Why is spiraling in transmission lines effective?

Electrically by spiraling the transmission lines is similar to winding a coil to some extent actually alters the reactance of the line. Providing better impedance matching like a balun thus minimizes the presence of standing waves along the length of the transmission lines.

ACSR is one of the most used conductors in transmission lines. It consists of alternate layers of stranded conductors, spiraled in opposite directions to hold the strands together, surrounding a core of steel strands. The purpose of introducing a steel core inside the stranded aluminum conductors is to obtain a high strength-to-weight ratio. A stranded conductor offers more flexibility and easier to manufacture than a solid large conductor. However, the total resistance is increased because the outside strands are larger than the inside strands on account of the spiraling. The resistance of each wound conductor at any layer, per unit length, is based on its total length as follows:

Loss in transmission line for low power factor
1. With low power factor we need higher rating transmission line. Plus as current transmission associated with joule loss. The more current means more joule loss. As also the reactive current travel from source to load and load end to source end too.

2. Unbalanced voltage. To maintain the voltage we need minimum amount of reactive power. But too much reactive power will make over voltage situation.

Loss in consumer side due to low power factor
1. High rating switchgear-With low power factor we will have to deal with high apparent power. Thus the switchgear like transformer, wiring, circuit breaker and other components will be of higher ratings.

2. High energy bill- The energy bill calculated on the basis of apparent power. With low power factor the apparent power is high with same active power. Thus consumer has to pay high energy bill.