Transposing scheme

A Verdrillschema is a scheme by which they are twisting of overhead lines by Verdrillmasten. In order to ensure a uniform coating of the capacitive operated with three-phase alternating current overhead line, each of the three conductors must hang in a place of the overhead line once. This yields depending on the cable type, the so-called α -, β - or γ - twists.

α - twist

In single-circuit three-phase lines twisting occurs at 1/3 and 2/3 of the line length ( α1 ). Since this leads to a different sequence of the phases are often used with the α2 scheme is divided in two at the 1/3-Verdrillung 1/6 and the phase sequence of the beginning and end of the line is the same.

β - twist

With two-circuit AC lines twisting take place twists when both lines are operated asynchronously, with a circuit at 1/3 and 2/3 of the line length and the other circuit at 1/ 9, 2/9, 3/9, 4/9, 5/ 9, 6 /9, 7/9 and 8/ 9 of the length of cable.

γ - twisting

In dual-circuit three-phase lines carried the twists, if both lines are operated synchronously, also at 1/ 3 and 2 /3 of the line length, the machining direction is always opposite to each other ( γ1 twist ). If the phase sequence to be equal again, a third of the twist is divided and the pipe according to the pattern 1/6, 1/3, 1/3, 1/6 of twisted ( twist γ2 ).

Special

Since in multi-circuit AC lines often caused by mutual interference between the circuits imbalance is greater than that caused by the structure of the cable, there are also twists do not match the Verdrillschema, wherein for three-phase cables it is not rare that the twisting point, the twisting takes place only between two phases.

Example

Verdrillschema of 1929 completed high-voltage line Hoheneck - Herbertingen (length: 123.5 km ). By 1964, this line carried two 220 kV three-phase circuits, since 1964, this line is a 380-kV/220-kV-Leitung. Originally, there were eight Verdrillstellen, since both circuits have operated asynchronously, today there are only two.

Swell

• Template: Internet resource / maintenance / access date not in ISO format Prof. Oswald: Lecture Electrical Power Systems I. University of Hannover, 2005, pp. 55ff, accessed on 29 December 2008 (PDF).

• Overhead line technology