckarwestheim line with 220 kV three-phase current (two upper levels) and 110 kV traction current (bundle of four lower level).
Right: Line to Neckarrems with 380 kV three-phase current (both upper levels) and 110 kV traction current (lower level).
A hybrid mast is an overhead line mast that carries circuits for different types of electricity. In principle, a three-phase current line and a traction current line, a high-voltage direct current transmission line (HVDC line) and a three-phase current line as well as an HVDC line and a traction current line can be run in parallel . However, only the first case is of practical interest, since until today (2011) no routes of traction power lines and HVDC lines have been implemented and there are only two very short parallel routes of three-phase and direct current lines, namely from the HVDC Volgograd-Donbass area of the terminal at the Volgograd hydropower plant and the HVDC Konti-Skan shortly before the Stenkullen converter station. ( Coordinates )
As a rule, a hybrid mast carries two circuits for traction current and two for three-phase current , with the lowest crossbeam being reserved for the traction current circuits on one level and the top crossbeams for the three-phase circuits . The three-phase circuits can also be arranged in a one- level arrangement or in a three- level arrangement ( fir tree mast , barrel mast ). In order not to excessively increase the tower height and the mast width, usually the arrangement of the three-phase circuits are like a two-level pylon .
In Switzerland there are also hybrid masts with three traverses, with a three-phase system on one half of the mast and two circuits for traction current on the other.
If the traction current line is routed on the same masts parallel to a three-phase current line with an operating voltage of more than 220 kV , the insulation of the traction current line should usually be rated for 220 kV because overvoltages can occur in the event of damage to the 380 kV line along the traction current line can overwhelm the 110 kV isolators of conventional railway power lines.
In Germany, hybrid masts usually have two names: a number of the energy supply company to which the three-phase circuits belong and a number of Deutsche Bahn.
