Transposition (telecommunications)

Transposition is the periodic swapping of positions of the conductors of a transmission line, in order to reduce crosstalk and otherwise improve transmission. In telecommunications this applies to balanced pairs whilst in power transmission lines three conductors are periodically transposed. Transposition is the periodic swapping of positions of the conductors of a transmission line, in order to reduce crosstalk and otherwise improve transmission. In telecommunications this applies to balanced pairs whilst in power transmission lines three conductors are periodically transposed. For cables, the swapping is gradual and continuous; that is the two or three conductors are twisted around each other. For communication cables this is called twisted pair. For overhead power lines or open pair communication lines, the conductors are exchanged at pylons, for example at transposition towers or at utility poles, respectively. The mutual influence of electrical conductors is reduced by transposition. Transposition also equalizes their impedance relative to ground, thus avoiding one-sided loads in three-phase electric power systems. Transposing is an effective measure for the reduction of inductively linked normal mode interferences.